# Running dual batteries



## Lincoln_on_24s (Mar 28, 2016)

I have a 95 Lincoln Town car. I have my normal stock battery upfront of course. And I've ran my power wire to my trunk. Fused at both ends of the cable between the batteries. And then my trunk battery for my car audio is grounded. I've had this setup for awhile. My car was in the shop for a little while and both batteries died. Do I charge one at a time to fully charged them both? I've tried to just charge my under the hood battery but car will die the following day. So overnight. 


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## High Resolution Audio (Sep 12, 2014)

Lincoln_on_24s said:


> I have a 95 Lincoln Town car. I have my normal stock battery upfront of course. And I've ran my power wire to my trunk. Fused at both ends of the cable between the batteries. And then my trunk battery for my car audio is grounded. I've had this setup for awhile. My car was in the shop for a little while and both batteries died. Do I charge one at a time to fully charged them both? I've tried to just charge my under the hood battery but car will die the following day. So overnight.
> 
> 
> Sent from my iPhone using Tapatalk


If you have a dead battery connected to a live battery, the dead battery will suck the life out of the live one. Or if you leave an old school battery charger connected to a single battery without it being plugged in and turned on. It will drain the energy from the live battery as well. 

You must charge both batteries simultaneously (or independently if they are different sizes, types etc ) then once they are both charged connect them. 

Another concern is that you may have a battery in the trunk that releases hydrogen gas when being charged. Hydrogen is extremely flammable. Is the trunk battery flooded (lead acid) , or sealed ?( gel or agm )

You are not suppose to mix the two types of batteries together. They each require different charging rates/ and voltages. 

Another concern is why did the batteries die in the first place?


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## Lincoln_on_24s (Mar 28, 2016)

The battery in the trunk is a Stinger spl agm battery. For car audio.


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## Lincoln_on_24s (Mar 28, 2016)

My car was at a mechanics house for a few months. Getting engine work so both batteries were in it sitting there. Through the cold and stuff.


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