Re: [EVDL] Alibaba/Aliexpress Lithium packs

[Willie via EV]

On 3/11/19 8:29 AM, Dan Baker via EV wrote:

Hello EVDL members

I'm looking at replacing the lead pack on my pontoon boat this year with a


A very interesting discussion.

I have had very good luck using 36v hoverboard batteries in 36v golf 
carts.  Massively paralleled, maybe as many as 40 HB batteries which are 
supposed to be 10S2P.  About 5 HB batteries seem sufficient to run a 
golf cart; the larger number I use for range.  Using standard 42v 
lithium chargers.


I started a 48v golf cart project using ~48v Volt modules.  I had not 
settled on a good charging solution at the time I put the project aside; 
no OTS chargers to match the Volt voltage seem available.


I believe it is Lawrence here that put some 12v Valences in a scooter. 
Maybe 2S for 24v.  I hope he keeps us apprised of successes and 
failures.  The 12v lead replacement batteries are attractive mainly 
because they can supposedly be charged with lead chargers and are 
supposedly "bullet proof" in dealing with over demand and over charging.


If the price is low enough, I, personally, am willing to try something 
that may not work.  I've bought some stuff through AliExpress and have 
been generally satisfied.


I encourage Dan to continue to post on his project.

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Re: [EVDL] Alibaba/Aliexpress Lithium packs

[Jay Summet via EV]

On 3/11/19 9:29 AM, Dan Baker via EV wrote:

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.
One issue with using multiple 12v or 48V drop in replacement batteries 
in an EV is that the BMS system may ONLY work at a maximum of 12 or 48 
volts. (e.g. if you put multiple in series, to get a total pack voltage 
of 120-144 volts (or more), the mosfets, etc used in the BMS to 
disconnect the individual batteries in a low-power or over-charge 
scenario may fail (spectacularly).


For example, the BattleBorn 12 volt battery specifically say that you 
can ONLY put them in series up to 48 volts (I expect they are using 60 
volt rated mosfets).


This depends entirely upon the BMS/battery construction (some of them 
just have a balancing BMS which is isolated, and does not even try to 
disconnect the battery from the rest of the system in an over or under 
voltage type of situation...these guys are actually safer to put in 
series...


Jay
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Re: [EVDL] Alibaba/Aliexpress Lithium packs

[Michael Ross via EV]

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  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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[EVDL] Alibaba/Aliexpress Lithium packs

[Dan Baker via EV]

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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