I've been the owner of many-a-battery which blew up, particularly inside of flashlights.

I've recently purchased a fairly-decent-quality flashlight, and I'd greatly like to prevent the battery from exploding/leaking inside of my expensive flashlight.

As a reference, here's the battery that I'm using:

(source: nitecorespecialist.com)

Why do batteries leak/explode, and what can be done to prevent this?

  • \$\begingroup\$ Here's a WikiPedia article about it. \$\endgroup\$
    – Ricardo
    Commented May 7, 2014 at 19:52
  • \$\begingroup\$ @Ricardo that link is about alkaline batteries, the one pictured looks more like a lithium one (3.7v, mentions high discharge, integrated protection) \$\endgroup\$
    – Gorloth
    Commented May 7, 2014 at 20:10

1 Answer 1



Thermal runaway is the main cause of lithium ion battery explosions. Once too much heat is generated, that causes the reaction to happen faster which generates more heat which causes the entire cell to start burning/exploding. This can be caused by poor manufacturing, an internal short caused by improper charging, or improper usage.

Leakage is caused by the same basic causes as stated before, but it's usually milder in effect and is due to heat or chemical reaction causing a boiling of the electrolyte or a chemical change which increases the pressure of cell. There's usually a safety valve that releases once a pressure is reached and out comes electrolyte and electrode materials. Once the safety valve goes usually the battery is toast.


  1. Buy li-ion batteries from a reputable source. This can be hard because there's plenty of Chinese companies that wrap crappy batteries in a case with a different brand name on them.
  2. Don't over charge them.
  3. Make sure you use a smart charger that does low current, constant current and then constant voltage charging.
  4. Don't over discharge them.
  5. Don't discharge them too fast. 1C is a reasonable guideline to follow to ensure longevity.
  6. Don't freeze the batteries, but keep them as cool as possible.

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