Amp Wiring and Battery Switch

I ran my new amp wiring to the battery switch and the ground to one of the batteries. Question: Does this sound right? Do I get into a problem if I have the switch set for battery 1 but the amp is grounded to battery 2?(seems ultimately they share a common ground).

Thanks for the help.

Your fine the way you have it but......why not wire your amp to the "both" or "all" position so your amp will work on either battery?

What kind of switch do you have, simple ON/OFF or a 1/BOTH/2/OFF? If it's the duel battery type switch, what post on the switch did you wire the amp Pos to? The best scenario would be to wire the amp directly to the battery Pos (same one as the ground) IMO.

(Message edited by chpthril on May 13, 2008)

You should run your power for the amp to one battery and not the switch. This way you have a dedicated battery used specifically for your tunes while still having a battery to be used for starting. This way you can switch batteries if you run a single one down playing tunes while not running the boat to charge the batteries. The two batteries should share the same ground due to you connecting them with a common ground wire. Battery 1 will then connect to the switch so you have the same ground. The switch is really just for the starter and alternator so if you run your amp battery down you can switch over to the other battery to start your ride in a pinch. That is how I wired mine and how I know I am good to go if I kill one battery while playing tunes and not riding in the afternoon when it gets chopped out and I just want to hang out while drinking and swimming.

That should work fine the perco only really controls access to the positive terminals form what I've seen.

As for Byron's ? I think it depends on how you want to run your stereo, I ran my "main stereo" ie HU and in boat speaker amp to the Perco but the extra amps for subs and tower speakers I've got wired directly to battery bank #2 so that they only run off that bank unless i turn it to all then they can run battery 1 down as well. I also figured that the perco probably wouldn't hold up well to 150+ amps (on the low side) running through it.

The switch has three posts, one for each battery and the other is the output. The switch has a 1,2,both, off setting so if I am worried about the tunes draining my battery I can just set the switch to 1 or 2 and then switch to the other battery to start the boat.

On my other boat I had 2 batteries and no switch and never had any problems. I would prefer running both if I can so the batteries don't get lopsided. I've heard you can fry the low battery when you run them separate and then switch to both because the full battery will flow power to the low battery at too high a rate.

You should look at the switch as having 2 terminals for the batteries and 1 INPUT from the alt, not an output. BATT 1 = "Starting" battery, BATT 2 = "House" battery, and C (common) is the charge from the alt. with your loads wired directly to the battery.

If wired correctly with the load pulling directly off the "House" battery, you can leave the switch in BATT 1 position, and it will be isolated. The only reason the move the switch is to recharge the battery after starting the engine. $.02

When 2 batteries of unequal charge are connected in parallel, they simply equalize.

My concern is the rate in which they equalize. There is no regulation to the charge rate of the low battery and the full battery will transfer power at a much higher rate than say a 10 amp charger.

Dont combine (switch on BOTH) your batteries until engine is running. Now you will be charging both, but you started the engine from the fully charged battery on position 1.

I still don't think you get my point. When I turn switch to both after starting the strong battery will be capable of delivering a charge to the low battery at it's cca rating which in this case is around 800 amps. Batteries are not designed to be charged that quickly. I know I have read this somewhere but can't remember where.

"I still don't think you get my point. When I turn switch to both after starting the strong battery will be capable of delivering a charge to the low battery at it's cca rating which in this case is around 800 amps. Batteries are not designed to be charged that quickly. I know I have read this somewhere but can't remember where."

Dont worry, that wont happen. Current flow is a result of load. The battery with the lower state of charge will not draw that kind of current from the battery.

Here is a simple definition of Cold Cranking Amps: "Cold cranking amps (CCA) is a measurement of the number of amps a battery can deliver at 0 ° F for 30 seconds and not drop below 7.2 volts. So a high CCA battery rating is good especially in cold weather.
"

Although your "Starting" battery had an 800 CCA rating, the discharged "house" battery will never put that kind of load on it to draw that amount of current.

also unless things have changed you NEVER want to change the position of the perco while the engine is running. If you drain bank two then just switch it to both and then start the engine, the temporary combination of the two banks will not effect the starting power of bank one enough to prevent it from getting you going.

When you combine to batteries they immediately equalize. If one is completely dead an done is fine the second you switch to both the dead one is going to draw voltage from the good till they are equal voltage.

If I were you I would spend the money and get a Sure Power smart Solenoid. It keeps the battery banks separate if the starting battery is low and then when that is charged to a proper voltage it parallels the battery banks and charges the house bank. Now I said that when they are paralleled the dead will rob from the good and then it will separate them until the starting is at the correct voltage and then combine them again. It goes through this cycle till both banks are to the correct voltage. The really nice part about this system is that it gives priority to the starting battery so you don't drain the system with your stereo and are left high an dry. When you use a system like this you should use all similar batteries. Don't mix AGM, gel and lead acid batteries.

Oh yeah, hook a large gauge wire to your battery positive and run that to some sort of distribution block. They make some with built in fuses and ones that don't have built in fuses. If you use the one without fuses just make sure and put an inline fuse somewhere between the distribution block and amp.

(Message edited by polarbill on May 16, 2008)