So I went to change the battery in a flashlight of the metal duralight variety (metal, can drive a truck over it, etc).  Anyway, I was surprised to see a 2600 mAh fat battery the size of a AA on steroids.  Never seen one before.  Doing  cursory glance on Amazon yields a few rechargeable models and a few 2800mAh that appear to fit, but wonderingif a 2800 will cause any adverse effects.  I don't want a rechargeable because they seem to run around $10 a pop to begin with, and I don't want to have to buy a charger.  Per HD's site, they don't even carry them, it appears,  Any inexpensive ideas?

2 hours ago, AlDente67 said:

Doing  cursory glance on Amazon yields a few rechargeable models and a few 2800mAh that appear to fit, but wonderingif a 2800 will cause any adverse effects. 

It won't cause adverse effects. The important part is the voltage and size. The storage capacity (mAh) will just determine how long it will last. More is better...

The Ah (not Ahhhhh but Amp hours) is the capacity of the "gas tank".  What you have is a3.7V, 18650 battery, (18mmx65mm).  They generally store between 2400 mAh (2.4Ah) to over 3500 mAh (3.5Ah).  More Amp hours is good, bigger gas tank, more range.....

Make sure the battery you get is a "button top", and not a flat top intended to be soldered to a circuit board.. 

17 hours ago, Scorpio64 said:

The Ah (not Ahhhhh but Amp hours) is the capacity of the "gas tank".  What you have is a3.7V, 18650 battery, (18mmx65mm).  They generally store between 2400 mAh (2.4Ah) to over 3500 mAh (3.5Ah).  More Amp hours is good, bigger gas tank, more range.....

Make sure the battery you get is a "button top", and not a flat top intended to be soldered to a circuit board.. 

You don't need a button top. Some flashlights are not sized to accept them. Flat tops will work. However, make sure it has protection circuitry if you don't know that the light does. If that is what you meant, a button top doesn't mean a protected cell, and a flat top doesn't mean an unprotected cell. 

As for the OP, if it's a rechargeable cell, you will only be replacing it with a rechargeable cell, and shipped, lithium ion batteries will only be about 75% charged. The supply chain won't let you treat them like primaries. 

Honestly, I'd post a pic. 

2800mah + aa on steroids sounds like an 18650, but there are lots of Li-ion cell formats. 

I have lights that take 18650 or 17670 batteries, and they have impressive runtimes over 123 based or AA based lights. A decent charger (i have a nitecore i4 4 channel charger iirc) and a couple spare batteries should be under $20-40, depending on how good quality you get.

Take a caliper and measure the diameter of the battery, that is the 18 (mm) in 18650, the 65 is the length, and 0 is apparently that is a cylinder. Don't get a battery larger than what is in the light unless you know it will fit.  I have some 17670 lights which are about .1mm too small to fit an 18650.

I have an EBL smart charger. I have been running rechargeable batteries for two years wont look back. It is nice not to be throwing out alkaline batteries every two weeks. so I always have a set ready to go for my work lights change them out charge them. yours will need 3.7 volt prioritized charger for the 18650 batt if that is what you have.

 

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