Question about a 2nd battery in truck

I have a 1995 Chevy K2500 truck with a 454 engine that I bought used a while back. It has 2 batteris in it and I do not know what the porpose of the second battery is for?

This second battery is currently unwired so I am not using it now. It had a small wire hooked to the positive terminal, looks like a 10ga. wire maybe green in color. It runs into a wiring harness so I can't tell exactly where it goes. It might go to a solenoid that is mounted up by the fender well on the drivers side but can't say for sure. This battery is also mounted on the driver side.

Anybody have any ideas?

Or it had a diesel motor in it at one time Steve.

Wood's right.
I had a '99 K2500 Chevy and ordered it with a plow prep package. It added the extra battery, trans and oil coolers. My guess is that you have the same set up. My new Avalanche has a spot for the 2nd battery, but it's empty.

Steve

Matt,
I doubt that you will find any selector switches on the truck...mine never had any. The two batteries just gave you more reserve.

Electric snowplow pumps pull as much or more power (amps)than the starter motor... they're operated for hours on end and almost always are operated at low engine rpm ( you raise the plow after pushing it into a pile,at idle)
...which is also at the alternators weakest output.

The isolater seperates the two batteries from each other (otherwise the "better" battery will be drawn down to the weaker batteries power). In the "old" days we could run a dual set-up with just one battery..no problem, but with todays computer controlled outfits, you'd have to talk to someone wiser than me on that subject.

Pete, I don't need the second battery and I was not planning on using it. I was just trying to get an idea of it's purpose.

I would not even posted this if I saw signs that there were heavier battery cables installed on this truck, and there might have been, but it sure looks like the lighter weight wiring was original and not added.

I hate beating this dead horse but this just doesn't add up. In my first post I said that this lighter weight Approx #10ga. wire is connected to the positve terminal of the second battery, this wire then connects to a solenoid on the fender well. What controls this solenoid? I can't trace the control wire or the power lead as it enters a wiring harness. Anybody have a wiring diagram?

Granted you all may be right and thanks for the comments. The snow plow setup seem the most logical for this truck.

I probably should just keep the hood closed and drive the truck, it runs great and makes an excellent tow vehicle for the 6500# cuddy, the only thing it won't do is pass a gas station

Im going with an old plow truck too. I push snow with a single battery dodge 2500 and back when we had the cummins ram with the dual batteries the plow was way faster. Id like to add a second to this truck but Havent got around to it.