im not sure if anyone has asked this but here goes. i would like find out if i could use a smaller battery say one from a 12volt atv or street bike and mount it next to my existing one with the only pupose to supply power to my door poppers when my main battery fails or is disconnected( when workin on it and what not) the reason im thinkin of doin this is because ive shaved both my inside and outside door handles and dont really what to have a hidden cable, inside i have a two piece polished aluminum over the whole area where the black plastic was.
another thing to i would need to has this wire into my charging system so it stays charged. if anyone has any info on this it would be great thanks - Joshua

 

Use a Power Wheels or electric scooter battery and a big diode. That and some wire should be all you need. The diode will allow the alt. to charge the extra battery, but if the main batt. voltage drops below the secondary batt voltage, the diode will isolate the secondary battery and keep it from draining....just make sure the diode can handle the charging current.

 

sounds like it might work does anyone have any idea on what size diode to get? also is a small 12volt batt going to have problems with being charger at 105amps or 140amps? ive blown up to batterys and a set of lights when a regulator in the alt went out and over charged the system. i wouldnt think this would be a problem but hey u never know. also would anyone like to draw a little wiring diagram, if its possible i would like to draw from the larger one and either manually or automaticly switch to the smaller if the main batt fails but both must be charger by the alt. thanks for the input - TOT

 

How about you just crawl through the hatch and pop the hood and jump your battery. The doors will open then. Or you could run some remote terminals like drag racers do so that you could just jump the battery from there.

 

The batteries won't charge at the full output rating of the alternator...most of that power goes to run the car and operate the accessories, plus it will have 2 batteries to charge instead of just one. If you're really worried about it, put like a 30-40 amp breaker in the charge wire to the secondary battery. I'd also go with a diode that can handle at least 50 amps. You can find big diodes at electrical supply places or online electrical stores.


When a regulator goes, the voltage in the system jumps up from 14.4 to about 17-18. That's what blows batteries....not excess current output.


The wiring is simple.....put the new battery close to the old one and ground it to the body. Put the diode (and fuse if you prefer) between the + terminals of the batteries. That way they'll both charge but the main electrical system will not drain the second battery. Wire the door poppers off the second battery only (no wiring in common with the main harness in the car) and ground to the body so that the poppers ALWAYS work off the 2nd battery. Make sure they work with the main battery disconnected, and make sure you get 14 volts to the second battery when the car is running. If you don't get 14v then the diode is probably backwards.

 

The battery will only pull the amperage (flow) that it needs. You could throw it on a 3,000,000 amp charger, and as long as the voltage (pressure) doesn't exceed the battery rating it will not overcharge. If you put a dead battery on a charger and watch it with an ammeter, you'll see the battery pull a ton of juice for a while, and then taper off gradually to just a trickle. That is unless you have a short or something between the plates