YACT: Dual Batteries

[imported_Pablo]

I'm looking into a two-battery setup. FOR MY CAR, NOT MY LAPTOP

Laptop in car powered by inverter, or directly from cig. lighter using an adapter.

I'd like to be able to leave it on overnight (downloads, etc) without worrying about trying to crank it up the next morning.

Question:
Is there a way to have it so that one battery can be drained almost completely while the other (main) battery is not drained? Then when you crank up the car, both are charged by the alternator?

Any help is appreciated.

 

[jtvang125]

1.I'm pretty sure if you wired both batteries together, they will be drained simultaneously. There might be a product out there that will do one by one, I dont know.
2. Deeply discharging a lead acid battery and then recharging it is really bad for it. It will quickly start to lose its ability to hold a charge. Also it puts a big strain on your alternator because they are there to maintain the battery, not to recharge a deeply discharged one.

Thank you for tuning into 'Automotive Batteries 101'.

 

[fbrdphreak]

Um, that is stupid. Charge the laptop on an AC outlet overnight and stop trying to do stupid things.

 

[NuroMancer]

War driver?
Hacking peoples internet?
Why do you need it in your car to DL overnight?
#2 get a laptop with better battery life or (AS MUCH as I hate saying it)
get a Dell 600m with 2 batteries... Combined life is like 9-10 hours

 

[imported_Pablo]

Originally posted by: fbrdphreak
Um, that is stupid. Charge the laptop on an AC outlet overnight and stop trying to do stupid things.

Like I give a sh!t about what you think is stupid?

Originally posted by: NuroMancer War driver?
Hacking peoples internet?
Why do you need it in your car to DL overnight?
#2 get a laptop with better battery life or (AS MUCH as I hate saying it)
get a Dell 600m with 2 batteries... Combined life is like 9-10 hours

I'm looking to power it with a deep cycle battery. The question is not about a laptop, the question is about the CAR. And no I don't need to wardrive. Just looking to see if any car electrical people know of a way that this can be done.

Has anybody had any experience with using batteries this way?


Without any more opinions

 

[Kelemvor]

You can get 2 batteries for most laptops. One normally goes in where the normal battery goes and the other can be swapped in where the removable drive (CD, DVD, etc) go. At least with Dell's you can do this.

But why would you want to leave it in the car instead of just bringing it inside? Probably get stolen at night or drain the car enough that it won't start up again.

 

[imported_Pablo]

Originally posted by: FrankyJunior
You can get 2 batteries for most laptops. One normally goes in where the normal battery goes and the other can be swapped in where the removable drive (CD, DVD, etc) go. At least with Dell's you can do this.

But why would you want to leave it in the car instead of just bringing it inside? Probably get stolen at night or drain the car enough that it won't start up again.

I think my OP was unclear. Its been edited.

 

[BHeemsoth]

Originally posted by: Pablo

Originally posted by: FrankyJunior
You can get 2 batteries for most laptops. One normally goes in where the normal battery goes and the other can be swapped in where the removable drive (CD, DVD, etc) go. At least with Dell's you can do this.

But why would you want to leave it in the car instead of just bringing it inside? Probably get stolen at night or drain the car enough that it won't start up again.

I think my OP was unclear. Its been edited.

Everyone understands your original post, we are simply offering alternatives to your bad idea.

You already received 1 very good answer in this thread regarding why you should not do it.

 

[ThisIsMatt]

To answer your question, as opposed to the other lame posts, you get your second battery, wire it in parallel with the first, but use a battery isolator inbetween. The isolator will allow you to charge the 2nd battery off your alternator like normal, but will let you drain the 2nd battery completely dead without affecting your primary (starter) battery. You're all set. Also, make the 2nd battery a deep cycle battery.

 

[ThisIsMatt]

Originally posted by: rpbri2886

Originally posted by: Pablo

Originally posted by: FrankyJunior
You can get 2 batteries for most laptops. One normally goes in where the normal battery goes and the other can be swapped in where the removable drive (CD, DVD, etc) go. At least with Dell's you can do this.

But why would you want to leave it in the car instead of just bringing it inside? Probably get stolen at night or drain the car enough that it won't start up again.

I think my OP was unclear. Its been edited.

Everyone understands your original post, we are simply offering alternatives to your bad idea.

You already received 1 very good answer in this thread regarding why you should not do it.

Uninformed good answers are just bad answers in disguise Maybe he doesn't want to drain his expensive laptop battery all the time? They can only be recharged a certain number of times...a car battery is quite a bit cheaper than laptop batteries.

 

[shoRunner]

this is done very often in car audio setups where they may use many batteries. check out some car audio forums i'm sure they'd be able to help you out.

 

[JustinGoodie]

fairly simple actually... just last fall we hooked up a dueling battery and massive system setup in a friend of mine's grand cherokee

first off, you definitely need a battery isolator, that's the key part here. next you have to decide where you want to mount the battery. if you're using it to power a system, i would suggest you put it in back with the amps and stuff, if you're just running the power inverter off it, the tuck it away in the engine bay or something.

anyways, the wiring isn't too bad, you going to have to disconnect the wire off your alternator and hook it to the isolator, then you'll have to run wires to either battery from the isolator, as well as a small gauge 12V switched power source (power antenna wire, accessory wire...) to the isolator to tell it when to turn on. from there, you just need to ground the second battery and you're in business, and can connect whatever you need to the 2nd battery.

furthermore, you definitely want to go with a deep cycle battery, preferably made by optima (check around, they're the best) I've got a red top, and i'm not too sure what the real difference between it and the yellow top are, but either one is a good choice. also, optimas are a gel-cell battery, which means that you can mount it in any direction (sideways, upside down... whatever), which makes the installation a lot more flexible.

 

[0roo0roo]

murder your altnerator. and yea deep cycle batteries. many are are for rv's and boats. should be some plugin chargers i bet. normal car batteries are damaged if you drain em anywhere near dead.

 

[ThisIsMatt]

Originally posted by: JustinGoodie
fairly simple actually... just last fall we hooked up a dueling battery and massive system setup in a friend of mine's grand cherokee

first off, you definitely need a battery isolator, that's the key part here. next you have to decide where you want to mount the battery. if you're using it to power a system, i would suggest you put it in back with the amps and stuff, if you're just running the power inverter off it, the tuck it away in the engine bay or something.

anyways, the wiring isn't too bad, you going to have to disconnect the wire off your alternator and hook it to the isolator, then you'll have to run wires to either battery from the isolator, as well as a small gauge 12V switched power source (power antenna wire, accessory wire...) to the isolator to tell it when to turn on. from there, you just need to ground the second battery and you're in business, and can connect whatever you need to the 2nd battery.

furthermore, you definitely want to go with a deep cycle battery, preferably made by optima (check around, they're the best) I've got a red top, and i'm not too sure what the real difference between it and the yellow top are, but either one is a good choice. also, optimas are a gel-cell battery, which means that you can mount it in any direction (sideways, upside down... whatever), which makes the installation a lot more flexible.

The red top is NOT a deep cycle battery, sorry.