2G Battery drain overnight

[ThunderChild]

You always need to check battery voltage 2 ways, with engine running + engine not running. When checking with it off and after car's been sitting overnight you're hoping to see 12.2-12.6 v but seeing 12.0v is not that uncommon and voltmeters do vary especially between budget ones. When checking with engine running I believe you should see approx 13.5-14.5v range.

I agree with most of what you said, especially checking running and not. One should also check with it above idle rpm.

However, if you have a battery reading 12.2v (that's 40% charge) from sitting overnight alone, you probably have a draw. Unless you make 20+ 5 mile trips in a day, you should never have a battery below 12.5v.

I just bought a brand new adv. Gold agm from sears, got home and tested it, 12.3v. Put a 15 amp charge on it, boom, 15.5v. would draw down to 10.1v with a 200a load after about 10 sec, batt was sulfated. Took it back and exchanged it, and this was a batt manufactured in November.

I don't put up with mediocre readings from electrical systems. If there's low or bad readings, I found out why and where.
Identify, isolate and eliminate, haha

 

[91Bomb]

However, if you have a battery reading 12.2v (that's 40% charge) from sitting overnight alone, you probably have a draw.

If brand new battery is 12.5-12.7v, how is 12.2v 40% less?

if I see 12.0v on my older battery after not starting car in a few days but it cranks right over + starts I'm not too worried.

 

[ThunderChild]

Because 6v is not 50% life. There are 6 cells in a battery, each at 2.1v. When you take out total voltage to 12.2v, you lose a massive potential to "push" current.

And I apologize, 12.2v is actually closer to 60%

Here is a good reference that is close to accurate

 

[98eclipse2015]

Clean battery terminals +connectors.

Batteries come with a month/year date stamp or sticker so check that. If you're having problems with one that's 4 yrs old or more then good chance you need a new battery. Getting 4-5 years battery life is considered normal even though they can last over 6 years depending on many factors.

Of course there are various ways to check a battery using a multimeter, hydrometer, load test, etc.

the battery is new and so are the terminals it turned out to be a bad alternator took my car in to get my new alternator tested along with my old one and yup turned out it was a bad one.

 

[JPringels]

currently having the same issue with my 96 TSi, replaced battery, terminals and ground wires and ring terminals, i get dashlights, key dinger and courtesy lights but no crank. jumped it with the charger and it started just fine, ran back into the car and now my battery light is on (wasnt before, with the same issue) think im going to dive into taking the alternator off after work and have it tested. i pulled the battery out of it and put it in my daily and started right up no fuss this morning. so i know the problem is not the battery but something drawing amps on it,

 

[luv2rallye]

If it won't crank but you have power to other things then you either have a weak battery or poor connections in the large battery cables (high resistance drops too much voltage so not enough voltage at starter terminals). May even be the cable itself.

 

[98eclipse2015]

currently having the same issue with my 96 TSi, replaced battery, terminals and ground wires and ring terminals, i get dashlights, key dinger and courtesy lights but no crank. jumped it with the charger and it started just fine, ran back into the car and now my battery light is on (wasnt before, with the same issue) think im going to dive into taking the alternator off after work and have it tested. i pulled the battery out of it and put it in my daily and started right up no fuss this morning. so i know the problem is not the battery but something drawing amps on it,

i had a battery drain that was killing my battery i fixed that for the most part. mine ended up being the keyhole light i just took the bulb out

 

[JPringels]

As soon as I get paid Friday and have the time, am gonna dive into it

 

[98eclipse2015]

it was the battery I have a red top now