I'm looking at reorganizing my battery bank of 6 - 6 Volt GC2(T-105), 3 pairs in parallel for my 12V 2kW inverter.

I'm planning on building 3 shelves, 1 on top the other, where each would hold a pair of batteries.

I would like to run main DC bus bar up the back of this shelving to tie each pair of batteries in.

I would like feedback on using copper bus bar to tie the pairs of batteries to the main DC bus instead of cables. Any issues with this approach? Should these battery interconnects be sized for 1/3 or all of the inverter's max current draw?

Also because aluminum is so much cheaper, could I use properly sized aluminum bar for the main bus bars? I would keep copper for the interconnects.

These bus bars will be on opposite sides of the shelf, about 2' apart. Should I use insulators or will screwing them to the kiln dried wood shelf frame work?

Lastly for venting, this is in a utility closet, should I enclose the battery shelves and vent the top to the outside or just vent the closet? There is a water pump, relays & light switches n the room, which could spark during operation.

Thank you!

Inside a house, I'd use a powered vent, or a vertical pipe for venting.

I've see somewhere in the last 6 months, someone who studied using copper water pipe as a buss bar, and had good results, I was thinking of it for myself, but with the following prep, clean and tin (solder, electronic solder, not lead free) the round pipe, then flatten it (drive my truck lengthwise down it) and reflow the solder job, so the inner walls are soldered together. This will help the copper resist corrosion, and yield a "bar" that I can drill and thru bolt, without the walls collapsing as I tighten the bolts. I'd use crimped lugs for the interconnects.

If the bars heated up, would they light the wood on fire ? How much would proper insulator standoffs cost ?

http://www.stormcopper.com/Electrical-Insulators.htm

Ok, maybe something other than $25 standoffs. Something from cut strips of plexiglass or lexan ?

you most certainly could use bussbars and it is probably better to do imho, but circumstances or availability usually dictate what one uses. try to be sure the busses are rated for higher current than the highest rating of any wire in any part of your system. if your system has for instance #2/0 and going to your inverter then try to get equal to or better than the rating for #4/0 for the battery interconnections. this helps keep high currents possible from the batteries and helps lower the resistance between batteries to help give a good balance.

i'd stay away from mixing copper and aluminum, but it can be done if the proper connections and precautions are taken.