How to wire a third battery

[delitubby]

Help needed.

I have a RIB with twin engines. Currently I have two batteries each charged by / starting a separate engine.

I want to wire in a third battery to supply the ancillary equipment (plotter, VHF, sounder, bilge pumps etc). Reason for this is that i want to run the auto bilge pump off the third battery so I don't run the risk of flattening a starting battery.

Hope that all makes sense.

The question i have is if i want to charge the third battery how do i do it? If i wire it to another battery (of greater amp/hr) in parallel to draw charge will that drain either of the connected batteries as the third battery i have is less amp/hr than the starter batteries? Or is it less hassle to just have the third battery the same amp/hr than a starter battery?

I look forward your thoughts!!

[Erin]

Do a search for BEP battery cluster with VSR regulator. I think it is Merlin Equipment on the south coast that do them. Makes for a very neat installation and good quality product. They do systems for one, two or three batts. Cant' remember their web address, but it's something like thepowerstore.co.uk

[martini]

I have a twin engine/triple battery set up, I used Bluesea automatic charging relays and battery switches. It works really well, the engines charge their starting batteries then switch over to charge the house battery when the starting batteries are full. Bonus is I can run all my accessories knowing that they cant take power from my starting batteries because they are isolated, all without having to remember to flick master switches on or off, its all taken care of by the ACR's.

Heres a link to a wiring diagram:

http://bluesea.com/files/resources/i...tions/6346.pdf

[Cookee]

Originally Posted by Erin

Do a search for BEP battery cluster with VSR regulator. I think it is Merlin Equipment on the south coast that do them. Makes for a very neat installation and good quality product. They do systems for one, two or three batts. Cant' remember their web address, but it's something like thepowerstore.co.uk

http://www.merlinequipment.com/

[SW RIB Charter]

As an alternative, we have two engines and two batteries each with their own isolator then a crossover switch. All the electronics, bilge pump, etc are fed from one side, so if that were to flatten then we just flip the crossover switch and start from the other battery.

[jwalker]

To answer your connection query, yes, you can link in parallel similar types of battery of different amp/hour rating and they will charge fine. There is a number of threads concerning battery configurations, always worth doing a search.