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Li-tec batteries from 2013 smart car

21K views 35 replies 8 participants last post by  jimmyaz 
#1 ·
Is anyone using salvage smart car cells from Li-tec? I just got some on ebay and will be learning about them...

I found this test that seems to show min/max cell voltages of 3 and 4.2:
http://energy.gov/sites/prod/files/2015/02/f19/batterySmart5544.pdf

It looks like the low-voltage knee is at 310v or 3.333 volts per cell.

and their graph starts at about 385v or 4.14 volts per cell.

Any more/better/different information out there?
 
#30 ·
You need to consider that the tiny little car only got 58 miles per charge.
How much bigger is your van?
I dont know if you know the back story to these, so here goes.
Li-tec messed up. They made great batteries, but the cases they put them in sometimes didnt do their job.
The cells would sometimes not fit perfectly in the case.
I have 6 packs with one bad cell in each. I took one apart, the corner of the bad cell was dented in.
From what i can tell, it looks like it was a short inside after that damage, but it didnt look like it caught fire or exploded, maybe more like a slow drain on the cell.
Since then, Li-tec has gone out of business, and all the warranties of the Smart car owners have been canceled.
They dont offer any replacement options.
I was told this by someone looking for a battery for their Smart Car after you bought the ones you have.
So, back to the ones I have, it is possible to replace the one bad cell. Would require a bit of work and would need to figure out how to make sure the BusBar connection was as good as when new.
I dont have the time to do that. I took the one apart for parts, and decided i didnt want to get too involved.
Still have the one for parts, most of the bus bars are still together.
The question is, do you have any interest in doing it yourself?
 
#31 ·
i haven't taken apart any of the 31 cell blocks.... but from what i have read it is much better to put individual cells in parallel and then series those than to use parallel blocks... im not sure i want to dig into the blocks but if i did then i could use more cells yes....

i have a few cells in each block that are slightly lower voltage but not much... haven't checked them in a while.
 
#32 ·
Here is the discharge curve of one Li-tec cell.
Tested from 4.2V to 3V at 20A. Got 48.8Ah
If you are only going from 124V to 113V, your voltage range is only 4V to 3.64V per cell. Not a whole lot of usage of the battery.
I programmed your voltage limits for the next test, but dont plan on waiting around for them. Interesting to see What capacity percent of the pack you are actually using.
As for the pack configuration, you are right. First parallel, then series.
However, i would like to point out that Honda Fit EV and the Prius prime both have a set up similar to yours. 3 strings of series paralleled together.
They however have a relay unit for every string of series to be able to turn them on and off individually. Im not sure, but they might only use one at a time, instead of all 3 at once.
Better? Probably.
Necessary? Maybe not.
 

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