Measuring solar charge through a Mastershunt

[stranded]

Following the very helpful advice here I have upgraded our Victron mppt regulator and am reassured that we should get sufficient charge on our winter mooring to keep the service batteries topped up.

My next challenge is to fiddle with the wiring to try to get the solar contribution reflected in the battery state of charge calculation. At the moment the regulator is connected directly to the battery terminals. As the shunt makes its calculations based on what goes through it, it doesn’t take account of the solar contribution and the displayed soc is slowly heading south - around 40% when I last looked. That doesn’t worry me too much at the moment but I am getting a bit concerned that when I finally get to connect to shore power in the future, the mains battery charger might try to do inappropriate things because it is being fed duff soc info by the shunt.

The Mastershunt manual suggests that if I connect the mppt to the load/charger side of the shunt then its output should be counted in the shunt calculations. Haven’t been onboard since discovering this to check where the shunt connects but presume it must be on the battery side of the main service battery on off switch or the mains charger output would not get to the batteries when the switch is off. In which case, could I simply connect the mppt +ve to the main switch battery side terminal? And should I then leave the mppt -ve a attached to the battery -ve, attach it to the main negative post, or something else?

As ever, I would be immensely grateful for any advice.

 

[Daverw]

We have ours connected as we would for any load with negative on shunt, the same as our charger, the smart shunt then see all in and out

 

[VicS]

Connect 1 & 3 directly to the battery

Connect battery charger and solar charging directly to 10 & 8

Connect loads to 10 & 8, with the isolating switch in the positive connection to 10

 

[stranded]

Thanks guys - I’ll connect it directly to the shunt load side +ve and -ve posts. Sorry for the dimness - I don’t consider myself especially thick on most things but I do struggle with how electrickery moves around eg whether the solar charge can swim against the tide of the load or, more likely, I suppose it kind of supplements the charge to the load until that is switched off then swims up to the battery. Or something. ?

 

[Daverw]

I explain it to admiral as solar is negative load, she seems to understand that

 

[stranded]

I explain it to admiral as solar is negative load, she seems to understand that

You’ve got a clever one there! Each time I try to learn I come against something else that bamboozles me. E.g I read recently that dc electricity actually flows from negative to positive, which is precisely the opposite to what I thought I understood. Sometimes I think it’s best to accept that ones brain might be full (of rubbish, admittedly, but even rubbish takes up space). TY again for trying though!