Replaced my battery a few weeks ago, less than a year old and was covered under warranty,and the alternator checked out fine at the time. Now the new battery is weak and alternator is still charging as needed. So what's next on the list of cuprits that would drain the battery slowly? I have no electrical component issues that are faulty, at least operationally including the belt.Could the starter be going bad?

 

Just a thought but I replaced my battery about a year and a half ago and then had it go bad again within 2-3 months. Apparently the battery had developed an internal leak and would no longer hold a charge. It was an Optima Red, they have a higher than normal failure rate from what I hear.

 

Does your truck make any sounds while it is off? Any clicking noises?

 

This battery, and the one before it, is an Interstate 1000 CCA (Advanced Auto purchase). The truck makes no noises after it is turned off, runs well, has no warning lights or codes - nothing unusual outside of eating batteries slowly. I will run over to Advanced and have them check out the 'new' battery before it dies completely as it just started showing weakness last Friday (slowcranking before finallystarting with typical tellale signs of battery going down).

 

Who teseted youir alternator?
How old is your serp belt?
So far everything leans towards the alternator not putting out enough...are you married?

 

Take your truck and have a load test done, as Spike mentioned, make sure to get the voltage reads at idle, then under load and at 2000 rpm's. The numbers you need to see are between 13.6 and 14.4 volts, any less and you have a problem.
Get back to us.

 

Check your battery connections for corosion or that whit crap. Also check the connections at the alternator and the starter.

 

Had the same symptoms on my 2000 SD few years ago. The recommendation of Disco Mike and Spike555 are absolutely right on, as I had the outputs checked and they were in the range specified.

If your output is within the spec then you may want to check if you have parasitic drain from the battery, by measuring amperage draw. What I did was the following:
[ul][*]Turn engine off, keys out of the ignition and in your pocket.[*]Disconnect negative terminal and hook in series an ammeter (Fluke multi-meter can measure up to 5 Amps).[*]Make sure you know your radio code if it is programmed into the radio.[*]Hooking an ammeter in series is simple, positive ammeter lead on negative battery post, negative lead on negative cable clamp.[*]Look at the reading, it needs to be below 100 milli-amps (< 0.1 A).[*]If higher (like 0.5 or 1 - 2 Amps) then you have a static drain form a device that is hooked up to the electrical system + 12 V, which will drain your battery.
[/ul]In my case, I discovered an aftermarket GPS locator system that was installed by the 1st owner. I disconnected it and never had a problem again.

Hope this helps.