I have 2 batteries!

[JoeKan]

I noticed when I bought my truck there were 2 batteries and a small black box (about 2"x2") mounted to my firewall and a white wire going to the other side with another small black box. I forgot all about it until now and realize that I've got something good! So, the way I see it, one battery is for the start up of truck and the other battery is for my trailer hook up. How can I tell how big my alternator? is?
Will I be able to run a heater this winter with this?
Thanks!!
Joe

 

[wuck]

What flavor is the engine in your truck? AFAIK, Diesels come with two starting batteries.

 

[ckent323]

Wuck,

Just an FYI - Some Diesel trucks only came with one battery. e.g. 1st gen Dodge Diesels which came with an 1150 CCA battery.

Your question about truck make and model and engine is appropriate to help sort out the alternator and OEM configuration.