2012 5.0

I bought a new motor craft battery since my old one was 5 years and I was having some battery drain issues. Which I think I fixed it was, bad relay on aftermarket LED light bar. After the new battery and relay replacement I haven’t had a dead battery where my truck won’t start.

So, I tested my alternator with a multimeter and it goes from 14.2 to 14.25 so I think it’s working.

So, the last time I turned off my truck I tested the battery couple hours later and it was sitting at 12.75 that was this Sunday the 19th, I haven’t used the truck since Sunday and today Wednesday 21st I tested the battery (truck off since Sunday) with a multi-meter and it’s at 12.64

Reading around the internet 12.6 and higher is considered 100% charged. So, my question is if the drop from 12.75 Sunday to 12.64 today Wednesday is normal? Or do I still have something draining my battery??? and whats a normal drop voltage??

 

I guess that normal is different for different vehicles due to different things that run 24/7, current leakage across the top of the battery due to moisture and battery acid on it and other bizarre factors but I certainly won't worry about 0.11 volt drop over 4 days. Even with nothing drawing power, all batteries have some amount of self-discharge.

 

Only to add to the above.^^

There is also a constant {micro-drain} due to onboard computer modules installed. Commonly known as "keep alive memory" (KAM)

 

So the drops im getting are okay?

 

I’d say that is a normal drop. It could be if you let the truck sit longer it would go back a little higher. Just a change in temp will affect your readings that small amount.

 

perfectly normal.

 

Thanks for the replies gents

 

FWIW Temperature change is one of the biggest causes of self discharge in lead acid batteries. The difference in temperature across each of the lead plates causes a difference in the EM potential and causes current to flow across the plate and that leads to the battery self discharging. This was the basis for the old wife's tale that you shouldn't set a LA battery directly on a concrete floor. In the early LA batteries with their thin cases, the cold concrete would chill the bottom of each of the battery plates and would cause the battery to self discharge, ie run down. This problem was well documented in LA batteries that were used in submarines where they were chilled because of being in contact with hull which was in turn in contact with cold seawater. In modern batteries, sitting on concrete was rarely a problem but now due to the very light construction necessary to meet the CAFE requirements, batteries could start to see that problem again.

 

Can Texas heat discharge a battery or only cold?

 

Anything that causes a temperature gradient (difference) across the battery can cause it. That's one reason why on the better built cars, they used to put insulation around the battery. But a lot of those improvments have been deleted in order to make vehicles cheaper, smaller, lighter and more fuel efficient. But ambiant cold or heat where the surrounding air is all at nearly the same temperature isn't nearly as much of a problem as sitting a battery on something like concrete which is at say 65 degrees and the room temperature at say 85 degrees. If you'd ever stood bare footed on a concrete floor for very long I'm sure that you know what I mean.