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

[prophead]

I do still have the stock monitor hooked up...it doesn't really serve a purpose though, as it's not accurate, and the Vatrer came with its own that plugs right into a RS486 port on the battery.

As for the runtime, I haven't tested it thoroughly, but so far it's looking like I got a little more than the Ryobi had even in it's first season.

I got 3 acres to mow, and on the stock batteries in the first season, I'd end with 10-20% (which I reduced doing as it's bad for the batteries), this new one has ended with 20-30%

Of course the stock batteries going from season 2-3 started going under 20% before half the yard was done.

I am considering doing a "drop in" conversion with the Chins battery. The question I am hoping someone can answer is "What happens when the battery runs out?"

With the stock AGM and the stock monitoring systems, it will stop the blades but the mower will still drive, allowing you to return to the charger.

With a conversion, will this thing just die?

Thanks for any input?

 

[Supervstech]

I am considering doing a "drop in" conversion with the Chins battery. The question I am hoping someone can answer is "What happens when the battery runs out?"

With the stock AGM and the stock monitoring systems, it will stop the blades but the mower will still drive, allowing you to return to the charger.

With a conversion, will this thing just die?

Thanks for any input?

With the conversion... ya wont run out of energy...

 

[Vigo]

^ Definitely possible!

But its likely the stock controls will still work the same way. The drop in battery BMS will probably cut out at 10.0 or 10.5v, so as long as the stock mower controls disengage the blades higher than that, it should still allow you to drive across a lawn before cutting out for good.

If you really want to know youll probably have to hit that blade cutoff voltage while actually watching voltage to see what exactly that voltage is.

 

[Daniel644]

I am considering doing a "drop in" conversion with the Chins battery. The question I am hoping someone can answer is "What happens when the battery runs out?"

With the stock AGM and the stock monitoring systems, it will stop the blades but the mower will still drive, allowing you to return to the charger.

With a conversion, will this thing just die?

Thanks for any input?

The voltage curve on Lifepo4 batteries is quite a bit more severe then the stock SLA's from the facebook group i'm in, if you drain the Lifepo4 battery low enough to have it cut off you are stuck, as it doesn't have the "bounce back" that SLA's get.
This is simply what i've read, I haven't confirmed this for myself yet as I have yet to do a conversion on my Zero Turn, my Chins battery is being used as a battery expansion for my Power Station, I haven't put it in the mower yet and might not ever, if I can swing the budget to do the full 280Ah cells that I wanna do.

 

[sun walker]

kinda unrelated, but how good are these electric sit on mowers?
I know Ryobi is a cheap brand but <3 years of battery life seems a bit poor.
I have a large area to mow, looking at sit on (prefer robotic), seems like a no brainer to upgrade to an electric, any recommendations?

 

[Crowz]

kinda unrelated, but how good are these electric sit on mowers?
I know Ryobi is a cheap brand but <3 years of battery life seems a bit poor.
I have a large area to mow, looking at sit on (prefer robotic), seems like a no brainer to upgrade to an electric, any recommendations?

Does seem a bit short lifespan wise. But that may be how they were treated.

My agm's in my cub zero turn electric are 4 years old now and still perform like new. I did make sure not to discharge them to far the entire time which no doubt helped.

 

[Daniel644]

kinda unrelated, but how good are these electric sit on mowers?
I know Ryobi is a cheap brand but <3 years of battery life seems a bit poor.
I have a large area to mow, looking at sit on (prefer robotic), seems like a no brainer to upgrade to an electric, any recommendations?

not great to be honest, I got my mower with just enough time to do a couple mows before the end of the season of 2021, my first set of batteries where at half their capacity inside of the first year, got them replaced under warranty in 2022, in 2023 the mower started jerking (like as if something was binding up in the drive system) and then I heard a POP and smoke started coming out so I shut it off, it had blown 2 capacitors out of the potting on the master deck controller, the service tech ended up replacing every motor controller and the wheel drive motors by the time he got it running right.

outside of that, when you side by side compare them to traditional gas mowers the tires are smaller and narrower and the deck suspension design isn't great on hills, when my mower was down due to the blown caps I borrowed a neighbors gas regular riding mower, it was a much smoother cut on the grade changes (like where the sloping yard levels out around the house, it didn't scalp the grass like the Ryobi does). I've also noticed that once the voltages start to drop that on the zero turn one drive motor will be stronger then the other drive mower, in my case the left wheel motor is climbing the hill on the side of the house faster then the right wheel motor, so I have to max out the right and bump the left to get just enough power to climb the hill and not go into my fence. Also after just a few cycles on the new OEM Batteries it was already starting to bog in the tall grass worse then when it was new.

 

[Crowz]

The cub zero turn I have is great. Its not a cut down mower just to be electric. It comes in a gas and electric version frame wise so it works great ride and cut wise. The run time on 4 100ah agm batteries is great too.

This is what I have :

Cub Cadet RZT S Zero Electric Zero-Turn Rider | Cub Cadet US

Find parts and product manuals for your RZT SX 42 Electric Zero-Turn Rider. Free shipping on parts orders over $45.

www.cubcadet.com

I think mine is discontinued though

 

[augiedoggy]

My 4 agm batteries still tested and worked fine even though they were 4 years old. I sold them for $50 to a guy who wanted them for a scooter.

I could tell by the time I was finishing up my lawn though that they were nearing the point of needing a charge. The issue with the ryobie is it would allow the operator to run the batteries down below 50% state of charge which damages the agm batteries. After replacing the 4 75ah batts with a single diy repurposed fiat 500 64ah pack I found I used about 18% of a charge to mow my lawn... So that means I got about 3 times the useful run time out of my lithium battery vs the AGM's. Also the 56-53v or so I was getting out of the NMC 14s pack I have now translated to a strong running mower overall it no longer bogged as easily in thick of damp grass which is a huge win for me. Ive since rearranged so of my packs and needed the fiat cells for a larger golf cart 72v upgrade and swapped in a 16s 90ah lifepo4 pack which also works great.

I have a lawn thats about 1/3 acre but has a lot of fenced areas and such to work around. I had a gas rider before this and I have to say the electric took some getting used too. ironically even though my old mower was a 42" deck and my new mower is a 38 I get my lawn done much quicker with the ryobie. It is weaker when it comes to tall thick neglected or wet grass though. Since I have solar on my roof and havent had an electric bill in almost 5 years the electric mower made sense for me. Plus I paid $380 for it used and broken which meant about $700 once I replaced the controller.

 

[yabert]

a single diy repurposed fiat 500 64ah pack

Cool! Pictures? Year? Size? Price?
Thanks

 

[augiedoggy]

Cool! Pictures? Year? Size? Price?
Thanks

They were these packs wired in series but I got them at b hookup.... I cut the last cel off from the series but left it in the pack for compression reasons.... ends up being a 48v pack for under $500 shipped.

Fiat 500e Battery Packs 5S/6S w/ Samsung Li-ion Cells

PLEASE READ THE DESCRIPTION CAREFULLY. Shipping to Lower 48 USA states via Fedex Ground only. Plz note that we can't ship to PO boxes. No international shipping including Hawaii, Guam, Puerto Rico. Non-USA customers click here. High-quality Fiat 500e EV Samsung cells! Limited batch, so act...

jag35.com

 

[Xebec]

I have been following for a while, is an “easy” option at this point for the larger Ryobi’s:

1. Buy the CHINS battery (or LiTime or something recommended by Will Prowse) - 48V, 100Ah with Bluetooth, and a charger. Charge new battery to 90-100%.
2. Remove old batteries
3. Secure new battery in place with wood and straps/padded metal brackets
4. Rework the charge port to accept the new charge port plug, wire charge port plug to new battery.
5. Disconnect the battery % gauge (does it matter?)
6. Wire the blue charge port wire to hot on the battery (bypassing the charger lockout)
7. Attach the regular wiring harness as usual (skimming - looks like blue wire from the mower electronics also connects to positive).
8. Use a Bluetooth app to monitor battery percentage while mowing

Is that it?

 

[augiedoggy]

I have been following for a while, is an “easy” option at this point for the larger Ryobi’s:

1. Buy the CHINS battery (or LiTime or something recommended by Will Prowse) - 48V, 100Ah with Bluetooth, and a charger. Charge new battery to 90-100%.
2. Remove old batteries
3. Secure new battery in place with wood and straps/padded metal brackets
4. Rework the charge port to accept the new charge port plug, wire charge port plug to new battery.
5. Disconnect the battery % gauge (does it matter?)
6. Wire the blue charge port wire to hot on the battery (bypassing the charger lockout)
7. Attach the regular wiring harness as usual (skimming - looks like blue wire from the mower electronics also connects to positive).
8. Use a Bluetooth app to monitor battery percentage while mowing

Is that it?

That will work. and 50ah is plenty for the 480rm mower since it never draws 50amps (typically its below 30amps when mowing ) and a 50ah lifepo4 battery will give about the same runtime as a 100-125ah lead acid.

I connect my charger directly to my pack and dont bother with the onboard port. I run the charger power cord through the steering wheel so I never forget to disconnect before using.

 

[Xebec]

That will work. and 50ah is plenty for the 480rm mower since it never draws 50amps (typically its below 30amps when mowing ) and a 50ah lifepo4 battery will give about the same runtime as a 100-125ah lead acid.

I connect my charger directly to my pack and dont bother with the onboard port. I run the charger power cord through the steering wheel so I never forget to disconnect before using.

Thanks! Installing the charger in the mower makes sense. Though assumes the charger is OK with hours of vibrations.. which it probably is.

I have the 115Ah Ryobi 54” (forget exact part #) and up to 3 acres to mow including a long / wide hill. I’d also like the LFP battery be available as an emergency backup for powering a fridge / other stuff for some time during an outage (connected to an Ecoflow Delta through the solar port).

Is the 50Ah LFP = ~ 100Ah Lead Acid because of discharging losses, and that you shouldn’t really discharge a LA below 30-50%?

 

[Hedges]

You can discharge AGM to 70% ~ 80% DoD. Gives similar Ah of cycle life, fewer cycles. Which is much less than LiFePO4; do you mow once a week some season of the year, or do you mow multiple times per day in a business?

I think people report deep cycling quickly killed mower batteries, but those who recharged after partial discharge had much better results. I think a voltmeter to indicate when to recharge, rather than running out of power first, would be good.

 

[jberger]

On the Ryobi's I think it's a combination of discharging too low and not charging often enough.
I put mine on the charger as soon as I'm done with it, and it's connected to a smart plug that power cycles the charger every morning to force the charger to restart a cycle and top them off everyday.

 

[ghosta]

On the Ryobi's I think it's a combination of discharging too low and not charging often enough.
I put mine on the charger as soon as I'm done with it, and it's connected to a smart plug that power cycles the charger every morning to force the charger to restart a cycle and top them off everyday.

 

[ghosta]

No, the batteries certainly do not need topping off every day! Once they are charged just let the charger do its job.

But you are correct that deep discharges and not recharging soon enough will shorten battery life.

Seems battery quality is another factor. Ive just retired a 20 year old Fullriver agm battery from my camper van.

 

[jberger]

If you leave it plugged into the factory charger, it doesn't appear to float.
The batteries appear to self discharge, and become unbalanced.
Triggering the charge everyday seems to keep them in much better balance.
This has been my experience with the factory charger and factory batteries.

 

[ghosta]

If you leave it plugged into the factory charger, it doesn't appear to float.
The batteries appear to self discharge, and become unbalanced.
Triggering the charge everyday seems to keep them in much better balance.
This has been my experience with the factory charger and factory batteries.

Im not sure what you think you are achieving with your charging plan but it certainly wont "balance" the batteries!

The batteries are actually Lead Acid batteries...what you could do is charge up each battery individually with a 12v charger from time to time. It does involve a bit of work to do this.