No power without jump pack, battery is charged.

[Connor]

Hi, so I just got my car out of storage for the summer I installed a new battery about a week ago, car only has power when I connect my jump pack, battery is fully charged, I’ve checked the connections at the battery and they are good, any suggestions? Thanks

 

[rubydist]

How do you know the battery is fully charged?

 

[Connor]

It may sound stupid but I found that my battery was indeed dead all along which I wasn’t expecting as it’s a brand new battery “a week old”, however after I charged it i left my car sit for a couple hours and now i have dim interior lights, car won’t crank, I’m assuming some kind of parasitic drain is occurring. When I jump start the car it runs fine, off the alternator.

How do you know the battery is fully charged?

 

[SHOdded]

battery quality isnt the same as it was 10+ years ago. they can be bad right out of the box.

i like Interstate brand myself back then. nowadays, i use various AGM brands, fav being Odyssey, but any agm battery from autozone advance auto oreillys or walmart should work well also.

you can test battery health with a digital tester like the solar ba9.

it could just be a parasitic draw but that typically shows up in lower voltage at the terminals after an overnight shutoff.

 

[Connor]

I’ll get the battery tested, it’s an agm battery, I was thinking maybe an alternator diode is shorted but the car runs fine off the alternator.

 

[SHOrod]

Getting the battery tested is a good idea. Did you happen to try starting the car immediately after charging the battery, or only after it sat a couple of hours? If the battery charger says the battery is charged but it won't provide enough current to start the engine, the battery may have a high internal resistance. Bonus points if you connect a multimeter and monitor what the voltage drops down to when trying to engage the starter motor. With the meter still connected to the battery terminals, if the engine starts and runs you can also get an idea if the alternator is working properly by measuring both the DC voltage and AC voltage at the battery. The DC voltage should be between 13.8 and 14.4 V after just starting the engine and the the AC voltage should be near 0 VAC. I'm not sure off the top of my head how much AC voltage would be considered too much and indicate a bad diode.

You could also disconnect the battery, charge it, let it sit a couple of hours, then reconnect and see if it will start the car to determine if there's an internal low resistance path causing the battery to self discharge.

High internal resistance or an internal low resistance "short" would both be battery defects and should be fully warrantied by the place you bought the battery from.

-Rod

 

[Connor]

Getting the battery tested is a good idea. Did you happen to try starting the car immediately after charging the battery, or only after it sat a couple of hours? If the battery charger says the battery is charged but it won't provide enough current to start the engine, the battery may have a high internal resistance. Bonus points if you connect a multimeter and monitor what the voltage drops down to when trying to engage the starter motor. With the meter still connected to the battery terminals, if the engine starts and runs you can also get an idea if the alternator is working properly by measuring both the DC voltage and AC voltage at the battery. The DC voltage should be between 13.8 and 14.4 V after just starting the engine and the the AC voltage should be near 0 VAC. I'm not sure off the top of my head how much AC voltage would be considered too much and indicate a bad diode.

You could also disconnect the battery, charge it, let it sit a couple of hours, then reconnect and see if it will start the car to determine if there's an internal low resistance path causing the battery to self discharge.

High internal resistance or an internal low resistance "short" would both be battery defects and should be fully warrantied by the place you bought the battery from.

-Rod

I charged it then started it let it run for a couple minutes shut it off then came back out a couple hours later and
The car had really dim lights and wouldn’t turn over

 

[rubydist]

So there is a pretty strong drain somewhere. As indicated above should help you figure out if it is the battery or the car. Hopefully its the battery - that's a lot easier to fix than a big drain somewhere in the car wiring...

 

[SHOdded]

I charged it then started it let it run for a couple minutes shut it off then came back out a couple hours later and
The car had really dim lights and wouldn’t turn over

do you remember what the battery voltage was when you attempted the restart? i have been able to do so off agm batteries sitting at 11V albeit slowly. In one case, due to the alternator having gone dead on me on the previous leg of my trip. on the return leg of my trip home, the battery voltage was below 9V on s 30 mile mostly highway drive. lost instrumentation after 25 miles. not something i would recommend for mixed driving or stopngo driving.

 

[SHOmont]

Happened to my on my Fairlane……Remove the cables and clean the posts and the inside of the cable terminals with a wire brush / battery brush.

 

[FastCAD]

Hi, so I just got my car out of storage for the summer I installed a new battery about a week ago, car only has power when I connect my jump pack, battery is fully charged, I’ve checked the connections at the battery and they are good, any suggestions? Thanks

starter solenoid drivers side fender.

 

[Greg Corcoran]

Conner, This may be a Captain Obvious reply, but you do have a charger with an AGM setting? An old school analog charger won't really charge an AGM properly. I had to go out and buy a new $120 electronic charger at NAPA when I got an AGM. It also does old school lead acid batteries at least... My 30 year old charger still works fine on traditional batteries, but couldn't work right on an AGM