full charge voltage for a123.

by bike4life » Jul 16 2021 8:19pm

running / full charge voltage for a123 cell...\

I have an 8p, 12s, a123 22650 / lifepo4 pack running my ebike.

I am charging it via a switchmode supply (36v DC, 30A) hooked up to a boost converter which steps it up to 43.2V (3.6v per cell x 12 = 43.2). This allows me currently due to the rating of the 1000w switchmode to charge the pack at 1000w (roughly 1 C or 2C idk someone else can calculate that), as i hooked my clamp meters and saw the switch supply was drawing 10 amps AC, roughly 1200w.

After around 30minutes from dead batteries (36v), the BMS trips and all charging stops, yeidling a pack voltage of 42.5v.

Is 42.5v the real full charge voltage for lifepo4. I thought it was like 44v? Its weird. I thought the BMS was weird so i removed the bms and charged it without and my switchmode supply would cut out after a few minutes (fans stopped, drew like 1/2 amp) as i assume the battery became infinite resistance / full charge and would not take any more juice.

I currently purchased 2 a123 pack from batteryhookup last year and wish i bought like 10 of them. Do you know when / if batteryhookup will add a123 packs in the future.

LAST QUESTION URGENT: I am thinkinf of having a hybrid bike. The a123 cells and bms are currently on a trailer which hitches on seatpost. The switching supply and boost converter and a123 pack is screwed into the trailer, meaning my charger and everything is on the trailer. I can fit a 2300w inverter gen on the trailer. I can basically have the battery charging all the time when i am runnning the ebike for infinite range. My question is would this degrade battery capacity. Someone i heard said the float charge for a123 is 3.45 volts, so for my hybrid infinite range should i lower the voltage to 3.45.... THANKS!!!!!!!!!!!!!!!!!

I have a second lifepo4 pack which i thought of paralleing in but i am worried that the generator infinite charging or what not float charging when i ride, will degrade capacity so i am keeping it as a spare.

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for reference, i get roughly 10-12 miles on this pack at 25-27mph top speed as the 40v is slower and the ebike motor is a 48v 1000w hub motor so its wired probably for a higher voltage idk? I feel like thats a little low as today i had to walk this thing home 5 miles (when i installed the hub motor i didnt install a free wheel cassette as i dont intend on pedaling its an ebike for sakes) since it ran out of charge which is why i want the infinite range generator hybrid thing or at least use the generator and flip it on when its running low so i am not stranded.

42 Volts is the normal charge level for a new LiFePO4 battery. It is like to decrease a bit with age.

I can fit a 2300w inverter gen on the trailer. I can basically have the battery charging all the time when i am running the ebike for infinite range.

Click to expand...

Just what are you planning to use to feed power to the inverter ... solar panels, ice generator, really long extension cord?
Perpetual engines and infinite power does not exist ... not even in the Star Trek movies.

its an inverter generator. I think infinite power can exist assuming an infinite universe, then it must have an infinite amount of mass assuming the concentration of mass / volume of space does not converge to 0, and since E= mc^2, we can conclude infinite energy.

we know our observable universe is like idk 100 billion lightyears, but the unobservable part very well could be infinite.

i think there is a lot we do not know about physics, in that, i wouldnt be suprised if infinite energy or something bizzare existed, but that doesnt mean i will fall for some perpetual motion scam device.

the problem i think with perpetual motion is entropy increases. if it is proven that this need not always be the case, perpetual motion would appear possible.

Are you talking a 12S LFP pack?

Anything above 41V will get you to Full.

Getting closer to 43V will not accomplish anything, and reduce cell longevity.

Your BMS may require a certain minimum to start balancig,

IMO if higher than say 41.5V for mor than an extra half hour once a week,

that means do not use that BMS for balancing