Mobility Scooter upgrade from AGM to LiFePo4 questionsi

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YellowBuzzaroundEX

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My 24V mobility scooter is a Golden Buzzaround XLS-HD.
It's Dynamic R50 controller specs say:
Continuous current 14A (driving full throttle on level ground).
Max current 40A for less than 60 seconds (accelerating or driving up a steep ramp).

I think that means (when accelerating or climbing a steep ramp) controller can draw a max of 40A for 60 seconds, then controller reduces back down to its usual 14A draw.

Am I understanding the above correctly?

The stock batteries are two 12V 21AH AGM batteries in series to make a 24V system.

I want to upgrade to two 12.8V 30AH LiFePo4 batteries in series to make a 25.6V system.

Here is the LiFePo4 battery I found https://astrolithium.com/products/copy-of-astro-lithium-12v-30ah-lithium-battery

Scooter controller rated continuous current 14A.
Battery rated continuous current 30A.

Scooter controller rated max current 40A < 60 seconds.
Battery rated max current 60A < 3 seconds.

Would that battery work, or would my controller overload the battery causing BMS shutoff or other problems?
 
YellowBuzzaroundEX said:
It's Dynamic R50 controller specs say:
Continuous current 14A (driving full throttle on level ground).
Max current 40A for less than 60 seconds (accelerating or driving up a steep ramp).

I think that means (when accelerating or climbing a steep ramp) controller can draw a max of 40A for 60 seconds, then controller reduces back down to its usual 14A draw.

Am I understanding the above correctly?
Click to expand...
It depends on what they set it up to do. The wording could mean either:

--it automatically rolls back to prevent overload and damage.

--it requires the user to never exceed the max current for more than that 60 seconds or damage may occur.

By that wording, it's not possible to tell which one it means.

It would make much more sense for it to do the first, especially since there is probably no user interface for monitoring anything about the system other than battery charge state. But that does not mean that it actually works that way.

To find out which one it does, for certain, you would need to test it, with a wattmeter or other means of monitoring current from battery to controller, under conditions that would cause it to pull at least 40A for more than 60 seconds, and see if it automatically rolls back to 14A, or continues to pull more current.
 
Looks good. So you're into some serious upgrade.
Had a look at some tech specs of the Dynamic R-series controllers you said you have, and it says there that they can operate with up to 32V power source. If you charge you new Lifepo4 batteries full you should get 2*14.5V = 29V - the scooter should be noticeably faster after fresh charge because RPM goes up with the voltage.
Check the speed, maybe you could go back to smaller wheels and you'd have the torque increase you want.
As a bonus, the specs say there should be some max speed regulation potentiometer in the controller - if you're lucky you can get 10% more max speed.
ps you need new charger for lifepo4 batteries
 
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rafalg said:
Looks good. So you're into some serious upgrade.
Had a look at some tech specs of the Dynamic R-series controllers you said you have, and it says there that they can operate with up to 32V power source. If you charge you new Lifepo4 batteries full you should get 2*14.5V = 29V - the scooter should be noticeably faster after fresh charge because RPM goes up with the voltage.
Check the speed, maybe you could go back to smaller wheels and you'd have the torque increase you want.
As a bonus, the specs say there should be some max speed regulation potentiometer in the controller - if you're lucky you can get 10% more max speed.
ps you need new charger for lifepo4 batteries
Click to expand...
I might not need LiFePo4 batteries because I already have achieved good speed on level ground. I'm now just looking for approx 10% better hill climbing.

I'm going to next try the current/amp increases by adjusting controller settings (with my existing AGM batteries) as suggested in this other thread... Motor Size Upgrade Question
 
YellowBuzzaroundEX said:
I might not need LiFePo4 batteries because I already have achieved good speed on level ground. I'm now just looking for approx 10% better hill climbing.
Click to expand...
On leven ground the current draw will be much less than when climbing hills. More powerful batteries will be able to supply more current without the voltage sag that less powerful batteries can.
AGM are not known for their high current capability, and the controller cannot compensate for low battery current.
A well chosen LFP battery set could provide more amp potential, more capacity and hence more range.…You really need some data from an ammeter/wattmeter to understand what is happening on those hills.
 
G8trwood said:
Are there decent 12v lifepo4 in the 25-30ah range?
Click to expand...
I've seen a few 12V LiFePo4 in 25AH & 30 AH. However, my present thinking is that I doubt two 12V LiFePo4 batteries in series would stay balanced when charged at 24V in series. My steering column has only one 24V charger plug

My present thinking is if I was going to use LiFePo4 in a 24V scooter, I'd rather use one 24V battery ideally; or if battery box layout requires two batteries, then use two 24V batteries in parallel. I think then batteries would stay balanced.

I'm not an expert, but that's my present thinking based on research I've done.
 
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these are high capacity batteries so it will take some time before they go out of balance. You can check the voltage every few months and charge up one of the batteries to equalize. But true, if you have a choice to go with 24 battery at similar cost then it's easier.
 
I haven’t seen 24v - 36v batteries around in the smaller form factor. I have seen the 12v 20-30ah just not from known to me suppliers. Most seem to use a 30a bms, although a couple reference being able to push 50-60 forx seconds.

I have a multi-bank charger and would use that to charge in series. I think a 50ah would fit in chair, but was trying to drop weight a bit.
 
G8trwood said:
I haven’t seen 24v - 36v batteries around in the smaller form factor. I have seen the 12v 20-30ah just not from known to me suppliers. Most seem to use a 30a bms, although a couple reference being able to push 50-60 forx seconds.

I have a multi-bank charger and would use that to charge in series. I think a 50ah would fit in chair, but was trying to drop weight a bit.
Click to expand...

Canadian Battery (CanBat) makes a LiFePo4 24V 12A battery in the correct form factor for my scooter with free shipping, including to the USA. I could use and charge two of those in parallel.

www.canbat.com

24V 12Ah lithium battery - LiFePO4 Canada - Free Shipping!

24V 12Ah lithium battery for deep cycle applications including electric wheelchairs and mobility scooters. LiFePO4 free shipping Canada-wide!
www.canbat.com www.canbat.com

There's also a French battery company making same form factor LiFePo4 24V 15A, but they don't ship to USA. I'm sure there are also others in Europe, but probably none that ship to USA.

Canada and especially Europe are ahead of USA in their thinking for converting lead battery scooters to LiFePo4.
 
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