How-To: Install Dual Batteries.

freddy137 · June 5, 2012

I have installed many dual battery systems over the years and the info Stan has given is true. The one exception that I have encountered is the failure to use an issolater is that when one battery goes bad it will kill the other and cause such a drain that both fail. I run a lot of electronics and communications equipment and prefer to leave it on at all times, with the exception of long down times. And it is for that reason I pull all my add ons off of the secondary battery which is a higher CCA or marine grade storage battery. This is issolated to insure that the cranking battery is always free for the normal truck operations. If the cranking battery should fail all I do is jump it off from the secondary. Also I connect my hot-wire to the issolater at the fusable juction from the alternator and run a seperate hard ground from the engine block. This usely makes a much neater and shorter run of cables. In any case I do recommend an issolater, they aren't that expensive and offer reliability isuance for my systems.

00Silverado4x4 · June 5, 2012

I have installed many dual battery systems over the years and the info Stan has given is true. The one exception that I have encountered is the failure to use an issolater is that when one battery goes bad it will kill the other and cause such a drain that both fail. I run a lot of electronics and communications equipment and prefer to leave it on at all times, with the exception of long down times. And it is for that reason I pull all my add ons off of the secondary battery which is a higher CCA or marine grade storage battery. This is issolated to insure that the cranking battery is always free for the normal truck operations. If the cranking battery should fail all I do is jump it off from the secondary. Also I connect my hot-wire to the issolater at the fusable juction from the alternator and run a seperate hard ground from the engine block. This usely makes a much neater and shorter run of cables. In any case I do recommend an issolater, they aren't that expensive and offer reliability isuance for my systems.

Want to set mine up? lol One of these days when I feel I truly need it I plan to run dual batteries but I don't run enough electrical to really warrant all that.

Have to edit my own post from a couple of years ago since I now have a different truck. I got lucky, the new truck was already wired up with the factory dual battery system. Also since I kept the battery out of my old truck and it's the same style and age as the one in the new truck, I threw it in. So far it seems to be working as advertised. Just need to double check with a voltmeter.

4.3 sierra · September 14, 2012

Nice install. did the same on my 08 sierra, same setup. I am a sparky by trade, and it always boggles my mind at how many people don't understand electricity, nice to see someone dow work correctly and neatly for once

silveradoprime · October 30, 2013

I would add an inline fuse onto the wiring for the second battery, its cheap insurance in case any shorts do happen and so your truck won't burn to the ground. Just my opinion.

99kon · December 17, 2013

Ill be doing this.

I have a second battery sitting around that i can use.
I did this on my polaris ranger just like OP stated. Ran them in parallel. Have had it like that for about a year now and have never had a problem. Running stereo equipment and leaving it on for extended periods of time.

TJMaine · June 4, 2014

Im considering doing this for the simple fact that Maine winters are brutal on batteries... tow trucks are hours away sometimes and I dont want to wait for a jump. Isolator seems like cheap insurance as wells as an inline fuse.

Rewillia · June 26, 2014

added a battery box only for storage of tow strap, etc. under the hood using the 2nd OEM installed battery tray, while i have no need to add a 2nd batt. ('14 Sierra-Denali 6.2L)