more second battery ?'s...set me straight

allright, I definitely want to add a second battery to run my stereo off of. I have an older PCM engine and a pretty big stereo system and I don't want to get stranded.

Someone give me the basics of what exactly would be needed to add a back up. I'll probably use a Perko switch since it seems to be the cheapest way to go.

Do I need both of the same type battery, or will different ones do? I know the Blue Tops seems to be top of the line, but will any deep-cycl marine battery be about as good.

I want to do the install myself, and I have a access to any tools I may need, so someone please just walk me through it...wires, fuses and everything.

local shop told me it would be about $400 for everything installed...I'm thinking I can do it for quite a bit less myself.

Here is what you need. Perko switch, cable(I used 4 gauge audio power cable nice and flexible), terminal ends for the cable, battery box, and a battery. The instructions in the perko switch will tell you how to hook it up. It is really that simple. One thing to consider is that your alternator will now be charging(depending on the switch setting) two batteries in parallel. I never had a problem, but it is just a thought.

Are you suggesting a bigger alternator?
I'm looking at doing the same thing.

Perko switches seem to be the overwhelming way for people to hook up a second battery. Any one know why?????

I used or Use a continious use heavy duty solonoid (stinger makes one) that switches the battery electronicly you can have 50 blue tops and if you forget to switch the perko over your going to kill your battery

Where do you get the Perko switch?

im doing the same thing.im gonna go w/ a battery isolator pt# 4805 @ www.skidim.com $48.00

Rich, You can get it at westmarine.com and Get a battery isolator too. The Isolator will eliminate what Grant is talking about.

Here You go....http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&langId=-1&catalogId=10001&productId=34883&catalogId=10001& classNum=12106&subdeptNum=544&storeNum=9

http://www.stingerelectronics.com/web/prods/fans.asp

I used a "mobile audio relay and battery isolater" this way i don't have to do a thing. hook it up and forget it, no switches no nothing. The one i got came from tweeters and is model pac-200 made by pacific accessory corporation www.go2pac.com.
good luck

how much?

Grant and Andrew, I'm with you on the solenoid. I installed a 200 amp continuous duty. I know I would forget to turn the stupid switch. Don't know why everyone wants the switch?

so the isolator's do the same thing as the Perko, but automatically?

Couldn't you still run down both batteries if you ran your house equipment for a long time, or does the isolator or Perko prevent this somehow?

yes

the isolator allows current to charge both batteries but seperates the draws so your stereo never draws juice from your starting battery and vice versa.

allright sounds good enough for me...isolators the way to go if it's totally automatic.

Is an isolator I can buy at West Marine for $100 any better than the $48 option linked above?

What about batteries...does it matter if the two are different make/model, or should they be the same?

Mine cost about $80.00????

I have a question on the isolator. I know they switch automatically to allow for recharging. I assume they do not switch if the battery that is hooked to the stereo goes dead right? Meaning, it will not draw off the second battery if the first battery goes dead. That would be a good thing to not happen. Hate to run down the back up battery.

One thing I like from my Perko switch is that I can turn off all my electrical power to the boat and not drain the battery over the long haul. The stereo memory and things run down the battery over time. Just a thought, but, the isolator sounds nice.

Well, Grant, are you going to keep us waiting? Tell us why!

Rod, I think that if your boat is to sit around for that long of an extended period of time, i would hook up a trickel charger. I use my boat 12 months of the year so i don't have that problem, however, recently 2 of my friends brought thier boats out for the season and both sets of batteries were toasted.

How does the installation go with an isolator. Is it very complicated? How does the isolator know when the boat engine is on therefore allowing both batteries to charge?

someone tell me about types of betteries. Consensus seems to be that the Blue Tops are the way to go, but they are also pricey. Is it worth the extra, or would a deep-cycle marine battery from Wal-Mart be about the same?

Should both batteries be the same type or does it matter?

I'd like to pick this stuff up this afternoon so I can work on it all tonight. Any quick help is appreciated. Thanks

I would be careful using any auto equipment in the boat. If they are mounted in a location that is sealed, and fuel fuems can get to them, then a spark can cause serious problems. This does not mean that they can't be used, but more so that their mounting location must be carefully planned to prevent a nice 4th of july show.

the stinger isolators are marine approved, they are sealed.

the wiring isn't much harder. with the isolator you need an extra wire that will activate it when the alternator is putting out a charge. you need a siwtched ignition wire which means a wire that's only charged when the engine is running. you can look under the dash on the ignition switch with a multi-meter or one of the 3 wires of 3-wire alternators. on my supra, it was the purple wire to the alternator. i spliced into that with a splicer from napa. verify with a multi-meter first.

the isolator will have a hot battery cable to each battery, a ground, and the switched wire i described above.

diagram?.... http://www.stingerelectronics.com/tech_department/sr200_sr80%20diagram.pdf


drunk monkey- both batteries should be of the same age and condition. you don't want a nice new battery and your old beater together, they can't hold or re-charge with the same efficiency. i just bought a new starting and a new deep cycle, big ones (group 29 and 31 i think).

You dont gotta go w/ the blue tops if they are out of your budget. They are better because the recharge faster, wont spill due to being sealed, and vibration do not adversely effect them as much as a wet cell from Wallmart. You can also abuse them more like run down the charge of battery or let it go dead and then recharge, with less damage to the battery.

But, the wet cell will do a good job if you maintain them. Keep acid levels up, keep them charged ect. Buy the biggest wet cell you can fit, like a group 31 or 29. And they two batteries you go w/ should be the same age, so pitch the current one and buy two new ones.

Sorry It took so long to get back I forgot about this post.

1. Yes all your batterys should be the same.
2. When buying batterys you should try to buy all your batterys at once and see or make sure they were all made in the same month. (I was told this by the battery man take it for what its worth) and thats what I did. But it makes sence when you put batterys in your flashlight you dont throw 2 new ones in with 2 old ones.
3. When running the solonoid like I posted a photo of It cant/wont draw from the aux battery(starting battery) unless you have the key on. Example: lets say you have the starting battery hooked up to the solonoid to be active when you turn the key is on and your boat is not running and you have your key ON and your stereo going YES its going to run down both battery's but thats not what you do.

IMO the solonoid is better than perko because it takes out the human-fudge factor (forgetting to switch it) its just one less thing among the 100 other thing you dont have to remember.

Grainger also carries DC relays:

http://www.grainger.com/Grainger/productdetail.jsp?xi=xi&ItemId=1611784827&ccitem=

It is best if both batteries are the same, but by using the an isolating relay, the effect of a weak battery robbing the stronger is less then if they where in a constant parallel circuit.