take along battery wiring to primary

Aaron_MN

Ok here is my situation: 
- I have a pair of batteries in parallel where the + from the CC is going to BAT1 and the - from the CC is going to BAT2 
- I have a 3rd battery that I like disconnecting same type as the above that i like to take with me outdoors. 
 * to connect BAT3 to the pair i am using MC4 connectors so that i can easily connect and disconnect.  My question is how should i have these connections i was thinking to extent the parallel to these or connect to the - of BAT1 and the + of BAT2 so basically opposite how the CC is connecting to the bank.  Thoughts?  should i connect in a semi parallel fashion or like the load to opposite terminals on the bank.      

Estragon

A couple of thoughts:

1. MC4 connectors aren't a particularly good way of making repetitive connections. They're designed to make/break connections in a solar array maybe 3-4 times over the 20 year life of the array. Something like an Anderson connector might be a better way to repeated make/break the connection.

2. You didn't say what the voltage of the batteries are, but assuming they're all 12v, in parallel, you would connect all "+" together and all "-" together. That would add current capacity, and keep voltage at 12v. Wiring "+" to "-" would add voltage. I don't know what "semi parallel" is. Ideally, you would want to move one of the connections (either + or -) to the diagonal end of the bank. Again, assuming all 12v batteries, you don't want to connect + to - . That would add voltage (12v to 24v), instead of capacity.

mcgivor

If you are suggesting a portable battery which is charged together with the pair, but discharged independently, my suggestion  would be to treat the mobile battery independently, having its own CC and panel, as  charging imbalances will occur.