Going to wire in a house battery, but have a question.

[buck3]

Alright. I am going to be working on the boat in the morning and a new house battery and charging relay. I currently have two agm with a battery selector switch, but want a dedicated house battery for this season.

But

Is there any reason not to put a d8 in? I left the switch on and the stereo on so I need to buy a new battery and wondering if a d8 deep cycle, that was left over from another project, was a good choice or not. I figure it is about 100lbs heavier then a group 27.

I figure that I have room under the deck for it instead of on the transom where the current battery is.

[Chaps]

Not if you are going to be charging it with the alternator on the Suzuki, it'd be like trying to fill up a bathtub with a teaspoon

[buck3]

I was just figuring it was going to be like the fuel tank in my truck. As long as I don't let it get too low then it doesn't hurt as bad to fill it up.

Maybe not though.

[Chaps]

Sorry for my flippant post, think I had a couple too many cervezas

Anyway, so now you've got a couple of agm's wired to everything through a 1-2-both switch? And you are adding a house battery and going to keep it isolated from the other two with a VSR charge relay? So your agm's will now be a dedicated starting bank?

[goatram]

Would you not have to have the same type of battery connected to the same, i.e. AGM to AGM, Lead Acid to Lead Acid. A smart charger can handle it at the house but on the boat running the mains?

[buck3]

Yes that's the plan. Kind of.
One of my agm's is bad. So I was going to replace it with a deep cycle for a house battery.

I figure that I can keep the 4pos battery switch(powering the motor only) with #1 being a AGM and #2 a D8. Then I was figuring that I can add a second 2pos battery switch off of the d8 and a charging relay to keep it charged.

I'm not a electrician by any means but I was thinking that the #1 battery would be isolated from the house battery #2. But I could still combine them with the 4pos switch if either went dead.

I don't have a real computer so I can't draw a diagram but is there any reason it won't work?

[buck3]

I didn't think about the compatibility of lead acid and agm with a relay charger. I guess I better look into that.

[Chaps]

The 4 position switch complicates things in a service scheme that has one start battery and one house battery IMO. In reality you don't need any switches (other than on/off for each battery if you want them). Just run the heavy engine lead to the + terminal on the start battery, another heavy lead from there to one of the big terminals on the VSR relay, from the other big terminal on the VSR relay another heavy lead to the + on the house battery, hook up the voltage sensing lead to the + on the start battery and you are done. Would I do an 8D for the house? No, you could, but the output from the Suzuki would have a heck of a time properly charging it IMO.