take along battery wiring to primary

Aaron_MNAaron_MN Posts: 4Registered Users
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.      


  • EstragonEstragon Posts: 2,838Registered Users ✭✭✭✭✭
    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.
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • mcgivormcgivor Posts: 2,205Solar Expert ✭✭✭✭✭
    edited October 2017 #3
    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. 
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 

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