dual battery setup

[Eric_M]

that answered my question perfectly, but 1 more question..... will a higher out-put alt. just bolt right up and use the same wiring connections as a stock one? thanks!

stupid people shouldnt breed!

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[orvacian]

It depends. The stock wiring is thick enough for the stock alternators output. If you double the output amperage you would probably want to use a heavier gauge wire. For 120 amp alt you would want at least 4 awg wire. The mounting depends on what type of alternator you get. I got mine from a e-bay retailer and it was exactly the same size as stock, it bolted right up.

[michael_loomis]

depends on the alternator you buy , but yes it "should" . its a good idea to increase the charging wire to 8 gauge also , as the factories mostly use 10 gauge , some ive seen small as 12.

[ntsqd]

Cole Hersee makes a constant duty solenoid just for this purpose, separating batteries when the ign is off. You can't push starter current thru it, but it'll handle everything else.

My general practice when adding stuff to an existing wiring system that has two batteries is to wire all of the added loads the the second battery. One option I like for hard service vehicles with separated batteries is to wire a Ford starter solenoid to put the batteries in parallel for self jump starting. Pull the solenoid's power from the second battery.

I've seen that advice about the two batteries needing to be the same or they will see-saw discharge each other many, many times. While I think it is a good idea to match the batteries, I think the damage potential (no pun intended) to the batteries is commonly overstated. A case in point is my '79 Suburban. It came with the dual battery option. They are wired directly in parallel from the factory, no isolator. One original battery is listed on the option sheet as having nearly a 1/4 again more capacity than the other battery.

TS

I used swerve around my halucinations, now I drive right thru them.

[orvacian]

The issue is not if the batteries will be damaged, rather that they will discharge while sitting in your driveway. Then you would be late to work and get fired, you cant pay your morgage so you get evicted, your wife leaves you because you are broke, then you get this super bad athletes foot and your leg has to be amputated, then you are crawling across the street and get hit by a semi. See how if you wire two different batteries in parallel, it could kill you!?!

<P ID="edit"><FONT SIZE=-1>Edited by orvacian on 02/12/03 11:29 PM (server time).</FONT></P>

[michael_loomis]

Thom , i 've always been told that without an isolator one battery could drain before the other and likewise charge faster/slower.

what is your opinion ? i've never seemed to have any really big issues but on yachts they ALL have isolators.

[ntsqd]

Maybe they will some see-saw discharge, but my point is that GM didn't think it was enough of an issue to include some isolation method in the dual battery option, one that paired disimilar sized batteries from the factory. One can argue that they are too costly for GM to consider using one, but GM would also take into consideration customer complaints and the cost of warrentying dead batteries if it were a huge issue.

Hell, I got fired and I wasn't even late to work.

I don't argue that some form of isolation can be a good thing. I do argue that an isolator is not a must-have part for dual battery installs. I do not believe you absolutely need to have one.

Boats have isolators for battery BANKS which are usually comprised of several to many batteries in each bank wired in parallel.

TS

I used swerve around my halucinations, now I drive right thru them.

[robert_encinas]

where did the athletes foot come from?lol

[Kritter]

While on the battery topic...extensive research was done to find the life of a battery and the conclusion was that a battery will last 37 months...hence the 36 month warranty so to everybody coming up on the 36 month...kill it now! People were paid boocoo bucks to do this research!

Kris
<A target="_blank" HREF=http://www.barneysprecision.com/fabproducts.htm> Fab Parts</A>

[Tyson]

I got a question then. I've seen a race truck that runs a regular optimum battery and the cold cranking one. THose are not the same battery, but how would I go by wiring that up to my truck. I know I'd want a switch of some sort so that the harding working battery could always start the truck and use the other for driving. Make sense. . .or is it that late hour where nothing really makes any sense?

Look at me, I can fly
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