Battery Switch Wiring Diagram

[Cheechako]

I think your windlass will draw more than starting your engine........ of course all my engines have started immediately! Guess I've been lucky....

[Maine Sail]

Originally Posted by sailvayu

Maine
The reason the batteries last longer is because they never get discharged. Sort of like your car battery. Of course you could use deep cycle batts but these are not designed for rapid discharge a starter uses. Ok I am not saying change everything out I am just saying this is what I like to use so others have something to think about. Yes using the ACR combiner with the switch is fine. Just make sure the combiner is rated for your load. This is the type of thing where there really is no "right" answer as there are many "right" ways to do it, I was just offering a suggestion.

Also I am not sure I would have a fuse on my starter circuit as you say. The common method is to run the starter cable directly to the battery, (with a off switch in circuit) But if that works for you then I see no harm. Fuses do get old and fail at the wrong times so I personally would not do that and ABYC does not require it in that location. Surge amps can get high and if the engine has a problem starting you could blow the fuse. Also if you have to crank a long time it could over heat the fuse and blow it. But on the other hand it is nice to have that protection.

I just feel it is best to keep the house wiring and engine wiring separate. Just my opinion. Your setup is fine too not saying you are wrong. And you are right if you are not doing a major rewire I would not say rip it all out and start over.

Thanks
Wayne Canning, AMS
projectboatzen.com

Not saying either way is right or wrong either. I also don't fuse my emergency start battery, though I have in the past with a large fuse and never had an issue. I based this fuse size on max rated cable amperage not the starter load so it was way above the starters 160 amp in-rush current draw.

Like your set up, the set up I described also never discharges the emergency/start battery so it should theoretically last about the same as yours.. For me I actually exercise my start battery, though not really necessary, about once a week by vacuuming my vessel using it.

With the set up the OP has he will never need to use any position on the switch other than 1/OFF. If he should kill his house battery then he could switch to bank 2 and re-start the engine.

There is absolutely nothing wrong with a dedicated hard wired start battery but it is a lot more work to do this for the OP. That is the only point I was trying to make.

[gpeacock]

Originally Posted by AaronJ

Thanks for the replies, Wayne and Maine Sail. I've updated my diagram with the charging relay you recommended. I'll use the switch in the following ways:

At dock, AC charging: Off
At dock, AC charging with me in boat: House Bank
Cranking Engine: Starter Bank
Cruising, Alt. charging: House Bank

So, I'll just remember to switch from Starter to House after I get the engine started.

Thanks,
Aaron

Im am also redoing my electrical system and have purchased the "add a battery" package from Bluesea (Add a Battery - PN 7650 - Blue Sea Systems) they say to connect the alternator to the switch not to house...
wiring diagram here: Upgrading Battery Switching and Charge Management with the ADD A BATTERY Dual Circuit System - Resources - Blue Sea Systems

Question 1: Where should the AC charger go. I have an old guest 2600 dual 3 stage. I can jumper out the second leed on it and let the ACR take care of controling the charging (do I connect to house or starter?) or I leave it connected to both bats.

Question 2: In this setup if you manage to drain your starter battery and need to switch to house to start, wont combining the two batteries run the risk of draining house as well?

[Strygaldwir]

I am not certain if it was in any of the other posts, but I'd add an on/off switch to your starter battery. If you have an a|B|off|Both switch on your house bank, this effectively lets you swap either bank, for either starter or house roles. If you put your alternator out put on the other side of the A|B|off|Both switch you could charge either battery instead of being limited to charging only the house bank or both.

[osirissail]

- - Do not forget to install a ANL bus fuse up close and personal to every battery's positive terminal. This is now a ABYC requirement and even beyond that I have seen a half dozen boats over the years burn to the waterline due to a dead short allowing max battery current to cause the battery cables to catch on fire. Every battery "bank" needs to have the bus fuse between the positive terminal and the battery cable running to your loads or battery switches.
- - If you are going to install a separate/dedicated engine starting battery then to install an "emergency" cross-over switch you need simply another cheap battery switch with only 1/2/off. Should your dedicated engine starting battery go dead or short out you want to be able to disconnect it from the engine starter and then connect the alternate (house battery) to the starter. Never parallel a dead battery with a good battery.
- - Specifically you connect the "common" terminal of the battery switch to the engine starter and then a battery cable from the #1 battery switch terminal to starting battery. The #2 terminal on the battery switch is connected to house bank batteries - ideally to the "common" terminal of the house banks battery switch which will allow you to choose which house bank battery you want to use to start the engine.
- - Without a dedicated starting battery your original diagram is fine - just add the battery ANL bus fuses and a "battery combiner" between the two battery banks.

[FSMike]

Aaron J -
After all this technical advice -
If you are going to turn the batteries to "off" at the dock when you aren't aboard -
Don't forget to make provision for a power source to your bilge pump.