Possible electric issue.

[tuckerdog1]

2015 5.0. Battery was getting old & I knew replacement was coming. About 2 weeks ago, try to start car & COMPLETELY dead. No lead up like hard start, just good one day, totally dead the next. Put on battery tender overnight and tender indicates bad battery. Get new battery nine days ago, and same thing happens. Running fine, and the next morning totally dead. Again, tender indicates bad battery ( I have 2 tenders, and both say bad ). Took battery back where I purchased it. They could not verify battery bad, because they said it needs at least 7.5 volts to determine that. Was reading 5 volts. Before warranty replacement, they have to attempt to charge it, so I'll find out tomorrow if they have any better luck than I did. I suppose a NEW battery could be BAD, but probably unlikely. Either way, if I get it charged up and returned, or get ANOTHER new battery under warranty, is there anything with the car that could be causing this? Don't want to just kill another battery.

Thanks

 

[EdP]

2015 5.0. Battery was getting old & I knew replacement was coming. About 2 weeks ago, try to start car & COMPLETELY dead. No lead up like hard start, just good one day, totally dead the next. Put on battery tender overnight and tender indicates bad battery. Get new battery nine days ago, and same thing happens. Running fine, and the next morning totally dead. Again, tender indicates bad battery ( I have 2 tenders, and both say bad ). Took battery back where I purchased it. They could not verify battery bad, because they said it needs at least 7.5 volts to determine that. Was reading 5 volts. Before warranty replacement, they have to attempt to charge it, so I'll find out tomorrow if they have any better luck than I did. I suppose a NEW battery could be BAD, but probably unlikely. Either way, if I get it charged up and returned, or get ANOTHER new battery under warranty, is there anything with the car that could be causing this? Don't want to just kill another battery.

Thanks

My thought i parasitic drain. Not the usual case though, but something not shutting off properly. Normal drain would have surfaced long ago so it is probably something new. Bad relay, light staying on, such as trunk light.

There have been threads here on how to check it.

 

[tuckerdog1]

Thanks Ed

 

[Orangepeeled]

Thanks Ed

Have you found out what was wrong? Having the same issue as you.

 

[G-390062]

The place I bought the new battery, was able to charge it, and this time it held the charge. No idea why it drained out initially. Wish I could send more helpful info.

 

[skipgen]

Gotta check the date codes when you buy the battery - shouldn't be more than 3 months old. Sometimes they sit on the shelf a lot longer than that.

 

[carguy75]

Have you found out what was wrong? Having the same issue as you.

I would have your alternator checked(charging and diode test) to see if the rectifier circuit in the alternator is working properly.

A bad rectifier in the alternator will allow too much AC voltage to enter the battery while charging and allow DC voltage to be pulled from the battery when the car is sitting. Both conditions will kill internal battery cells(new or old) which prevents a battery from holding a proper charge while charging; hence a bad battery when tested.

 

[skipgen]

I would have your alternator checked(charging and diode test) to see if the rectifier circuit in the alternator is working properly.

A bad rectifier in the alternator will allow too much AC voltage to enter the battery while charging and allow DC voltage to be pulled from the battery when the car is sitting. Both conditions will kill internal battery cells(new or old) which prevents a battery from holding a proper charge while charging; hence a bad battery when tested.

When my battery failed, it took the alternator with it. Or so it seemed.

 

[joegr]

When my battery failed, it took the alternator with it. Or so it seemed.

I don't think it's that unusual for one to take out the other.

 

[carguy75]

When my battery failed, it took the alternator with it. Or so it seemed.

How so? What make you think a bad battery damaged the alternator?

I never heard of a bad battery damaging a good alternator, but anything is possible. Generally, the bad alternator damage the battery by allowing AC voltage or not charging the battery and allowing the battery to get a low discharge state.

However, it is possible a bad battery that will not hold a charge could have damaged the alternator by keeping it constantly running in an failed attempt to charge the dead battery until it burned out a circuit.

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[joegr]

...However, it is possible a bad battery that will not hold a charge could have damaged the alternator by keeping it constantly running in an failed attempt to charge the dead battery until it burned out a circuit.

This

 

[skipgen]

How so? What make you think a bad battery damaged the alternator?

I never heard of a bad battery damaging a good alternator, but anything is possible. Generally, the bad alternator damage the battery by allowing AC voltage or not charging the battery and allowing the battery to get a low discharge state.

However, it is possible a bad battery that will not hold a charge could have damaged the alternator by keeping it constantly running in an failed attempt to charge the dead battery until it burned out a circuit.

It was the original "Rocket" brand battery... It failed pretty suddenly, charge light just came on in traffic - didn't telegraph it's imminent demise w/ slow cranking, etc. Might have been a short somewhere. Had it tested (dead), replaced with new AGM & charge light still on in the cluster. Alternator was dead as well. My mechanic was a able to find a Denso replacement pretty easily & I was back in business.