Where to connect the negative solar cable?

[onlinelee]

Hi Friends,

Im just about to do my first solar install and hoped you guys could confirm what I think... Please see attached, this is my battery monitor set up. I don't want to mess up the data this provides by attaching my negative from the solar panel to the wrong place. I think its attached to the shunt, right? If so, what side? As always, thanx in advance for your comments.

 

[Maine Sail]

Goes on the "load side" of the shunt where NASA shows the dashed "original cables" connecting.

If you don't know the physical tested capacity of your batteries, in ampere hours, I would suggest not using the BM1 for SOC purposes... Amperage and voltage is fine but just don't count on it for SOC...

 

[onlinelee]

Hey Maine Sail, thats what I thought, super, thanx. I just completed the 2 hour test you suggested for my 270AmpH battery bank. After fully charging and resting for 24 hours I had 12.8v, I then drew 13.5 Amps for 2 hours and after finishing the reading was 12.3v but 24 hours later recovered to 12.6v - I kind of think this is acceptable? Interesting about SOC reading, this does show a little odd sometimes.