2nd battery double check

dadunc205x · Newbie Joined: 17 Jun 2004 Posts: 23 City: Santa Barbara

Ok im about to install 2 batteries, and i want to know if what im doing will work fine. I searched a lot, but i just want a second opinion. Battery 1: marine non- deep cycle. Battery 2: deep cycle. I'll also use a perko to switch between the two batteries. I'll have all the stock electronics hooked up to battery one. And on battery two i'll have the head unit and a 600 watt amp for sub, and two lights. When driving i'll have the switch on both batteries, and when stopped i'll used batt 2 to listen to music, then switch to batt 1/2 to start the boat and run the boat....... by the way i dont have and fat sacks or anything else. How long will a battery last when playing the stereo when the boats off? anything special i should look for? thanks a lot

DiyGuy · Soul Rider Joined: 26 Dec 2003 Posts: 460

In general, you should not run with the A/B swith on BOTH. They are disimilar batteries, where one can over charge and the other not. There are many articles on why not to do this. In fact, there are directions on the back of the retail package about proper use.

Battery management is critical. You could switch to an isolator which would handle all the work for you, or you just do careful monitoring of the batteries with the Perko switch making certain, you main crank/start battery is most definately out-of-the-loop while sitting, engine off, pumping out the tunes from the amps and other hi-amp drain circuits.

Finally, with the engine running, never rotoate the switch to or through the OFF position. Always go from "B" to BOTH to "A" and reverse when managing your charge.

tmbrown · Outlaw Joined: 03 Jul 2004 Posts: 218 City: East Roseville

What you're doing sounds pretty much exactly like what I'm about to do... I'm gonna do it with two optima's... but like DiyGuy suggested, I'm using an isolator... so 1 runs the pumps and the normal critical engine stuff, like starting, where the other will do just the stereo and the accessory lights... then when you're running/charging, both will charge together. Anybody not had success with that?

DiyGuy · Soul Rider Joined: 26 Dec 2003 Posts: 460

One thing easily missed is your head unit is generally hooked up to a switch on your panel....therefore it is taking some drain off your 'primary' battery. In some cases, even, when using the switch or isolator, the 'backflow', if you will, can defeat the charging process, although a well installed isolator should still recognize which batt is low and needs the most attention.

dadunc205x · Newbie Joined: 17 Jun 2004 Posts: 23 City: Santa Barbara

i may then return the perko and get an isolator instead. I saw an isolator at pep boys, and it was rated at 90 amps. Is that enough? basically if i hook up my headunit and amp to the second, and leave the first how it is, the isolator will do what the perko does, but without me switching it.

DiyGuy · Soul Rider Joined: 26 Dec 2003 Posts: 460

That is what you would expect it to do. As good as isolators are, I am a skeptic on them. I prefer to manage my power and know for a fact what batt is taking the lion share of the load, always reserving a known good battery that is totally out of the loop for starting and associated essentials.

To my knowledge, only a properly wired Perko A/B/All/Off switch can (foolproof) do that.

And, yep...you would want to take the HU power and the yellow memory wire off the main switch panel and connect direct, (including your ground wires) with your amps on the party battery.

If you wanted to continue to use the panel switch to turn on your stereo stuff, that could be done by a simple very low drain relay that simply triggers what would amount to your "B" (party battery).

640Pressman · Addict Joined: 14 Nov 2003 Posts: 753

I have always been told to run the perko and the isolator. Run the perko on the #1 battery and use #2 for a reserve and the isolator will keep them both charged.

gotcoorsgotwake · Criminal Joined: 01 Mar 2004 Posts: 84 City: Mundelein

Diyguy - I have ran a continuous duty solenoid (125 amp), which allows me to run a small dash switch to tie the batteries together. The switch recieves its power from an engine hot wire, which disconnects the two batteries when not running. I used a diode over the coil of the solenoid to prevent kickback. It works well, and no big switch.
In other words,
Engine on & switch on - batteries tied together
Engine on & switch off - Batt 1 charges
Engine off and switch on batteries disconnect

Just another way to go. I should add that the batteries need to be the same.