Solar Wiring and Mastervolt MICC

[leolady too]

I am about to fit two 250W solar panels via a Tracer MPPT to four 110 AH sealed batteries in a 12V setup. The existing system has a Mastervolt MICC panel.

 

Is it OK to connect the output from the tracer direct to the batteries (with a fuse in the +ve lead near the batteries) or should I connect it somehow via the panel. If the latter, please tell me how (in baby talk please)

[nicknorman]

The positive can go on to the batteries as you say (with fuse). The MICC measure current in the negative wires and needs to sense all current going in and out of the battery negative, and so the solar negative lead must go on the side of the shunt away from the battery -ve. In other words, there should be nothing connected to the battery negatives except the shunt.

[leolady too]

Many thanks, I'll do as you advise.

[bastion]

The positive can go on to the batteries as you say (with fuse). The MICC measure current in the negative wires and needs to sense all current going in and out of the battery negative, and so the solar negative lead must go on the side of the shunt away from the battery -ve. In other words, there should be nothing connected to the battery negatives except the shunt.

Is this the same for a Victron panel?

[Keith M]

If the panel uses a shunt then yes

 

All current in and out of the batteries must go via the shunt

 

Keith

[bastion]

thanks

[Sea Dog]

When these guys correctly connect their solar to the non-battery side of their shunts, the MICC (or other battery monitor) will see the charge current supplied by the panels. That's a good thing, but when the panels dip in output due to cloud or daylight issues, will the battery monitor not see the low current as an indication of a full battery bank, thus screwing up the State of Charge indication?

[nicknorman]

When these guys correctly connect their solar to the non-battery side of their shunts, the MICC (or other battery monitor) will see the charge current supplied by the panels. That's a good thing, but when the panels dip in output due to cloud or daylight issues, will the battery monitor not see the low current as an indication of a full battery bank, thus screwing up the State of Charge indication?

No, the monitors don't just look at current. If they did, the SoC display would go to 100% as soon as you stopped the engine etc. they look for a combination of low current and voltage up at at least float voltage, and that sustained for a certain amount of time. Typically less time for higher voltages. You can configure not only the tail current but also the float voltage.

[Sea Dog]

Swift and helpful Nick, thanks!

[Paul C]

No, the monitors don't just look at current. If they did, the SoC display would go to 100% as soon as you stopped the engine etc. they look for a combination of low current and voltage up at at least float voltage, and that sustained for a certain amount of time. Typically less time for higher voltages. You can configure not only the tail current but also the float voltage.

 

You can also configure how long the "certain amount of time" is (on the Victron BMV702).