installing a dual battery system

[SandEagle]

i have a ton of electronics in my ride. two dashcams that run 24/7, aftermarket fogs, 4 headrest unit monitors, gps, etc. i plan to add aux spotlights and other devices and am worried about the battery drain.

wha about fabricating some dual battery setup? has anyone done this? i read there are two ways to do it, one that doubles the ouput to 24v, and the other running in some sort of parallel with the existing. i guess the latter is what i need. if i connect the two in parallel, will the devices on 2nd battery shut down when car is turned off?

 

[disappoint]

if i connect the two in parallel, will the devices on 2nd battery shut down when car is turned off?

The devices will not shut down if they are directly connected to the battery. Devices should always go through the fusebox or at least be fused anyway. If they are connected to accessory point on the fusebox then they should shut down when the key is out.

This also depends how the car is wired and can vary from one manufacturer to another. Some cars for example have power to the cigarette lighter port all the time, mine does not.

 

[SandEagle]

The devices will not shut down if they are directly connected to the battery. Devices should always go through the fusebox or at least be fused anyway. If they are connected to accessory point on the fusebox then they should shut down when the key is out.

This also depends how the car is wired and can vary from one manufacturer to another. Some cars for example have power to the cigarette lighter port all the time, mine does not.

would it be possible to wire the lighter outlets to 2nd battery?
even if your car doesnt have the lighter port on at all times, you can change that on most cars easily.
http://wiki.answers.com/Q/How_do_you_make_the_cigarette_lighter_work_without_the_ingition_being_on

 

[jagec]

Are you worried about the battery draining when the car is off? But only the dash cams will be running at that point, right?

As long as your alternator can handle the load of the entertainment devices+lights+etc., you should be fine.

 

[Knavish]

Do you understand how the alternator works in the car's electrical system? The battery is really just there to start the car and supply power to things when the engine is shut off. Some people need to get a high output alternator when they install a bunch of extra electrical stuff or a big car stereo. The output of batteries and alternators is typically rated in amps. You should be able to figure out how many amps each of your devices pulls and then check if your alternator has enough capacity.

You definitely do not want to replace your car battery with two batteries in series. This will give you 24 Volts, and none of your equipment is rated to run at 24V. If you put two batteries in parallel, it would double the capacity (in amps) you can pull, but I think you should be more concerned about the alternator.

 

[BUTCH1]

No, LOL, you can't run a 12V system on 24 volts unless frying everything electrical in your car sounds like fun to you..

 

[SandEagle]

Do you understand how the alternator works in the car's electrical system? The battery is really just there to start the car and supply power to things when the engine is shut off. Some people need to get a high output alternator when they install a bunch of extra electrical stuff or a big car stereo. The output of batteries and alternators is typically rated in amps. You should be able to figure out how many amps each of your devices pulls and then check if your alternator has enough capacity.

You definitely do not want to replace your car battery with two batteries in series. This will give you 24 Volts, and none of your equipment is rated to run at 24V. If you put two batteries in parallel, it would double the capacity (in amps) you can pull, but I think you should be more concerned about the alternator.

this is the problem. i don't know how the alternator plays into this. i will look into a higher output alternator. thanks

 

[LTC8K6]

If your alternator can't keep up, your car will let you know with a dashboard light.

As long as you don't see an indication of a charging system problem, your alternator is keeping up with the load.

 

[rommelrommel]

You should be getting someone with a clue to do this for you.

 

[SandEagle]

You should be getting someone with a clue to do this for you.

and someone with a clue should only respond to this thread. be gone.

 

[jaedaliu]

and someone with a clue should only respond to this thread. be gone.

I know that his post was short and reads rude, but his advice is actually pretty good. It seems like you don't understand voltage, and that's a pretty important thing with electronics. I would be worried that you are going to hurt yourself or your car in the process.

How much stuff are you going to be running with the car off? If it's just the 2 dash cams, you're probably fine as is. You could pay $$$ and get the optima yellow top deep draw battery if you're worried about draining the one you have now.

 

[SandEagle]

I know that his post was short and reads rude, but his advice is actually pretty good. It seems like you don't understand voltage, and that's a pretty important thing with electronics. I would be worried that you are going to hurt yourself or your car in the process.

How much stuff are you going to be running with the car off? If it's just the 2 dash cams, you're probably fine as is. You could pay $$$ and get the optima yellow top deep draw battery if you're worried about draining the one you have now.

i dont understand voltage much, yes. and i plan to get work done by a pro. but it doesnt hurt to get some info firsthand so i dont sound like a doof to the mechanic. i plan to run some crazy things from my car. it will be my mobile command center.

 

[LTC8K6]

The main question is whether the car will be running or not. If it will be running, then you may need an upgraded alternator. If not, then you may need a deep cycle battery and maybe a switch.

You may just need to keep a jump starter pack in the vehicle in case you kill the battery.

 

[SandEagle]

The main question is whether the car will be running or not. If it will be running, then you may need an upgraded alternator. If not, then you may need a deep cycle battery and maybe a switch.

You may just need to keep a jump starter pack in the vehicle in case you kill the battery.

thanks for that bit of infom. the only thing that runs when the car is off is the dashcams, but i have a battery discharge prevention kit for that (powermagic). the rest of the equipment will run while car is running. upgaded alternator, optima yellow, and jump starter all sound perfect.

 

[monkeydelmagico]

What's the big deal with running a deep cycle or a secondary battery in parallel? I see it all the time for marine/boat applications. A secondary battery with a power cutoff circuit is used for RV's too. You might want to check on RV.net. Some of the advice is good though. A high output alternator combined with the highest amp rating battery you can fit in the stock location couldn't hurt.

 

[disappoint]

would it be possible to wire the lighter outlets to 2nd battery?

Almost anything is possible with enough time, labor, money or magic. Just kidding about that last one.

Yes it's possible. What's the difference if you connect it to the first battery or the second if they are both in parallel?

Are you going to have a switch and switch between the 2 batteries?

You should just connect the 2 batteries in parallel, that should be enough to increase your battery capacity.

Oh and, just in case your mechanic forgets or doesn't know what he's doing, make sure everything is properly fused, and by that I mean make sure the fuses blow before the wires do.

 

[thedarkwolf]

You need to keep the batteries isolated from one another. I'm lazy so I'll just copy somebody else.

"I run two batteries in my Tribute and have done so on many vehicles. There are two different ways to isolate the batteries. First I should say that "yes" it will work without an isolator. You can directly put them together this way. The problem is you'll shorten the life of the batteries due to the capacitance and discharge rate differences. Just a matter of time.

The first way is to use a solid state isolator. This is a rather large component with heat fins on it and usually three large lugs. It has an amperage rating on it which needs to match what your alternator is capable of putting out. Basically when the car is off the batteries are separated. When the car is on they are still separated. What happens is the electronics in the isolator detects which battery needs the charge and sends the current accordingly. It switches back and forth many times. It's completely solid state so you'll never hear anything. This is the best way to go but it's more expensive than the second way.

The second way is to use a large solenoid. Usually a 100 or 200 amp. This is just like a starting solenoid. It keeps the batteries separate until you turn the key and then connects the aux battery to the main. Usually used in diesel trucks for more starting current. Then the batteries both charge together. You don't really need to worry about the discharging of them because the alternator is pushing out more current than they store.

The best thing to do is to get a larger alternator.

FWIW the second method is what I always use. The solenoid I have was $65 and works great."