posted
Okay. I know that you should use an isolator if you have two different batteries. But why?
Let's say you have a yellowtop and your factory batt.
I know that your factory battery really won't be doing much except providing a little more reserve for playing with the car off. When the car is on, the yellowtop will pretty much be doing all the work. But what does this hurt? People say one battery will drain the other one when the car is off. Why is this? The batteries will equalize the voltage between them very quickly, but then they just sit there, right? There is no reason for one to drain the other when they are just sitting around. Am I missing something? I just don't understand why it is a bad thing to have two different batteries. It isn't optimal, but wouldn't it be (slightly) better than simply replacing the factory battery?
posted
ok i have ran many types of batteries parralell in many occasions all 12 volt of course
all a battery isolator allows you too do is run your amps with your car off without discharging the battery that starts your car basically a set of rectifiers that only allow energy too flow one direction and not the other its not matter that one battery will discharge the other cause if it is i am in a klot of trouble with all the batteries in the bed of the truck
well the main reason for an isolator is stated above if you wire the stock battery and the reserve battery parralell you have the chance of running your starting battery down too the point of which you wont be able too start your car
isolator isolates the batteries to their specific purpose
posted
Thank you! When people said one batt will drain the other when the car is off, I thought they meant with all accessories off. So do you not need an isolator if you won't play your system with the car off? I still don't understand why everyone says an isolator is not necessary if you have two identical batteries if that's what an isolator does.
posted
i'm gunna take a stab at this. if i remeber corectly electrons want to flow from where there is a high grouping to a place where there are not many to have more room to move around. if one of the batteries is full and one is half full electrons will flow from the full battery to the half full battery. how does a battery charger work it simply supplies available power to the terminal of the charger when the battery is hooked up to power flows from the source where it is abundant to where there is none. so for the first lil while of having a full and half full batt hooked up to each other you basically have a charger for the half full batt. i dunno its sounds somewhat scientific, knowledgable people dont flame me too bad Posts: 471 | From: burlington vt | Registered: Oct 2002
| IP: Logged |
quote:Originally posted by seanl20: i'm gunna take a stab at this. if i remeber corectly electrons want to flow from where there is a high grouping to a place where there are not many to have more room to move around. if one of the batteries is full and one is half full electrons will flow from the full battery to the half full battery. how does a battery charger work it simply supplies available power to the terminal of the charger when the battery is hooked up to power flows from the source where it is abundant to where there is none. so for the first lil while of having a full and half full batt hooked up to each other you basically have a charger for the half full batt. i dunno its sounds somewhat scientific, knowledgable people dont flame me too bad
Well, the half-full batt. would draw on the full battery until the terminal voltage on both was the same, but basically I agree with you. I just don't see why this is bad for the batteries/electrical system. While driving, I would expect the Yellowtop to do most of the work due to it's low internal resistance. The factory batt would supply some current too because it isn't possible to drain one and do nothing to the other when there is no isolator. The only thing I can think of is that the isolator is just preventing the factory battery from running down while you're bumping just because the reason you buy a second battery in the first place is to keep from killing the factory batt. I guess if you pull enough current for long enough when driving, then kill the engine then your car might not start? I suppose the biggest benefit of an isolator, though, would just be to save the factory battery from repeatedly running it down? Would you need an isolator if, for instance, you had two different deep cycle batteries? Oi...I'm not making much sense...
posted
Well, which ever battery has the lowest ESR will constantly be draining the other battery unless some form of isolation is used. An actual isolator isn't the best way to do things since they have diodes which cause on automatic voltage loss. A charging relay is better since it will only allow the battery in the rear to charge while the car is charging and not drain the front battery. The best way would be to have all of the same batteries. That way would wouldn't need a relay or an isolator.
-------------------- Team Image Dynamics/Zapco/Werewolf/JK Lab Team Kinetik Sick Bastard Audio SQ Who feels it knows it Posts: 7866 | From: Charlotte,NC USA | Registered: May 1999
| IP: Logged |
![[Confused]](confused.gif)
![[Wink]](wink.gif)
![[Roll Eyes]](rolleyes.gif)
Printer-friendly view of this topic