Baffled by Battery Selector Switch Set-up

[Adams]

I was messing around this weekend checking out some the problems and stumbled across the battery selector switch working different than I thought it was supposed to operate. I have twin engines and the Engine Selector switch only starts the starboard engine. It will start the starboard engine in any of the three positions (1, 2 or Both) but does not start the port engine. The house batttery Selector switch starts the port engine only, again in any of the three positions.

I thought the Battery Selector switch was supposed to start both engines? It has two deep cycle batteries. The house battery side is only a single standard marine battery.

I reread the manual and think this set-up is wrong but before I start rewiring can anyone expalin how it should work? If it is correct as set-up should I add a 2nd battery to the House side for extra starting power?

 

[Chris1956]

Re: Baffled by Battery Selector Switch Set-up

How many total batteries do you have and what is the "House" load?

The way I thought it would be neat to set it up requires two battery switches and four batteries, as such:

Two batteries would be for starting the engines and the other two would be connected in parallel and used to supply the house load. Starting Battery 1 would start engine 1 when set in position one on switch one. Starting battery 2 would start engine two when set in position two on switch two. Starting battery 1 could be used to start engine two by changing the setting on switch two to position 1. The same setup for the other engine. The house batteries would be charged thru battery combiners to the two starting batteries.

The advantage of this system is that your starting batteries will always be fully charged, you never have to flip switches unless a battery goes bad, and you can start any engine from any starting battery, with the flip of a switch.

 

[Silvertip]

Re: Baffled by Battery Selector Switch Set-up

You better take another look. If the "house" battery is a standard marine starting battery that's an incorrect application. If the deep cycles are used for starting, that's also an incorrect application. In other words, this is entirely backwards. You have two engines, so with one start battery, which engine does the charging, and what is the other engine connected to. It is not a good idea to parallel the two charging systems. As mentioned, you really need dedicated starting batteries and using the deep cycles for house duty.

 

[Adams]

Re: Baffled by Battery Selector Switch Set-up

You guys confirmed that the current set-up is incorrect. I bought the boat last summer and continue to find some really puzzling setups. It will take a little tracing work to determine how & why the engine selector switch only allows power to the starboard engine regardless of which position the selector is moved to. I will also get the correct battery arrangement.

Thanks

 

[Silvertip]

Re: Baffled by Battery Selector Switch Set-up

That switch is better called a battery selector switch meaning it selects the battery used for starting, charging, and house. It may indeed be rigged up to use one battery to start both engines which is also poor application of the switch. Each engine should have its own starting battery.

 

[Adams]

Re: Baffled by Battery Selector Switch Set-up

If each engine should have a separate battery bank then what happens if one side goes bad? I thought the ability to 'select" between battery banks was a positive that works like a back-up. And if each bank starts an engine how do you decide between deep cycles and standard marine batteries? I am even more confused now.

 

[JoLin]

Re: Baffled by Battery Selector Switch Set-up

"If each engine should have a separate battery bank then what happens if one side goes bad?"

That's precisely WHY you want a dedicated starting battery for each engine. So a dead battery won't strand you. Listen to these guys. They know their stuff. You haven't answered yet for how many batteries you have on the boat. Folks here will help you get them wired up right.

(If you have room on the boat you can always carry a jump starter for a dead battery emergency)

 

[TBarCYa]

Re: Baffled by Battery Selector Switch Set-up

Here's how I would do it but keep in mind that I've never wired a boat with twins...

One starting battery on each side and one switch on each side. House batteries get connected to position 2 on port switch, port starting battery to position 1. On starboard switch, starting battery on position 1 and port starting battery on position 2.

Basically, both switches go to position one for starting then the port switch gets changed to 1&2 to charge the starting and house batteries but the starboard switch stays on position 1 to charge the starting battery. In the event that the starboard battery fails switch the port switch to OFF or 2, then set the starboard switch to 2 and start the engine from the port starting battery. If the port battery fails, set the port switch to 2 and use the house batteries to start.

There's probably a better way, but that's how I'd do it.

 

[Uraijit]

Re: Baffled by Battery Selector Switch Set-up

I'd do it with two separate engine batteries, and two switches.

Set it up so that position 1 on switch 1 goes from port battery to port engine
Postition 2 should go from to starboard enging

Position 1 on switch 2 goes from starboard battery to starboard engine, position goes to port engine.

If one battery goes dead, just flip the switch for the other battery, and fire it up.

The engine batteries should just be standard batteries.

Then, use a battery isolator to charge your deep cycle "house batteries". This way all of your batteries always get a full charge, and there's no possibility of your house batteries draining your startup batteries.

http://www.e-marine-inc.com/products/alternators/iso2alt3bat.html

In that picture, "battery 3" would just connect to both of your deep cycles. Since they work as a "bank" they don't need to be isolated from each other.

 

[PondTunes]

Re: Baffled by Battery Selector Switch Set-up

Try this setup if you're still dealing with this:

Normal Operation:

Switch "A" in position #1, Switch "B" in position #2, Either battery can crank either engine.. The house battery is charged by engine #1 a disconnect or isolator can be used to prevent the house battery from draining battery #1..

 

[Adams]

Re: Baffled by Battery Selector Switch Set-up

I have a single battery on the port side and two batteries on the starboard side. The single is a standard marine battery while the dual side are both deep cycles.

I need to install a GPS and fuel flow line and decided to have a specialist just do the work and check the battery set-ups at the same time. I will closely observe as I realize I don't know enough yet to risk screwing up the electrical system.

Thanks for the input. The diagram is really helpful.