Parasitic battery drain

[wyosteve]

I'm resurrecting this topic since it 'got me'! About 3 weeks ago after not driving my truck for a few weeks, I found the batteries dead. They were Optima Red Tops that were at least 9 and possibly 10 years old, so I make a trip to Sam's Club for 2 new Optimas. Install them, truck fires right up. Let it sit for another week, batteries dead again. Charge them, sits for 2 days, same result--dead batteries. Only then do I get smart enough to search the forums and find many threads about this problem. Long story short-- no. 51 fuse revealed a 1 amp draw with everything shut off and key out of ignition. Turns out to be the instrument cluster as discussed in archive threads. Going to cost about $1100 after all is said and done, but it's the first problem with the truck other than routine u-joint replacement and I just turned 100k. Truck started and ran fine and if being driven every day, I probably wouldn't have noticed it for a while. Only thing different was when locking the doors with the remote, the lights would flash, but no horn honk. Hope this helps someone if they experience the same issue.

 

[jelag]

You could have something else wrong... using ohm's law and assuming that your batteries are at least 110-120 amp hour batteries... . See if you agree with my thoughts...

(2) 110 amp hour batteries will store 220 (1 amp draw) for 220 hours... or a 5 amp draw for (220/5) 24 hours... the key here... is that if you only had a 1 amp draw at the end of say 3 days (72 hours) you'd still have about 60% of your battery capacity left and your truck might still start but at least would crank for a few seconds...

So I can only assume that you have more than a 1 amp draw if the batteries are flat in 2 days... or they weren't fully charged to begin with... .