Quote: Originally Posted by breimann
Well,
A relay wouldnt give me a voltage drop like an isolator - but,
In theory, I would need to use the same battery as whats in there now, right?
not exactly true.
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Also, is there a danger of overcharging a batt? For example, if my main batt is charged and my second batt is 1/2 dead, then the alternator is going to make juice to charge the second battery, wouldnt that harm the first one?
i've never seen a car batt. that was overcharged while being used by a car(altho there are some very rare cases too rare to include in here). car batt. are designed to withstand the harsh electrical environment of the automobile. the only problem you might have is trying to make the two batt. charged in equilibrium if one is half flat. even so, alternator are not designed to charge an almost flat battery. that batt. should be charged properly by a battery charger with an stable 14v current.
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Also, correct me if I am wrong but doesnt a battery isolator prevent overcharging of the primary battery?
even if you don't have a batt. isolator your car's elec. mechanism will do this.
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I like the idea of not having a voltage drop w/ a relay but I do not want to risk hurting a battery. Wizard, what guage wire did you use, and what batteries? How long has your setup been working for?
It seems the more research and the more information I collect, the harder it is to make the final decision. I appreciate everybody's input! Thanks!
in my 15 years of automobile experience (we use to customize car as a family business) i never had a case of a car overcharging a battery except from using main socket or a cheap charger. the problem you should be worrying about really is a flat battery.