Thanks for Good Advice on batteries and chargers!

[fmerkel]

I don't know about you, but if I'm using a light for something like wreck or cave diving, I want the damn thing to work while I've got it turned on, regardless of it it's going flat. If there's ANYTHING left in the battery, I want the flashlight to turn that voltage it into visible light for me to use, not for some battery PCB (printed circuit board) to decide I'm about to harm the battery, and cut things off.

Functionally that's faulty reasoning, especially while diving. The PCB protection circuit cut-off is generally below 3.0v, somewhere in the 2.5-2.8v region depending on the chip used and quality of the electronics. There is essentially no capacity left in a lithium cell below 3.0v UNLESS the draw is high and the cell is kind of lame so that the protection is activated. In that case it doesn't matter because the light is going out, one way or another, either a PCB cut-off, or simply dying due to lack of capacity. In a very lame light it would slowly dim away. The DIV05 is not a lame light. It pulls some amps. A lame light (low amp draw like early LED lights) last 'forever' anyway, but are pathetic.

Amp draw: 2.3-2.8A (advertised current draw varies depending on site) I measured 2.78A at the tailcap
Burn Time: 1.5 hrs (advertised). 3 hrs with 3400mAh Panasonic (my results)

You need a backup. Cave and wreck diving, 2 backups.

 

[BEVANJ]

I do always carry 3. Primary light, and 2x backup.

My point is that if the **** hits the fan, if there is anything left in that battery, I want it turned into light, even if it only looks like a candle. I'd disagree with you, there is still probably a couple of hundred MAH left in a descent quality cell after 3.0V. I'd much rather be able to get my hands on it if possible, even if it does trash the cell.

 

[fmerkel]

I may have to get me one of those fancy chargers, unless I can find just a meter. I've got two xtar chargers but neither of mine indicate battery capacity. Thanks for the link to that one!

If you are pulling laptop cells, yeah, you ought to get one of those 'fancy chargers'. Liitokala 500 engineer can be had for under $30 pretty easily.

 

[Aanderson81]

Sadly you have to be careful even with name brand cells. I bought a pair of LG cells from amazon (3rd party seller fulfilled by amazon) that just didnt seem quite like the others. They seem to be knock off cells that were rewrapped. I havent been able to test them for capacity yet but had i not had other LG cells I probably wouldn't have known. Its going to become a larger problem before it gets better in the industry.

 

[eelnoraa]

I do always carry 3. Primary light, and 2x backup.

My point is that if the **** hits the fan, if there is anything left in that battery, I want it turned into light, even if it only looks like a candle. I'd disagree with you, there is still probably a couple of hundred MAH left in a descent quality cell after 3.0V. I'd much rather be able to get my hands on it if possible, even if it does trash the cell.

All instruments, lights or what not, should cut off when Li-on reach certain voltage. Most if not all the lights out there already doing it whether you want it or now. This is because keep draining a relatively high load on Li-on cell will generate heat and fire. Fire from Li-on, even water can't put off. Contrary to what public believes, Li-ON gets more dangerous when over drain than over charge.

 

[BEVANJ]

Eelnoraa, I'm very aware of the fire risk, and what lithium does when mixed with water - I used to fly tons of R/C models when I was younger.

Using quality 18650 cells that are rated with a descent discharge current, running them completely flat in a 1A to 2A dive light is not going to cause the cell to leak or explode - it'll simply tail away to 0v. Cheap and nasty cells, different story...

Prime example, and with a dead short...

It all depends on the quality of the cells, and I guess the big message to get across is don't buy nasty fake cells.

 

[kelemvor]

If you are pulling laptop cells, yeah, you ought to get one of those 'fancy chargers'. Liitokala 500 engineer can be had for under $30 pretty easily.

Thanks! I ordered one.

 

[kelemvor]

Charger arrived today! I guess now I'll find out what's what with my stockpile of reclaimed cells. I also have a couple "UltraFire" cells that came with a gift from a friend.

 

[fmerkel]

Charger arrived today! I guess now I'll find out what's what with my stockpile of reclaimed cells. I also have a couple "UltraFire" cells that came with a gift from a friend.

You'll like it. Look at the specs. Discharge amps depend on the charge amps setting. For 18650 I use 500-1A minimum. [Normal] is more accurate than [Fast].
If you are loading it up for 4xcell and max charge-discharge it is useful to put a small fan on it or at least set it on some kind of platform allowing good air circulation. Discharge is via resistors > produces heat.

 

[joe10540]

I had the great displeasure of buying fake 18650's when I got them they weren't even half the weight of my ultrafires so I cut one open and it had about one third full of battery goo and the end was connected with a wire. I still use them even though the test out at 400-600MAH and my ultrafires test between 600-1000. Just purchased two lights and was able to get four hours of burn time on low with the ultrafires and two hours on high and I was happy with that from a $40 light.

Then I ordered some legitimate 18650s that were guaranteed to test over their 3000MAH rating. True to their word they all test around 3100 so I tried a burn test on high thinking it was two hours with the best batteries I had before so I'd be thrilled if I got four hours. Well that light burned for 6+ hours on high! By my math that's 12 hours of burn time on low. All that improvement for less than $30 worth of batteries. I've learned that the weight of the batteries is a good indicator of quality but more important is finding a seller that backs them up and will replace them if they test lower than what they are rated at.