Batteries with Bus Bar?

timsim00

Hello,

I currently have 4 6V @230Ah batteries, in series (12V) and parallel (460Ah).

I have the Charge Controller and Inverter cables attached directly to the battery posts.  What I am trying to do is create the same 12V @ 460Ah configuration, but using POS/NEG bus bars.

Does this configuration look like I will achieve what I am looking for?

vtmaps

Looks OK to me... except one thing... the length of the cables must be the same for each of the 12 volt batteries that are in parallel.  It's a smart move to use bus bars.

Where will you put your fuses/circuit breakers?  Are you thinking of having a battery monitor?  If so, where will you put the shunt?

--vtMaps

timsim00

vtmaps said:

Looks OK to me... except one thing... the length of the cables must be the same for each of the 12 volt batteries that are in parallel.  It's a smart move to use bus bars.

Where will you put your fuses/circuit breakers?  Are you thinking of having a battery monitor?  If so, where will you put the shunt?

--vtMaps

Perfect @vtmaps !

Yes, I will have fuses/disconnect switches after the bus bar to each the inverter and CC.  I use 200A for both.

Also, I will make sure to use the same cable (length) for all of those four connections, that way the drop is the same.

vtmaps

timsim00 said:

Also, I will make sure to use the same cable (length) for all of those four connections, that way the drop is the same.

No two cables have to be the same length, but the sum of the lengths in each string must be equal.  In other words A+B+C = D+E+F.

The cables from the batteries to the bus bars are unfused.  They should be very well protected, in other words they should be in conduit.  The conduit runs from the battery box to the box with the bus bars.  The conduit should enter the battery box below the tops of the batteries.  This will keep hydrogen gas from rising up into the conduit.

timsim00 said:

Yes, I will have fuses/disconnect switches after the bus bar to each the inverter and CC.  I use 200A for both.

If you can, use circuit breakers rather than fuses with switches.  It will probably be less expensive.  Midnite makes some boxes that can hold the bus bars as well as the circuit breakers.

--vtMaps

timsim00

@vtmaps

Thank you very much.  I have taken the precaution of having both sides equal 48".  Should be good to go now, thank you for pointing that out.  I had originally assumed as long as my pos legs were the same I was good.

Thanks again.

vtmaps said:

timsim00 said:

Also, I will make sure to use the same cable (length) for all of those four connections, that way the drop is the same.

No two cables have to be the same length, but the sum of the lengths in each string must be equal.  In other words A+B+C = D+E+F.

The cables from the batteries to the bus bars are unfused.  They should be very well protected, in other words they should be in conduit.  The conduit runs from the battery box to the box with the bus bars.  The conduit should enter the battery box below the tops of the batteries.  This will keep hydrogen gas from rising up into the conduit.

timsim00 said:

Yes, I will have fuses/disconnect switches after the bus bar to each the inverter and CC.  I use 200A for both.

If you can, use circuit breakers rather than fuses with switches.  It will probably be less expensive.  Midnite makes some boxes that can hold the bus bars as well as the circuit breakers.

--vtMaps

Xizang

All the above makes sense.  But I have a question:  For smaller systems with only 2,3, or 4 batteries, instead of a copper bus bar, what's wrong with bolting one end of all the positive, and one end of all the negative cables together - effectively stacking a 'bus bar' of copper cable lugs on a stainless steel bolt and flat washers and tightening?   Yes, keeping the sets cable length the same.

timsim00

@Xizang
Thank you for your input.  You are right in the long run, a small system it might not be an issue.  What I had a problem with originally was I was frying my PWM charge controller, post here, finding that it was loose connections and my adding/changing things around the battery posts, was more than likely the culprit.  I decided to completely redo my wiring/equipment.  This included adding bus bars for the 4 batteries I have now. 

In the near future I will be going to 6 and then 8 batteries, so this will be useful.

Xizang said:

All the above makes sense.  But I have a question:  For smaller systems with only 2,3, or 4 batteries, instead of a copper bus bar, what's wrong with bolting one end of all the positive, and one end of all the negative cables together - effectively stacking a 'bus bar' of copper cable lugs on a stainless steel bolt and flat washers and tightening?   Yes, keeping the sets cable length the same.