[EVDL List]

Re: [EVDL] Phd in Materials Science on LiFePO4 batteries video WAS: Lithium 60ah 144v

With my order of SE/CALB cells I also received a PDF with a listing of all
the cells in the entire shipment. Looking through that I can see there were
enough cells that could have been grouped within 2 ahs of each other. My
100ah cells came in between 110-114 but could have been selected to be
between 110-111, 111-112, or 112-113 as that's where the majority of cells
were. I can see paying a bit extra to remove the few 114ah outliers which
they could still sell in a small grouped pack. They could even get a higher
price for those by selling them as 105 or 110ah cells. Throwing resistance
into the mix would make things more difficult but I think getting similar
capacity would go a long way to making management much easier.
If they grouped the cells at the factory from the entire production run they
could probably get them even closer.

EVDL Administrator wrote:
>
> On 14 Dec 2010 at 20:42, AMPhibian wrote:
>
>> I just think we'll get more bang for the buck by pushing for more closely
>> matched cells, even if we have to pay extra, than paying for a monitoring
>> system which doesn't actually fix the problem of mismatched cells.
>
> That was part of Solectria's secret for getting 4-6 years of life out of
> gel
> batteries in the Force. They used batteries with very tight manufacturing
> tolerances, instead of using equalizers or a BMS.
>
> They did fit some cars with a BMS, but I think it was mostly when they
> were
> using Hawkers prior to adopting the East Penn / Sonnenschein gel
> batteries.
>
> But then look at Lee Hart's experience. He got something like 10 years
> out
> of a pack of AGMs with his balancer.
>
> I also think you're going to have trouble finding highly consistent
> lithium
> cells, unless you're willing to play MUCH more - as in several times more
> -
> than the Chinese lithiums go for. But I could be wrong.
>
> David Roden - Akron, Ohio, USA
> EVDL Administrator
>
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