My experience (limited and dated to be sure) is you get what you pay for.
In particular, a cheaper pack with a no name source, the cells may not be
well matched in capacity and the BMS may be total crap. I tried to carry on
conversations with a couple suppliers at this tier and found that they knew
almost nothing about the cells they used, or how to test them to see if
they had any quality and consistency. They offered graphs and specs that
made no sense at all. Axes not labeled, missing information, etc. I believe
they were running long tests at levels that would never damage or detect a
defective cell, but they had a lot of repititions so it sounded OK. If you
don't know much about the cells in your packs, then you can't set up the
battery management so it does a good job.

Its a jungle out there.

On Mon, Mar 11, 2019, 9:35 AM Dan Baker via EV <ev@lists.evdl.org> wrote:

> Hello EVDL members
>
> I'm looking at replacing the lead pack on my pontoon boat this year with a
> much lighter lithium solution.  I see on Aliexpress that they have 12v and
> 48v 100ah packs with built in BMS that look be the best prices I've seen.
>  These are brands I have not heard before (GTK/Demuda, etc) The area I live
> in doesn't have a lot of EVs so finding used cells for DIY is quite
> sparse.  Anyone have any experience with purchasing packs from Aliexpress,
> are they any good?
>
> Thank you
> Dan
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