Dual Battery installation - House battery help required
 

Hi there, just purchased my first Mariah, its a 218 with dark blue stripe and Volvo 5.0GL. First on the list of things to do is a twin battery installation. I want ot use the BEP VSR system of Engine start / Emerg Parallel / Hopuse battery with an integral charging diode. Question is, for determining the house battery powered equipment and engine start, am I correct in doing the following:

Connect Engine start battery through isolation switch to main battery + to start solenoid.

Connect House battery through isolation switch to cockpit fuseboard red power supply.

Isolate cockpit fuesboard supply wire from existing circuit as this will be tied in with the existing engine wiring somehow.

I have looked in all the online manuals etc and cannot find out where the feed for the fuseboard originates from, it does not come off the battery, so it must be spliced into the instrument live feed cable at some point. Does anybody know where its liekly to be taken from?

Re: Dual Battery installation - House battery help required
 

Here's what I did for my second battery

1. Got the Blue Sea Systems "Add a battery" kit that contains a dual battery switch and a automatic charging relay (ACR). I went the ACR route as there is no voltage drop across the relay like there is across a Diode.

2. On my Z225, the house electrical connection is to the starter solenoid . I disconnected everything other than the starter battery lead from the starter and connected them to the new house battery. I also added a 100Amp fuse on the new house battery's lead terminal to be safe.

3. I connected the single alternator charging output (orange wire) to the house battery since that gets used the most and connected the ACR relay so that the alternator charges both batteries. The 50A output of the stock alternator is sufficient to charge two batteries (through a 10A fuse of course).

4. I also made sure the Starting Isolation lead on the ACR was connected to the starter solenoid activation lead, so the house battery is isolated from the charging circuit during starting.

Finally, to make sure that the boat balance was not significantly disrupted by adding the second battery (27, I moved both starter and house batteries to the aft port side. That meant increasing the length of the starter and house lead wires from their standard 5ft to 7ft. this meant upping the wire guage to 4AWG. Moving the batteries to Port now has the boat in perfect balance.