Needing help with 21700 battery choices.
 

5000mh batteries range in price from $7 to $28. What should I look for to power my Lumintop B01 headlight. I’m pretty excited about this. 500 charges should get me 10 years of nightime commutes.

If you visit flashlight sites such as Budget Light Forum you will find recommendations on which batteries get the most positive reviews. Those are all well known brands such as NCR/Panasonic and Samsung. There are lots of sources for these batteries far less expensive than $24. I've compared different 18650 batteries in the same bike headlight. My favorite is NCR/Panasonic 18650B which have an honest 3,400 mAh rating. Some of the cheaper Chinese made batteries with optimistic ratings ran the light one fourth to one half of the time before needing recharge.

Thanks VegasTriker. I asked my question over there. My B01 can take a 21700 but I wonder what the most efficient battery would be. I assume high capacity 5000mAh and low draw 10A?

I never looked at the current drawn by my flashlight or by the bike headlight I used to test a whole bunch of different 18650 batteries. The flashlight has a Cree XML-T6 LED and the headlight seems to be two Cree Q5 LEDs. Even the newer Cree XM-L2 has a maximum drive current of 3000 mA. I'm not into high priced flashlights but do like to use batteries that don't need to be charged frequently. I don't know exactly what current draw constitutes "high drain" but would think that is the case for cordless tools like a drill. Lumitop lists the output for the $40 B01 headlight as 900 lumens which would be consistent with using either a single T-6 or L2 Cree LED. The T-6 tops out at about 950 lumens and the L2 at 1100 lumens. If so, the battery drain should be 3A or less.

Howdy - I can't quite tell from your question how familiar you are with battery terminology. This being the internets, let me chime in with many fancy words that may or may not help anything.
- as previously mentioned, many of the super-cheap Chinese batteries are likely not to meet the amp-hour rating listed on the battery. Or maybe only do so at some very low current draw. .... and I don't think I'm supposed to mention how the Chinese-Communists are persecuting Uyghurs, so I won't even bring it up that really cheap batteries could be made with slave labor. Like Jews in concentration camps in WWII Germany....
-- sticking with the Japanese (Panasonic) or S Koreans (Samsung, LG Chem) is a good way to filter out garbage.
The amp hour rating is exactly what you'd think. If you have a wildly inefficient light drawing 10A, you get 1/2 an hour. Maybe less due to other discharge inefficiencies and heat. Also keep in mind that batteries don't like cold weather, so you'll get shorter run time as the temps drop.

Doing a really quick search, I see you can get Samsung 5000mAh batteries for about $5.
https://www.18650batterystore.com/products/samsung-50e
- there's a spec sheet link that shows max discharge current at 14.7A. I see your light has some kind of turbo mode. Maybe the current demand aligns to that - where the 6min time limit is so nothing burst into flames.

https://lumintop.com/product/b01/
5 hours on high beam - so I'm guessing a 1A draw with a 5Ah battery (= 1000mA draw with a 5000mAh battery)
2A charging current = 5Ah / 2A = 2.5hours to charge your battery to full. Don't know what you're using for charging, but that charge current is up to whatever you plug into. Not up to the battery. So if you have some kind of wall wart, it might show something like:
120V A/C input -- 5V DC output 1800mA (so you'd only be charging at 1.8A or whatever is listed. Do the maths for the time to recharge.)

OK - hopefully the pros who do this for fun will chime in with better info. I'm stuck doing this kind of thing for work, so I feel like I just typed a work email... busmans's holiday.....