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

I have been following this thread for a while. I am surprised how many people claim their original batteries failed after just one season. Did you regularly drain the batteries below 50%?

As a reference, I have about 60 hrs on my 100AH Ryobi. There there is some capacity loss but not much. This is my third season.

This tractor is advertised as capable of up to 2.5 hrs run time. Clearly, people who use it as advertised will end up with useless junk after just one year. Isn't this a good case for a class action based on false advertising?

My lawn is about 1 acre. Knowing that AGM batteries suffer if drained below 50%, I never used this tractor for more than an hr before I would recharge it. However, if the manufacturer claims 2.5 hrs is fine and does not warn against it, I think the tractor should be perfectly capable of doing this regularly without any harm.

I think Ryobi screwed up customers, intentionally, and they continue to do so. The tractor should simply prevent the user from draining batteries below 50% if doing so is critical to durability.
 
WWG said:
I have been following this thread for a while. I am surprised how many people claim their original batteries failed after just one season. Did you regularly drain the batteries below 50%?

As a reference, I have about 60 hrs on my 100AH Ryobi. There there is some capacity loss but not much. This is my third season.

This tractor is advertised as capable of up to 2.5 hrs run time. Clearly, people who use it as advertised will end up with useless junk after just one year. Isn't this a good case for a class action based on false advertising?

My lawn is about 1 acre. Knowing that AGM batteries suffer if drained below 50%, I never used this tractor for more than an hr before I would recharge it. However, if the manufacturer claims 2.5 hrs is fine and does not warn against it, I think the tractor should be perfectly capable of doing this regularly without any harm.

I think Ryobi screwed up customers, intentionally, and they continue to do so. The tractor should simply prevent the user from draining batteries below 50% if doing so is critical to durability.
Click to expand...
Had my 100ah zero turn since 10/2019. Don't know the hrs on it cause the battery gauge had to be replaced thru Ryobi once and I just replaced that gauge with a good battery monitor and never bothered to check hrs. I can say it has seen plenty of use on our 4 1/2 acre property.

I never got 2.5 hrs mowing out of a charge.

Almost always ran the batteries down to where the blades shut off, about 15% on the gauge. After 2 1/2 years, the original batteries still had useful life in them and I could get about 40 mins or about 1/2 - 3/4 acre out of a charge. I used the hell out of those batteries and the mower, but also took good care of them. In my case, neither the batteries nor the mower became useless junk after a year.

All the old batteries test good on my cheap battery tester and I already started using them for my boat.

Ryobi definitely knew that battery durability would be an issue, hence the 1 year battery warranty vs the 3 yr mower warranty. I think a lawsuit would be an uphill battle. Who knows what type of perfect conditions they tested these mowers on but I'll bet they were the best possible. There's a lot of variables to consider with things like this.
 
Little different situation
Bought a used 1985 lifted EZ go 36 volt golf cart ? with Trojan flooded cell batteries ?. Got another 3 years out of them. Started dying and range went way down.
Studied all my options then ordered 3 12 volt lithium batteries.
Saw Big Battery had an all in one battery called the gator max with charger and I cancelled my other order.
Bought the gator max, removed old batteries which I got a payout on from a recycler, slipped in the new battery, hooked it up and it’s worked flawless ever since. Rarely have to charge it. I saved almost 300 pounds to boot ?.
I believe they also have a 48 volt battery.
 
WWG said:
I have been following this thread for a while. I am surprised how many people claim their original batteries failed after just one season. Did you regularly drain the batteries below 50%?
Click to expand...

after 2 years of running the Ryobi down into yellow/red with 75Ah batteries, they were almost useless. about 1/2 acre mowed relatively infrequently.
 
I tried with mine to keep it over 50%, but wasn't always disciplined enough and a few times got far below. But, the percentage displayed in the stock gauge is based on voltage, not on true SoC, so it's kinda meaningless to begin with.

2 years in, I was only getting about 20 minutes per charge. When I tested the batteries 3 were fine and one was bad. This seems to be the common predicament. I don't know if this is a common failure mode with series AGM batteries, or whether there's some bad quality control with the Leoch ones.

I agree that it's very disingenuous of Ryobi to advertise "up to 2.5 acres". I wonder if they just based that on the theoretical amount based on what 100 Ah can get out of this mower's power consumption, and not on any actual testing.
 
bcb7514 said:
Glad I ran across this thread and enjoy seeing all of the conversions.

Looking at possibly going with the plug in play option of the LiFePO4 12v 100Ah batteries to save some time and also because I’m not super trusting of myself to not screw up something by building a custom setup.

Ampere Time LiFePO4 Deep Cycle Battery 12V 100Ah with Built-in BMS, Perfect for Replace Most of Backup Power and Off Grid Applications... https://a.co/d/7lj6J1N

Is there anything else specific I would need or need to do besides simply pulling out the OEM batteries and putting these in?

I’ve seen others mention being able to use the original charger, but also mention setting a timer to unplug to be safe. Normally I leave the original batteries on the chargers all the time. This just a best safety practice? Cause any issues should I forget to unplug after swapping to the LiFePO batteries?

I feel like I know just enough to be dangerous at the moment.

Thanks!
Click to expand...
You can just drop the 100Ah 12v lifepo4 batteries in and use the existing charger. The reason it’s suggested to use a timer is because the original charger will try to over charge the batteries due to the fact that the charge profile is meant for AGM lead acid batteries. The BMS in the lifepo4 cells should prevent that, but it’s not good practice to rely on that safety mechanism to stop charging. Also, it may still be allowing the cell voltage up to a 3.65v which isn’t great for longevity. This is why many have replaced the stock battery meter with a meter that uses a shunt to track how much amp hours have been consumed and set a timer to charge to 80%. The stock DeltaQ charger charges at about 14a so it’s easy to do the math to figure out how long to set the timer for.

Definitely don’t leave it on the charger all the time.

For my setup with a 105ah 16S battery with a Bluetooth-enabled BMS, I’ve just been charging every 3-4 mows and watch the charge level and voltage and just unplug the charger when I know it’s somewhere between 80-90%. If I forget, I have my BMS set with a 3.50v cell high voltage cutoff, which is basically fully charged for my cells.
 
I would go with drop in cells that come with it’s own charger.
My 36 volt all in one unit came with it’s own charger. I took the old one to a recycle place. Why cheap out when you are spending hundreds if not thousands of dollars ? on a battery replacement? ?
 
ryobilifepo4user said:
Thank you for all the comments. I have a lot to process and test, then I will get back with what I find. One question: what does this statement mean @AMDPower?

If a BMS cuts off, how would a full charge be obtained? I suspect this is a simple concept I am missing.

Nevermind, I think I found it here (I did read this whole thread previously, but it's a lot to retain).
Click to expand...
@ryobilifepo4user did you ever figure out your issue? I’m seeing the same thing. Charged 4 12v 100ah ampere time batteries, connected everything the way it was (didn’t replace gauge or change anything else yet), turned the key, one clunk then nothing. Now turning the key doesn’t do anything. Batteries in series reading 54.0V. maybe I’ll try charging in parallel for a bit to better balance? How balanced must they be? Really hope there’s a solution here, I was very excited to get my mower back.

Anyone have any other ideas?

Thanks so much in advance!
 

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Skabam287 said:
@ryobilifepo4user did you ever figure out your issue? I’m seeing the same thing. Charged 4 12v 100ah ampere time batteries, connected everything the way it was (didn’t replace gauge or change anything else yet), turned the key, one clunk then nothing. Now turning the key doesn’t do anything. Batteries in series reading 54.0V. maybe I’ll try charging in parallel for a bit to better balance? How balanced must they be? Really hope there’s a solution here, I was very excited to get my mower back.

Anyone have any other ideas?

Thanks so much in advance!
Click to expand...
Btw my individual battery readings are 13.50v, 13.56v, 13.53v, 13.39v. Maybe that last one is too out of balance?
 
Skabam287 said:
@ryobilifepo4user did you ever figure out your issue? I’m seeing the same thing. Charged 4 12v 100ah ampere time batteries, connected everything the way it was (didn’t replace gauge or change anything else yet), turned the key, one clunk then nothing. Now turning the key doesn’t do anything. Batteries in series reading 54.0V. maybe I’ll try charging in parallel for a bit to better balance? How balanced must they be? Really hope there’s a solution here, I was very excited to get my mower back.

Anyone have any other ideas?

Thanks so much in advance!
Click to expand...

Did you try to "wake" the batteries or BMS back up by using a power supply to apply 48v to them? Worked for me twice. Lots of info out there on how to do this.
 
Thanks @Jakeman not yet but I’ll give that a shot if it happens after letting the batteries balance in parallel first. The instructions that came with the batteries actually mention it is recommended to connect in parallel for 12-24 hours prior to using them in series. I just gotta go out and get some cables to connect then that way cause the little ones that came with the mower won’t be enough for parallel.

Any idea what bms protection is tripping to cause it in the first place? The downside of these off the shelf 12v is not having access to the bms data.
 
Skabam287 said:
Thanks @Jakeman not yet but I’ll give that a shot if it happens after letting the batteries balance in parallel first. The instructions that came with the batteries actually mention it is recommended to connect in parallel for 12-24 hours prior to using them in series. I just gotta go out and get some cables to connect then that way cause the little ones that came with the mower won’t be enough for parallel.

Any idea what bms protection is tripping to cause it in the first place? The downside of these off the shelf 12v is not having access to the bms data.
Click to expand...

Just re-read your post. If you have 54v, I don't think they need to be "woken up". Mine showed almost no voltage at all when it happened. Sorry, no other idea, hopefully following the instructions will do the trick. I'm new at this, trying to learn as I go and share what I've learned.

I had to make cables to hook 2 of the old AGM batteries from the mower in parallel to use in my boat. Luckily I had some old welding cable and ordered some ends from Amazon.

My battery is an "off the shelf" 48v with no access to the BMS data as well. Mine shut down twice and I think I know what caused it. Both times I had been mowing, stopped the mower and let it sit outside. Think it got too much sun and caused some heat to build up around the battery, causing the BMS to trip. It is surrounded by black plastic without a lot of air circulation. I now park it in the shade or in the garage and haven't had the problem since.

One of the reasons I went with the 48v is, hopefully, not having to worry about balancing or any other issues with multiple batteries. I do realize my "single" battery is a collection of 16, 3.2v cells. It was almost plug and play except for having to secure the battery differently. Just charge it and go.
 
So good news for my conversion, I’m up and running. Balanced the batteries in parallel for a day, then re installed in series. My first time hooking everything up I again got the one clunk and dead mower but I just unplugged and replugged the main Anderson connector and for some reason all was good after that. Now finally for a first mow tomorrow and will try to figure out if I’ll be good using the delta q charger or switch to a 48v lifepo4 one I got (though I’d want to splice in the delta q charger plug). I also haven’t yet installed the new gauge but plan to in the near future. Wanted to make sure I was running before figuring out those next steps. Thanks again to all contributors in the thread for helping us newbies figure this out! (And thanks to an amazing neighbor who cut my lawn for a few weeks while I was down!)
 
Been spending WAAAAY too much time researching all this. Thanks everyone for all the info. =)

So my AmpereTime batteries just arrived (4x 12v 100ah), but I've been frustrated finding a decent 48v charger. It seems like most of the 48v chargers have weird issues, like arcing or fuses not actually being connected to anything!

My plan:
1. Use the standard Ryobi charger
2. Get a Junctek battery monitor/shunt https://a.co/d/83fmAe8
3. Use it's option to control a relay to be able to disconnect the third pin on the charger port, which should stop charging. If the third pin disconnecting doesn't stop it, I could also put a bigger relay into the actual charger circuit.
4. Set it to trigger the relay when voltage goes over a certain level (for protection, and because I'd prefer not to go to 100% SOC)
5. Bonus: also can work as low temp charger cutoff since AmpereTime batteries don't have that built in

Does that make sense? In addition to being able to continue using the charger, I'd get a bluetooth battery monitor with a decent little display and data logging. The Junctek only costs about $30 more than the other monitor/shunt options.
 
I think the payoff of extended life cycles combined with complication isn't worth it especially for a lawn mower application that sees relatively infrequent charge cycles.
For example, if you charge 100% SOC every time once a week and only get 1000 cycles, that's 20 years super conservatively for ordinary homeowners.
By then, our LiFePO4 batteries will be old school and we'll have dumped them like we're dumping AGMs now.
Regardless, if you haven't already, get a BMS or manually balance periodically.

Use this opportunity as an excuse to purchase an AIO 48V inverter as I think they can charge your 48V batteries with custom parameters. JK.
 
Unfortunately, traffic on this thread has slowed considerably but I hope you get a more educated answer. I have also researched too much and went down many Rabbit holes in the process. Your plan sounds good to me for what that's worth!

I use, either the original charger or a 10 amp lifepo4 charger that I talked the battery supplier into sending me for free! The lifepo4 charger isn't the best, but it does work without any weird issues. Saved me $120.

Because my run times are so much better now, I don't have to charge as often. I want to keep things simple, so I'm resisting modifying or buying anything else, except to add an RXV plug to the new charger so I don't have to remove the battery cover, unplug the Anderson connector and hook the new charger up.

I may try a timer, which I already have, if I'm not going to be around to monitor the charge. I have been keeping charging limited to around 80% and recharge at 20%, roughly.

Don't know what your battery situation was before you switched, but I think you'll be pleasantly surprised at how well the new batteries work.
Good luck!
 
I finally got my "off the shelf" battery. And...it works. It fit in the tray perfectly (after removing the dividers...which are just held on with adhesive). I plugged it in and drove it around the yard for a couple of laps. I still need to mount a bracket or something to hold it down since I don't have the center bolt hole. And I will probably get a better charger. Anyway, for anyone looking for a simpler solution here is the guy in China I used (Mr Leo). He communicates very well and delivered as promised. The only issue I had was with FedEx...they failed to deliver it the last mile and I had to ultimately go to the local hub to pick it up.

1659146165854.png

1659145576118.png
1659145607919.png
 
110V 5A charger for $12.50 is awesome. If it works and you can wait overnight, why get a better one?

15S -- make sure you don't use the Ryobi charger.
 
That's an interesting looking battery, seemingly made for mowers, maybe Ryobi specific as it fit right into the tray? I hadn't seen anything like that during my research.

I fabricated a simple hold down at approx the center of the battery with a steel bar on top of the battery with a piece of all-thread on either side, holding it down to the frame. I had to add spacers to the bottom of the tray, as seen in the pic, as the battery was quite a bit smaller than the tray. I had to drill 2 holes in the frame for the all-thread.

My mower is the 100 amp zero turn.
 
Skabam287 said:
My first time hooking everything up I again got the one clunk and dead mower but I just unplugged and replugged the main Anderson connector and for some reason all was good after that.
Click to expand...
Did this problem ever come up for you again? I have the same setup (4x 100ah Ampere Time 12v batteries) and am also getting a clunk and then no power when I turn on the mower. When I disconnect and then reconnect the Anderson connector, I do get power again, but another clunk as soon as I turn on mower. I checked the voltage across each battery after the clunk, and they each had 13.x volts, except the one with it’s negative terminal hooked up to mower, so seems like it’s BMS is getting tripped. Before the clunk, I measure 53.x volts on the charging port, and the Ryobi charger does work (just quickly plugged it in to check). I also tried turning the key the other way to aux, which doesn’t cause a clunk or power to die, but also doesn’t turn anything on for the mower (no meter, no lights).
 
Last edited:
RipRiley said:
I finally got my "off the shelf" battery. And...it works. It fit in the tray perfectly (after removing the dividers...which are just held on with adhesive). I plugged it in and drove it around the yard for a couple of laps. I still need to mount a bracket or something to hold it down since I don't have the center bolt hole. And I will probably get a better charger. Anyway, for anyone looking for a simpler solution here is the guy in China I used (Mr Leo). He communicates very well and delivered as promised. The only issue I had was with FedEx...they failed to deliver it the last mile and I had to ultimately go to the local hub to pick it up.

View attachment 104692

View attachment 104690
View attachment 104691
Click to expand...
Hey @RipRiley, how is this setup working for you? Are you happy with it? How are you charging the battery? Can you post more details? What did you have to do to get this installed and up and running? Do you use a different battery gauge or the stock one?
 
RipRiley said:
I finally got my "off the shelf" battery. And...it works. It fit in the tray perfectly (after removing the dividers...which are just held on with adhesive). I plugged it in and drove it around the yard for a couple of laps. I still need to mount a bracket or something to hold it down since I don't have the center bolt hole. And I will probably get a better charger. Anyway, for anyone looking for a simpler solution here is the guy in China I used (Mr Leo). He communicates very well and delivered as promised. The only issue I had was with FedEx...they failed to deliver it the last mile and I had to ultimately go to the local hub to pick it up.

View attachment 104692

View attachment 104690
View attachment 104691
Click to expand...
Did you order this directly from them? I don't see this battery on their website.
 
Jakeman said:
Finally made the change! Yesterday I finished swapping the original batteries to this:

Also replaced the charge indicator:

Entertained the idea to build a 150 ah battery but the snow would be flying before I'd have it finished.

Wasn't exactly plug and play as the new battery needs to be secured differently. Got it finished yesterday afternoon, held my breath, and plugged the Ryobi charger in. No problems. New battery monitor showed a charge rate of 14.4 amps, which settled in at 13.5 after a short while. The monitor showed the battery as being pretty low in charge, 2 or 3 bars. Kept an eye on it for about 8 hrs until it reached 9 bars. Shortly after that the monitor started fluctuating a lot, I immediately unplugged the charger. The monitor read 90.1 amp hrs. and 90% charge. I have not calibrated the monitor so I know these numbers may not be accurate, but this was good enough for me.

Tried it out today. Mower worked fine, ran it for about 1 1/2 hrs. Monitor showed 53% remaining. I'm very happy with that! Original batteries would've been dead long before that.

The only thing I'm not sure about is, do I continue to use the Ryobi charger? I don' know anything about the BMS in the new battery, just that it claims to protect from overcharge, etc. I babysat it to hopefully avoid the problem AMDPower originally had with his.

I want to thank everyone here for their help and the information they shared.
Click to expand...
@Jakeman, what were the dimensions of the battery that you purchased?
 
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