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

These sort of issues are why companies spend much time and resources on R&D to eliminate such problems, or at least try to reduce them. Vermin, vibrations, environmental ingress, human idiocy are all things they seek to mitigate through design.
 
It does look like mouse pee. Maybe the plating on the copper isn't a solid as you thought. I would remove the bus bar, thoroughly clean all surfaces - not just the contact surfaces - and reinstall.
 
I opened my battery after about 5 hours of very bumpy mowing to check things out and I saw no loosening of bolts. I did build one #2 AWG interconnect with plans to replace my bus bars, but quickly decided that it's really not much better than the bus bars. Have a look at the picture: with the large lugs I was only able to fit in about 1.5" of wire and had to strain to bend the wire to get this one to fit. It was putting quite a bit of force on the battery studs and really didn't seem flexible at all. I don't have much overhead clearance to poke the wire upwards in my box, so this was a nonstarter for me. I put the bus bar back in place. I did replace the OEM nuts with nylon locking nuts, so I have more confidence nothing will come loose.


IMG_7494.jpg
 
HRTKD said:
Correct me if I'm wrong, but the balance leads on the studs on the left and right hand sides of the picture appear to be under the cable lug. If so, you want the balance lead on top of the cable lug.
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You're correct. I noticed that when I was replacing the nuts with the nyloc nuts and corrected it. Thanks!
 
Sunday afternoon I was mowing the lawn for the 4th time and lost all power. When it quit the meter on the mower was showing 47.9 volts, 69.98AH capacity, and 46.0%. I checked the main fuse on the mower and it was still good. There were no loose wires or obvious signs of problems. I opened the BT app for the BMS and it showed 0% capacity, the voltage matched the 47.9 on the meter. The lowest cell was just under 2.9vdc and the highest just over 3.1vdc. Temperature on the 3 sensors average about 87°F.

I got the mower back up to the house and plugged in the AIMS charger but it wouldn't charge. The charger wouldn't even start, no LED indicators lit up on it. I pulled the battery pack and opened the box to see if there was any visible signs of problems. I can't see anything wrong, no loose wires, no loose nuts, nothing burned, no smell of burning. It looks just like it did when I put it in the mower.

Today when I went out to dig into it more, the meter was now 49.24VDC, 68.94AH, and 46%. It still doesn't charge though. I even connected the BMS leads to the charger to bypass anything on the mower that might be causing a problem. Still it doesn't charge.

The log data from the app doesn't show any red notes that would indicate a reason why it shut down. I did find in the parameter settings the cycle is set to 80AH which is probably why it shutoff at 69.98AH remaining, given my pack is 150AH total capacity.

So I can't find anything wrong, there's no indications in the BMS log of any errors.

The only thing I can see for why it quit was that it dropped below 70AH capacity. But why won't it charge now?

Any suggestions would be helpful.

display1.jpgdisplay2.jpg


battery.jpgBMS1.jpg
 
Meshdish63 said:
Sunday afternoon I was mowing the lawn for the 4th time and lost all power. When it quit the meter on the mower was showing 47.9 volts, 69.98AH capacity, and 46.0%. I checked the main fuse on the mower and it was still good. There were no loose wires or obvious signs of problems. I opened the BT app for the BMS and it showed 0% capacity, the voltage matched the 47.9 on the meter. The lowest cell was just under 2.9vdc and the highest just over 3.1vdc. Temperature on the 3 sensors average about 87°F.

I got the mower back up to the house and plugged in the AIMS charger but it wouldn't charge. The charger wouldn't even start, no LED indicators lit up on it. I pulled the battery pack and opened the box to see if there was any visible signs of problems. I can't see anything wrong, no loose wires, no loose nuts, nothing burned, no smell of burning. It looks just like it did when I put it in the mower.

Today when I went out to dig into it more, the meter was now 49.24VDC, 68.94AH, and 46%. It still doesn't charge though. I even connected the BMS leads to the charger to bypass anything on the mower that might be causing a problem. Still it doesn't charge.

The log data from the app doesn't show any red notes that would indicate a reason why it shut down. I did find in the parameter settings the cycle is set to 80AH which is probably why it shutoff at 69.98AH remaining, given my pack is 150AH total capacity.

So I can't find anything wrong, there's no indications in the BMS log of any errors.

The only thing I can see for why it quit was that it dropped below 70AH capacity. But why won't it charge now?

Any suggestions would be helpful.
View attachment 94010


View attachment 94013View attachment 94014
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What is your protection cell undervoltage set to ? It cuts if off on your app screen
 
Meshdish63 said:
Sunday afternoon I was mowing the lawn for the 4th time and lost all power. When it quit the meter on the mower was showing 47.9 volts, 69.98AH capacity, and 46.0%. I checked the main fuse on the mower and it was still good. There were no loose wires or obvious signs of problems. I opened the BT app for the BMS and it showed 0% capacity, the voltage matched the 47.9 on the meter. The lowest cell was just under 2.9vdc and the highest just over 3.1vdc. Temperature on the 3 sensors average about 87°F.

I got the mower back up to the house and plugged in the AIMS charger but it wouldn't charge. The charger wouldn't even start, no LED indicators lit up on it. I pulled the battery pack and opened the box to see if there was any visible signs of problems. I can't see anything wrong, no loose wires, no loose nuts, nothing burned, no smell of burning. It looks just like it did when I put it in the mower.

Today when I went out to dig into it more, the meter was now 49.24VDC, 68.94AH, and 46%. It still doesn't charge though. I even connected the BMS leads to the charger to bypass anything on the mower that might be causing a problem. Still it doesn't charge.

The log data from the app doesn't show any red notes that would indicate a reason why it shut down. I did find in the parameter settings the cycle is set to 80AH which is probably why it shutoff at 69.98AH remaining, given my pack is 150AH total capacity.

So I can't find anything wrong, there's no indications in the BMS log of any errors.

The only thing I can see for why it quit was that it dropped below 70AH capacity. But why won't it charge now?

Any suggestions would be helpful.

View attachment 94009View attachment 94010


View attachment 94013View attachment 94014
Click to expand...
Did you confirm the output voltage on a DMM? My guess is that it'll read 0, as your app shows the battery discharge is turned "off," probably because of the max Ah setting you put in. Click that toggle button while connected to the charger and it should start up. The AIMs charger is a smart charger and won't deliver current until it senses a voltage.
 
UltrasoundJelly said:
Did you confirm the output voltage on a DMM? My guess is that it'll read 0, as your app shows the battery discharge is turned "off," probably because of the max Ah setting you put in. Click that toggle button while connected to the charger and it should start up. The AIMs charger is a smart charger and won't deliver current until it senses a voltage.
Click to expand...
I did not check output voltage on a DMM. If it's 0 I'll toggle the button to see what happens. I'll do that when I get home from work in a few hours and report back.

Thanks bobbie_ohio and UltrasoundJelly for the quick responses!
 
Meshdish63 said:
I did not check output voltage on a DMM. If it's 0 I'll toggle the button to see what happens. I'll do that when I get home from work in a few hours and report back.

Thanks bobbie_ohio and UltrasoundJelly for the quick responses!
Click to expand...
Yep, no output voltage. Toggled the discharge button and it came then turned off. I changed the cycle capacity from from 80ah to 90ah and now it's on and charging.

I didn't realize those buttons on the app could be toggled.

Thank you UltrasoundJelly
 
Meshdish63 said:
Yep, no output voltage. Toggled the discharge button and it came then turned off. I changed the cycle capacity from from 80ah to 90ah and now it's on and charging.

I didn't realize those buttons on the app could be toggled.

Thank you UltrasoundJelly
Click to expand...
Yeah, it's kinda cool that you can software-disable the charge and output. Though, it seems that the way engineers design BMSs is for them primarily to be for battery protection, and not routinely regulate the depth of charge/discharge. For me, it would be cool if the BMS would allow a max 80% SOC and then disable charging, but I guess the BMS leaves that up to the charger. Would be nice to have some standardized method of communication between charger and BMS so they can together optimize battery life.
 
UltrasoundJelly said:
Would be nice to have some standardized method of communication between charger and BMS so they can together optimize battery life.
Click to expand...

To make use of what you've got, read SoC then use spring-wound timer to put in limited Ah charge?
Occasionally, you'd want to hold it above knee to allow balancing.
 
That’s what I’m doing now. I find that charging for 2 hours at 12 amps gets me 30-40% charge, just enough for my mow.

Interestingly I find that the BMS reported SOC drifts from what the shunt reads over a month or so. Charging to 100% syncs them up again.
 
"Shunt" meaning a separate shunt and electronics?
No surprise the two would differ. Basic accuracy is probably spec'd around 2%. Likely needs some calibration process to be at all accurate.
 

This guy was ready to replace the SLAs after only 1 season. Looks like he's no stranger to LiFePo4 conversions, so I wont be surprised if he follows along this path. He also does a decent breakdown on the current state of the battery powered zero turn market.
 
Hello.

Using information I found in this forum and another video, I decided to do a LiFePO4 conversion on my Ryobi zero-turn mower. I carefully and meticulously removed each bolt and connector and laid them out in order removed.

With the tray removed, I replaced each battery one-for-one with a Canbat 60 AH LiFePO4 battery. They are able to be used in banks in series or parallel. Before installing the new batteries, I charged each one individually using a Genuis 5 amp 12v charger.

I carefully put everything back together in reverse. It all went well and I felt confident of the procedure.

Unfortunately, having turned the key to on and hearing the normal "clunk" engage, nothing works: no lights around the buttons, no guage, no headlights; no signs of life. Even worse, after doing it a few times, I no longer here the normal "clunk" engage when turning the key to on.

From this, I have two questions:
  1. What could possibly be the problem why nothing would run? I was under the impression this would be a relatively one-for-one swap out, that all connections could remain in place, and the system would work, except for the gauge that would be inaccurate (which would be fine). Perhaps I was actually supposed to leave some wire disconnected after the conversion?

  2. Now that I don't hear the "clunk" when turning the key, I assume I have destroyed some other electronic component. What is the most likely component to have been damaged and how do I get to it and test it?
I am quite disheartened and I greatly appreciate any insight and help that those here can find time to provide.

Thank you.
 
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Sorry to hear. Regarding your first question, it could be a number of things. For starters, I would check that the overall series voltage of the batteries is what it should be (mid 50's, or up to 58V when fully charged), and continuity test on the main fuse.
Regarding your second question, it could be related to the lockout circuit. See posts #356-360. However, I would not address this until you confirm the proper setup of your battery bank with a meter.
 
Look at all of this thread. I had same problem with no clunk. There is a blue wire that needs tied to the high voltage. On the original wiring , it was going to a post on the original charge port, from there it went as a red wire to a pig tail off the main battery connection. I cut their little connector off on the main battery side keeping the wires as long as possible. I bought an Anderson 30a 10g connector and crimped one end to my charger. The other end I crimped to the red and black little pig tail (10guage) wires and in the process crimped that blue wire with the red on the side coming off the main pack. The clunk should come back once you connect that blue wire to 48v+
Post 360 here is a pic of the connector I ended up cutting off and reusing the wires. I’ll get a pic of my new connector in a few minutes
 
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Slightly off topic but does anyhow have any mower blade motor specs? Like RPM, kW etc? I'd like to build a finish mower pull-behind and either buy some factory motors/controllers or have a basic understanding of how powerful they need to be.
 
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