Sudden battery death

[NoahDL88]

The batteries in my Pinz have been troopers for the last 2 years. The truck sat for about 6 months while I was rebuilding the transmission and after a day on trickle charge started right up. I didn't bother to check before I charged, so I don't know if it needed it.

At the beginning of the month the fam went on a road trip to Oregon, averaged 15mpg and everything was great.

After sitting for a couple of weeks with the battery disconnect off the batteries read about 10.5 and 9.0 volts. It's been sitting on the 10amp charger alternating batteries for the last few days with no effect. Even with the 50 amp "start" I was at best able to get a have a rotation out of the engine before the starter stalled out.

I'm kind of stumped, I'll have more time to look at it tomorrow, but I'm guessing it's one of a couple things:

1 The batteries didn't like sitting for so long and then being driven 500 miles with the alt going full tilt
2 The alternator wasn't hooked back up correctly when I put the transmission back in (ground wire or something)
3 Either the batteries, the alternator or the starter just up and died.
4 battery disconnect switch is unhappy (headlights are fine)

[michaelh712]

Wet cell or AGM?

[eToothpaste]

If they were well charged before and after the 6 month rest, that's not likely the problem. Depending on the battery manufacturer, 6 months is usually as long as they should sit without a charge.



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[edzz]

First off if the batteries are not taking a charge from a battery charger (try it with a different charger also to rule out a bad charger) the batteries should be replaced (yes you can have them tested by a shop first) before you attempt further repair.

The batteries in my Pinz have been troopers for the last 2 years.

--So we are to understand that the batteries were new two years ago? You may still have some warranty.

At the beginning of the month the fam went on a road trip to Oregon, averaged 15mpg and everything was great.

--Batteries will have little effect on the mpg of a Pinz, it aren’t no Prius. Couldn’t resist

After sitting for a couple of weeks with the battery disconnect off the batteries read about 10.5 and 9.0 volts. It's been sitting on the 10amp charger alternating batteries for the last few days with no effect. Even with the 50 amp "start" I was at best able to get a have a rotation out of the engine before the starter stalled out.

--We are working on the assumption that the charger is good.

1 The batteries didn't like sitting for so long and then being driven 500 miles with the alt going full tilt

--if they are “wet cell” batteries and were low on water you may have cooked them.

2 The alternator wasn't hooked back up correctly when I put the transmission back in (ground wire or something)

--why would the alternator have been disconnected to work on the transmission?

3 Either the batteries, the alternator or the starter just up and died.

--my vote would be the batteries have failed

4 battery disconnect switch is unhappy (headlights are fine)

--you say headlights are fine. -- With headlights on try cranking the motor (poor man’s battery test) do the headlights dim significantly when starter button is pressed? If yes suspect low battery voltage. Time to pull out the old test meter and find out what’s happening.