OT: Cold temp effect on charging

My new 20v dewalt batteries won't charge if they are cold or too hot.

GM recommends using a charger designed for AGM batteries that keeps the charging voltage under 14.8 v.

My car has set inside a 50 degree garage for past two weeks. Lot of bells and whistles that drains the battery. BTW< GM recommends not using a trickle charger.

Went out of town the other day. Turned the voltmeter on display. Charging voltage went to 14.8 v for about 30 minutes. Then slowly it increase to 15 v as the battery cooled off, 15 degrees outside

We stopped for lunch for about an hour.

On the return trip, 150 miles, the charging rate went to 15.2 volts. So much for keeping charging voltage below 14.8 v on an AGM.

I'm only guessing that the car's computer looks at temperature and adjusts charging voltage.

I connected my battery minder to a cold battery in pole barn. It too has a temperature monitor. Charger didn't want to work in the cold.

Does anyone have a link to show that temperature has an effect on a battery's ability to be charged? I read someplace that booster chargers capable of 200+ amps may cause a COLD battery to fill with hydrogen and go BOOM.

Anyone experience a big bang using a booster chargers on cold batteries? I saw one. Big flash and acid all over. Lucky no one was close to battery at the time.

I've see several batteries blow up, never in the extreme cold or heat. Always at what I'd call normal temps.

One other factor has to be involved to make em explode. An ignition source. Often that source is the clamps either going on or coming off with the charger still turned on. Seeing as chargers are most often used in cold weather?

Rick

George After reading all your post on the digital battery checker I go to thinking I might need one. Seems you have the Midtronics BPT 300. Some guy on U tube rated the top 7 models and it was not in the mix. He did rate the little yellow HF as number 5 . I went by HF last night and it is $69.00 less the 20%cupon . I am sure I can find the midtronics on e bay. Is there some reason you liked that model other than price and is it still working as you think it should. HF also had a unit that had two meters but not digital using carbon pile that seemed interesting but again not digital and would take some getting used to .

The GM dealer I used to work for used Midtronics Battery testers, was about three in the shop and think they were labeled GM. Right before I retired in 2013 a fancy charger/ tester showed up, all the new vehicles had to have the batt.s charged with that as part of predelivery and any battery warranty claim had to have the charger print off attached to the repair order. Every body hated that dam thing because it was slow and didn't pay much if anything.

I think you are right. Definitely need a spark and H2. If a battery is
producing hydrogen it's also generating O2. That's why when battery is low on
electrolyte, you just add H2O. Under normal charging most batteries don't
require adding water.

Voltage regulators have been temperature compensated since the beginning , but, they didn't do a real good job. Modern way is with a temperature sensor under the battery mounting in the car and the computer does a real good job of compensating voltage.

We all know it takes more voltage to push a charge into a battery as the charge state of the battery rises. That is why a voltmeter will show a lower voltage at battery when being charged at a slow rate and that will continue to rise as the battery comes to full charge.


Also, the higher the rate you charge a battery, the more voltage it takes to push that charge into the battery and that is why when you start your car or tractor a voltmeter will go to the normally higher reading on your voltmeter because your alternator is capable of pushing all the battery will accept at regulated voltage.


A cold battery takes more voltage to push the charge in so that is why the regulators are temperature compensated. Also, a dead battery that has been dead for a while requires more voltage to accept a charge but voltage may come back down depending on amperes being pushed into battery. A regulator or computer doesn't know if battery is dead so it may not charge it at all because it will regulate at normal voltage settings


As far as blowing up battery, either dead or cold, it takes more voltage and if charger is capable of that higher voltage it will try to push that higher rate in causing much more agitation in battery thus more hydrogen gas build up. So, give it the spark needed and boom. Some times a high rate of charge will just blow up battery from pressure build up if no spark occurred. Seem many badly bulged battery. That explosion is normally not as violent though.


Charging is all about EMF and counter EMF. Electro Motive Force.

I think you have a lot more potential of a battery blowing up due to an internal short than charging a good battery at 15V.

Some batteries are just plain worn out.

I've only seen one battery blow. It was only a few weeks old. Sub zero temps. Brother's car wouldn't start so we used a 200 amp charger and the battery blew the instant I hit the starter switch. Good thing my brother was sitting beside me inside the car.

Good lesson, don't to be belly up the the front bumper when jump starting or using a boost charger.

You really think hitting a cold battery with 200 amps is a good idea?

I would blow up if you did it to me too.

(quoted from post at 13:58:56 02/10/19) I've only seen one battery blow. It was only a few weeks old. Sub zero temps. Brother's car wouldn't start so we used a 200 amp charger and the battery blew the instant I hit the starter switch. Good thing my brother was sitting beside me inside the car.

Good lesson, don't to be belly up the the front bumper when jump starting or using a boost charger.

Click to expand...

Ever notice how much the case on a frozen battery bulges?

Even when thawed,they often remain bulged.

It's not to hard to imagine a damaged or broken connection between plates or cells inside the battery from the ice shoving things around.

When you boost or put a load on the damaged battery and the connection fails/arcs what do you suppose happens to the air and hydrogen mixture inside the battery?

jm
Yes mine is a Midtronics BPT 300. I had to get it off the internet because there isn't a place in town that sells that brand.

No doctor can predict someone?s future health, just like there is no meter made that can predict the future health of any battery. Some batteries may be good today and dead tomorrow. People see a Dr to day and dead before they get home or die in Dr office.

This is what Battery University has to say about testing
No practical method exists to quantify all conditions of a battery in a short, comprehensive test. State-of-health (SoH) cannot be measured per se, it can only be estimated to various degrees of accuracy based on available symptoms. If the symptoms are vague or not present, a reliable measurement is not possible. When testing a battery, three SoH indicators must be evaluated:

Capacity, the ability to store energy
Internal resistance, the capability to deliver current, and
Self-discharge, reflecting mechanical integrity and stress-related conditions.

There is a lot of confusion and concessionary about battery testing. I read an article where Ford doesn't recommending load testing, only use a voltmeter.

Yet some people on YT will say a digital tester lied to them and a cheap digital may do just that.

Go to Snap On and their digitals cost $800. Bet if the person who paid that much thought theirs lies, Snap on wouldn't be selling them.

Some places I've read say not to use carbon testor on AGM and other said it's ok.

You can't use a hydrometer to test an AGM battery.

I've read where testing a battery should be done 24-48 hours after you take it off a charger so you aren't measuring surface charge of battery.

So believe it or not, use the tester you want or trust. I have both carbon and digital. The last thing I want to do is discharge a battery and have to wait to bring it back to full charge before using it. Which is what is recommended when replacing an alternator, fully charge the battery.

My brother applied 200 amps to his car.
I'm a believer in slow charging and waiting a half day to bring a totally dead battery to full charge before using it. I've burnt up 3 alternators with dead or almost dead batteries. Good think the alternators were Auto zones lifetime alternators and they never questioned what I did to burn them up. My car had a parasitic load draining battery on an old 70's Cadillac.

(quoted from post at 16:07:31 02/10/19) My brother applied 200 amps to his car.
I'm a believer in slow charging and waiting a half day to bring a totally dead battery to full charge before using it. I've burnt up 3 alternators with dead or almost dead batteries. Good think the alternators were Auto zones lifetime alternators and they never questioned what I did to burn them up. My car had a parasitic load draining battery on an old 70's Cadillac.

Click to expand...

Could be a 200amp charger but it would be hard pressed shove 200amps into the battery unless it was dead, dead ,dead with a terminal Voltage below 9 or 10 volts .

Thanks I knew this 2as a topic you had some good experience in. I have relied on the load tester for years but after following all your post just seemed time to move to the digital meter. May still pick up one just not certain what brand, in that article that checked and came back with the top 7 seemed there was always one thing that was not perfect on most of them like not recommended for AGM batteries, or smaller leads or something so I am going to do some more reading. Again thanks for the quick answer. We have something close to 100 batteries here on the farm so need to get what does the best job.

https://www.searchautoparts.com/mot...339JQNDJUK2VqAsz-DnoXS-fwg&amp;_hsmi=69708565

Maybe some tip here...