how on earth am i to charge one cell?

emaayan

emaayan

100 kW
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israel
from all of this?
20130820_193454.jpg
so i need to use the imax b6 charger, but do i need to seperate everyone here? i think they are glued to one another as well.

this is a 16s8p, and one of the cells here is not balanaced, as you can see from voltage sense values,
3.093 3.093
6.18 3.087
9.3 3.12
12.43 3.13
15.57 3.14
18.69 3.12
21.81 3.12
24.94 3.13
28.05 3.11
31.19 3.14
34.02 2.83
37.14 3.12
40.1 2.96
43.2 3.1
46.3 3.1
49.4 3.1
 
Do not separate the pack..

Just tap into the + and - of the group that needs charging via the balance plug, or solder a small gauge lead to the group temporarily, alligator clips also work but are sketchy sometimes in a big pack..

you set your charger to 1 cell, lifepo4, 2 amps, and let it go...

with patience, you can charge all groups, one at a time, to full voltage 3.65v

just make sure you got the polarity right.. :wink:
 
and then?
 
the problem is that i think the plus of the group that needs to be charged is UNDER the cells, but how can i tap into the balancing plug? i mean it would charge every group between them .
 
the balance connector has all those pins..

pin 1, 2, 3, 4, 5, etc...

pin 1 and 2 for group 1

pin 2 and 3 for group 2

pin 3 and 4 for group 3

etc..

those pins are very close to each other, so i would recommend using an matching connector that allows you to tap into the lines without risking a short.

I've done this with an RC lipo pack adapter and andersons ..



Above

Red to blue = group 1
blue to yellow = group 2
yellow to orange = group 3

the + is always the pin on the RED side of the row.. negative towards the other end..

You can also start from the negative side of the row working your way towards the positive end..
 
oh you mean the balancing connector of the imax, i don't have that, i though just to connect alligators to the groups that needs charing.
 
Well, the plus of any group is hte minus of the next more positive one, so if you can access either one, it is the same point. On most cylindrical cells, the outer casing is also an electrical connection to one pole or the other, so if there's a safe place to expose the casing thru the insulation sleeve you can connect a charge point there (though you'd probably have to hold it in place with a magnet or your hand, as you won't want to solder anything there and it probably wont' safely stay on it's own).

If you can't access either one from this side, and you don't ahve a balance connector/plug already on the pack, you'll have to open up the other side of the pack to do it.

If you don't have a balance plug already on the pack, you might want to add one that can directly plug into your charger, since it is capable of doing the balancing on it's own.

(EDIT: never mind, I couldn't see the picture due to bandwidth limitations on my wifi when I first posted...now it comes up and I see your balance plug--sorry about that!)

If you don't know how to add one, or what some of the things I'm talking about are, you might want to read up on the various pack repair threads (such as my Vpower thread), or the many pack design and build threads, as many of them discuss this, some in lots of detail including connector and wiring choices.
 
This sort of problem is precisely why I chose to avoid cylindrical cells similar to these. Troubleshooting and doing things such as what you are trying to do seems exceptionally difficult.

The shape and weight is not ideal when using larger pouches, but everything has it's pros and cons.

Eep, I almost forgot to say what I wanted to say exactly. I'd consider selling that pack and looking to buy and mount something else. This probably sounds like such a pain, but it will probably beat dealing with an issue such as this on a routine basis.
 
i'm assuming you don't mean the balancing plug of the bms right? (the one that has 16 red wires connected to it).
 
these are 26650 a123 cells, the didn't come in anything else, in this size.
 
that's what i thought, but assume the 11 pin leads to the effected group, how can i access the group's ground?
 
The positive of one group is the negative of the next group, and vice-versa.

At the top or bottom group of the stack, the main battery pack output would be the positive or negative of that group.
 
so so i should just connect the balance charger + to pin 11 and it's - to pin 12?
 
O.k you have given small info with big questions. There is more in what you are not telling us than telling.
These is 16s8p A123 pack lifepo4 with a bms and charger all working and you have checked the charger voltage. Is all this true ?
Put it charger on and charge it. ?
What are triing to do with the pack ? keep as a 16s8p ?
 
i'm investigating how come a pack that is rated 18.4 (16 * 2.3) is really 15.4, the reason i know is that i used speedict current meter to ride it all the way till it was drained.

the problem was that the system shutdown when voltage was no where near the cut-off (at 46.7 volts) further more, even after recharging all the way, the voltage slowly came down to around 55 volts, while it should be 58.4 as far i understand.
 
It shuts down because one of the cell groups reached the LVC of the bms. It's that simple. That's what happens when a pack isn't perfectly balanced,. Charge voltage for a 16s pack should be 3.65V per cell group. Once taken off the charger, that voltage should stabilize at 3.6V or less.
If you want to fix it, you have to identify the weak cell group, take the weak cells out of the pack and replace them. A pita, but really simple.
 
Amberwolf did a thread on repairing those multi round cell pack. You find the weak string then cut it in half on find the weak half of that parelle string. Then test and cut that string in half to you find the one or ones. Lot's of time and work and could be trouble as the cells are not dead but very alive. Like go put some steel wool on a little 9v. Yes fire.
 
uhh... before you cut anything......... dertermine to what extend the problem really is.

if you can manually top off every group and regain a significant portion of the usable capacity and it holds up for a few months, i would not touch it.

if you manually top them off and the loss in capacity is still significant, then yeah... surgery time.
 
Sorry I just answered the question. But allways go down the list first. Maybe we can make a list. Between you and ? Dmumn ect. Just a run down test list. The A-B- C's so to speak.
But charging one cell or parelle of cells you have to watch it. Plus timer. plus alarm. because the next person who hasn't walked down that path, let us know. Who wants to watch paint dry.

P.S. sorry Peddle .O .Y (It's so funny I had to roll it.) Plus just did 20miles. Great.
It's just a joke.
 
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