Is there an internal battery?

[tischneid]

I left my lights on (key in ingition) today and had a dead battey. After a quick jump start, I was on my way. I was glad to see my radio presets were still there, but the "trip a" odometer was erased. Are there some things that have an internal battery to save them in the case of a dead battery? Also, how is the main odometer saved?

[ChrisM]

Originally Posted by tischneid

I left my lights on (key in ingition) today and had a dead battey. After a quick jump start, I was on my way. I was glad to see my radio presets were still there, but the "trip a" odometer was erased. Are there some things that have an internal battery to save them in the case of a dead battery? Also, how is the main odometer saved?

I honestly don't remember. I don't think there is one though. You'd think I would remember since I have had my radio out about 5 times. I think what happened was that you had enough voltage in your system to remember your radio presets but not enough juice to start the truck. You should only need about 9 volts of power to retain radio settings and such but it takes a higher voltage (???) to retain the trip odometer settings.

My battery was low on Saturday morning which required a jump start (bad cell in the battery) and had the same lost trip odometer mileage but retained radio presets.