Ryobi Zero-Turn Mower SLA to LiFePo4 Conversion - (Updated - Build Complete With Pics!)

You'd want swappable batteries or swappable mowers with one or two on the charger at the home/workshop using a large PV array / grid support as needed.

Swappable large economical battery bank. PV at home charges one bank while you carry the other in the truck to recharge smaller, more expensive batteries for tools.

The more practical, affordable, "Green" solution (although harder to explain to the Great Unwashed) is GT PV at home, recharge portable batteries in truck at night, use those batteries to recharge tool batteries on the go during the day.

A Ford Lightning or other EV with utility outlets would be ideal. But DIY battery more economical. Throw a PV panel on the roof as an advertising sign.

Greetings everyone. I hope everyone had a great holiday season.


This weekend I decided to start my conversion.

I picked up the following items to treat this as the least invasive drop-in replacement solution:


Batteries:

Ampere Time 12V 100Ah LiFePO4 Lithium Battery, 4000+ Deep Cycle Lithium Iron Phosphate Battery, Built-in 100A BMS (https://www.amazon.com/dp/B0BCKHFR26?psc=1&ref=ppx_yo2ov_dt_b_product_details)



Battery Indicator:

CAMWAY Battery Monitor 8-120V 0-500A Voltmeter Ammeter Voltage Current Meter Backlight
(https://www.amazon.com/gp/product/B088RG27LS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)



Charger:

ULTRA FAST 48V 15 AMP DAKOTA LITHIUM LIFEPO4 BATTERY CHARGER
(https://dakotalithium.com/product/4...4-battery-charger-for-lithium-iron-batteries/)

Victron Energy Blue Smart IP65 12-Volt 5 amp Battery Charger (Bluetooth)
(https://www.amazon.com/dp/B07TLCT7X7?psc=1&ref=ppx_yo2ov_dt_b_product_details)

Note that I used the Victron for individually charging my new LiFePo batteries since it came so highly recommended. However, the charger automatically installed a new firmware update which I discovered gave me some very wonky results when trying to charge in the Li-ion setting taking far longer than it should have or never entering the proper phases. I would normally have to reset my history and reconnect the plugs to get it to register. It seems like a problem with the firmware when I looked up the issue online. Use this charger with caution.

Cables:

Anderson Power Products SB50 Connector Kit, 50 Amps, Gray Housing, w/ 10 12 AWG, 6319 (1 Pair)
(https://www.amazon.com/dp/B07CHD4JCK?psc=1&ref=ppx_yo2ov_dt_b_product_details)

Drive-up EZGO RXV 48 Volt Charger Receptacle with Wire / 3-Pin Triangle Charger Plug Handle EZGO Charging Port OEM#604321 611219 602529 Golf Cart
(https://www.amazon.com/dp/B082S9BH7R?psc=1&ref=ppx_yo2ov_dt_b_product_details)

Work done:
I was able to remove my old Leoch batteries and drop in the new Ampere Time batteries. I reused all existing cabling. One observation with the four 12V 100Ah batteries is that they seem to be a bit taller than the original Leoch. Using the plastic Ryobi battery terminal cover plates it is just a bit too tall to use the long hold-down screw with the washer and lock washer installed. I was able to install the bolt without the washers. I may need to look into a longer bolt.

I validated all of my batteries were charged and balanced to about 53.3V before and after the install.

When I went to turn on the mower I heard the relay click but no power showed on the original meter. Measuring the voltage at the original charge port showed low to no voltage. I disconnected the main Anderson plug to the batteries and tested the voltage to the battery which was reading 53.3V. I feared I had somehow nuked my charger port again. I reconnected the main Anderson plug again and remeasured the voltage at the charger port. The charger read the normal 53.3V. Whew!

I then turned the mower on again, heard the relay click…again no power. Disconnecting and reconnecting the battery returned to proper voltage.

I then decided to leave the multimeter probes for measuring voltage connected to the charge port so that I could observe the voltage change when I turned the key on. When I did this…the mower came on and read 100% on the meter!

I disconnected my multimeter and was able to turn the mower on and off without issue (at least so far). I’m not exactly sure if the mulitmeter being connected was a fluke, or if it provided just enough momentary resistance that it allowed the circuits to properly turn on the electronics. I still haven’t tried mowing or other heavy loads but the lights, blades, beepers, etc…are all functioning. Maybe someone can explain what the connected multimeter in DC voltage testing mode actually did to allow the mower to turn on. Regardless, I’ll take that win!

Now I’m onto the next step of installing the new power gauge. I followed the advice of many on this forum that have used the Camway battery monitor off of Amazon. The sampler block on this monitor is enormous.

I opened up the control panel and removed the old battery indicator. This indicator has a single plug with three wires (two green and one black). There isn’t a lot of slack in the existing wiring, so I wasn’t trying to cut connectors in case I needed to hook up the original indicator. Also, there are no labels for what the different wires are used for on the original indicator.

Where I’m scratching my head a bit is how people hooked up the new Camway monitor since its instructions show cables going back to the battery. The existing wiring is also using green and black vs red and black. After some multimeter voltage testing it seems like existing wiring has the green wires as the battery pos and the black wire is hooked up to battery negative.

I guess, my first question is if anyone has a photo of how they did the wiring connections to the new camway monitor from the existing Ryboi wiring? See attached pictures.

If not:

Do I need to connect both green wires from the legacy Ryobi indicator to the new Camway or just one?

Do I just connect a single black wire from legacy Ryobi wiring to the B- connector on the Camway?

No wires will come from the P- connector on the camway?

How did folks mount/secure the Camway sensor block to their mower?


Any advice and/or pictures on how the Camway indicator was wired and secured into your conversion would be greatly appreciated.

Kavalliero said:

Greetings everyone. I hope everyone had a great holiday season.


This weekend I decided to start my conversion.

I picked up the following items to treat this as the least invasive drop-in replacement solution:


Batteries:

Ampere Time 12V 100Ah LiFePO4 Lithium Battery, 4000+ Deep Cycle Lithium Iron Phosphate Battery, Built-in 100A BMS (https://www.amazon.com/dp/B0BCKHFR26?psc=1&ref=ppx_yo2ov_dt_b_product_details)



Battery Indicator:

CAMWAY Battery Monitor 8-120V 0-500A Voltmeter Ammeter Voltage Current Meter Backlight
(https://www.amazon.com/gp/product/B088RG27LS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)



Charger:

ULTRA FAST 48V 15 AMP DAKOTA LITHIUM LIFEPO4 BATTERY CHARGER
(https://dakotalithium.com/product/4...4-battery-charger-for-lithium-iron-batteries/)

Victron Energy Blue Smart IP65 12-Volt 5 amp Battery Charger (Bluetooth)
(https://www.amazon.com/dp/B07TLCT7X7?psc=1&ref=ppx_yo2ov_dt_b_product_details)

Note that I used the Victron for individually charging my new LiFePo batteries since it came so highly recommended. However, the charger automatically installed a new firmware update which I discovered gave me some very wonky results when trying to charge in the Li-ion setting taking far longer than it should have or never entering the proper phases. I would normally have to reset my history and reconnect the plugs to get it to register. It seems like a problem with the firmware when I looked up the issue online. Use this charger with caution.

Cables:

Anderson Power Products SB50 Connector Kit, 50 Amps, Gray Housing, w/ 10 12 AWG, 6319 (1 Pair)
(https://www.amazon.com/dp/B07CHD4JCK?psc=1&ref=ppx_yo2ov_dt_b_product_details)

Drive-up EZGO RXV 48 Volt Charger Receptacle with Wire / 3-Pin Triangle Charger Plug Handle EZGO Charging Port OEM#604321 611219 602529 Golf Cart
(https://www.amazon.com/dp/B082S9BH7R?psc=1&ref=ppx_yo2ov_dt_b_product_details)

Work done:
I was able to remove my old Leoch batteries and drop in the new Ampere Time batteries. I reused all existing cabling. One observation with the four 12V 100Ah batteries is that they seem to be a bit taller than the original Leoch. Using the plastic Ryobi battery terminal cover plates it is just a bit too tall to use the long hold-down screw with the washer and lock washer installed. I was able to install the bolt without the washers. I may need to look into a longer bolt.

I validated all of my batteries were charged and balanced to about 53.3V before and after the install.

When I went to turn on the mower I heard the relay click but no power showed on the original meter. Measuring the voltage at the original charge port showed low to no voltage. I disconnected the main Anderson plug to the batteries and tested the voltage to the battery which was reading 53.3V. I feared I had somehow nuked my charger port again. I reconnected the main Anderson plug again and remeasured the voltage at the charger port. The charger read the normal 53.3V. Whew!

I then turned the mower on again, heard the relay click…again no power. Disconnecting and reconnecting the battery returned to proper voltage.

I then decided to leave the multimeter probes for measuring voltage connected to the charge port so that I could observe the voltage change when I turned the key on. When I did this…the mower came on and read 100% on the meter!

I disconnected my multimeter and was able to turn the mower on and off without issue (at least so far). I’m not exactly sure if the mulitmeter being connected was a fluke, or if it provided just enough momentary resistance that it allowed the circuits to properly turn on the electronics. I still haven’t tried mowing or other heavy loads but the lights, blades, beepers, etc…are all functioning. Maybe someone can explain what the connected multimeter in DC voltage testing mode actually did to allow the mower to turn on. Regardless, I’ll take that win!

Now I’m onto the next step of installing the new power gauge. I followed the advice of many on this forum that have used the Camway battery monitor off of Amazon. The sampler block on this monitor is enormous.

I opened up the control panel and removed the old battery indicator. This indicator has a single plug with three wires (two green and one black). There isn’t a lot of slack in the existing wiring, so I wasn’t trying to cut connectors in case I needed to hook up the original indicator. Also, there are no labels for what the different wires are used for on the original indicator.

Where I’m scratching my head a bit is how people hooked up the new Camway monitor since its instructions show cables going back to the battery. The existing wiring is also using green and black vs red and black. After some multimeter voltage testing it seems like existing wiring has the green wires as the battery pos and the black wire is hooked up to battery negative.

I guess, my first question is if anyone has a photo of how they did the wiring connections to the new camway monitor from the existing Ryboi wiring? See attached pictures.

If not:

Do I need to connect both green wires from the legacy Ryobi indicator to the new Camway or just one? UPDATE: Both green wires need to be connected to both B+ screws on the Camway. 18-22awg wires should be sufficient for connecting into the pins of the existing indicator plug.

Click to expand...

Kavalliero said:

Do I just connect a single black wire from legacy Ryobi wiring to the B- connector on the Camway? UPDATE: I can confirm that you only need to have a single 18-22awg wire from the existing plug to the small Camway B- terminal.

No wires will come from the P- connector on the camway? UPDATE: Doesn't seem to be required.

How did folks mount/secure the Camway sensor block to their mower? This is still an open question that would be great to see how people mounted this. In theory it could be wired to hang below the indicator, but I would prefer it to not move around. I'm thinking of drilling some holes through the side of of the plastic housing next to the seat into the area below the indicator and then use bolts to mount the new Camway sensor block to the inside of that cavity just below the indicator. If anyone has a better suggestion, I'm all ears!

Click to expand...

If you want the monitor to function, you need to connect the load negative cable to P-

You will want to hook the shunt up to the battery. I don't think the wires from the old meter will work. I took the plastic piece off the shunt and bolted B- directly to the negative threaded terminal and P- to the negative load cable. Positive wire for the shunt I hooked up directly to battery. This keeps the meter on all the time but I have mine hooked up to solar so it doesn't matter to me.

The new gauge is bigger than the original one so you will need to make the opening bigger in the metal holder. If you have the right tools it is pretty easy, if you don't it is a pain. Otherwise you could mount it somewhere else.

Buff said:

You will want to hook the shunt up to the battery. I don't think the wires from the old meter will work. I took the plastic piece off the shunt and bolted B- directly to the negative threaded terminal and P- to the negative load cable. Positive wire for the shunt I hooked up directly to battery. This keeps the meter on all the time but I have mine hooked up to solar so it doesn't matter to me.

The new gauge is bigger than the original one so you will need to make the opening bigger in the metal holder. If you have the right tools it is pretty easy, if you don't it is a pain. Otherwise you could mount it somewhere else.

Click to expand...

Thanks Buff and Supervstech. Hooking it up to the battery seemed to make the most sense when installed to a solar solution. However, for this mower application I wasn't looking for the meter to be on the whole time. There also seems to be somekind of lockout logic built into the wiring for the old meter on the mower. If I leave any of the wires disconnected the mower wont turn on. As soon as I ran a wire from black on the old meter wiring to the B- on the shunt and two wires from the green wires on the old meter wiring to the two B+ terminals on the shunt everything turned on and worked. The new camway monitor display lit up, seemed to read the voltage and current in realtime. I could calibrate all the settings on the monitor. Maybe it isn't actually working even though the monitor seems to be reporting using the wiring to the old monitor.

As far as mounting the shunt, I guess you answered that part when you said you removed the plastic and screwed directly to the battery terminal. When it comes to mounting the monitor display I agree that it took some work. I used a large step drill to widen the hole a bit more and a metal file to finish off the edge. No issues on that part. I was mainly figuring out where to put the shunt if I was able to reuse the old monitor wiring for the task.

If you did this conversion with the new meter did you have any issues with mower powering on if the old wiring wasn't used?

If I were to reuse the existing wiring would I need to add another line to the P- side like this?


I would be interested to hear what other people have done in regards to this Camway monitor. Again, trying to go with the least invasive "drop in" approach to minimize wiring changes. Note that I'm using the RY48ZTR100 100ah zero turn model mower which has a different monitor than the older 30" RM380 mower with the steering wheel.

I did find an interesting video on Youtube for a RM380 mower:



Does this jive with the recommedation on how to install for the zero turn model? If so, on the ZTR what did folks do with the old monitor plug/wires? Are they just left disconnected with no further action? I couldn't turn the mower on if the old monitor wires were not connected.

Ah, yeah I have an older RM480 38" non-zero turn and leaving the connector unplugged from the old meter works for it. Perhaps they changed the wiring with the new zero-turn ones or they were different to begin with. Hopefully someone with a newer zero-turn has an answer!

Buff said:

Ah, yeah I have an older RM480 38" non-zero turn and leaving the connector unplugged from the old meter works for it. Perhaps they changed the wiring with the new zero-turn ones or they were different to begin with. Hopefully someone with a newer zero-turn has an answer!

Click to expand...

Thanks for confirming. I've already found several differences between what you need to do to make the RM480 work vs the RY48ZTR. I'm hoping someone else on the forum can chime in on what they did for the ZTR models when installing the Camway (AiLi) monitor to save me from pulling out my hair. Trial and error has gotten me so far, but trying to avoid that "broken clock is right twice a day" situation by thinking I have something right and it blowing up later.

New update. I "completed" my conversion this weekend. As a recap, I have the zero turn 100ah model (RY48ZTR100). I used 4 "drop in" Ampere Time 12v 100ah batteries, and the Camway/AiLi Battery Monitor for the new batteries. I'm using the Dakota Lithium 48v 15A battery charger hooked up to a BL Link mechanical timer.

I say "completed" in quotes because the system works but it isn't 100%. Not sure what can be done to improve the install and experience. From my earlier posts, when I had just converted the batteries and still had the original Ryobi monitor in place the relay would clunk when the key was turned on, battery showed full charge but the rest of the power system wasn't registering any volts. I would have to disconnect and reconnect the main battery anderson plug to "reset" the system. Eventually I had my multimeter probes to test voltage at the charge port when I turned it on and it worked.

Subsequently I hooked the new Camway monitor up to the pins on the plug used to hookup the Ryobi monitor. Once I had all wires "jumped to the new monitor shunt everything turned on and seemed to be reading proper voltage. Even though this wasn't the way the shunt was supposed to be wired it seemed to work. However, per the feedback from Buff and Supervstech I installed the Camway/AiLi shunt to the battery. Interestingly enough, when I did this I was able to turn the mower on without having anything connected to the old monitor plug which was not my past experience getting the unit turned on. The system seemed to turn on and off without any issues, so I was happy...for a moment.

I went back about 30-40 min later. I could see the new monitor was still reading the proper battery information (since it is always on after connecting directly to the battery). I went to turn the unit on and the monitor readout started to breakdown like you see on a low battery and then turned off completely. The batteries were not reading any meaningful voltage vs a full charge. It seemed like the battery BMS had kicked in and shut the power down to the batteries. I hooked up my Dakota charger to the charge port and turned it on momentarily. This woke the batteries back up and the monitor was again showing the proper information. I was also able to turn the mower on after this "primer charge".

I did a full yard mow without any issues (yes I can still mow in Florida in the winter even if the grass isn't growing as quickly). I left the mower for about 20-30 min to go do some edging and blowing, and when I came back I was able to turn the mower on again. However, when I tried to re-engage the blades the blade motors did a slow partial start and stopped. It was like they lacked the juice to spin up. I was able to put the mower into drive and after I drove around a moment I was able to spin up the blades.

So the system works and starts normally as long as I don't leave the mower sit "off" for more than 25min. If it sits longer, it seems to trip the BMS when I start the system up which requires me to use my charger to almost act as a "jump start". Since I normally mow non-stop it isn't too bad to just "prime" the system with a battery charge before I start it up, but it is pretty annoying. I don't know why the BMS would be tripping under these startups after the mower is sitting off for more than 30min. I don't want to potentially be damaging any of the mower controller electronics.

I've seen other people on the forum talking about installing "pre-charge" circuit, and Hedges normally suggests some kind of inline resistor like a light bulb. I'd rather not go the lightbulb route, but I'm wondering if anyone else has had a similar experience with their conversion and what they may have done to resolve it. I'm not sure if this is an issue specific with the AmpereTime batteries and its BMS. I'm suspecting there is a momentary current rush on startup that is tripping the battery BMS. However, the system seems to start fine once it has been started once. That seems to indicate the system needed the capacitors on the mower charge controller to be charged up enough and if it sits idle for more than 30 min the capacitors drain. I have seen references to people with golf carts needing a "pre-charge" circuit. I have seen references to a solenoid, resistor, and diode being used in a precharge circuit. I'm curious if anyone has had to go this route (if they think this is my problem) and has any links to parts I can quickly assemble designed for this purpose?

Thanks!

Hi All,
Thanks for your knowledge, effort and expertise; I've been marvelling at you all from afar. I've run into a problem and was wondering if anyone could help. A little bit of background... I've installed a 48V 100ah battery into a RM480e mower. I had a quick ride around and it seemed to work fine. When I tried to charge the battery through the charging port with a 48V 25A LiFePo4 charger it didn't work. I was able to do a charge by attaching the pins directly to the battery terminals temporarily with alligator clips. The battery charged to 100%, as indicated on the charger as well as the battery's indicator, but after a couple of hours of remaining parked and not in use the battery's indicator read 87%. I have just recharged the battery by the same means after a small amount of use and the battery quickly rose back up to 100% on the battery's indicator after the charger put 2ah into the battery.

I've attached photos of the charger and battery at 6 seconds, 45 seconds and 6 minutes.

As you can see, it seems to have gone from 85 to 100% in 45 seconds. It is now 10 minutes or so since I took those photos and the battery now reads 94% and is falling.

My questions are:
- Is my battery being fully charged?
- Why does the SoC indicated on the battery fall without use?
- What do I need to do to get the charging port working?
- The battery specifications say charge voltage is 56.8 - 58.4v. Is it a problem that it is going beyond this range?
- Is the voltage difference between the charger and battery a problem?

I really am a bit out of my depth - thank you for whatever help you can give!

Battery https://voltx.com.au/products/voltx-48v-100ah-premium
Charger
(I'm in Australia so these are Australian sites)

Ok, so I think the battery capacity indicator is just inaccurate because using volts to ascertain state of charge is an inexact science...

voltman said:

Ok, so I think the battery capacity indicator is just inaccurate because using volts to ascertain state of charge is an inexact science...

Click to expand...

How is your VoltX battery performing? I've just ordered the same one for my Ryobi Zero Turn.

schmism said:

another option is to control a disconnect relay and wire the motor directly to the relay. Then you dont have to have a high current BMS to pass 200+ amps to the motor. and instead just monitor battery voltage and trigger the relay when H/L Vco.

This is what http://www.electrodacus.com/ does. However they only support 8s at the moment. Its my understanding that some of the Daly BMS can also be used to trigger the right kinds of relays for this kind of setup.

Click to expand...

I’m a little late to this thread but qucc (recommended) and chargery (not recommended) use external relays.

RyobiZeroTurn said:

How is your VoltX battery performing? I've just ordered the same one for my Ryobi Zero Turn.

Click to expand...

It's a well built battery at a good price. The indicator on the front is a bit of a gimmick, just don't expect it to give an accurate reading. Apart from that, I think it's a good drop in solution. Having said that, I don't have the equipment to run all the tests.

I've actually decided I'd like to go through the process of building a battery though, so will probably go with 160Ah cells rather than the voltX battery.

UltrasoundJelly said:

I've finished my build and successfully mowed my yard with the new battery. 100 Ah cells, 16s Overkill BMS. Mowed my entire yard 0.8 acre on 22° slope using 30% of the battery capacity (80% → 50% SOC). One nice thing: with the old SLA OEM setup the fuel gauge would swing 20-30% depending on whether the battery was under load ( voltage vs SOC lookup table I presume ). I never knew that the actual percent was with the SLAs. With the shunt it's really nice knowing the exact SOC.

Max current while mowing with the new battery 108 Amps as reported by Overkill app, which did make me a little nervous. It must've been very brief since the 100A OEM battery fuse didn't blow. My old OEM battery was the 70Ah SLA. It might be placebo effect, but the mower seems peppier going up hills (shedding almost 200 pounds of lead and having more max current to work with I presume). I noticed no difference in center of gravity change: the mower doesn't seem any more likely to tip.

• The design I used is a modded version of @rio 's brilliant build, here are the changes I made
  • added the middle lid notch to accept the steel lid brace (rough cut using a jigsaw)
  • used high quality 1/2" birch plywood for the sides and bottom, 3/4" for the lid and middle spacers
  • box held together with #6 screws and waterproof wood glue
  • middle spacers screwed into side
  • outside finished with 3 coats of spar polyurethane
  • 5 mm EVA foam (white Cosplay foam from Hobby Lobby) to pad the hold-down braces under the lid
  • 3d printed shunt holder, dust cap and stabilizers for middle brace, and the mains dust cap
  • used this enormous stepper bit to enlarge the hole for the shunt display, took 10 minutes with hand drill
• I destroyed my OEM charging port by plugging in the AIMS Charger the first time causing a large arc from (we suspect) the inrush current filling the charger capacitors from the battery. I have a complaint filed with AIMS Corp to see if this is normal. Here's how I repaired:
  • removed OEM charger receptacle and plug
  • replaced with Anderson SB50 plugs
  • 3d modeled the receptacle to hold the SB50 onto the mower (see pics)
  • connected the blue wire from the lockout circuit to battery positive, permanently disabling the lockout†
  • going to build a $20 protection circuit to prevent this moving forward using a diode and resistor in parallel
  • for now I have been disabling the battery using iOS app, then connecting AIMS charger, last turning battery on to charge without arcing

Here's a full Tinkercad of my build. I've been keeping SOC max 80% for battery life. AIMS charger set to charge LiFePo4 @ 15 amps. Planning to add a mechanical timer, estimate how long it will take to reach ~80% and have it turn off after that duration.

† With rio's help we reverse engineered the lockout circuit in case anyone wants to see how it works, and how I decided to connect the lockout circuit to battery positive, see pic.

Click to expand...

New comer here, I have read through the this thread a few times and I want to start out by saying thanks you for for all the great info and sharing your experiences. I am starting to gather up the parts to convert my RM480e. It sat in the garage all last year since the SLA are totally dead and I'm ready to get it running again with a new setup.


Do you happen to have an STL for the Andserson SB50 plug you made for the charger? I purchased the AIMS charger that was mentioned several times I figured I might as well swap out the original charger plug while I’m doing the build so I don’t have any arcing issue like you did the first time.

Ryobi Riders seems to have an off the shelf solution...

Hopefully now that it is spring and the folks in colder climates are now starting to get their mowers out of the shed for use...and watching this thread a bit more closely to provide feedback.

As an update to my conversion project:

I still haven't figured out the whole jumpstart issue and why it looks like the four AmpereTime 12v 100ah lithium batteries seem to just kill the power to the mower if I try to turn on the mower when it hasn't been receiving a direct charge for more than 30 min even though the batteries are are between 80-100% charge. I suspect there is something with the BMS in one or more of the batteries but I haven't been able to prove it. So my default procedure was to turn on the charger to get some juice flowing..then turn on the mower with the charger on, then turn off the charger and remove the plug. Wonky experience but seemed to do the trick for my first 4 mows without issue.

After my first couple successful mows only using about 30-35ah of charge of the 100ah available I decided it was working with the hassle of this initial "jumpstart" and just recycled my old SLA batteries. However on my 4th mow everything worked fine until my last pass when the power just suddenly dropped out and shut off the mower. I rolled it back to the shed...plugged it into the charger..the battery monitor lit back up and showed I had only used about 27ah charge and was at over 70% charage. I was able to turn it on and drive it around, but within a few min of turning on the blades the power would fully repeat and cut out again. My amp readout never showed me going over 70amp and it would even cut out sitting still and just running the blades consuming only 20-25amp. So it was't a voltage issue, charge issue, or amperage issue.

I hit the same problem again on my 5th mow where the power would just drop out after using about 27ah of charge. So at least it is a little consisent on where the power fails but I don't know why. Even though these four 12v100ah ampereTime batteries are rated for series installs and the runtime use and discharge is well within their limits it just seems like something the bms doesn't like. It seems like under the worst loads the amps will peak around 75amps and under normal conditions I'm between 45-55amp or less. I don't know how much more time and money it is worth to invest further in this from my perspective unless someone has some good advice on how to troubleshoot this issue vs cutting my losses and buying a new mower and trying to sell this one as used that is designed with lithium in mind. It could be the mower, something with the charger, or something with the AmpereTime batteries.

Living in Florida I never stop mowing...I just mowed less between nov-feb. We are in full on spring now with temps back in the mid 80s. So I don't have time to mess around during my next 9 months of heaving growing. If I don't find an answer to salvage this project I'm either back to my backup push mower or investing in something new.

Help is appreciated.

Kavalliero said:

Hopefully now that it is spring and the folks in colder climates are now starting to get their mowers out of the shed for use...and watching this thread a bit more closely to provide feedback.

As an update to my conversion project:

I still haven't figured out the whole jumpstart issue and why it looks like the four AmpereTime 12v 100ah lithium batteries seem to just kill the power to the mower if I try to turn on the mower when it hasn't been receiving a direct charge for more than 30 min even though the batteries are are between 80-100% charge. I suspect there is something with the BMS in one or more of the batteries but I haven't been able to prove it. So my default procedure was to turn on the charger to get some juice flowing..then turn on the mower with the charger on, then turn off the charger and remove the plug. Wonky experience but seemed to do the trick for my first 4 mows without issue.

After my first couple successful mows only using about 30-35ah of charge of the 100ah available I decided it was working with the hassle of this initial "jumpstart" and just recycled my old SLA batteries. However on my 4th mow everything worked fine until my last pass when the power just suddenly dropped out and shut off the mower. I rolled it back to the shed...plugged it into the charger..the battery monitor lit back up and showed I had only used about 27ah charge and was at over 70% charage. I was able to turn it on and drive it around, but within a few min of turning on the blades the power would fully repeat and cut out again. My amp readout never showed me going over 70amp and it would even cut out sitting still and just running the blades consuming only 20-25amp. So it was't a voltage issue, charge issue, or amperage issue.

I hit the same problem again on my 5th mow where the power would just drop out after using about 27ah of charge. So at least it is a little consisent on where the power fails but I don't know why. Even though these four 12v100ah ampereTime batteries are rated for series installs and the runtime use and discharge is well within their limits it just seems like something the bms doesn't like. It seems like under the worst loads the amps will peak around 75amps and under normal conditions I'm between 45-55amp or less. I don't know how much more time and money it is worth to invest further in this from my perspective unless someone has some good advice on how to troubleshoot this issue vs cutting my losses and buying a new mower and trying to sell this one as used that is designed with lithium in mind. It could be the mower, something with the charger, or something with the AmpereTime batteries.

Living in Florida I never stop mowing...I just mowed less between nov-feb. We are in full on spring now with temps back in the mid 80s. So I don't have time to mess around during my next 9 months of heaving growing. If I don't find an answer to salvage this project I'm either back to my backup push mower or investing in something new.

Help is appreciated.

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I would install 4 volt meters one on each battery and look to see exactly what is dropping out when the mower stops.
You could have a defective BMS or cell in one of the batteries.

Let’s see some pics of how you have them connected to each other.

Kavalliero said:

Hopefully now that it is spring and the folks in colder climates are now starting to get their mowers out of the shed for use...and watching this thread a bit more closely to provide feedback.

As an update to my conversion project:

I still haven't figured out the whole jumpstart issue and why it looks like the four AmpereTime 12v 100ah lithium batteries seem to just kill the power to the mower if I try to turn on the mower when it hasn't been receiving a direct charge for more than 30 min even though the batteries are are between 80-100% charge. I suspect there is something with the BMS in one or more of the batteries but I haven't been able to prove it. So my default procedure was to turn on the charger to get some juice flowing..then turn on the mower with the charger on, then turn off the charger and remove the plug. Wonky experience but seemed to do the trick for my first 4 mows without issue.

After my first couple successful mows only using about 30-35ah of charge of the 100ah available I decided it was working with the hassle of this initial "jumpstart" and just recycled my old SLA batteries. However on my 4th mow everything worked fine until my last pass when the power just suddenly dropped out and shut off the mower. I rolled it back to the shed...plugged it into the charger..the battery monitor lit back up and showed I had only used about 27ah charge and was at over 70% charage. I was able to turn it on and drive it around, but within a few min of turning on the blades the power would fully repeat and cut out again. My amp readout never showed me going over 70amp and it would even cut out sitting still and just running the blades consuming only 20-25amp. So it was't a voltage issue, charge issue, or amperage issue.

I hit the same problem again on my 5th mow where the power would just drop out after using about 27ah of charge. So at least it is a little consisent on where the power fails but I don't know why. Even though these four 12v100ah ampereTime batteries are rated for series installs and the runtime use and discharge is well within their limits it just seems like something the bms doesn't like. It seems like under the worst loads the amps will peak around 75amps and under normal conditions I'm between 45-55amp or less. I don't know how much more time and money it is worth to invest further in this from my perspective unless someone has some good advice on how to troubleshoot this issue vs cutting my losses and buying a new mower and trying to sell this one as used that is designed with lithium in mind. It could be the mower, something with the charger, or something with the AmpereTime batteries.

Living in Florida I never stop mowing...I just mowed less between nov-feb. We are in full on spring now with temps back in the mid 80s. So I don't have time to mess around during my next 9 months of heaving growing. If I don't find an answer to salvage this project I'm either back to my backup push mower or investing in something new.

Help is appreciated.

Click to expand...

If you give up and decide to sell it all, let me know… I might be up for a trip down there.

Supervstech said:

If you give up and decide to sell it all, let me know… I might be up for a trip down there.

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See attached photos of how it is all connected. Reused nearly all the existing wiring except adding an extra length of cable between the shunt and the lead negative terminal. I had seen some people directly bolt the shunt directly to the negative terminal using a longer M8 bolt but I didn't feel as confident with that due to the platic shunt bracket preventing direct contact with the battery terminal unless someone says it isn't an issue.

I had removed the plastic battery terminal covers since the Ampere Time batteries seemed to be just a fraction taller than the original Leoch SLA batteries. This prevented the top hold-down bracket from being secured to the frame with the long hex bolt unless I removed the spring washer. I didn't want to use threadlock on the bolt so I just removed the covers so I could keep tension on the hold-down bracket bolt.

The rest of it seemed pretty straightforward except for the "jumpstart" issue and now the sudden power failure.

@Supervstech are you suggesting there is a way to hook a voltmeter up to each battery to test for a specific battery fault while the unit is in operation? If so, please explain. I haven't actually tested this before, but it would seem that the suggestion Option 1 is to get four voltmeters, attach each to the pos-neg terminals of each battery. Drive the mower around and when the power dies, see which voltmeter goes dead. Option 2 would be tp drive around until the mower dies...pull the batteries out of the mower, disconnect the wiring, and test each battery separately.

Of course if all the batteries still read the correct voltage after the power cuts out...that would indicate there is something wrong with the mower control board. Am I following correctly? If so, that seems like some reasonable troubleshooting and sound advice without investing more. If it is a faulty battery then AmpereTime should replace it. The question then would be if the battery failed because of manufacturer defect or if there was something the mower did to cause the battery to fail.

Please correct if I am misunderstanding something.

I have included some pictures of the installed packs. I also have a picture where I show the orginal meter and the new Camway monitor. You can see that the mower only had 87.3 hours on it before I did the conversion and about 3 hours post conversion. So it wasn't even that heavily used before my SLAs gave up the ghost.

If for some reason I decide to give up on this, I would certainly be willing to sell the mower with the batteries. Heck, I may be willing to do that anyways if an offer is reasonable. Feel free to direct message me if that is of interest. Not sure where you're based, but I'm out of Maitland, Florida (suburb on the north side of Orlando).

Yes, I would get 4 12V digital volt meters, connect one to each battery, and see if one cuts out when the mower fails to run.
100Ah batteries should have no issue with that mower load.

Supervstech said:

Yes, I would get 4 12V digital volt meters, connect one to each battery, and see if one cuts out when the mower fails to run.
100Ah batteries should have no issue with that mower load.

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Agreed that the 100Ah batteries shouldn't be having an issue. Well yesterday I mowed again and it only did 20% of my yard. So each time it is mowing less. When I started the mower the AiLi/Camway monitor said the state of charge was at 100% which made sense with the amount of time I let my Dakota Lithium 48v 15ah charger run after each mow. Normally only using about 30-40ah out of the 100Ah batteries. So about 2-3 hours charge is usually sufficient. Dakota doesn't recommend leaving the batteries sit on the charger, so I just installed a mechanical timer to shut the power off after the charge. The Camway monitor seemed to be accurate when reading the voltage, current use, etc...especially for the time I was mowing, so seeing the monitor report 100% charge all seemed to add up.

Well after the mower died I decided to pull the battery packs and test the voltage as well as to prepare for installing the four 12v digital voltmeters. The results were interesting. three of the four packs were all down to fluctuating around 12.89 volts with the fourth (the one supporting the initial Bpos connection for the charger/pack) reading 11.47v. So that puts that battery to about 1-2% charge and the other 3 down to about 15-20% charge. Highly suspect that the batteries would be that out of sync when they were all balanced intially.

It does answer one key question, the Ampere Time BMS didn't actually shutoff the battery since they are were all reading voltages. However, the voltage levels clearly were not where they were supposed to be. However, I'm not exactly sure what this tells me beyond the BMS not killing the battery power resulting in shutting the mower off. With the batteries so low and one so far out of balance I would expect that to cause the mower to behave eratically and power down due to overall insufficent voltage, and clearly there isn't enough charge to actually mow my lawn based on the multimeter results. What I haven't been able to determine is why the batteries are not taking a charge when the Camway monitor said they were.

With the Camway effectively always on since it is wired directly to the batteries through the shunt there is always a trickle current, but for a 100ah battery back and its operational current for the display is less than 50mA this should have been negligible to the charge between mows. There is nothing else wired any differently that I am aware of that would explain a power drain to that magnitude over 6-7 days.

I'm not sure if it is that one low battery has something going on with it that impacted the other 3 and is throwing the charging and everything else out of whack.

I'm currently trying to individually charge and top and balance each battery. I should have the voltmeters in a couple of days. I'll get it all hooked back up in series and see what comes back.

Note that I'm charging through the original charge port. With all the connectors hooked up the same as the original SLA batteries were installed. I wasn't seeing that as an issue unless for some reason the charge wasn't actually flowing as I expected, something with leaving the tri-plug charge handle connected to the charge port even though the charger was off somehow created a slow drain, or one of those other lockout/relay circuits creating some kind of voltage drain over 7 days. Still doesn't explain why the Camway would read 100% though since it is connected directly the battery terminals.

Any insight would be recommended. Seems odd to have these issues where I did the least amount of changes possible to the mower to support the conversion.

Batteries wired in series can and do go out of sync. A good battery may charge up faster than a lesser battery and once the good battery stops charging (the BMS stops the charge), the lesser battery can no longer get a charge.

If you want a 48 volt battery, build a 48 volt battery. Putting 12 volt batteries in series can lead to problems like you're seeing. That may not be the root cause of your issue, but it could be.

HRTKD said:

Batteries wired in series can and do go out of sync. A good battery may charge up faster than a lesser battery and once the good battery stops charging (the BMS stops the charge), the lesser battery can no longer get a charge.

If you want a 48 volt battery, build a 48 volt battery. Putting 12 volt batteries in series can lead to problems like you're seeing. That may not be the root cause of your issue, but it could be.

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Appreciate the input. If the one battery is this far out of whack it could certainly explain part of what I'm seeing. Maybe a replacement battery would be in order, but I am really hesitant to invest even more into the system. A 48v 100ah AmpereTime/LiTime battery would run about $1600 and other brands go up from there. Not really feeling like building a pack with what I have already sunk into this conversion. This is turning into a more costly investment than just replacing with SLA batteries for something as silly as "luck of the draw" on an individual battery. At $1600 I'm 25% of the way towards a more up to date lithium mower from Ryobi, Ego, or Greenworks.

Do you think changing the order of the batteries in the series would help mitigate some of this?

Regardless...frustrating.