Main/Solar/220V Connection Dilemma

[IceLaur]

Hello,

I have a boat with 3 batteries (x100Amp). Everything is running on 12V.

Two Lead-Acid batteries (Engine/Start Battery and Service/Auxiliary Battery) which came by default with the boat.

The third AGM battery has been mounted after, only for the Solar 170W panel to charge other stuff not connected with the main circuits of the boat. (like a refrigerator and a 220V Inverter thru a 30Amp MPPT controller)

What I want to do is to add a second identical Solar 170W Panel to charge my Service/Auxiliary Battery because I don’t want to check every time this battery which slowly is draining when I keep the boat main switch on with engine off.

Which is the best professional way to do this, avoiding any kind of problems that can break the safety rules?

Should I add a second MPPT Solar Controller for the boat auxiliary battery?
Can I charge both Lead-Acid battery like this? Any chance to put Engine electronics in danger?

There is also a Shore 220V Battery Charger connected to these two batteries.
Maybe I can connect both Solar Panels to same MPPT Solar Panel and from there to a 220V Inverter wired also to the Battery Charger? It will work?


There is also a Circuit Breaker involved in this and fuse panels everywhere.

I am looking for a simple professional solution that gives me peace of mind but no failures, fire or explosions.


Thank you very much for your help.

[HeinSdL]

Welcome to the forum IceLaur.

I would be inclined to combine the house batteries into one bank and charge that bank with all the solar panels through one MPPT.

Otherwise I think you'd need two MPPTs resulting in two separate systems and you could indeed charge one with the other either via a DCtoDC charger or via the inverter/battery charger route. But that would be a lot more complicated than just wiring all the batteries in parallel and treat them as one bank.

[IceLaur]

Originally Posted by HeinSdL

Welcome to the forum IceLaur.

I would be inclined to combine the house batteries into one bank and charge that bank with all the solar panels through one MPPT.

Thank You.


I don't know if I combine all three batteries (two lead acids and an AGM) into one bank using one MPPT will create some charging issues/anomalies because in MPPT Settings I have to choose type of battery (Lead, AGM, Gel, LifePo4 etc)


What do you think about his?

Originally Posted by HeinSdL

Otherwise I think you'd need two MPPTs resulting in two separate systems and you could indeed charge one with the other either via a DCtoDC charger or via the inverter/battery charger route. But that would be a lot more complicated than just wiring all the batteries in parallel and treat them as one bank.

If I choose this option via inverter/battery charger, what do you think is gonna happen if I plug-in also the Shore Power Socket?

[sailingharry]

That changes the situation. It is not generally considered good to combine the AGM and the FLA. You could move the AGM to the starter position and combine the other two batteries into a single bank.

Otherwise, a separate charge controller is the correct answer. This does have an added benefit. The ideal setup for solar panels is a separate charge controller for each panel, allowing the system to adapt to uneven shadowing. If you set it up as two separate systems, and then in the future combine the batteries, you will already be positioned with two charge controllers, the ideal solution.

300Ah total isn't a lot of power. What is your boat?

[IceLaur]

Is a 23 feet power boat: Jeanneau Merry Fisher 695 S2 (2022).

[HeinSdL]

Yes right, didn't read carefully enough to see the different battery types. So then not such a good idea to combine. Nevertheless, to design the system based on the current battery mismatch might mean unnecessary costs which are better incurred perhaps building the single battery bank, ie replacing the standalone battery.