On 4/9/2013 3:51 AM, Danny Miller wrote:
Can these effectively be paralleled? I recall hearing there was a
problem with that... but people say lots of things, like battery memory.
No, you do not want to parallel them. Nicad cell voltage *drops* when it
reaches full charge. If you parallel cells, then one of them reaches
full first, its voltage drops, and so prevents the other cell from
reaching full.
There are also some temperature instability problems with parallel cells
at high currents. The voltage drops as temperature rises, so the hotter
cell hogs the current, which makes it get still hotter, hogging more
current, etc.
If you need more capacity, wire them as two long strings. Then use
series diodes to connect the two strings in parallel. On pair of diodes
is needed for discharge current, and a second pair of diodes is needed
for charging current. The diodes keep the two packs "honest", so one
won't sabotage the other.
--
Ring the bells that still can ring
Forget your perfect offering
There is a crack in everything
That's how the light gets in.
-- Leonard Cohen, from "Anthem"
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
_______________________________________________
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
http://lists.evdl.org/listinfo.cgi/ev-evdl.org
For EV drag racing discussion, please use NEDRA
(http://groups.yahoo.com/group/NEDRA)
