My Lifepo4 dies quickly

[1000watt]

I got a Vpower 36v 10AH A123 Lifepo4 from China. I charged it last night and took it for a spin and only got a few houses down the street before it hit the LVC and died. Is there a tester I can plug-in to the harness to check each cell or should I just start removing the tape?

 

[dnmun]

plug the sense wire cable back into the socket on the BMS.

you have 11 sense wires and 12 cells. the bottom of cell #1 is the B- spot on the BMS. the top of the #12 is the red wire P+ spot on the BMS.

put the battery on the charger, measure the cell voltages of each cell from #1 to #12.measure the first between B- spot and the first pin in the sense plug socket where it is soldered into the pcb.

measure each cell after that by putting the probes on adjacent pins, next is #2 which is between the first pin and the second pin, and so on up to the top and the last cell, #12 is between the top pin and the P+ spot. measure while charging. do not short the pins to each other with the voltmeter probe. that is very bad. stick the tip of the voltmeter probe into the solder at the base to make it stick. don't short them.

post up the list of cell voltages here on your thread. don't short the pins when measuring! measure while charging. use the 20V DC scale. the first pin is on the far left i think. verify by examination or with the voltmeter. put the red probe on the higher pin and the black probe on the lower pin, they should be positive voltage in that order.

 

[1000watt]

Okay thank you very much for taking the time to write all that. I will Check the voltages tomorrow.

 

[999zip999]

I put some shrink tube or tape on the probe and just let the tip show. Be careful not to short when checking.
1. 3.65v
2. 3.33v
3. ect.
What's with the A123's are they in that pack ?

 

[DAND214]

Vpower is still around?

After you measure the cell voltage charge the battery overnight and then check again. Charge and short runs in the beginning, then charge again.
I'm sure you've heard that before.

A123's? that's what i thought. Normaly Vpower uses crap 18650 sub standard cells.

Good luck.

Dan

 

[dnmun]

we won't know anything until he measures the channel voltages.

the one i got to work on had a totally dead first row and it never even worked. it was shorted out in the factory when they dropped it on the floor and shorted the first row positive to the case and killed the first row by draining to zero, even before it had sense wires and tape.

it was so poorly constructed that the big red and black wires, where they were supposedly crimped into the big connector, were never crimped, just inserted into the connector so that when i worked on it the connector just fell off.

 

[d8veh]

Those batteries are so easily damaged. There's virtually no protection for the cells. You only have to drop it on the table too hard, which is easy because they're heavy, and you can squish the cells, which shorts them out. When you've fixed it, add some extra foam around it.

 

[1000watt]

With charger (on) green light on (charged)

(1) 4.12v
(2) 4.48v
(3) 7.87v
(4) 11.97v
(5) 15.70v
(6) 19.07v
(7) 0v
(8) 0v
(9) 0v
(10) 0v
(11) 0v
(12) 0v

 

[dnmun]

that cannot be right. if you cannot measure the individual cell voltages there then go ahead and pull the shrink wrap or duck tape off the battery and take pictures and post them up here.

 

[1000watt]

that cannot be right. if you cannot measure the individual cell voltages there then go ahead and pull the shrink wrap or duck tape off the battery and take pictures and post them up here.

Yeah, cells 7 and up had no voltage.

 

[dnmun]

go ahead and strip it down since you gotta work on it for sure. then maybe we will see what happened.

 

[1000watt]

go ahead and strip it down since you gotta work on it for sure. then maybe we will see what happened.

ok thanks

 

[dnmun]

i still have some parts for them too, and maybe it won't be so bad when we look at it.

but i think your measurements are squirrely so i have hope it can be restored.

 

[1000watt]

The tape and glue is very sticky and hard to remove. I am working on it. :?

 

[dnmun]

the tape on the ends was stuck onto mine so tight that the metal straps that tied the cells together in parallel pulled apart at the spot welds when i peeled it up.

try to roll the tape off sideways, push down on the tabs as you peel it so there is not too much force pulling it off the end of the cell.

 

[1000watt]

the tape on the ends was stuck onto mine so tight that the metal straps that tied the cells together in parallel pulled apart at the spot welds when i peeled it up.

try to roll the tape off sideways, push down on the tabs as you peel it so there is not too much force pulling it off the end of the cell.

ok thanks for tip

 

[1000watt]

ok got most of the tape and cardboard off. I forgot to mention, when I got the battery from china just a few weeks ago I checked the voltage and it was 32.7v
So whats the procedure to check voltage? Looks like there are 6 groups of 6 batteries. Do you want voltage from each group?

 

[dnmun]

there are twelve cells of 3 cylinders wide each. the white plastic insulator around the neck is only on the positive end, to keep the anode from shorting to the case.

measure each cell, set of three, and post them up here. you can charge them while you measure but just need to know first how bad it is. start at the right side where the black wire comes off the bottom of the #1 cell.

Vpower is building them different now. using the big 26650s now?

 

[1000watt]

1. 3.50v
2. 3.52v
3. 3.35v
4. 3.54v
5. 3.51v
6. 3.34v
7. 3.36v
8. 3.59v
9. 3.37v
10. 3.36v
11. 3.49v
12. 3.41v

 

[dnmun]

all good, better than expected. put it on the charger and let it charge and charge until it hits 3.9V on any of those cells. do you have a wattmeter or ammeter you can use to measure the charging current? alligator clips to clip the voltmeter probes in the charging circuit? you could use the ammeter function of the DVM to measure the charging current that way.

set the meter to the 10A range and put the probe lead in the 10A spot on the front. if you use the ammeter at high currents other than the 10A set up then it will burn up the meter. this is where having two helps. way

 

[dogman dan]

Backing up a bit, Are you trying to use that 10 ah pack as if it was a 10c rated A123 pack? Because if you are, that might be why it seems to have no capacity.

In other words, are you trying to get more than 15-20 amps out of it? Looks constructed ok, but when I went to the site they listed only 2c lifepo4 for sale. Or at least I could not find a link to "A123's" despite some text about them on page one.

 

[1000watt]

I have a wattsup meter on the bike, im only pulling 20A. But I have a three level switch and I set it for 10A Max and battery was still cutting out.

 

[dnmun]

what are the voltages now after charging for a day? it should have charged up by now.

 

[1000watt]

what are the voltages now after charging for a day? it should have charged up by now.

I didn't have a chance to charge it yesterday because I had to leave the house and I didn't want to leave it unattended. I'm going to give it a good charge today and see how it goes.

 

[dogman dan]

Ok, I thought maybe you had a big motor and a 40 amps controller on it, thinking you bought an A123 pack.

But at 1c, you should be seeing 75% of expected capacity even from a v power pack.