Why doesn't battery water freeze

With how cold it is around the country right now, I was just wondering, why doesn’t the water in batteries freeze? or can it?

It can but all the chemicals in there lower the freezing point so it is not likely to freeze in the lower 48.

Yep, it’s a sulfuric acid solution, which keeps it from freezing. HOWEVER, if your battery’s dead it can freeze, because most of the sulfate is chemically bound with the lead, leaving very weak acid in the battery.

Right; don’t let your battery go completely dead in very cold weather. The casing may crack and spill concentrated acid all over.

The “water” in your battery is called the “electrolyte”, and is diluted sulphuric acid.

Modern car batteries are filled with a “gel”. In older style batteries where you add water, the water really becomes acid and just replaces water that has evaporated during the charge and discharge cycles of the battery. Those batteries won’t freeze if they are at or close to fully charged. Discharged batteries did freeze and the expansion caused by the freezing would bulge out the case and often crack it.

A gel filled battery that is completely discharged might just “freeze” also. Not sure if the case on these would burst and crack or not.

Most still make acid electrolyte batteries. Some specialty brands, like Optima, uses gel technology, but typical brands, like Diehard and Interstate is still acid electrolyte. Typical maintenance-free batteries just do a better job of preventing the water from evaporating and escaping than the old-style batteries that you had to check periodically.

Good question, and all the answers are correct. Back in the winter of 1969-70 in Madison, WI, I did see a VW van with a frozen battery. That winter the high temp for for first 3 weeks of Jan was +5F. And my manual transmission car would surge forwad a tiny bit when I engaged the clutch while in Neutral.

I had a friend who sent his wife to a place that rhymes with ears, all we have is the gel cel, they told her, fine she said. $285! I think Gel Cells are in the minority. Pardon the hijack but how come the soda you by from an outdoor machine is never frozen, are there heaters in the pop machines?

The pop has sugar. Easy to freeze diet sodas.

art1966–Small world! In the early '70’s me & my brother were visiting a college friend of his in Madison, WI. Christmas break, January, I think. One night it got -30 F. The battery water in our 1969 International Travelall froze solid. We couldn’t believe it, but now I realize a fully discharged battery’s electrolyte can freeze at -15F.

We used get drunk at the Amber Grill. Do you remember that place?

Yes, cold weather is bad. I lived through two Februaries in Maine where the high temperature was zero. Lots of cars were dead. Some cars and trucks engines would stall out when you let the clutch out in neutral. Couldn’t decide whether to be impressed or depressed.

Here near Philly it doesn’t get real cold, but I think in winter of '79-'80 we had a cold snap where it was below zero F several mornings in a row. Any marginal batteries, & there were a lot, wouldn’t crank. I worked at a Triple A Mobil station. We had 2 tow trucks & 2 drivers & got 24 hours behind. A customer would call for a jump at 8 AM on a particular day & we’d have to tell them we’d be out at 8 AM the next day.

Yes, modern soda machines are set up like heat pumps. If the inside of the machine gets too cold, they reverse the flow of the refrigerant to warm it up.

Nice highjack.

Umm, water can’t turn into acid.

“the water really becomes acid”

Waterboy, I just went to ‘ears’ dot com. They do sell gel batteries, but also liquid acid maintenance-free a lot cheaper. and $285? Online, they go for $189. Your friend got taken.

You don’t think I tried to tell him that! His wife does all the bills so he never saw the receipt, only heard the total, perhaps they did something else besides the battery in addition. All he knew was a new battery then out the door was $285.

Sorry for the delay in responding. I was typing a response when wife summoned me for something more important. Then the snow started. Then the power went off for about 30 hours. Anyhow,…

I don’t remember Amber Grill, but I’m not much of a bar person. I did go to one, Brat & Brew (???), on State St. (???) right by the UW Hospital for lunch once or twice. I do remember that the in Sept '69 the tradition was “weekend begins noon thursday.” Within a few months it was all you could do to dodge between the uprising students and the untrained, but enthusiastic, sheriff’s deputies as you tried to get to classes. An interesting time to be on campus. But that’s not a topic for this forum.

Just to keep it appropriate to this forum (as long as we are hijacking the thread) my 1969 Porsche 912 suffered a broken valve spring that Fall Semester; then a cracked head in the Spring or Summer; then another broken valve spring in January '71 when I was moving back home. My dream car, but I grew to hate it. I realized that Porsche’s reputation for longevity was only because the insane owners were willing to invest infinite time and money to keep them going. Maybe things are different 40 years later.

I don’t think that you will find, or ever would have ever found gelled electrolyte batteries in cars. It is not appropriate for automotive starting batteries. They have charge and discharge rates that are way too low.

It is getting harder to find them anywhere now. That technology is being largely replaced by Adsorbed Glass Mat (AGM) batteries. They are both sealed types so people get AGM mixed up with the the older type gelled electrolyte types. I am not a battery chemist or engineer, but the former seems to be superior in almost every way.