how on earth am i to charge one cell?

well after charging the entire pack all of them are not 3.44 volts except one which is 3.4, so i should charge that one alone right?
(shouldn't it be 3.6 ? or maybe because it's not balanced)
 
if you sit and watch. But as I said 3.4 to 3.45 and to to 3.5v or 3.59v. is about as full as a cell will take. Or you can full charge to3.8v with the bms to let the bms draw down and balance to 3.6v. But the hair between 3.5 and 3.6volt or 3.8 is small. As you monitor over time and see or many just a little more but how cares on 1,000 cycles or much lesss.
Boil boil troll in trouble.
 
but i don't get it ,if all the cells are full how come i keep getting only 15ah. and not 18?
 
first of all ALL it is not your job to test a battery till it's limit's and why ? It's a 1,000 cycle battery and you wake it up in one charge from the dead ? How would you fill ? Oh yes ten totally discharge on a 1,000 plus cycle battery. You should wake upGive it some cycles and time or try. No Macdonalds and plus cheese no mustatd ? tryl and let it breach first.
 
Do you mean to tell that the several discharge process of a new battery can mean the difference if 3 amp? How many discharge cycles are we talking about?
 
No I'm telling you to do the next cheapesy bthing and balance all the cells with the charger and bms and give it a time to fill up. And don't run it to the lowest level before dischargeing that low. Got it. First fill the cells.
 
FWIW, it only takes one bad cell in the entire package to cut your capacity of the entire pack. Each cell in each group of parallel cells is good for 2.5 ah or whatever, so one bad one cuts the entire packs capacity by that much.

So it's not unheard of at all, for packs made from so many cells to have one weak one sneak in. It may have passed initial testing, but then developed a problem in just a few cycles.

But at least some of your cells should be good enough, for some of your cell groups to charge to 3.65v, and then hold at least 3.5v overnight.

However, the b6 will slightly undercharge the battery ( to 3.5v per cell I think). Balance it up, then put it back on the big charger, and see if you can get 58v out of it overnight( 3.6v).

If you measured 15 ah on the very first cycle of a brand new pack, that is no surprise at all. It can take 2-3 cycles to get new cells to charge fully. So I tend to say give it 5-6 light discharges and long recharges to perk up and balance the pack. You see the same thing to some extent with old packs that have been stored for quite some time as well.
 
emaayan said:
but i don't get it ,if all the cells are full how come i keep getting only 15ah. and not 18?
Click to expand...
I don't know about that particular battery, but if the cells themselves total up to 18Ah for 100% depth of discharge, from absolutely full, then with a BMS on there it's easily possible for it to only give you a portion of the full capacity. The BMS may well be set for an HVC that is lower than the absolute max capacity, and for an LVC that is higher than the absolute lowest discharge, in order to let the battery have a longer lifetime.

AFAICR my old used Vpower/CammyCC LiFePO4 pack was like that, after I'd pulled the bad cells out of it.


But another possibility is that you have a runt cell or group (or several) that don't actually have full capacity--to test that you'd monitor the voltage on each group during discharge, and as it gets lower and lower as you use it, you'll start seeing some groups that dip a lot lower than others in voltage under heavier loads, and end up at lower resting voltages when the pack is empty.

You'll also probably see higher voltages on those groups during charging, at least during the higher-current portions, because their resistance is probably higher.


There's lots of battery repair and build threads discussing all this if you need further explanations. ;)
 
ok, i'll accept that it might not allow fully usage of the battery, but 3 AMPS of 18.4 is like 16% , that's rather an over kill for a battery life time.
 
you have to put the battery on the charger and let it charge to full voltage and balance the pack. you have one cell that has never fully charged up because you don't leave it on the charger. measure all the cell voltages while it is fully charged and post them here. measure while it is charging.
 
that's what i did, after the full charge all cells groups were 3.44 volts except one which was 3.40, what i'm doing is charge each group individually up to 3.5 and then charge them back with the charger.
 
tell me about it, after i finish charging, if i wait a while the voltage begins to drop slowly..
 
That's not good. That smells like worn out or defect cells to me. Which would naturally have less capacity, since "full" for them is less capacity that full for good cells.

There is surface charge (above 3.5v), but good cells should charge to 3.6v or more, if they are offered the voltage. Then surface charge may dissipate, but good cells won't drop below 3.5v by much.
 
what, ALL of them are defected? i just finished single charging each cell up to 3.55, i then charged the whole pack a little more until the charger stopped at 57.4 volts. (didn't check the specific voltage of cell.

i'm gonna leave them as they are for the night, see by how much if any will it drop.

my old battery had the same effect, it would charge up to 58 volts, then it would slowly drop down to 54-53. these were samsung 18650
 
If no lower than 3.45v or ? More the better. It dosn't give you capacity. Then there's I.R.
Writing down a list helps over time.
1. 3.45v
2. 3.55v
3. 3.50v.
ect.
Plus i like voltpheakes single cell charger they stop at 3.60v or 3.65v. great for lifepo4.
 
There are plenty of examples of scams out there with A123's. Old can look good as new, and that label makes em gold.

Not accusing your vendor. He may have been mislead. Maybe I'm the confused one, are these supposed to be A grade new cells?

I'm just saying, it sure doesn't sound to me like how A grade new A123 cells would act. Ought to charge to 3.65 if your charger is not the problem. Then if NEW, they should hold that overnight, till you touch the throttle. Only after some use would A grade cells of that quality be expected to not hold a charge of at least 3.5v.

If not brand new, then it's a question of just how old. We all know good cells get sorted out of packs with one or two bad cells. They may work great for a long time, but never act like new cells.
 
I dunno, it's a matter of opinion, as long as they get to 3.5v while charging, they are fully charged... ( you might be able to get a few mah into them over this, but it's almost insignificant )

Cells that do not hold 3.6v overnight sitting idle does not mean they are bad, i have a bunch of A123 M1 cells from dewalt packs that drop to 3.4v after a few hours off the charger and they deliver their claimed 2.3ah each. ( + ~ - 100 mah )
 
Mybe you can tell us the story on this battery. Where did you buy ? From what vendor ? You have a second meter ? It easy for us to see voltage as.

1. 3.45v
2. 3.55v
3. 3.49v



16. 3.55v
 
well i can tell you that after leaving the battery for a whole day, un-connected all the cells are still at 3.55 volts, although i initially charged up to 57 volts it's not 56.8, if' that's not balacned i don't know what is.

the story of teh battery is rather simple, i heard that a123 cells are very good batteries, and i heard that they went backrupt, so i figured i'd better order them before they run out. but i didn't want any block size battery on my behind, as i hate to not use the real-estate triangle i have, so i went to a123rc as i figured they hold these batteries. after ordering a few cells to see if they are legit, we went back and forth about the maximum triangle shaped battery we could fit, and they came up with 16s8p configuration, however for the bms, i didn't want to use their's because cellman was selling smaller and better ones spec wise, so i bought it from him and had him send it directly to them, after they did all the testing on the bms and cells, they send it to me.
i also ordered a 10amp charger, when initially connected to the battery ,sparks flew, and the charger stopped working, when i opened the battery i noticed they didn't place a pre-charge resistor on it.
 
There's no switch on charger
 
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