Battery Bussing [RE-wrenches]

[Allan Sindelar]

Kurt,
    We wire battery cables to diagonally opposite corners of the bank, with
interconnects of sufficient size to allow the strings to all work as a set.
We sometimes add intermediate parallel interconnects, but not always.
    I would avoid running different positives to different B+ terminals.
While I can't prove it, I suspect that unbalanced loads between the two
inverters would negate the benefits of diagonal bank wiring and cause uneven
battery performance if the negatives are bonded at the shunt. I would tie
both B+ cables to the same B+ terminal, and tie the same B- cables from the
shunt to the diagonally opposite B- terminal. Use oversized parallel
interconnects, as you need to size for about 535 amps--I'd suggest a single
4/0 I/C for each and at least one set of intermediate parallel interconnects
at the 12V point. Make sure the parallel B- negatives are exactly the same
length and size, so they carry equal amounts of current, as sometimes
they'll be maxed out.
    You might also consider NOT balancing the loads between the two. That's
for grid wimps. There's no particular reason to do so with inverters.
Instead, put the dirty and surge loads (within capacity) on one and the
lights and electronics on the other, so the lights never flicker when the
pump comes on. Or put the continuous and ghost loads on one and the
intermittent loads on the other, so that one unit sleeps a lot.
    Note that if you run both AC outputs to the same load center, your
inverters will phase wild in relation to each other. You must have a neutral
buss rated for double the amps output of each inverter. If you use a common
neutral conductor from the inverters' AC out, it too must be double
ampacity.
    By not stacking, each inverter can sleep independently of the other. And
if one ever fails, you can jumper the main lugs in the load center while
it's away.
Hope this helps.
Allan at PawsitivEnnn

----- Original Message -----
From: "Kurt Nelson" <sunwise at cheqnet.net>
I am adding a second SW2512, and as there are no 240 volt loads, I am
setting it up as two seperate inverters, each independantly powering
approximately half the system loads.  There are a couple reasons why I am
not using the parallel stacking kit and transformer from Trace (which would
solve this problem), but the decision was made to make it seperate inverters
on one battery.

I wired the battery cables for the second inverter to the other opposite
ends of the battery from the first inverter thinking this would balance the
battery, but both sets of negative cables go through the same meter shunt.

It would seem that this this will allow both inverters to draw from just
their "ends" of the battery.

I have of course made an attempt to balance the loads between the two
inverters which should help to reduce the problem of drawing down one end of
the battery more than the other, but is there still a concern?  Perhaps both
inverters should be wired to the same opposing ends of the battery.

Thanks,

Kurt Nelson

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

==^================================================================
EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9
Or send an email To: RE-wrenches-unsubscribe at topica.com
This email was sent to: michael.welch at homepower.com

T O P I C A -- Register now to manage your mail!
http://www.topica.com/partner/tag02/register
==^================================================================