MPPT Solar and Sterling shore power connections

[Delfini]

I have a 240V Sterling marine twin output 12v battery charger located underneath the cockpit and each of the twin outputs connected to either the 3 x domestic batteries or 1 x crank battery bank/s - I plan on installing my new 2 x 100w solar panels through a Victron MPPT controller installed next to the Sterling on a ply bulkhead

Given the MPPT has only 1 x 12v output can I connect the output to both of the 2 x outputs on the Sterling to save running wires in parallel to the existing twin charging cables) or will this cause the Sterling a problem when trying to decide if domestics or cranking battery have reached full charge ?

I plan to isolate the solar when charging the batteries from 240v and alternator charging of both banks is via a VSR relay - not sure if thats relevant ?

Thanks for any advice

 

[VicS]

I have a 240V Sterling marine twin output 12v battery charger located underneath the cockpit and each of the twin outputs connected to either the 3 x domestic batteries or 1 x crank battery bank/s - I plan on installing my new 2 x 100w solar panels through a Victron MPPT controller installed next to the Sterling on a ply bulkhead

Given the MPPT has only 1 x 12v output can I connect the output to both of the 2 x outputs on the Sterling to save running wires in parallel to the existing twin charging cables) or will this cause the Sterling a problem when trying to decide if domestics or cranking battery have reached full charge ?

I plan to isolate the solar when charging the batteries from 240v and alternator charging of both banks is via a VSR relay - not sure if thats relevant ?

Thanks for any advice

What you are suggesting will combine the outputs of the Sterling and, if I understand correctly, make a permanent link with unsuitable wiring of the two battery banks.


I would use a dual sensing VSR

Connect the alternator output to the engine start battery to make that the priority for the alternator to recharge after starting the engine.

I'd connect the solar charging to the domestic battery to make that first priority for the solar system

If permissible I would combine the outputs of the Sterling charger and connect it also to the domestic battery to make that the first priority for the Sterling.
Alternatively connect it in the normal way with one output to each battery bank and accept that as soon as either battery is charged the VSR will link both anyway.

I don't see the need to isolate the solar system when charging from the alternator or from the Sterling charger. If you do it may be necessary to isolate the solar panels from the controller rather than the controller from the batteries.
You don't give details of the Victron MPPT controller so I have not attempted to find and read its instructions.

 

[PaulRainbow]

I wouldn't disagree with Vic.

What you are suggesting will combine the outputs of the Sterling and, if I understand correctly, make a permanent link with unsuitable wiring of the two battery banks.[/quote

Yes, a definitely bad idea.

I would use a dual sensing VSR

Connect the alternator output to the engine start battery to make that the priority for the alternator to recharge after starting the engine.

I'd connect the solar charging to the domestic battery to make that first priority for the solar system

Yes to all of that.

If permissible I would combine the outputs of the Sterling charger and connect it also to the domestic battery to make that the first priority for the Sterling.
Alternatively connect it in the normal way with one output to each battery bank and accept that as soon as either battery is charged the VSR will link both anyway.

I'd leave the Sterling connected in the normal way, with the engine battery, having first priority. It's generally going to be fully charged, so doesn't make much difference. But if it is low i'd like to get it charged back up faster.

I don't see the need to isolate the solar system when charging from the alternator or from the Sterling charger.

Absolutely. Unnecessary and a waste of time.

One thing i would add, the mains charger will do such a good job of charging the batteries that there might not be much for the solar panels to do. I leave the mains charger off most of the time and keep an eye on the batteries when i'm onboard, if they start to get low i put the mains charger on for a while. When not onboard i leave the mains charger off, the solar panels easily keep the batteries fully charged.