premature lvc by overdischarge?

[Enpro]

My two 36v/15ah goldenmotor lifepo4 packs (rated for 30amps continue,60 amps peak according to goldenmotors that is..) in series and already after a couple of miles the lcv kicks in.
I got them hooked up to a 72v 45a crytalyte controller which is a little too much I know but even if I run only at half throttle the same thing happens.
At full charge they both measure 41v and after the lcv one pack reads 41v and the other 39v even with diodes. (without diodes same thing happens)
Faulty pack or am I just pulling too many amps?

[Bikemad]

Do you have any means of measuring the actual voltage and current being used when it cuts out? This would give a good indication of whether the batteries were continuously being worked too hard, forcing the weakest one to shut down first.

Unless the LVC is higher on the GM LiFePO₄ packs, I would expect the individual battery voltage to be around 32V under load before the battery's LVC should cut in.

Alan
 

[Enpro]

okay this is whats happening.
Full charged packs (81v) only drop to 70v max at fullthrottle.
After 4 km of easy low throttle riding combined voltage starts to drop to 79v (Pack 1= 41v , pack 2= 39/38.6)
Then voltage drops to 68v when full throttling only for a few seconds.
Then aftr couple minutes more riding lvc from pack 2 kicks in and pack still measures 38.6v
Trying to restart, lvc kicks in at only 5v sag and like 30% throttle.

And does anyone know the exact specs of the cells that are in these packs?
I found a few lifepo4 cells with 16ah and they are rated at 160amps continuously

[GM Canada]

My two 36v/15ah goldenmotor lifepo4 packs (rated for 30amps continue,60 amps peak according to goldenmotors that is..) in series and already after a couple of miles the lcv kicks in.
I got them hooked up to a 72v 45a crytalyte controller which is a little too much I know but even if I run only at half throttle the same thing happens.
At full charge they both measure 41v and after the lcv one pack reads 41v and the other 39v even with diodes. (without diodes same thing happens)
Faulty pack or am I just pulling too many amps?

I know this may not help. But exactly what batteries do you have. I have not heard of 36v15ah gm batteries.

The Lithium we had were 36v16
The LiFePO4 we have now are 36v12

These are the aluminum cased batteries. Is that what you have? Do you have a picture of your batteries and possibly the label. I know this will not resolve your issue but more clarity can't hurt.

Gary

[Enpro]

I can't really find much info on these batteries to start with but they are the second ones on this page. www.goldenmotor.com/batterypack.htm
And also the box in which they came says lifepo4 so really hope they are because if they are just limno2 that means they have a lower discharge rate and I'm wrecking them for sure now.
I will post some pics of the inside of one of my packs so you can see exactly what's in them.

[Enpro]

Here are the pics I promised:

Please ignore the horrible paintjob

It clearly says lfp 3616s so doesnt that meant its a lifepo4 pack?
There are 40 cells in the pack

Group voltages are 4v per 4 cells which is kind of strange for a lifepo4 cells?

[Cornelius]

That does looks like the LiMn cells to me...

Without knowing for certain; I thought they used those square cells in LiFePo packs?

[Bikemad]

I totally agree with Cornelius, it's definitely one of the earlier type Lithium Manganese Packs you have there!

The labelling is definitely misleading, but GM have been using the "LFP" prefix in the battery codes for the last three years on all of their Lithium Manganese Rack Packs.

Alan
 

[GM Canada]

The new GM LiFePO4 packs have (LT) on the label after the battery size and a green paper label that stains easily as you can see. Why paper

This is one of my personal 48V10AH LiFePO4 packs



Gary

[tex tiles]

That's the same one I have, the old style. They were duds. Nothing but grief and headaches. They stopped making them because they had so many problems. And mine started acting just like yours a short while after I purchased it.
My GM bike kit has been great and worked well for years, but those GM batteries were expensive junk. Hopefully their newer designed ones are working better for people.

[Enpro]

So what am I suppose to do now?
I opened up my packs so my warranty is gone but now they have a much lower chance of surviving my 45amp controller because limno2 has a even lower discharge rate then lifepo4 right?
Do I have the right to claim new packs if they really are limno2? and how do I prove they aren't lifepo4's?

[tex tiles]

Does your receipt say you purchased lifepo4?

[Enpro]

yep

[tex tiles]

Then I would demand they be replaced with the actual items you ordered. It's not the point that they are defective or that you opened them, it's that they sent you a different product than what you payed for.

Plus they are defective.......

[Leslie]

http://www.alibaba.com/product-gs/507403016/Headway_36V10Ah_LiMnO2_LiFePO4_lithium_battery.html

For a little more weight LiFePo4 live longer the LiMn02.


It depends on the cell, pouch cells are a bit lame on the max discharge side, where as the canister cells preform much better.

I believe it's because canisters stop the gases from bulging the cell structure and pouches puff up from the heat under high loads. I would bet running a pouch pack in a hot environment is much different to a internal resistance generated type heat at heavy load times..

Temperature performance is not cut and dry.