Troubleshooting GM Lithium 36v16ah battery... help

[csm]

I am doing troubleshooting of a Golden Motor 36v16ah Lithium battery (see case label below). It initially had charged voltage of about 42volts I believe, and was producing close to 600wh of power. Recently the capacity has dropped down to about 200wh of power. The voltage at full charge is at about 41.5v.

The battery has had about 500 charge cycles. I am trying to figure out why there is been such a dramatic drop in total capacity (approximately 60 percent lost in total power capacity). I have opened up and see there appear to be 40 cells. And I presume that the cells are arranged in four packs of 10 cells in series. And the 4 packs are then connected together in parallel. I am supposing that perhaps 2 or 3 of the packs are somehow not connected. Perhaps a break in the circuit of some of the packs? I have opened up to examine and test the cells. But I am not clear how to free the cells from within the aluminum case.

Any ideas on how to remove the cell pack assembly from the aluminum housing?

Any thoughts on what might be causing this condition?

[Cornelius]

To get the cell configuration straight; there are 4 cells in parallel (making a 3,7V/16Ah pack), which there are 10 of in series.

With 500 charge cycles behind it, I guess your pack are near the end of its life. On paper, the specs says 800-1000 cycles - but that's on paper. My pack gave up after around 200 cycles...

I bought an 'iCharger 1010' charger that's capable of charging 10 cells with up to 10A, and it has an usb port for logging and loads of charging programs. With that charger, I saw that each cell group charged and discharged rather close to each other, but the capacity was reduced to around 9Ah for the whole pack, and I couldn't run more than 10-15km before lvd kicked in, opposed to 35-40km when new... (Over half the capacity, but only 1/3 of the range, due to tired cells..)

When the capacity of the cells are reduced, so are their capability to deliver top amps without significant voltage drops...

The cells are mounted in some plastic frames that are hot-glued to the aluminium frame. To get the cells out, you have to break those hot-glue points loose with a flat screwdriver or similar, then slide the whole package out.
But with 500 cycles, I think you will find that all cells are equally reduced in capacity...

[Cornelius]

Please!

Do not be afraid to use your eyes when looking at the battery; I told you how. You said you have had the end caps off, so, look at it and you'll see how to disassemble it. From what you describe, I guess all guarantees are out, so - do not be afraid to take what life have to offer... 

I saw you found my post regarding the iCharger, so you have all the answers you ask for there regarding that one (in that link there...). I paid closer to $300 for it here, but Norway are a rich and expensive country to live in.

I find it unlikely that a 500+ cycle battery fails because of a mechanical failure versus an electronic wear failure. if you find a cell/cell group that are weak, and replaces that cell/group on a battery that are so old; it won't be many cycles before you have to replace other cells too.

I'm sorry if I sounds a bit short, but it sounded like you asked me how to button up a shirt...