97 Sierra W/stock Dual Batteries

[Pitboy2]

Just bought 97 Sierra Z71 5.7L. It looks like factory dual battery setup. Can anyone tell me what the purpose of 2 batteries? One has heavy gauge cable going to the starter and the other only has about 12 gauge wire. Obviously the second batt. does not help in starting due to the light wiring. The pos. of batt 2 goes though a solinoid, what controls it? Any info will be appreciated. Thanks

[97SierraGMC]

if one battery dies the solenoid should keep the other one from dieing. i will be putting dual batteries in my truck this summer.

 

btw your missing an air filter

[Pitboy2]

It breathes better that way . Just kidding, filter getting rercharged.

 

So can 2nd batt. start truck? If not, whats the point?

[97SierraGMC]

i dont think your setup can.

 

are they thick wires going between the two?

[Pitboy2]

No the 2 are not joined together.

[builderpaul]

Just bought 97 Sierra Z71 5.7L. It looks like factory dual battery setup. Can anyone tell me what the purpose of 2 batteries? One has heavy gauge cable going to the starter and the other only has about 12 gauge wire. Obviously the second batt. does not help in starting due to the light wiring. The pos. of batt 2 goes though a solinoid, what controls it? Any info will be appreciated. Thanks

This is called an isolated battery. It is used to power any accessory you use without the engine running.

The power to a trailer would be hooked to this, or a high draw sound system. I have a 2500 watt inverter hooked to mine. I can use power tools most of the day and not have to worry about the truck starting. You can draw only from this battery, even run it down and still have the main battery available to start. Once truck starts it recharges the isolated battery. You can jump from this battery to the main with one cable between positives, if needed.