21700 or 18650 - just starting out

Hooked on Fenix

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I'd suggest a Nitecore MH10 v.2. It's a gateway light. Comes with a 21700, but you have to spend more on spare cells if you want 5 amp batteries to get the maximum runtime (you can get 3 unprotected 5 amp cells for the $15 difference in price between this light and the MH12 v2 at 18650batterystore.com excluding shipping). Can use unprotected cells, so you can buy spares cheap. That leads to buying a separate charger so you aren't waiting for one cell at a time to charge in the light. Can use 18650s and 2 123A cells as well. Why chose between 18650 and 21700? Have both.
 

WYlightGUY

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Dec 13, 2004
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Thanks for the MH10 recommendation. I did not realize it can utilize 18650 and 21700 batteries.

One newb question regarding batteries: What is the difference/importance of "protected" vs "non-protected" cells. Are they interchangeable?
 

Hooked on Fenix

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Protected batteries have a circuit that shuts them down when they are being drained too low to save them from getting ruined, and other protections for safety. Unprotected cells do not. Protected cells are also a bit longer and have a button top that make them work in far more types of lights. For unprotected cells, you want a light with springs for both battery contacts or it may not work. Putting a rare earth magnet on the positive end of the unprotected battery will make it work in most lights without springs for both battery contacts. The Nitecore MH10 v.2 has springs for both contacts for 21700s. It doesn't for the battery magazine for 18650s but still works with unprotected 18650s. The MH10 v.2 also has a battery indicator to test voltage while off and give you an idea of when to change batteries while on. Because of this, it's pretty safe to use unprotected cells in the light as long as you're holding or monitoring it. If you ceiling bounce the light overnight on a high setting and fall asleep, that's when I'd suggest using protected cells.
 

Chicken Drumstick

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Protected batteries have a circuit that shuts them down when they are being drained too low to save them from getting ruined, and other protections for safety. Unprotected cells do not. Protected cells are also a bit longer and have a button top that make them work in far more types of lights. For unprotected cells, you want a light with springs for both battery contacts or it may not work. Putting a rare earth magnet on the positive end of the unprotected battery will make it work in most lights without springs for both battery contacts. The Nitecore MH10 v.2 has springs for both contacts for 21700s. It doesn't for the battery magazine for 18650s but still works with unprotected 18650s. The MH10 v.2 also has a battery indicator to test voltage while off and give you an idea of when to change batteries while on. Because of this, it's pretty safe to use unprotected cells in the light as long as you're holding or monitoring it. If you ceiling bounce the light overnight on a high setting and fall asleep, that's when I'd suggest using protected cells.
Lots of lights will work with unprotected cells, you don't need 2 springs. Just the correct length battery tube and contacts. Quite a few lights will not work with longer protected batteries.

It is perfectly safe to use unprotected batteries. And it is pretty easy to visually see when they are low on voltage. Draining them completely might ruin them or reduce their life.

As a rule unprotected cells are a slightly safer chemistry than most protected ones.
 

Hooked on Fenix

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I should add that some lights are sized that they will only accept unprotected cells (Zebralight for example). Many Nitecore lights without springs on both ends will only work on protected cells, or unprotected cells with a magnet on positive end. Yes, many lights will work with unprotected cells without springs on both ends, but don't assume they always will. It's best to research the specific light and if it will work for your needs. As far as safety goes, that isn't something I'd take lightly. I hear about battery explosions all the time. Teslas in Florida exploding, a battery storage facility in Arizona on fire, people's vapes blowing up, etc. It's rare, but it happens. Buy quality cells, use a good charger (doesn't trickle charge when done), and don't subject your batteries to unnecessarily abuse that will short them out.
 

KITROBASKIN

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Is there any flashlight manufacturer that suggests using a magnet on the positive side to get some battery to work? Thinking no. Wondering if somehow the magnet might shift so that contact with the body and the positive of the battery might initiate some kind of florid expression?
 

Hooked on Fenix

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Is there any flashlight manufacturer that suggests using a magnet on the positive side to get some battery to work? Thinking no. Wondering if somehow the magnet might shift so that contact with the body and the positive of the battery might initiate some kind of florid expression?
If you're worried about something like that, use a light where that is not required, use protected cells instead, or carefully solder a blob or spring on the positive terminal of the cell.
 
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