Probably the wrong area to ask this question but I need to buy a couple 18650 rechargeable batteries for my flashlights. Looked on eBay and I didn’t recognize any of the brands on there. Anyone here recommend a good brand and maybe where to find them.
Thanks in advance!

Maybe put this in the Lounge? You'll probably get more help, there.

What flashlights?

Try www.allbattery.com or www.batteryjunction.com

plenty of 18650 batteries to choose from. button top or flat top, different mah ratings.

Does your flashlight require protected cells? Probably a worthwhile purchase. It only costs a little more.

Fenix brand but looking at a couple streamlights that use the same battery

I have used trustfire 3000mAh for several years in a fenix light, no complaints have worked great.

 
Just make sure you get protected cells (they have a circuit added to protect against overheating and catching on fire).
 
Pila makes a nice charger.
 

 

illumn.com has a good reputation.

Get Japanese or Korean cells - Sanyo, Sony, Samsung, and Panasonic. Avoid Chinese made batteries. Batteries with "fire" in the name are a warning of the batteries' eventual fate.

Some rebranders use good batteries. I'd trust Fenix, but they are expensive. Olight are fine. Others are too, but check and see whose battery is actually in there.

Don't cheap out on lithium batteries. The bad ones can be dangerous. They can overheat, discharge gas and explode. Or catch fire. Or both. Spend an extra few bucks.

Most devices have enough space that you can use a protected cell (there is a tiny overload circuit attached to the battery), but some devices cannot and rely on a protection circuit in the device. Usually, if an unprotected cell is needed, they will tell you. Most devices will have a protection circuit internally, so a protected cell is belt and suspenders.

I've a pair of Tenergy 18650s I've been using in one of my lights for a couple years.

Hard to say how many times they'll cycle. They last so long for me I only swap 'em about every two years

I just stocked-up on three sets of four AW 16340s (CR123-sized IMR chemistry) for my wireless IP cameras. AW has a really good reputation. Might be hard to find, right now, though.

Nitecore hits the price and performance sweet spot for me. And they make a variety of smart chargers.

^^^ NiteCore here... they have some very nice offerings (flashlights, batteries and chargers).

I have 4 AWs and 2 Fenix. All have been great. I've been using some of the AWs for 6 or 7 years and they still hold a good charge.

I also have a Pila charger.

They sure have gone up in price over the last few years.

Panasonic NCR18650PF High Drain Rechargeable Li-Ion Battery - 2900mAh or
Sony 18650 VTC5 High-drain - 12C 30A Li-Ion Battery - 2600mAh

Both are very good. Can be had in different capacities.
For a flashlight, I recommend getting protected cells (so you don't completely drain them).

I use 2600 mAh Tenergy ones. Cheap and effective. I use the crap out of them, some fail, some last years, under less harsh conditions I'd expect them to last 4-5 years, I usually get 2-3 years.