Weak moped after SLA to LiFePO4 conversion

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Odox
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Last seen: 8 years 3 months ago
Joined: Saturday, August 28, 2010 - 02:34
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Weak moped after SLA to LiFePO4 conversion

Hello folks, I'm working on a conversion of my moped from the SLA to LiFePO4. Everything has gone well except accelation and range. The moped is considerably worse than before. I want to know if it is normal for a 1500W hub motor moped to drop the voltage from 57.8V to approximately 42V when starting from a flat surface? The controller is set to not pull more than 30A and 36,8V from the battery. I have charge the pac about 15 times since I installed it. The voltage of each cell is 3.62V-3.67V and 3.05V-3.16V after a 20 min drive. I will make a log of each cell during drive when time will be on my side. My guess is that the controller holds back when the voltage drops.

My new setup is:
16 Foxx Power 20Ah batteries
Evassable Capacitor-16S-30A-BMS
240w Charger 58.4V
Kellycontroller KBS72120

marylandbob
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Points: 524
Re: Weak moped after SLA to LiFePO4 conversion

Looks as if your battery is too small! Try doubling the capacity, to at least 40 AH. The cells you are using apparently do not take well to high-rate discharge, so adding another identical pack in parallel may fix the problem.

Robert M. Curry

LeftieBiker
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Joined: Saturday, July 9, 2011 - 04:36
Points: 886
Re: Weak moped after SLA to LiFePO4 conversion

I think the other posters are right. SLA packs have lots of disadvantages, but they do tend to put out more amps at once for a given capacity.

Odox
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Last seen: 8 years 3 months ago
Joined: Saturday, August 28, 2010 - 02:34
Points: 4
Re: Weak moped after SLA to LiFePO4 conversion

Regarding the range. I came with ease 35-40km on one charge with 38Ah SLA batteries. With the 20 Ah LiFePO4, I barely make 17-18km. (got 16km to my work)

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