It appears the battery drains even when truck isn't being run.
After my latest charge battery was up to 13.02 v, 4 days later it was 12.16v, and 4 days again it was 12.05.

I believe at 12.05v the battery is now at 50% charge, and about as low as you'd ever want it to be, without incurring permanent damage to the plates.

So why is this happening, and what steps should I take ??

Thanks for any help.

 

It is probably just a bad battery. How old is it?

 

You'd do best to perform the battery drain test following the specific directions in the service manual for your vehicle (which you failed to remotely identify).

 

battery drain test specific to a vehicle? What is that?

 

The point is to FOLLOW THE DIRECTIONS as well as identify what is being worked on. Failure to FOLLOW THE DIRECTIONS is a common reason for incorrect battery drain diagnostics. Generally, for Fords, there may be minor differences regarding the required timeout interval.

 

Thanks for the above responses.
Unfortunately s'vice manual doesn't offer any help in batt. drain procedures.

The batt. is 3 yrs old and lightly used.

Sorry, I neglected to mention I then recharged the batt. to 12.95v and disconnected the -ve terminal, and so far 3 days later is still at the same 12.95v.

Ron

 

Actually, it does. See section 414-00 of the WSM. The specific procedure is there. It is attached. See how much easier it is to provide specifics when the vehicle under consideration is known?

A battery that is disconnected should maintain its internal charge almost indefinitely, there's only a tiny bit of internal current leakage typically present unless the battery is failing.

 

man I'm so interested. What is WSM?

 

WorkShop Manual

 

See how much easier it is to provide specifics when the vehicle under consideration is known?

Good stuff, thanks.

Guess I'll have to purchase a WSM

 

If you provide specifics for what you need, it's pretty easy to post excerpts that give you the information needed to get you going.

Of course, it's always handy to have your own set of manuals for stuff down the road. I've managed to accumulate a set that covers from 1992 to 2014 model years.

 

"A good set of manuals" might be in the offing for Christmas.....lol

 

Removing the battery and having it Load Tested at a local Autoparts store is a good start. I would also use a battery brush and clean the terminals from any corrosion. When at the Autoparts store of your choice grab a set of the felt anticorrosion pads red/green to go between the cables and battery.

Return with results.

Next step if battery passes would be testing the alternator. If battery fails replace.

 

Ha ! Why didn't I think of that ?

Thanks will get to it Monday.!