I have a parallel dual battery setup with 2 Odyssey Extreme 37/78 AGM batteries.with an isolation solenoid and delayed trigger for 90 seconds after startup. Contactor is a 225A 100% duty cycle, 600 Peak Inrush Trombetta.

I do not have them fused yet. I take it ANL 80A is basic, Where would you put them? Before and after the solenoid or one closer to the primary? How about resetable breakers?
Any brand or source recommendations?

Thanks

 

Put them as close to the 12v battery terminal as feasible on your main power wires. So it looks like one between your isolator and 2nd battery and then one on that parallel wire (this will be the large AWG wire that you have added in) nearest to the first battery.

80A is a very small fuse, is your 2nd battery not used for much?

 

Size the protection devices for the wire sizes they are protecting. There are charts across the net for this. One advantage of a resettable circuit breaker is additional easy isolation points. Circuit breakers also tend to have a slower curves than fuses so they handle inrush current better than fuses and wont get week over time if the inrush gets into the melt time of the fuse.

 

Thank You Guys.

 

Back again, I confess I had my setup all wrong being my 2005 has the RVC load sensor on the ground cable. I had them on different ground points. The voltage gauge was all over the place between 13v & 15+v, Live & learn.

My question now is on the isolation solenoid. I have a time delay relay set for 1.5 minutes after key on with the big idea this would indicate my primary is healthy at start up and would charge a little before the secondary connected.
It has been demonstrated to me how when one battery is for example 12.5V another is 13.0V and you parallel them for a few seconds, then disconnect, they will meter the same. Kind of like a duel fuel tank system equalizes.

So it seems I would be toggling things a lot. How wide a range I don't know or bad for the batteries or system it is I have no idea. Thats why I ask.

My main reason now is having is a backup battery and to have it isolated if I need to jump someone off, I always shut the engine down is for said.I used to run aftermarket audio, wench, 100WAtt halogens. Not anymore.

 

After your isolator connects the batteries, they will stay connected until key off won't they?

 

Yes it will

 

So what is the problem or your question? It seems fine to me, your batteries will connect during running and charge both of them, then disconnect when off, which is ideal for mismatched batteries and how you want to use them.

Did you fix the problem with the grounds and charging system then?

 

Thank You, Just asking because I'm not that experienced.Both batteries are identical.You answered my question about the isolator.

I called Mechman Alternators with questions and got a link to correct my mess and am following using 2AWG. This will fix my grounding there and my confusing the RVC system.
The alternator being a 160A and the new charge wire being a short 4AWG will have a 200A ANL fuse.
I read I should fuse the batteries also but cannot find what size fuse. 2AWG on both with a 8 foot run to the secondary, maybe 6 foot to the starter.
http://alcphoto.net/truck/mechmen_2wire_dualbatts.jpg.
Why is it so @&$#v difficult to load pictures here?

 

Easy as using the image tags...

(however some websites prohibit hotlinking)

If connecting per above with the addition of the isolator on the positive between the two batteries, I would not worry with a fuse there as long as it is adequately protected from chaffing or heat sources. I definitely would not fuse the starter wire. The inrush on the starter would slowly eat away at even a large fuse and may leave you stranded at an inopportune time. The fuse in the routing above is mostly to protect the alternator from a faulted battery.