Installation of a backup battery

[Nigella]

Hello there, guys!

I'd like to add a backup battery to a vehicle so that I can use one battery to power the radios and other electronics all of the time without draining the primary battery.

I searched the forums but couldn't find any information on how to accomplish this.

I'd be grateful if someone could explain how to connect this.

 

[Captain Kilowatt]

You need a battery isolator to do it properly. It allows both batteries to charge but running one down will not draw the other one down.

 

[AudioShockwav]

Rental car set up on vacation one time was a marine battery in a case, hr2510 radio, 2xmrf454 amp and mag mount.
Used it two weeks on the road charged battery twice during that time at family's place.
Cheap, simple and easy for that purpose.
If your going to run it long term, as Captain said above run some 10 gauge up to start battery and add a switch to isolate while parked.
Are you planning static mobile?

73
Jeff

 

[Eldorado828]

Just some words of caution

I'd like to add, please if you're planning to install batteries in the passenger compartment make sure you're using the proper type battery. Kinetik, Optima amongst a few others make a safe sealed battery that you can use inside the vehicle.

When I did car audio, I saw a lot of unsafe things done by others. One of those was folks using batteries that vent gases or liquids inside vehicles, not a very safe idea. Fires, inhalation or explosions hazards are not what you want to risk for the sake of powering devices.

 

[Shadetree Mechanic]

That's a good point @Eldorado828. I had a girlfriend one time who had a teenaged brother with a complete car stereo and sub woofer system installed in his bedroom. He powered it with a car battery and 10 amp battery charger. A byproduct of charging a battery is Hydrogen gas. A sealed AGM battery keeps the gas inside, a regular car battery doesn't. Needless to say, Hydrogen gas is extremely explosive. One day he was messing around and jumped a spark at the battery and it blew the top of the battery clean off! I had to help him to wash the battery acid out of his eyes. Luckily he was not injured, and we all learned a valuable lesson that day.

The two main types of isolators are:

1) The solenoid type, like a big fat relay that turns on and off with the vehicle. Connects batteries together for charging when running, disconnects batteries when not running.

2) Diode isolator type keeps batteries separated from each other at all times. Has a loss of about 1/2 volt when charging due to the diodes in use. (usually not a big problem)


Here is a video that I found:

 

[144inBama]

A battery isolator, as mentioned, is the correct way to do it. You can also use a a 12VDC contactor wired NO and wired to your vehicles ACC. This way when your ignition is on, you will be charging/using both batteries, when the ignition is off you will only be using the secondary battery leaving the primary unused. Something like this.....

 

[144inBama]

That's a good point @Eldorado828. I had a girlfriend one time who had a teenaged brother with a complete car stereo and sub woofer system installed in his bedroom. He powered it with a car battery and 10 amp battery charger. A byproduct of charging a battery is Hydrogen gas. A sealed AGM battery keeps the gas inside, a regular car battery doesn't. Needless to say, Hydrogen gas is extremely explosive. One day he was messing around and jumped a spark at the battery and it blew the top of the battery clean off! I had to help him to wash the battery acid out of his eyes. Luckily he was not injured, and we all learned a valuable lesson that day.

The two main types of isolators are:

1) The solenoid type, like a big fat relay that turns on and off with the vehicle. Connects batteries together for charging when running, disconnects batteries when not running.

2) Diode isolator type keeps batteries separated from each other at all times. Has a loss of about 1/2 volt when charging due to the diodes in use. (usually not a big problem)


Here is a video that I found:

Well hell....you beat me to it....LOL

 

[groundwire]

Hello there, guys!

I'd like to add a backup battery to a vehicle so that I can use one battery to power the radios and other electronics all of the time without draining the primary battery.

I searched the forums but couldn't find any information on how to accomplish this.

I'd be grateful if someone could explain how to connect this.

just look up how the boat guys do it, super simple. 2 batteries, a switchable isolater wire it up, done.