Isolator or battery switch?

[waynerh]

Greetings,

I am trying to set up a second battery and am having a difficult time with an isolator. It seems that I can't find a 3 pole isolator and the 4 pole doesn't work. Some say to just get a switch, but I enjoy the convienence of an isolator.
Any opinions? I really don't care about turning the batteries off because they stay in untill winter and I trailer the boat.

Thanks for the help!

waynerh

 

[PondTunes]

Re: Isolator or battery switch?

One other problem with an isolator is they have a small voltage drop so your batteries don't get the full voltage coming to them off the alternator. You might look at the blue-sea-system's add-a-battery system it uses a smart relay that connects the batteries when the alternator is charging.

 

[PolishPrince]

Re: Isolator or battery switch?

You are correct, there is a voltage drop with an isolator. I did a lot of research and found that an ACR (Automatic Charging Relay) does a much better job. It senses the voltage of one or both batteries (your choice) When it is above 13.2 VDC (alternator output) it automatically connects the batteries together and charges both of them. When it drops below ~12.8 VDC (engine off) they disconnect. These voltage thresholds are adjustable in case you have an engine with an alternator that's a little on the weak side. They make several models from a small one for pleasure boats to larger ones for diesel powered yachts. There is no voltage drop with an ACR. With a float charger hooked up when you're in port, both batteries are at peak performance and ready to go. I also added a battery switch to jump Batt A to Batt B should the need arise. In addition I have an LED mounted adjacent to the volt meter on the instrument panel that illuminates when the batteries are automatically connected. All this is spelled out in the instructions. I purchased my ACR online.
You can get more detail including instructions and wiring on the ACR at
http://bluesea.com/category/2/productline/overview/386
Good Luck