Recommended inverter switch + setup for 2 batteries?

[Photographer]

I would like to charge two batteries in my boat. I have a 115hp Yamaha outboard. I would like to have both batteries charged while out to make sure that I don't get stuck out on the ocean.

Do they batteries have to be the same capacity/type?
Which inverter switch do you recommend?
Can you help me how to set up the batteries wit the switch?

THANKS so much!

[boatbod]

Either a simple 1-all-2 battery switch or a Blue Sea ACR will get the job done. The latter is foolproof, the former you have to remember to switch back and forth.

Sent from my SM-N920V using Cruisers Sailing Forum mobile app

[exMaggieDrum]

Do a search on here for battery combiners, chargers, and such. There have been hundreds of threads on this, many very recent (as in last couple of weeks). There are pros and cons to the different ways to do it.

It goes beyond just charging a start and house battery design. It really should be a "holistic" design that includes: which battery will be charged by the alternator (house or start), type of switches, Echo-Charger/Duo Charger/other dc to dc chargers, types of batteries if they are different, etc.

The solution may be simple but the decisions are not trivial.

It's not clear to me how an inverter is part of your question though for an outboard boat on the water. You can use an inverter/charger to charge batteries while on the dock with shore power but it won't do anything for you on the water. Your outboard will have an alternator that usually goes to a start battery. An echo charger may be all you need or a 1-2-all switch. I'm not a big fan of 1-2-all switches for what you want to do. It is too easy to leave it on "all" while you are running the motor and then both batteries will run down at the same time if your charging fails. A duo charger can do a better job of charging two different types of batteries.

But if you are very careful and isolate your batteries after charging them both up, a 1-2-all switch is the simplest way to go.

Look at the Blue Sea site. It has some configurations but remember they are trying to get you to buy their products not necessarily give you what is best for you. They do work though. Here is one product they sell: https://www.bluesea.com/products/764...tery_Kit_-_65A

Here is their wiring diagram: https://www.bluesea.com/systems/42/2...ectical_System

But this system uses a battery combiner and there are pros and cons to that setup.

[Stu Jackson]

Inverters do not charge batteries, they remove power from the batteries. Thought you'd like to know.

[a64pilot]

I just did a quick internet Google search for "adding a second battery to a boat" or similar.
these are the results
https://www.google.com/webhp?sourcei...boat%20diagram