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

David Nelson wrote:
> This blog entry [Jack Rickard's] has an excellent video about LiFePO4 batteries. I
> recommend that every one watch it if they even have a remote interest
> in these batteries. Here is a quote from the blog about the professor:
>
As usual, jack went off half-cocked on his quest to prove that if he
can't make a good BMS, then obviously no one can. Here's a explanation
posted on
http://www.diyelectriccar.com/forums/showthread.php/lecture-lifepo4-cells-52773.html
by Dmitri:

Here is how I understood it. Single cell management is the ability to
remove individual cell from the circuit and/or reroute energy around it,
such that single cell failure does not stop the whole pack. This
requires power electronics ( like IGBT modules ) for each cell, to be
able to route energy around bad/empty cell. Some people proposed such
BMS schemes, even on this forum, but for anyone familiar with
electronics involved its 100% clear that such solution is not cost
effective. I think this is what Jay was referring to, he actually
mentioned bypassing a cell.

String management, the way I understood him, is monitoring cell level
voltages and taking action upon entire pack, i.e. stopping
charge/discharge when any cell goes outside of norm. He actually
mentioned cell level monitoring using simple cheap circuits. This type
of management is precicely[sic] what most affordable BMS systems do. Its
a string management, based on cell level monitoring.
 
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