All accessories are hooked up to my deep cycle (radio, trim,etc etc) Yesterday I was putting in a new Starting battery in the battery 2 location, when I unhooked the ground of the #2 battery the radio went off?????

I have the ground cable running from batt #2 to the top post on batt #1 because my mechanic left the ground unhooked when he had the motor out and I didn't think it would affect anything.

I don't want the starting battery to drain from the stereo!!!!!!!!!!!!!!!!!!!!!! Is it because I had the battery switch on all and them being grounded together it "connected" them, also is it bad for the batteries to be grounded together?? (I thought the grounding spot was the same for both anyway?) I know different size batteries shouldn't be paralleled together is this kinda doing that?

thanks PJ

All grounds should be hooked together. In current Formulas, all the negative leads from the batteries go to a grounding plate. Each engine block then also attaches to that plate, as does house power ground and the bonding system. If your boat does not have a grounding plate, I would make sure that each battery's negative cable goes to the engine block (usually a bellhousing stud).

Are you sure that Battery 2 is your house battery, and that both battery negative cables go to a ground? The battery switch was not in the "Both" position, I assume?

<Oops. Just re-read your post a bit more carefully. If your switch was in the "All" position, I'd say that your house battery is d-e-a-d.>

thanks Spray

I was kinda of thinking that the house batt was dead I left it in the boat over the winter and had been jamming the radio while I was cleaning.

So the radio was running off of the starting battery? even though they are not connected because I had the batt switch on all (which connects them)?

So on the water I should leave the switch on the batt I want to use even if the stereo and amps are only connected to #1 to avoid draining the other?

(I was replacing both batts so the house batt being dead was expected)

Now my next question is when running should the switch be on all to charge both or should I charge one at a time (#1 and #2) separately

thanks again

Yes and Yes.

This question I need help with also. My limited knowledge tells me to keep the switch on both. However, I would think the wiring would be designed to charge both regardless.

Unless you have a battery isolator or battery combiner, they will not both charge unless the switch is on "All". If you have one or the other, they will be wired between the alternator and the batteries or the switch. Doubtful a 223 wold have one.

no isolator here but I have looked at them and might add one after this season, thanks again guys

Bear in mind that the diodes in an isolator will reduce your charging voltage by a tenth or two. Read the instruction manual, and check with the local alternator shop to see if your alternator can be adjusted. To do it correctly, you will have to disconnect the alternator lead from the engine wiring harness and insert the isolator in-line to both the house and cranking batteries.

Combiners are simpler, but often more expensive. They are basically just a relay that combines the batteries as long as the primary battery is fully charged. If it drops, the combiner will isolate it from the house supply.

http://www.yandina.com/combInfo.htm#up

I found a lot of useful info about combiners and parallel wiring etc etc.......... According to this info you can parallel any size together as long as they are 12 volt and be OK