Battery bus bar source [RE-wrenches]

[Darryl Thayer]

Hi Randy
I worry about all these sealed batteries in parallel. 
The sealed battery has a very steep voltage
temperature curve, and when in parallel one of the
batteries having a shorted cell or overheating and
thermal run away occurs.  That means that all the
energy from the other batteries will discharge into
the failed cell.  There are several examples of this
in our industry.  

Far out idea -that I have not tried- follows.
If you can not find a higher voltage solution, perhaps
a C/5 fuse in series or use and Outback combiner box
and a breaker in series with each battery. I think the
combiner has 10 or 12 openings per combiner box.  Keep
the wire lengths the same and use the two bus
configuration in each combiner.  s 

As to Bus bar material, The rule of thumb, and I think
it might be in NEC is 1000 amps per square inch of
cross section.  What I have done is purchase the
copper and drill cut and then take to a local plating
shop and have it tin plated. 
Darryl

--- Randy Brooks <Randy at BrooksSolar.com> wrote:
> Wrenches,
> 
> I have a customer who already has four 12v
> inverter/chargers (ProSine 
> 2.0) and 20 (!) 12v, 200ah, sealed batteries and
> wants me to wire up 
> the system to work with his generator.  I'm
> considering paralleling 
> four batteries together (because four fit on each
> shelf of the racking 
> system the customer already has) and then
> paralleling the five strings 
> to bus bars through a 250 amp fuse on each string. 
> Then connecting the 
> bus bars to an OutBack PSDC with 250 amp breakers
> for two inverters 
> (all he needs based on a load evaluation.)  4/0
> cable throughout.  
> Where can I get 250 amp bus bar material, or do I
> need to make them 
> from copper bar?  Any other suggestions would be
> appreciated.
> 
> thanks,
> 
> Randy Brooks
> Brooks Solar, Inc.



		
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