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Unread 03-15-2009, 04:11 PM   #1
petey156
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dual batterys and alternators?

I am thinking for my cj5 instread of buying 2 new batteries I install another 1 wire alternator and have it charge a smaller battery like a motor cycle battery snd then link them together with a solenoid. controlled from a switch in the cab, for the purpose of self jump starting.
right now i dont see why this wont work...??? let me know what you think, I am just trying to save money by using the parts i already have ( alternator, motor cycle battery) the only con from the traditional 2 battery setup is total storage, for winches and lights.

Thanks

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Unread 03-15-2009, 05:55 PM   #2
TBrock
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Not sure a MC battery has the CCA to turn over an auto engine.
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Unread 03-15-2009, 06:57 PM   #3
LibertyJeeper
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Why would not just go with 2 normals batteries seems a whole like better, easier and cheaper. If you just want something for jumping you jeep you can get one of those portable jumping batteries.
By the time you rework the pulley system to incorporate the second alt.
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Unread 03-15-2009, 07:31 PM   #4
whittlecj
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search for jeephammer's treatise on dual batteries. Lots of good information there. I don't think there is anyway that a MC battery would be useful to jump the jeep.
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Unread 03-15-2009, 07:33 PM   #5
petey156
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the room i have for my 2nd battery is very limited, 6x9x10, I want to add to the factory battery tray because the tray bolts come from behind the heater box inside out, there fore i have to pull the dash and heater to put a ture drual battery tray in. So i a motorcycle battery is out i will look at the parts store for the smallest they have, Since i only have room for one large battery I want to add a smaller one, this setup will also give me redundency in my charging system, if alternator #1 craps out i only have to switch 1 wire to get me home.,

will a single wire delco alternator maintain a second battery with no load?
does anyone know how many cranking amps a motorcycle requires, and how many i could get away with for starting?
thanks
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Unread 03-15-2009, 09:03 PM   #6
mike06X
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why not use the 1-alternator, and wire a dual/single/momentary switch like older RV's used? Dual mode; when key on, alternator charges both batteries; key off -or- or switch single; charges main / and momentary; you hold it and it will "jump" aux to main for starting a dead engine battery..i can explain better and give you a diagram if you want too..
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Unread 03-15-2009, 09:55 PM   #7
Coiz
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You typically want a battery with cca that are 2.5x the CID of the engine. So a 304 should use a 750 cca battery. Motorcycle batteries average around 200 cca
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Unread 03-16-2009, 11:09 AM   #8
JeepHammer
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Try this tread,

http://www.jeepforum.com/forum/f8/dual-batterys-493384/

Can't use two different size, kind or age batteries or one will over charge and cook.

To run two different size, kind, age batteries, you need a CHARGE ISOLATOR,
A gadget that is kind of a regulator for EACH BATTERY...
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Unread 03-16-2009, 11:51 AM   #9
duffer
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I think worrying about the failure of a Delco alternator is a gross waste of time. They are pretty durable units, especially the gen I versions. In 45 plus years of hitting the woods, I have never had one fail. As noted above, a mc battery will be of little use and really is a waste of both time and money. You will be way ahead to invest in the most heavy duty battery you can find to fit your present location and buy a Powermaster 100 amp (or bigger), one wire alternator.
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Unread 03-16-2009, 07:37 PM   #10
flips21
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I am confused

Quote:
Originally Posted by JeepHammer View Post
Can't use two different size, kind or age batteries or one will over charge and cook.
Jeephammer,

I have a red top and a blue top on my CJ and am concerned about the implications. How would a battery overcharge if the regulator is controlling to the correct voltage?

If you had two batteries in series, I understand the need for them to be matched, (with the regulated voltage being twice what a single battery would need, an imbalance in the batteries could expose one to more voltage than it can handle until it fails), but with two in parallel, wouldn't the second battery see the same voltage as a single battery system? How does it overcharge?

Thanks,

Flip
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Unread 03-16-2009, 08:12 PM   #11
petey156
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yeah I started the other thread, thanks for the help though
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Unread 03-16-2009, 10:02 PM   #12
whittlecj
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Quote:
Originally Posted by petey156 View Post
yeah I started the other thread, thanks for the help though
Just noticed that! Were you shopping for a different answer?
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Unread 03-16-2009, 11:03 PM   #13
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Dumb question - why are you trying to do this? It governs a lot of the following choices you'll have to make.
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Unread 03-17-2009, 06:23 AM   #14
Mike Romain
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Quote:
Originally Posted by flips21 View Post
I have a red top and a blue top on my CJ and am concerned about the implications. How would a battery overcharge if the regulator is controlling to the correct voltage?
Different battery sizes and types need different charging rates. One will start to boil before the other deep cell one is charged usually.

In Optima's case this is bad news fast, those glass mats don't like to be overheated. I recently blew my blue top's top off when charging it. I think it was froze...

They make regulator solenoids for this exact problem, mixing a red and a blue.
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Unread 03-17-2009, 02:47 PM   #15
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Quote:
Originally Posted by duffer View Post
I think worrying about the failure of a Delco alternator is a gross waste of time. They are pretty durable units, especially the gen I versions. In 45 plus years of hitting the woods, I have never had one fail. As noted above, a mc battery will be of little use and really is a waste of both time and money. You will be way ahead to invest in the most heavy duty battery you can find to fit your present location and buy a Powermaster 100 amp (or bigger), one wire alternator.
I'd stay away from the 'Miricle' alternators, like 'Mean Green' or 'Power Master'...
I spent 10 years owning a starter and alternator rebuild shop, and you simply CAN NOT sustain the amperages they claim out of the case size they claim...

Stick with the SI or CS series of Delco Remy alternators,
I use THE CHEAP Remanufactured from the discount stores all the time, no problems...

AND,
Dual batteries IS your backup to the alternator failing...
Dual batteries will more than get you back in from the trails to civilization unless you have every electrical accessory to man turned on inside the vehicle.

My alternator gave up in my 'Big' jeep about 10 minutes into the trail ride, and I drove trails all day, then drove to the parts store to get a $27 remanufactured replacment.

I cooked the alternator in the little jeep about three years ago when I forgot to unhook it before welding off the batteries...
Again, the dual batteries finished the day, got me in afterwards to the parts store for a $30 remanufactured Replacment.
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