Battery Isolator Question

[Miguels]

As long as you have an AGM under the hood, I wouldn't think you would need a battery isolator unless you plan on jamming for long periods of time, and want to be sure to save some juice under the hood to start your ride.

Someone correct me if I'm wrong.

You don't need a battery isolator whether it's AGM or lead-acid or whatever else, but it's been said that supposedly using an AGM and different battery type will lower the resting voltage and life-span of the AGM of the shorter life battery. I haven't seen any proof of this yet, but if anyone has some I'd like to see it. OP, unless you plan to jam with the car not running, don't get the isolator. If you're just afraid of mixing the AGM and a lead-acid, then i say don't be. Wire it, save up and grab another AGM. It doesn't have to be XS.

You haven't seen proof that wet cells rest at a lower voltage than agm's?

That's the reason people say not to because the wet cell will pull the agm down to its resting voltage.

does that prove that the life span is shorter because two different type batteries on the same circuit share a common voltage? No. Where's the proof that it shortens the life span? i know they have different resting voltages normally, my old duralast gold always sat at 12.3 whereas the AGM's i have are 12.8. I haven't wired an AGM and wet cell together to see if it changes the resting voltage, and i don't have enough money to spare to test it myself. so if there's some available proof/documentation of any kind showing a shorter life span in that configuration, are you able to guide me in the right direction?

you gave bad advise on your earlier post.. never jam with car off or suggest an isolator to use for that matter. it will take less than a minute before those batteries are dead. a few minutes after that the amp is toast for low voltage.. once you turn the car on the dead batteries in the rear will tax the living life of the alternator damaging it in the process.. if you have a high output alternator you will run the risk of having your batteries explode in your trunk.. ever happen to think why battery manufacturers and battery charger manufacturers recommend charging a battery no more then at 25a and smaller batteries at an even lower amperage? those dead batteries will make the alt max out charging it at the maximum and causing batteries to heat up and swell up.. try charging a battery at 300a buddy

[reedal]

Well now I know right? I don't use one, and never intended to, and have always understood that using one is the way to go when wanting to separate your power sources when playing with the car off. I agree that it's a terrible idea due to low voltage. As for giving bad advice, it might not be recommended due to the damages that can come from it, but that is what it is supposed to allow you to do is it not?