2007 21-EC Battery Charger/Isolator Wiring

Our boat, built in April of 2007, has the Promariner isolator in the DC system. It appears that our house battery is not maintained by the Guest Charge Pro shore power charger. I have looked at the wiring diagram posted on the site, but it does not match the wiring on this particular boat. I searched for similar problems on the forum, but found nothing. I also searched for a wiring diagram from Promariner but struck out there. It appears their emphasis is now on galvanic isolators and the battery isolators are an afterthought.

The charger is wired only to the positive lead of the start battery and to the common negative of both batteries. Only the alternator is wired to the "A" terminal of the isolator.

Wired as it is, and with my (limited) understanding of isolators, the isolator will not pass current from the charger connected to one battery (the start battery in our case) to the other battery (our house battery). Is that correct?

Is this the correct wiring for the charger, or should (can) the charger positive also be carried to the "A" terminal on the isolator if the house battery is to be charged from shore power?

I plan to ask Promariner about this, too, but do not know how well they are supporting the battery isolators now.

Thanks.

The earlier model Ranger R21 2007 had a "one bank" battery charger on them that maintained the house battery bank only. If you are looking to charge both batteries with the onboard charger, you will need to purchase a "dual bank" guest charger. They make the dual bank that will plug in the same way as your existing model with a bit higher output for charge. This is the easiest solution in my opinion.

There are a few other ways around this that are also pretty simple. You could install a on/off switch between the two batteries which would act as a emergency parallel switch by connecting the Engine Positive and House positive. If you were at the dock with the charger turned on, you could engage the switch making your battery bank one big bank allowing your single bank battery charger to charge both of the batteries. Guest does not really like this as the charger is only rated for a pretty small output but it is an inexpensive way to bypass that.

The other way would be to install a charging relay which would do the exact same thing and install the same way but do it automatically. The only down side to this is you do not get the parallel feature as you would with a switch.

Thanks Andrew. Ours is wired to charge only the start battery instead of the house battery. If moving the output from the charger to the "A" terminal on the isolator is not practical, my other thought was to just buy another 6 Amp charger identical to the one already on board and to wire it to the house battery.

One way or another, I'll get it done. I did want verify if what I was seeing is what you expected, and apparently it is except for which battery was connected to the charger in our case. The house battery has been replaced at some point and perhaps the change was done then by the installer.