This is a 27R AC Delco Professional 42 month battery dated 8/2018 and rated at 710 CCA that came in my 03 Sequoia. Truck started and ran fine yesterday. This morning, nothing. Couldn't even unlock with the remote. Battery tester couldn't even take a reading. After swapping in a battery from another car, I brought it inside to warm up. A few hours later I try testing it again and it shows 9.5 volts and a few CCA saying to charge and retest. So I do that, and now it's at over 13 volts and 650 CCA which is acceptable for a 3+ year old battery. I was expecting to see something like, bad cell. So why did it go completely dead in one day all by itself? I didn't leave anything on, but will know for sure when I start it tomorrow on the swapped battery.
Unusual battery behavior
- Thread starter atikovi
- Start date
Let it sit overnight and retest it
Will do.
Nick1994
$100 site donor 2024
Probably need more testing. Maybe a light is getting stuck on from a door switch? Does it have an under hood light or glovebox light that's getting stuck on?
Took about 2 hours to charge at 20 amps. Didn't leave any light on that wasn't on the day before.
20amp for 2 hours doesnt mean the battery took 20 amps...
that wouldnt be long enough for a full charge from dead.
Sounds like battery issue.. but might want to do a parasitic draw test.
I don't know how many amps it took, I just put it on the 20 amp setting and the charger automatically stops charging when completed. THAT took about 2 hours. No, it wasn't dead when I started charging but at 9.5 volts and 006 CCAs.
below 11.9V is considered dead. 9.xx is deader but possibly resuscitation can be successful.
It's always been that way for me with Delco batteries. One day great, next day dead. Delco batteries never give warning, they just die a sudden death. It would be a core tomorrow on a new battery.
Should have taken much longer. Sounds like it has no capacity left
Well right now it's showing 672 CCA.
Its got a broken internal connection. It acts like an intermittent open, like when a light bulb filament breaks not burns and shifting its position makes it work until you tilt it or bump it. Have you tested it with a carbon pile tester that actually puts a 300 or 400 amp load on it or just one of those condition meters. If it is broken internally the carbon pile tester will probably burn the connection open permanently, it will be better than driving down the road and hit a bump and have it open up again then fry your alternator.
A battery that isnt dead but reads 9.xx then charges full in 1/3 time and reads fine has a physical issue. As I alluded to several posts ago probably an intermittent connection internally. Just hooking up a capacitive battery tester isnt going to tell anything new at this point.
The CCA rating is directly derived from the internal resistance of the battery its not using some magic to know everything there is to know about the battery. I've had a few that tested relatively ok that would fail a load test with low charge then charge up fully in a short time.. Its just a tool.
So how would such a battery be warrantied if it tests ok?
JHZR2
Staff member
This behavior tells me that it is a load from the vehicle. Reminds me of when I had a bad diode in the alternator. Dissipated a lot of energy, dragged the battery down.
The chemistry will recover. So you will see something when letting it sit open circuit assuming it isn’t totally hosed. A short cell would mean it couldn’t give you 13v, as you lost 2.x volts in series. The presence of voltage doesn’t mean there’s really something there. Did you load test it for 650, or at least 325, or did a conductance tester tell you that number? While I like those meters to give some semblance of an estimate of impedance, I’d have my doubts on trusting them in fringe scenarios. That’s not what they’re calibrated for…
JHZR2
Staff member
Load test it.
This meter most often condemns perfectly good batteries, which after a few days on a conditioner, test perfectly fine, so I'm surprised it didn't say this one is bad.
The way those meters work is that they generate a very small AC current. The good ones do this in several different frequencies and they then measure the impedance and capacitance. they use these numbers plugged into a formula to predict the CA and health of the battery. They dont actually measure CA, just voltage and impedance/capacitance. This works OK for a battery in normal wear circumstances but their real value is in comparing the value when new to the degradation over time. The old way of measuring Specific gravity and heavy load testing was more accurate but sealed batteries and untrained techs made it necessary to find some other way to either pass or condemn a battery for warranty. But as you have experienced in anything other than normal conditions they fail miserably.
If it checks OK, use it.
Similar threads
