[RE-wrenches] Battery interconnect cable length

[R Ray Walters]

My experience is that parallel jumpers need to be equal. Also, if running parallel strings, then the series jumpers would need to be equal to the wiring path of the other parallel string.
I've actually added extra cable length, so that all parallel  strings would truly be equal.
On a single series string though, it shouldn't matter; all cells will get equal current regardless. 

R. Walters
ray at solarray.com
Solar Engineer




On Jun 6, 2011, at 2:14 PM, penobscotsolar at midmaine.com wrote:

> Hi Ben,
>   We've done a lot of this type of system using Surrette KS series batts.
> I haven't ever asked the question you did, but experience told me that
> differing battery lengths are more important than some give credit for.
> I  actually  use slightly longer (16" cables) and , in cases where we
> run two rows of twelve cells (typical) we can use a 16" cable to span
> the front row to back by using a right angle lug on either end of that
> cable. It works, as we have many (over 200) battery based systems out
> there, from Maine to Antigua), some for as many as 16 years, still
> operating well. Of course, this also depends on the customers ability
> to adequately equalize, water, keep terminals clean, etc. etc......just
> one mans experience.....
> 
> Daryl DeJoy
> NABCEP Certified PV installer
> Penobscot Solar Design
> 
> 
> 
> 
>> Since batteries seem to be a hot topic lately, I've got a question...
>> ...in a single 48V string, (24 x 2V) if each interconnect cable  is
>> 14"-4/0awg and one cable in the middle of the string must be longer (btwn
>> 20"-24" total length)...
>> How detrimental will that be to the overall efficiency?
>> 
>> Should it be OK or should the awg size for the longer cable be larger?
>> What other factors should I consider?
>> 
>> Thanks,
>> benn
>> Sent from a 'smart' phone, with tiny keys. Please excuse shortcuts and
>> typos.
>> _