Battery charge

No, reggy 2. I'd be interested to hear the science behind that one.

I watched an episode of Aussie Gold Hunters where two aboriginal guys had a flat battery. So they dug a hole, put the battery in it and back filled with hot sand from around the camp fire. Cranked the engine the next morning.
Keith

A cold battery that is weak will work better if warmed up a bit. It does not charge the battery, just allows it to deliver what charge it has easier.

A flat battery is a flat battery, nothing will come out if there is nothing in there no matter what temp it is.

That is why chargers have temperature compensation, it takes a higher voltage to charge a battery as its temperature rises due to its terminal voltage rising.

My Optima for instance will be sitting at 12.7V on a warmish morning, on a cold morning it might be down to 12.5V. Heating up the battery makes the chemical reaction more efficient.

"The standard rating for batteries is at room temperature 25 degrees C (about 77 F). At approximately -22 degrees F (-30 C), battery Ah capacity drops to 50%. At freezing, capacity is reduced by 20%. Capacity is increased at higher temperatures – at 122 degrees F, battery capacity would be about 12% higher."

Apparently helps to re-inflate tyres also if your pump fails.

Aborigines have a great sense of humour. What's the bet that they buried one of THESE with the battery?

Thanks everyone, very funny

I've heard of this. I tried it but it didn't work.

When I was young and broke, I often had to pour hot water on the battery to get it to kick the engine over. It sounds like the same strategy, heating the battery. It doesn't charge it.

It is possibly like the Aspro fix. If you try a battery to start a motor there are times where you will not get a second response from the battery if you retry a second time right after the first. The oldtimers often used to advise that if you put an Aspro in each cell then that would charge it enough to have a second go. The truth of the matter was that it took a bit of time to find and add the Aspros. If you had waited the same time as it took to do your Aspro fix you would have got the same response from the battery without wasting the Aspros.

As the others said, by raising the temperature of the battery a little and adding the necessary waiting period you can get a second go from the battery.

I was stuck out in the desert one morning with 8 paying passengers and a flat battery! I'd heard somewhere that if you put a cup of water into a billy, then drain each cell into the billy as well, then put it on the fire and bring it just to the boil.
Refill the cells, reinstall the battery then wait 10 minutes. If it's going to work, you'll only get one chance to start the vehicle. One chance was all I needed and it worked!
It impressed the passengers, but I did pick up a new battery later in the day.

There’s little tricks to get a go out of a suss battery, as discussed.
There’s also plenty of myths.
Such as don’t store batteries on concrete. I presume this one comes from the cool temperature of the concrete. Cool doesn’t hurt as said previously. But when I was retailing batteries, I had rubber mat under stock at floor level, but I only did that to keep the myth believing customers happy.
Had a Harley owner that put a piece of rubber under his side stand, reckoned the battery went flat if he didn’t??
I often advised farmers etc after needing to jump start something, to put the battery on the charger for a good charge. A lot of the time the tractorute or whatever would start ok for days or weeks after , so seem ok. As after a lot of testing over the years I don’t believe the vehicle alternator will fully charge the battery.
I had a truck operator that was complaining about poor battery performance. He had trucks and loaders that weren’t in constant use , I went thru the whole yard any of the infrequently used batteries were all under the 12.4 volts that is regarded as minimum voltage. Some would start , just. His constant used gear batteries were fine.
The modern sealed batteries, can’t be tested with a hydrometer, which is the best way to determine if a lead acid is fully charged. My testing over the years also revealed that most automatic/float chargers don’t get the battery right up either.
Another thing about batteries, is , most of us hate buying them ( we seem to think they should last forever) when that are quite often only a small part of our budget. Especially when you look at farming operations, spending 100’s of thousands on chemical,fertiliser, fuel and machinery. A couple of thousand on batteries is a drop in the ocean.
I had one of our vehicles batteries get a bit sad recently, first up I was having that aversion to making the purchase, but then thought oh well it’s 5 years old , which is a reasonable age, so I got over it and put a new one in .
Cheers all
It’s an interesting discussion.