Why do Batteries leak?

[Blowmax10]

I've had a couple of good flashlights destroyed when the batteries in them leaked. I've always wondered why this happens so I did some research

Most standard disposable batteries consist of a metal pot that forms one electrode this contains the liquid or jelly electrolyte and a central conducting rod as the other electrode. Discharging the battery dissolves the metal pot and eventually allows the electrolyte to leak out. Old fashioned batteries used to leak very badly because they only had a cardboard jacket and they could start leaking well before they were fully discharged. Nowadays all batteries are "leak proof" and have a metal case around the cardboard jacket and this considerably reduces the risk of leaking and batteries will not leak until they have been discharged well beyond any useful level but if you leave discharged batteries inside a unit or accidentally discharge them totally by leaving something switched on they will leak electrolyte.

The most important thing to remember is this: dead batteries will eventually leak. And all batteries will gradually self-discharge (even if they are not operating the device they are installed in, and even when they not installed at all but just sitting on a shelf or in a drawer, they will slowly lose energy capacity over the passing of time). So, no matter how good the brand name, your batteries will eventually go dead even if you don't use them, and when they go dead they will eventually leak. These simple facts lead to just three easy rules, which must be followed without exception to protect your investment
in flashlights and other battery-operated equipment.

Remove batteries when equipment is stored -
Whenever a given device will not be used for any extended period of time (one month or more), remove and properly store its batteries.* In extreme conditions, such as the car glove box in the summer in hotter climates, install the batteries only when needed.

Always remove dead batteries immediately -
All dead batteries are subject to very rapid leakage.* When the batteries can no longer effectively power the device, remove them at once and take them to a recycling center. If the device has several batteries, always replace every one of them at the same time.

Hope that helps

[Rmplstlskn]

Yeah, I have lost a few battery-powered items to battery leakage... But if the metal contacts are not too badly corroded by the acid, you can clean them up with VINEGAR. It dissolves that acid crusty stuff... I now leave batteries outside my best gear, but it makes it much more of a hassle when I need it, or when an event triggers a bug out...

[eeyore]

Yep very good post , about 4 days late for me (lol). Of course i know they leak and have ruined several over the few years because i was too lazy to turn the batteries backwards or to put a piece of tape on top to break the connection. I found a few prepping for the hurricane last week. it has to be easier for the person that uses them all the time. I have a bunch but only really use them a couple of times a year.

[monkeybird]

So, no matter how good the brand name, your batteries will eventually go dead even if you don't use them, and when they go dead they will eventually leak.

How long will batteries purchased for LTS actually last sitting on the shelf?

[Blowmax10]

How long will batteries purchased for LTS actually last sitting on the shelf?

I found this

Simple Guidelines for Storing Batteries

Primary batteries store well. Alkaline and primary lithium batteries can be stored for 10 years with moderate loss capacity.

Remove battery from the equipment and store in a dry and cool place.

Avoid freezing. Batteries freeze more easily if in discharged state.

Charge lead acid before storing and monitor the voltage or specific gravity frequently; apply a boost if below 2.10V/cell or an SG below 1.225.

Nickel-based batteries can be stored for five years and longer, even at zero voltage; prime before use.

Lithium-ion must be stored in a charged state, ideally 40 percent. This assures that the battery will not drop below 2.50V/cell with self-discharge and fall asleep.

Discard Li-ion if the voltage has stayed below 2.00/V/cell for more than a week.

There is a detailed article HERE

[CLT46910]

I have a lot of flashlights around my place. I got into the habit if checking them once every three months or so to see if the batteries and discharged or not.

I also got to using a number of rechargeable lights as well. I keep them in their chargers and that seems to help as well. I got them mounted all over the house. One at the front door, back door, the headboard of my bed, the headboard of my daughters bed and one each in the car and truck. You have to watch the ones in the vehicles, they will run the vehicle battery down if not driven in a while. I got sick and did not drive my work truck for a period of time, battery run down twice on me and had to be recharged.

You can find those rechargeable lights that will take regular batteries if your rechargeable batteries go bad or run down. I found those to be very comforting. I keep lots of batteries of all sizes in the house so we have a lot of battery power...LOL

[Matt In Oklahoma]

I wish I had seen that about the heat, i lost a good flashlight in my GMHB the other day

[Grantmeliberty]

The so-called "heavy duty" batteries which are sold today are of the carbon-zinc type with an electrolyte of sulfuric acid mixed with manganese dioxide. The sulfuric acid would eat away the zinc can style electrode and then continue on to whatever else was available.
The problem today is that the alkaline style batteries such as the Duracell copper tops and all of the other alkaline cells may also corrode your equipment. The first time I had a problem was in the early 90's when I had a 3 D cell Maglite in my vehicle which I hadn't hardly used, corrode the inside of the flashlight. The center cell was totally corroded while the other two cells were at full charge. I took the light apart, cleaned the corrosion out and put in a single new cell to go with the other two and used the light for years. The point is that the alkalines can and will corrode even if they have a full charge.
More recently I have purchased small LED lights from Costco which included Duracell batteries, AA and AAA type. I had two different flashlights with essentially new batteries, corrode internally. I had a friend with an atomic clock which failed, again with Duracell batteries. I emailed pictures of the failed cells in my flashlights and got reimbursed from Proctor and Gamble, the parent to Duracell, although the coupon for new batteries got used to get some 9 volt style because I have never been bit by them.
I have been using the Kirkland brand alkaline cells for years now and I have never had one of them corrode.
I use lots of rechargeable NiMh cells, and I have never seen any of them corrode, although I suppose the possibility exists. The Eneloop cells by Sanyo are a low self-discharge technology which is reputed to hold 75 percent of charge after 3 years on the shelf. That is enough for me to consider phasing out all of my alkalines in my flashlights.
The Eneloop cells are made in Japan rather than in China which gives me a bit more confidence in their quality.

[Mr.Grey]

We use wind up torches around our house and barns, the LED ones seem to do the job well enough. I only keep a few batteries around these days, for devices used in the house, such as the remote and the smoke alarms.

[monkeybird]

Thanks Blowmax. The article was excellent. So, storing your batteries in the refrigerator, no the freezer (32 degrees F or 0 degrees Celsius) extends the battery life of your batteries. The article said for around 10 years!. However, extreme temperatures will destroy the battery. i.e. freezing or over heating. I destroyed a cell phone leaving it in my car. A ten year life is excellent.

[Ruthmary]

Most batteries I buy have a use-by date on the packaging and I've found that to be fairly accurate. Cheaper batteries tend not to last so long. Stoer them in a cool dry place and they will last longer.

[Bill Foster]

Last Christmas, I purchased batteries at Home Depot. They were selling a 32 pack of AA alkaline batteries for $5.00. Probably a loss leader, but I went back a couple of times and got more. This year I plan on stocking up on AAAs. if they want to give them away this year. I keep batteries in my cool subterranean basement. I tested some AAs today. They were marked good until 2004, still tested good.