I suspect BCM... thoughts?

[TrybalRage]

Well, unfortunately it left me sit again today. Same behavior. No gear indicator when key on, no crank.

Ugh.

Battery is back down to 12.25 volts as well. So either this thing isn't holding a charge, or something's still drawing it down. It's still under warranty so I'm going to replace it either way.

 

[TrybalRage]

Well my current draw (if I did it right) is right around 13mA. Alternator is putting out 14.8V. Took the battery to Autozone and they told me it tested fine, but when I take it home and put it on the charger it's only showing half full.

 

[Geotrash]

Is it an AGM battery? I’ve had the same thing happen with an AGM battery and thought I had a parasitic drain. New conventional battery solved the problem for good.

 

[TrybalRage]

Is it an AGM battery? I’ve had the same thing happen with an AGM battery and thought I had a parasitic drain. New conventional battery solved the problem for good.

Nope, conventional Duralast Gold from autozone. Of course if their little tester doesn't show an issue, they won't replace it under warranty.

 

[sunureu13]

That sucks Have you tried checking grounding through all the pins for the BCM connectors?
BCM was my issue but now I'm having trouble programming my BCM. That's an issue for another thread though.

 

[TrybalRage]

That sucks Have you tried checking grounding through all the pins for the BCM connectors?
BCM was my issue but now I'm having trouble programming my BCM. That's an issue for another thread though.

No, I have not. I've been focusing on why this damn battery keeps losing charge. Parasitic draw is around 14mA, which supposedly is acceptable. Alternator putting out over 14V. But when I drive it and then check it a little while later, voltage is down.

Seems like when I get a no-start/no-response condition, the voltage is around 12.25 every time. When I put the battery on a charger and get it to a full state, it seems like I don't have the problem for a little while. So I don't know if when the voltage drops <12.3 it's making the computer(s) freak out?

Maybe I'm chasing the wrong thing. But the parts store tells me the battery is fine. However when I put my charger on it, it takes forever to get fully charged. Is a "slow charging" battery a thing? Like the car is drawing down more than the battery will accept in return from the alternator?

 

[Fless]

No, I have not. I've been focusing on why this damn battery keeps losing charge. Parasitic draw is around 14mA, which supposedly is acceptable. Alternator putting out over 14V. But when I drive it and then check it a little while later, voltage is down.

Seems like when I get a no-start/no-response condition, the voltage is around 12.25 every time. When I put the battery on a charger and get it to a full state, it seems like I don't have the problem for a little while. So I don't know if when the voltage drops <12.3 it's making the computer(s) freak out?

Maybe I'm chasing the wrong thing. But the parts store tells me the battery is fine. However when I put my charger on it, it takes forever to get fully charged. Is a "slow charging" battery a thing? Like the car is drawing down more than the battery will accept in return from the alternator?

Pretty much any draw under 50mv at full sleep is acceptable, although usually it's a bit less, around 30 or 40, so that seems to be okay. How are you measuring that, with an inline ammeter or an inductive clamp?

Battery charging rate is dependent on your charger's settings; does it indicate what the amp rate is when it takes forever to charge the battery?

 

[Joseph Garcia]

When you say that the auto parts store tested your battery, did they take it out of the truck and put it on a bench tester? IMO, that it the only real way to fully test a battery.

 

[TrybalRage]

Pretty much any draw under 50mv at full sleep is acceptable, although usually it's a bit less, around 30 or 40, so that seems to be okay. How are you measuring that, with an inline ammeter or an inductive clamp?

Battery charging rate is dependent on your charger's settings; does it indicate what the amp rate is when it takes forever to charge the battery?

It's not that fancy of a charger, it has 2-4-6 Amp options. This was on the 6A setting, from 12.25 to full takes like 12 hours or more. On other batteries I've used it on I can top them off in 2-4 hours.

Edit: I'm measuring by using a multimeter from the negative battery post to the cable when it's disconnected.

 

[TrybalRage]

When you say that the auto parts store tested your battery, did they take it out of the truck and put it on a bench tester? IMO, that it the only real way to fully test a battery.

I took it out of the truck and brought it in. They had a little box with what looked like jumper cable clamps on it. Of course I had recently topped it off when I took it in so the voltage was fine, but I thought it would be able to test for other stuff (amps, etc). Maybe not. I'm gonna let it draw down again (it's at 12.3V again right now) and take it in again.