1 minute review of the Kaidomain L-ion D cell

[cfromc]

Just to say up front; I don't have any output or run-time charts. It will take me longer to write this than the time I spent with the cells. But for some initial impressions:

I got 2 D cells from Kaidomain. After waiting the requisite 2 weeks or so for the cells I finally got them and immediately looked them over. They look decent from the outsite, the plastic covering is uniform, the positive terminal is ever so slightly raised and looks thick. The cells came in charged to around 3.78V. They took approximately 6 hours to charge on my Ultrafire WF-139, which is 2+ hours longer than my LG 2400s take when they are starting at 3.5-36V. I could see an 8 hour charge time after these Ds get down to 3.6V.

After a charge to 4.2V I let the cells rest for a few minutes and then put them in my 2D ROP-Hi and.....nothing. I opened the tailcap and pushed on the cells and there was no movement. I took the cells out and added a magnet to the positive end. Put them back in and...WOW. My dual integrating ocular spheres indicate that there is a noticable difference in output over the 18650s. I took the ROP outside to verify the increased output. I am unsure if there is any more throw yet beause of this limited test, but the trees in the distrance definitely were brighter than with the 2400s.

I expected the light to be brighter due to a decreased voltage sag from the D cells but I am just happy that the difference was so obvious. I'm going to have more run-time and increased output. The downside is increased charging time (with my charger). Bulb life may be reduced but I did not have an instaflash, even though I only rested the cells for a few minutes. A possible downside is that there is twice as much energy in these cells and that would mean twice as much power if the cell disassembles itself, but I mitigate that risk by being a little anal and checking the voltage of the batteries between uses and checking the voltage periodically throughout the charge cycle.

Overall, especially for the price, I'd say :thumbsup:

 

[DM51]

It would be interesting to know the run-time you are getting, after you've done a full discharge. If they are 5 Ah cells, you should get just about 2x as long as your 2400 mAh 18650s.

 

[barkingmad]

They are about 4500mah capacity even under quite high load...

 

[cfromc]

I will be happy with 1 hour runtime, which is about double what the 18650s were doing.

 

[VidPro]

myself i would be more interested in a 2 month or 1 year review
so i can tell if its the same junk we got before

also insert disclaimer about how rediculously stupid it is to put these in a incadescent hotwire, untill they have a protection curcuit on them.
you do what you want , assuming you know what your doing, but fact is without protection an incan has the chance of making them dead and also possibly dangerous, so that has to be noted. also some D cells are not to be charged to the full 4.2v. so you know what your doing, but others reading this might get bad ideas, and make errors.

 

[cfromc]

myself i would be more interested in a 2 month or 1 year review
so i can tell if its the same junk we got before

also insert disclaimer about how rediculously stupid it is to put these in a incadescent hotwire, untill they have a protection curcuit on them.
you do what you want , assuming you know what your doing, but fact is without protection an incan has the chance of making them dead and also possibly dangerous, so that has to be noted. also some D cells are not to be charged to the full 4.2v. so you know what your doing, but others reading this might get bad ideas, and make errors.

Thank you for your kind words VidPro. I should have noted in the initial post that I am ridiculously stupid...sorrrrry. The post was labelled as a review, not a recommendation. Perhaps this direct quote from the initial post will set your mind at ease just a little tiny bit:

"A possible downside is that there is twice as much energy in these cells and that would mean twice as much power if the cell disassembles itself, but I mitigate that risk by being a little anal and checking the voltage of the batteries between uses and checking the voltage periodically throughout the charge cycle."

Your note about not all (L-ion) D cells should be charged to 4.2V has me guessing which ones don't? I wasn't aware that there were others on the market currenty. I know there is a thread about some that have a nominal voltage of 3.55V, but I didn't know those were available yet. I would have to imagine that if someone was to spend ~$40-50 each for a cell, they would have some idea on how to use them, but of course, I am assuming at that point, so you are correct that my lack of "warning" about charging cells to 4.2V is a dangerous omission.

P.S. I'd rather use unprotected L-ion cells to run a hotwire than use PRC Battery Station CR123a to run anything.

 

[VidPro]

i didnt say YOU were stupid for doing it, i was saying a disclaimer might indicate that, so people dont damage the cell. and they will i assure you.
there is a vast quantity of people, just like myself that will try anything that was just put in a REVIEW. and in less time than it takes to start the newspaper on fire with thier new toy, they will end up with a ruined cell.
there is about 100 readers to each written hunk of materials on a forum, that is 100 people who will think they can do it too, that means some percentage of them well , , , you know if you had put it in the review section, i would still put in a disclaimer, unprotected cells are supposed to be for packmakers who will put protection on them, its in the li-ion book :-o

i donno about the voltage, i have a SPEC sheet for the SAFT one i bought, says MAX 4.1, also says it on the cell itself.
but i cant get a spec sheet for the cheap ones, they do not act the same way at all. i have treated mine to only the 4.1 and they still became weak, and higher in self discharge, and "flakey" just like a lot of the ultrafire and such type cells.

D lithiums have existed for about 4-5 years now, but they were not on the market indeed, about 8-12 months ago some exactally like this came out, then there was safety ummm things, and they went away. i managed to get only a few. they arent available now :-( perobably because people didnt put protection on them, and used them in incadescents in series , , , and didnt know the ramifications of doing that.

i would be totally tempted to try the Kai ones, and see what kinda quality they have going, but its that burn me once thing.
the saft cells which can start a fire with a 1C charge (according to ONE user) have worked great now for years, without any signs of acting flakey.

 

[cfromc]

I've been waiting for some good D cells to come along but have been disappointed each time as nothing has come to fruition. The ones that seem promising are very expensive, but still never seem to materialize. Kai is working on a protection circuit D size cell and AW may or may not have something in the future. I felt that my LG 18650s worked but were at their limits pushing 4.0A. These cells may actually be safer for me because they will be running closer to .9C rather than at 2C. Time will tell. I would consider recharging and constant high-rate discharging to be the most dangerous times when using l-ion cells. At both times I "think" that these cells are much farther away from their limits than the 18650s. When charging the cells for the first time they felt cold, which means they were probably just at room temperature.

Ideally, a protected, 5000mAh or more D cell, at a reasonable cost, would be the way to go. I'm not too excited about spending $50 each though. I'm guessing that Kai's will be closer to $20. I am glad that Kai is asking people on the forums for good parameters of the protection circuit. Perhaps we will have a good alternative. I'm not so happy that I had already ordered these before I heard that Kai may have some protected ones, but oh well. Such is life.

Someday we will have high capacity, high output, protected cells that don't cost and arm and a leg.

 

[jimjones3630]

In your analysis of these D size cells have compared or think comparible to A123s or Emolis? Both size wise are 27mm diameter comparibale to C size 25mm. Length 67mm, 70mm respectively 2 of either will fit in 2 D size mag. Capacity 2200mah, 26700mah are less than D cells, but comparied to some of the overseas D size with measured 3000mah capacity are on par, and have flat discharge rate. I like them and have converted most of my lights over, just never liked lossing brightness with other cells when they get 50% used.

http://www.candlepowerforums.com/vb/showthread.php?t=177108