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

[Jakeman]

In believe what jberger was referring to was the original AGM batteries. Once the original charger reached full charge it didn't "float" charge them, that's why many would periodically disconnect, then re-connect the charger to keep the batteries topped off. I experienced this myself with my Ryobi zero turn...before I switched to Lifepo4's.

I don't believe this would balance anything, just top them off. Charging each individually would be best, but a real pain.

 

[augiedoggy]

In believe what jberger was referring to was the original AGM batteries. Once the original charger reached full charge it didn't "float" charge them, that's why many would periodically disconnect, then re-connect the charger to keep the batteries topped off. I experienced this myself with my Ryobi zero turn...before I switched to Lifepo4's.

I don't believe this would balance anything, just top them off. Charging each individually would be best, but a real pain.

Well if that was true which it may be that having the charger recycled would indeed help ensure the lagging batteries are given more charging time and it would improve "balance"
The timer trick is used often with golf carts since those chargers work the same way now and the batteries start self discharging once the charger is turned off.

To be clear on my post above I dont have my lithium charger installed onboard. I have the old fashioned red and black clips and just connect them manually to the posts which I have facing the rear of my cart right now. I have purchased xt60 connectors and if I dont wire up my original port ill use them eventually. honestly I will most likely just throw a couple of my extra solar panles on my garden shed roof and use one of my left over mppt boost charge controllers left over from my solar powered golf cart build to charge the mower since I dont have electricity in my shed and only mow once a week.

 

[Jakeman]

Well if that was true which it may be that having the charger recycled would indeed help ensure the lagging batteries are given more charging time and it would improve "balance"
The timer trick is used often with golf carts since those chargers work the same way now and the batteries start self discharging once the charger is turned off.

To be clear on my post above I dont have my lithium charger installed onboard. I have the old fashioned red and black clips and just connect them manually to the posts which I have facing the rear of my cart right now. I have purchased xt60 connectors and if I dont wire up my original port ill use them eventually. honestly I will most likely just throw a couple of my extra solar panles on my garden shed roof and use one of my left over mppt boost charge controllers left over from my solar powered golf cart build to charge the mower since I dont have electricity in my shed and only mow once a week.

Can't argue that, especially since I'm no battery expert. I just go by my own experiences and what I read. Thought I read somewhere that batteries connected in series will be limited during charging to what the weakest battery will charge to and the healthier batteries won't get to their full potential, unless each is charged separately. I suppose if all batteries are very close to equal, there shouldn't be a problem with balance?

On my conversion I just wired a 48v golf cart plug to my lithium charger and charge thru the existing port.

 

[augiedoggy]

Can't argue that, especially since I'm no battery expert. I just go by my own experiences and what I read. Thought I read somewhere that batteries connected in series will be limited during charging to what the weakest battery will charge to and the healthier batteries won't get to their full potential, unless each is charged separately. I suppose if all batteries are very close to equal, there shouldn't be a problem with balance?

On my conversion I just wired a 48v golf cart plug to my lithium charger and charge thru the existing port.

That is true when we are talking about lithium batteries with thier own bms wired in series baecause when one battery reches full charge the bms shuts off continuity to prevent over charging and then all the charging to the other batteries is stopped.
lead acid chargers work differently as well as the batteries. theres no bms to shut them off and the chargers typically have some sort of absorption stage for the batteries to fully charge and catch up to each other in soc.

 

[ghosta]

This is the self discharge graph for the original Leoch batteries. You can see that it takes months for any significant self discharge unless the batteries are stored in a hot environment like a boiler room for example. Whether or not the mower is used regularly, leaving the charger connected as recommended by Ryobi will keep the batteries topped up perfectly...there won't be much, if any work at all for the charger after the inital charge.

 

[augiedoggy]

So I'm just sharing a quoted post from a golf cart forum I belong to because i feel its relevant here. I was previously unaware of these differences between AGM and FLA.


"AGM batteries in series have a similar problem to lithium when charging them, regardless of the charging profile.

AGM do not like to be overcharged and their life will be considerably reduced by doing so. When charging batteries in series one or more will always reach a high voltage first. Since the whole pack is still at a lower voltage, the charger keeps going, pushing that one battery beyond its safe maximum voltage, shortening its life. Lithium batteries have BMS’s to prevent this, AGM don’t. Flooded Lead Acid can tolerate being overcharged much better.

As already suggested, look at Lithium, but once again, not 4 x 12v, one (or more) 48v"

 

[tmag14]

I've read through what I can on this rather long thread and appreciate all the information. My 54" 48v Ryobi will not even mow the shortest of grass, my wife basically uses it as a glorified golf cart with our 3 year old. It seems that a basic "drop in" is possible, is that true with no other modifications? If so can someone please post the items needed for this (just a battery?). I love DIY but am cramped for time as I change jobs. I just need to mow my 3-4 acres, please!

 

[Jakeman]

The most basic"drop in" solution would be 4 - 12v lifepo4's, the same size and post configuration as your originals. The new batteries need to be balanced before use, according to the experts. I believe this would come closest to "plug and play", other than going with 4 original AGM's.

I have the 42" version, so I don't know if the dimensions are the same as the 54", but the one battery solution will require some modifications. My "one battery" conversion required a fabricated hold down and modification of the battery cables. Wasn't difficult, but not "drop in".

Hopefully someone who has done the conversion on a 54" will chime in.

 

[tmag14]

The most basic"drop in" solution would be 4 - 12v lifepo4's, the same size and post configuration as your originals. The new batteries need to be balanced before use, according to the experts. I believe this would come closest to "plug and play", other than going with 4 original AGM's.

I have the 42" version, so I don't know if the dimensions are the same as the 54", but the one battery solution will require some modifications. My "one battery" conversion required a fabricated hold down and modification of the battery cables. Wasn't difficult, but not "drop in".

Hopefully someone who has done the conversion on a 54" will chime in.

The one battery drop in would work too for me.

 

[Jakeman]

I believe the 54" is 115ah. Haven't seen 115ah in a single battery, however I've seen 120ah ones. You're not limited to 115ah, you can go higher but that'll come at a cost.

 

[Supervstech]

I believe the 54" is 115ah. Haven't seen 115ah in a single battery, however I've seen 120ah ones. You're not limited to 115ah, you can go higher but that'll come at a cost.

Yup

 

[jberger]

Upgraded my Ryobi riding mower (not zero turn) over the weekend with (2) Eco-worthy 48v 50ah metal cased batteries.

48V 50Ah Stackable LiFePO4 Battery | ECO-WORTHY

ECO-WORTHY LiFePO4 48V Lithium Iron Phosphate Battery has twice the power, half the weight, and lasts 8 times longer than a sealed lead acid battery, no maintenance, extremely safe and very low toxicity for environment. Our line of LiFePO4 offer a solution to demanding applications that require...

www.eco-worthy.com

They were on sale for $368 each, with free shipping, so the deal was too good to pass up. The OEM AGM batteries were no longer strong enough to let me cut the front and back yards in a single day. The 50ah packs fit easily in the battery tray for the riding mower, with plenty of room to spare and the mower runs without needing a pre-charge resistor or rewiring.

I gave it test run yesterday, and cut the entire yard today without issue. My back yard has a steep grade and the mower had no issues with power or BMS tripping at all. I might have been able to get away with just 1 pack, but I wanted the extra amps for the hills.

I think the biggest difference is the power of the blade motors, especially in heavy grass. I overseeded with annual rye and the AGM's would really bog down on the hill when it hit the dense grass, the blades would sometimes quit on the really thick patches. That issue is gone with the LFP packs, and the resulting cut quality shows up as both blade motors resist bogging down when it's really thick.

I am using the SC-48 charger with the new packs, but I don't leave it unattended. It's plugged into a smart switch and I've been testing how long the pack needs to charge based on voltage. I'm just charging up to around 80% since they appear to have power to space. If you thought the on board SOC meter was bad with AGM, you should see how useless it is with LFP. It never moved off 100%. The on board volt meter consistently reads .1 volt off from the packs themselves, I assume there is some averaging going on in the controller.

Just wanted to share for those who might be looking for options.

 

[Xebec]

EDIT: Epoch battery below is too tall for the ZT540e. The max Z height of the battery setup in the ZT540e is somewhere around 9".

Is there any reason this battery wouldn’t work well for a ZT540e (54”) Ryobi?

48V 100Ah LiFePO4 Battery - Heated & Bluetooth

Discover the 48V 100Ah LiFePO4 Battery with internal heating, Bluetooth compatibility, and IP67 rating. Perfect for deep cycle applications in marine, fishing, and mobile power. 11-year manufacturer warranty.

www.epochbatteries.com

It’s definitely on the more expensive side, but 120A continuous output, 200A for 60 seconds peak discharge (= no inrush device needed?). Heated, Bluetooth app, and from the reviews by Will Prowse - the internals look durable. (Even strapped down these batteries receive a lot of vibrations in riding mowers). I don’t like what I’m seeing about Chins lately, and Epoch seems a little better than Vatrer for warranty and company longevity.

Also, are all battery terminals the same size for batteries like this? (I.e. can I re-use the cables / terminal connectors from the existing Ryboi 12V batteries and shunt to this?).

 

[tmag14]

Upgraded my Ryobi riding mower (not zero turn) over the weekend with (2) Eco-worthy 48v 50ah metal cased batteries.

48V 50Ah Stackable LiFePO4 Battery | ECO-WORTHY

ECO-WORTHY LiFePO4 48V Lithium Iron Phosphate Battery has twice the power, half the weight, and lasts 8 times longer than a sealed lead acid battery, no maintenance, extremely safe and very low toxicity for environment. Our line of LiFePO4 offer a solution to demanding applications that require...

www.eco-worthy.com

They were on sale for $368 each, with free shipping, so the deal was too good to pass up. The OEM AGM batteries were no longer strong enough to let me cut the front and back yards in a single day. The 50ah packs fit easily in the battery tray for the riding mower, with plenty of room to spare and the mower runs without needing a pre-charge resistor or rewiring.

I gave it test run yesterday, and cut the entire yard today without issue. My back yard has a steep grade and the mower had no issues with power or BMS tripping at all. I might have been able to get away with just 1 pack, but I wanted the extra amps for the hills.

I think the biggest difference is the power of the blade motors, especially in heavy grass. I overseeded with annual rye and the AGM's would really bog down on the hill when it hit the dense grass, the blades would sometimes quit on the really thick patches. That issue is gone with the LFP packs, and the resulting cut quality shows up as both blade motors resist bogging down when it's really thick.

I am using the SC-48 charger with the new packs, but I don't leave it unattended. It's plugged into a smart switch and I've been testing how long the pack needs to charge based on voltage. I'm just charging up to around 80% since they appear to have power to space. If you thought the on board SOC meter was bad with AGM, you should see how useless it is with LFP. It never moved off 100%. The on board volt meter consistently reads .1 volt off from the packs themselves, I assume there is some averaging going on in the controller.

Just wanted to share for those who might be looking for options.

Did you have a code to get that price? Showing $549 now, says sale too.

 

[Xebec]

Upgraded my Ryobi riding mower (not zero turn) over the weekend with (2) Eco-worthy 48v 50ah metal cased batteries.

48V 50Ah Stackable LiFePO4 Battery | ECO-WORTHY

ECO-WORTHY LiFePO4 48V Lithium Iron Phosphate Battery has twice the power, half the weight, and lasts 8 times longer than a sealed lead acid battery, no maintenance, extremely safe and very low toxicity for environment. Our line of LiFePO4 offer a solution to demanding applications that require...

www.eco-worthy.com

They were on sale for $368 each, with free shipping, so the deal was too good to pass up. The OEM AGM batteries were no longer strong enough to let me cut the front and back yards in a single day. The 50ah packs fit easily in the battery tray for the riding mower, with plenty of room to spare and the mower runs without needing a pre-charge resistor or rewiring.

Just wanted to share for those who might be looking for options.

Just curious - do you stack these on top of each other, or side by side? And did you just make your own cables for running in parallel?

These seem like a better bet than the Chins given some of the quality issues posted recently

 

[jberger]

Just curious - do you stack these on top of each other, or side by side? And did you just make your own cables for running in parallel?

These seem like a better bet than the Chins given some of the quality issues posted recently

I did just stack them, with a couple of strips of industrial velcro on top/bottom, then used a ratchet strap to make sure they are secure in the battery tray. This let me just slide the entire pack tray in/out as needed when finalizing the setup. It also means I can pull the entire setup out if needed later.
I did NOT use the top locking frame with the center bolt, the tray is fixed in place with the bolts at the rear of the frame.
For the cabling, I reused the anderson connector and cable from the original battery, then a couple of jumpers I had in my spares pile. Just needed (2) 6" or 8" jumpers in addition to the OEM wires to complete the stack.

The code has probably expired, at the time it was "president20" for Presidents Day.

In regards to the quality of the pack, here's an interior pic with the insulating sheet removed. I'm happy with the physical packaging, I hope the BMS holds up.

 

[Xebec]

Thanks - which model ryobi are you running? (Or at least what was the original capacity battery?)

 

[jberger]

Thanks - which model ryobi are you running? (Or at least what was the original capacity battery?)

RM-480-E with the 100ah pack.

 

[Supervstech]

Heh... ya think this is a popular upgrade?

 

[prophead]

Well I did it. I purchased and installed this CHINS battery https://www.amazon.com/gp/product/B0B96ZDVW8/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&th=1 into my Ryobi ZT540E.

The mower works as expected. However I have 2 issues that I am hoping someone on here can help with.

1. The battery meter is "stuck" at 100%. I anticipated this so had also purchased this meter https://www.amazon.com/gp/product/B0BM3S8N6D/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&th=1
which is supposed to work with LifePO4 batteries. However it inspires zero confidence, having a firmware update that "successfully" updates but then shows as an available update again in an infinite loop, battery percentages that get stuck at 0, etc. So it's going back. Does anyone on here have recommendations on a battery guage? Ideally I would like to be able to remove the old guage and replace it with something that also has an hour meter. Also, will I need a shunt to get accurate readings?

2. My CHINS battery Bluetooth doesn't appear to work. I installed the BAT-BMS app from the Play Store however the instructions are a bit hard to decipher. This is what it says "Search the battery Bluetooth number by mobile phone". I assume when I open the app, it should show the battery as an option to connect to? However, nothing shows up. if I am supposed to be entering a code of some kind where do I find it? Does anyone on here have experience with these CHINS batteries Bluetooth that can chime in with what I am doing wrong?

Below are some pictures of the battery tray. I modified the original bracket to fit the CHINS. Would it be a good idea to add some cushion underneath or are these batteries robust enough that it isn't necessary?