18500 vs. 17670 major difference?

[cfromc]

The more I learn about L-ion batteries the more I seem to not know. I've heard (read actually) that the 18650s drive lamps harder than some of the other battery options, even though the voltage is the same. I assume this is because the larger battery has more mAh. I recently read a post where I believe mdocod spoke about bulb longevity, and, if I understand correctly, the 18650 will drive certain bulbs harder (specifically, I believe the P91 was mentioned) and therefore reduce the life of the bulb. I am going to go to rechargeable on my C3 and mdocod advised me that the 17500 cells should not be used with the P91 due to the high amperage draw. So either I don't use the P91, or I don't use the 17500. Well, I like having options so I'm thinking about either 2x17670s or 2x18500s. Either way I will need to purchase something besides the batteries: either a A19 type extender or a Leef 2x18500 body. The advantage with the A19 is that its cheaper and can be removed, the advantage with the 2x18500 is that I could still use 3x123s if necessary with no change at all (and basically create a new flashlight if I add a head and tailcap). My question is, does the 18500 drive a bulb harder/less/or the same as the 17670? I believe the 17670 is 1600 mAh while the 18500 is 1500 mAh, so it appears that the 17670 should drive harder, but, I've assumed in the past, and been wrong.

 

[NotRegulated]

Re: 18500 vs. 17670 major difference? (long)

I can't answer your question as the battery differences but it sounds like you want to drive the P91 bulb.

I am currently using three setups for this. 2x17670, 2x18500 and 2x18650. All three work without double clicking. 17500's require double clicking and are not really suited to the P91 but work great with the P90 and other similiar bulbs.

The 18650 gives the most runtime and the 17670 and 18500 give about the same runtime. The P91 drives the 17670's and 18500's harder than the 18650's. In my opinion, the 2x18650 is the best setup of the three. I'm using a LEEF body with Surefire bezel and tailcap for my 18650 and 18500 setups. The 17670's run in a Surefire 9p with an A19 extender.
For bulb choices, when you use the 17670's or 18500's, you are better off with the Lumens Factory H-09 or E-09 bulbs. The E-09 works great in the 2x18650 setup too.

An A19 adaptor for your 9P costs half as much as a new LEEF body but for a few dollars more, you can get say a 2x18500 Leef body and use 18500's or 2 CR123 primaries.

 

[cfromc]

Thanks Notregulated. I'm guessing you are getting about 30 minutes with 2x18650s and a very white beam. Have you been running these set-ups long enough to have gone through any lamps, and if so, does the 18650 set-up burn them up quickly? The reason I think I would like the P91 is because I want a lot of flood for this light.

 

[mdocod]

the P91 is definitely a flood champion of tactical lamps. If you are willing to go with the extended length, and pony up for a leefbody, I highly recommend 2x18650 for the P91, it'll run about 40 minutes, which is amazing for this size and output level.

My question is, does the 18500 drive a bulb harder/less/or the same as the 17670? I believe the 17670 is 1600 mAh while the 18500 is 1500 mAh, so it appears that the 17670 should drive harder, but, I've assumed in the past, and been wrong.

the difference between 18500s and 17670s is going to be almost negligible in actual use, and will vary depending on which brand of cells you compare. Obviously the 2x18500 has that advantage of being a more reasonable body length while still providing enough cell capacity to run a P91 for about 25 minutes safely.

as you are probably learning there are so many options to consider, it's almost mind-boggling. Eventually, you'll probably find yourself owning several configurations to gives a balanced set of options to choose from. I usually keep 2-4 tactical lights on me at any given time with various levels of brightness and runtime to choose from. lol

 

[Steve L]

There are two main differences between a 18650 and 17670 . The first being that a 18650 is 18mm wide and 65 mm long, a 17670 is 17mm wide and 67 mm long. The second difference is the mah rating. They both have the same voltage so think of the mah as how much stored energy the battery has(since there the same voltage). A 2400mah battery is equal to 2.4ah, so if your light draws 1 amp you would get 2.4 hours of runtime. With the 1800mah battery you would get 1.8 hours of runtime. The only other thing would be the discharge rating of the battery, say it's 2C(2 x mah of battery) for the 2400mah battery you would be able to draw 4.8 amps safely, with the 1800mah battery you would only be able to draw 3.6amps safely.