Testing battery at home

[mb32]

I've noticed in the last few weeks my G35 is turning over a bit slower after sitting.

The battery is an Everstart Maxx 24F and is about 3.5 years old.

I checked the battery voltage this afternoon with a multimeter and the battery is only showing 11.6 volts after the car has been sitting for 2 days. My commute used to be about 30km one way but is now only about 3km one way. Could this be impacting the battery life?

Walmart will still pro-rate the battery. Not sure how much I will get back towards a new one.

Any other simple tests I can do at home before I go ahead and swap it?

 

[gathermewool]

Is that 11.6 volts after sitting correct or did you mean 12.6VDC?

If your battery only sees such short commutes with no longer driving and no other battery upkeep, I wouldn't expect a very long life (i.e., as long as it could have lasted)

 

[eljefino]

11.6 is not normal, it's about 20% state-of-charge.

Your style of short-tripping might not get you to 100% SOC but should hit 85%. Batteries are easier to charge the deader they are.

I'd see what walmart can get you. And warm the car up in the driveway a bit here and there.

 

[mb32]

Only the last few months have been short commutes. And it's 11.6 VDC so definitely a very low state of charge.

Just went and started the car up and the voltage dropped to about 8 volts.

I have had a dash cam hardwired in for over 2 years, but it shuts off when voltage gets below 12.4. Never had a problem before.

I think the short trips the last few months probably didn't help.

Will go and try to do an exchange at Walmart.

 

[JHZR2]

11.6 is not right. You should be greater than 12V, and a full battery is 12.6V.

8v under load is not unexpected from a near dead battery.

A carbon pile load tester would be one way to test.

 

[gathermewool]

Originally Posted by mb32
Only the last few months have been short commutes. And it's 11.6 VDC so definitely a very low state of charge.

Just went and started the car up and the voltage dropped to about 8 volts.

I have had a dash cam hardwired in for over 2 years, but it shuts off when voltage gets below 12.4. Never had a problem before.

I think the short trips the last few months probably didn't help.

Will go and try to do an exchange at Walmart.


Can you please check the 11.6 again? How are you measuring this? Digital multi-meter?

I would get rid of the dash-cam and buy one with a battery, unless you have one so good that it's not financially feasible to do so. I just got a decent cam for $50 with a battery, instead of one of the many, many sub $30 ones.

 

[Wolf359]

Originally Posted by eljefino
11.6 is not normal, it's about 20% state-of-charge.

Your style of short-tripping might not get you to 100% SOC but should hit 85%. Batteries are easier to charge the deader they are.

I'd see what walmart can get you. And warm the car up in the driveway a bit here and there.


Right, that's 20% state of charge at 70 degrees with no load with the battery at rest for a couple hours.

In the winter with a load, it's totally different.

Get a cheap battery charger like this 8amp Schumacher on Amazon for $18 and charge it up.

https://www.amazon.com/Schumacher-SC1279-12V-Rapid-Charger/dp/B07DM22XTN

 

[mb32]

Originally Posted by gathermewool
Originally Posted by mb32
Only the last few months have been short commutes. And it's 11.6 VDC so definitely a very low state of charge.

Just went and started the car up and the voltage dropped to about 8 volts.

I have had a dash cam hardwired in for over 2 years, but it shuts off when voltage gets below 12.4. Never had a problem before.

I think the short trips the last few months probably didn't help.

Will go and try to do an exchange at Walmart.


Can you please check the 11.6 again? How are you measuring this? Digital multi-meter?

I would get rid of the dash-cam and buy one with a battery, unless you have one so good that it's not financially feasible to do so. I just got a decent cam for $50 with a battery, instead of one of the many, many sub $30 ones.



The battery was indeed showing 11.6 Volts while tested using a digital multi-meter. Ambient temperature was 10 degrees celsius and car had been sitting in underground garage for 2 days around that temperature.

The dash cam was about $200 (Thinkware F50). It turns off after the battery voltage drops to a preset level. It is motion activated and does not record continuously.

Alternator is showing strong. It was showing 14.6 Volts steady immediately after startup when the battery was showing 11.6 Volts.

Going to take the old battery into Walmart and get a new one.

 

[mb32]

Went into my local Walmart to exchange the battery.

They didn't really know how the warranty applies since they weren't an auto service location, but do sell batteries.The battery casing on the defective battery had a sticker that states 9 years warranty with 3 years free replacement. I was about 6 months out of the free replacement period.

They initially stated that I would have to deal with the manufacturer for the warranty. Don't quite understand that since I had the original receipt. They had a supervisor okay to exchange the battery with a new one this one time only. Ended up paying $43 to get a new battery. Don't know if this is right or not, or how the pro rated warranty is calculated, but it seemed reasonable for a brand new replacement battery so I went ahead with it.

Car turns over much faster now. Didn't realize how weak the old battery must have been. Next time I will have it load tested before the 3 year replacement period expires since the warranty exchange process was far from straight forward.

 

[gathermewool]

If you're able to, I would invest in an extension cord and a cheap charger. Charge as often as you're able to and your next battery will likely last a lot more than 42 months.

 

[user52165]

Originally Posted by gathermewool
If you're able to, I would invest in an extension cord and a cheap charger. Charge as often as you're able to and your next battery will likely last a lot more than 42 months.


But make sure that is a "smart" charger that regulates the charge and will switch to a maintain mode. Otherwise you risk overcharging with disastrous results.

 

[NYEngineer]

You have a DMM. Here's a great test. Put the leads across the battery so it displays the voltage. Prop the meter so you can see it from the driver's seat. Start the car while watching the meter and see what the voltage drops to.

At 3.5 years with a now short commute, you probably won't have a long happy relationship with that battery. I commute to the railroad station which is only about a mile and a half away from my house. My battery was 3.5 years old too. I replaced it last month. Easier to do it now than in the morning when it's 12 degrees and I've missed my train.