357mag1
Enlightened
Just got it. I didn't notice PMs piling up in my inbox. Thanks for the heads up.
Best rechargeable "D" cell
- Thread starter 6thtexas
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Just got it. I didn't notice PMs piling up in my inbox. Thanks for the heads up.
You know, I'm thinking about the LION option. If the TK70 steps down from turbo to high when only 3.8v is available from the batteries, wouldn't a LION step down too soon? If you charge 2 LION 32600 cells to say 4.2v and then use them in the TK70 the TK70 would step down when the LIONs are only what, 70% capacity remaining? Because LION cells are rated at 3.7v.
Did a runtime test of 4 of 8 Tenergys fresh off "soft" "condition" mode from my Maha 808S charger. 1 hour 2 minutes till the light stepped down from turbo to high. You can hear the driver in the light at the end squealing. It sounded like a dive bomb and then went silent haha.
Of the other 4 that were finishing the "soft" "conditioning" mode, 1 battery ended with the other 4 that went into the TK70, but 3 just kept on taking charge from the charger, blinking with the 3 capacitiy indicators on full. After over an hour and a half of continuous blinking, after the last of the other 5 batteries finished, I just took them off the charger. Is that OK? My assumption was that these 3 are crap cells and the charger is having a difficult time distinguishing their final capacity which is why the charger keeps trying to feed them charge till done.
I tested the TK70 in the tub in cool water. The head and heatsink were just a tad warm even under the cool water at 1 hour 2 minutes. But not hot at all.
Of the other 4 that were finishing the "soft" "conditioning" mode, 1 battery ended with the other 4 that went into the TK70, but 3 just kept on taking charge from the charger, blinking with the 3 capacitiy indicators on full. After over an hour and a half of continuous blinking, after the last of the other 5 batteries finished, I just took them off the charger. Is that OK? My assumption was that these 3 are crap cells and the charger is having a difficult time distinguishing their final capacity which is why the charger keeps trying to feed them charge till done.
I tested the TK70 in the tub in cool water. The head and heatsink were just a tad warm even under the cool water at 1 hour 2 minutes. But not hot at all.
357mag1
Enlightened
Voltage in series is additive. Lithiums shouldn't be drained below 3v so even drained they would still have 6v not counting for voltage sag.
357mag1
Enlightened
Actually they were probably your better quality cells as far as capacity is concerned. The first one off conditioning on my Maha 808 is the cell that tested lowest in capacity. The cells that could go over 8000mah took much longer. The reason for this is they take longer to charge and discharge. So contrary to what you thought those are probably your highest capacity cells.
357mag1, please help me understand. So two LION cells at full charge each are 4.2v x 2 = 8.4v. So nominal LION cell voltage is 3.7v x 2 = 7.4v. If each cell was discharged to 3v each (the safe minimum), that's 3v x 2 = 6v. With no battery protection, the TK70 driver would not step down from turbo to high until just 3.8v was available. So it would drain the LION cells down to 1.9v each x 2 = 3.8v.
357mag1
Enlightened
You are correct, if the batteries are not protected it would drain them too low. Once you do that a Lithium cell is questionable at best and can be quite dangerous. In this respect Nimh chemistry is much safer and more rugged.
I think you are correct. That second batch of batteries, the 3 that I took off the charger charging 1.5 hours longer, 1 that finished previously with the rest, lasted 1 hour 10 minutes on turbo in my light. That's pretty darn good! I thought I read somewhere that the TK50 battery tube fits on the TK70 tube. I'll have to confirm it but if so and I can find a distributor that sells the tube only then I'll spring for it. If I can get more runtime with the light and with less squealing at the end of turbo mode (which would scare the fish away maybe?) then I think that's ideal.
357mag1
Enlightened
The AccuEvolution cells which test out between 8500 -8900mah struggle to reach 60 minutes. That higher voltage under load makes a difference, the TK70 on Turbo draws over 1amp more from the AccuEvolution cells due to voltage sag which depletes the cell quicker.
I just tried it and the TK50 battery tube fits. I added the spacer and used 3 D cells to make sure it made proper electrical contact and it does. The TK70 spacer doesn't seat into the TK50 tube deep enough for the O-ring to seal. This applies to the TK70 tailcap as well. The O-ring is still exposed when it is screwed down tight on the TK50 tube. You would need a TK50 tailcap as well or someone to modify the TK70 cap length to fit. Problem is once modified the TK70 tailcap wouldn't make contact on the TK70 tubes.
I'm assuming you intend to use Lithium-Ion cells. Remember two of them are about .8inches longer than two Nimh D cells. You have about an inch of spring to work with in the TK50 tailcap so it could be done. It would be an unbalanced light though, very head heavy and tend to want to tip toward the head unless you placed your hand around the switches.
Not trying to dampen your enthusiasm just bringing to light any potential issues I can foresee. You might as well buy the TK50 outright, it is a great little light.
hank
Flashlight Enthusiast
On conditioning -- I have a Maha C9000 (the AA-size charger).
It has a 2.0A power supply.
I can extend the contacts with clips and wires and magnets to handle these Tenergy D cells.
How do I set it up to condition/break in these cells -- how many can it handle at what charge/discharge settings?
It has a 2.0A power supply.
I can extend the contacts with clips and wires and magnets to handle these Tenergy D cells.
How do I set it up to condition/break in these cells -- how many can it handle at what charge/discharge settings?
hank
Flashlight Enthusiast
On conditioning -- I have a Maha C9000 (the AA-size charger).
It has a 2.0A power supply.
I can extend the contacts with clips and wires and magnets to handle these Tenergy D cells.
How do I set it up to condition/break in these cells -- how many can it handle at what charge/discharge settings?
It has a 2.0A power supply.
I can extend the contacts with clips and wires and magnets to handle these Tenergy D cells.
How do I set it up to condition/break in these cells -- how many can it handle at what charge/discharge settings?
Hmm I need the waterproofness and that's too much modding so I'll stick with the stock tubes. I have a bunch of those 2AA to D cell adapters which have plastic bodies. I would simply cut one in half and then cut it down further, solder 16 gauge copper wire on the inside, and electrical tape it shut. That way I shouldn't have to cut the tailspring and have a perfect "dummy" cell.
I would put the dummy cell as the 1st cell in the 3D tube, so the weight of the LION batteries would be on the handle end helping to balance out the light a bit. My problem is how the heck to LION cells even work then with this light? Unprotected cells will be overdischarged so they don't work. The Novae which are the only protected LION 32650 cells I know of tha tare supposd to be quality, don't work either because their protection circuit kicks in. So what LION cells do I use??
Although they have not arrived in the mail yet, I bought a set of those AAA to AA adapters. I bought a wooden dowel at Home Depot for $1. I will solder 20 gage solid copper wire (plastic sheath like all wire, but the copper is not braided) to the inside postiive and negative ends of the AAA AA adapters. Then I will cut the wooden dowel down to the size of an AAA battery and put it in the adapters to keep tension on soldered ends from being yanked out. I also bought those 2D cell series adapters in Radioshack for $2 each. I will wire them up as individual cells to each AAA AA adapter to put in the C9000.
hank
Flashlight Enthusiast
Sounds good; I was thinking of using alligator clips but the plastic-adapter-and-dowel sounds like a better electrical contact.
I'll get the same stuff and follow along behind. Do you have a notion if you can condition more than one of these D cells at a time, given the 2.0A power supply?
I'll get the same stuff and follow along behind. Do you have a notion if you can condition more than one of these D cells at a time, given the 2.0A power supply?
357mag1
Enlightened
For a spacer I've used copper pipe with a cap on the end the spring pushes on. You could cap both ends I just let the pipe push against the negative end of the battery. Then I used PVC pipe for a sleeve and the copper pipe fit inside of it. You could use aluminum rod and just wrap it with tape to take up the slack inside the PVC pipe.
When performing the test for you on the TK70 I just used a bolt inside PVC with a coin shaped rare earth magnet to get the proper spacing. It wasn't fancy but is solid and quick.
I just tried a runtime with the Novae batteries and the light went dead at 4min 12sec so they difinitely wouldn't do you any good.
My only plan for using the C9000 with my D cells was to do a discharge at 1 amp per cell. 1 amp is the max discharge rate the C9000 will allow. Since I'm essentially discharging batteries wouldn't that use very little power from the outlet? I didn't know the power supply draws a max of 2amps from the outlet. That doesn't make sense though because if you just charge four AA batteries at 1 amp each, that's 4 amps.
357mag1
Enlightened
The C9000 can actually put out 2amps to all 4 cells for a total of 8amps. Multiply 8x1.5volts and you achieve power in watts. In this case 12watts consumed to provide 2amps to all 4 cells. The power supply (wall unit) for the C9000 provides 12v x 2amps for a total of 24watts. Since nothing is perfect the unit may draw 15-16 watts from the wall to power all 4 channels at 2amps.
You are correct that during discharge very little is needed from the power supply. The main limitation is getting rid of the heat as that power from the cell has to go somewhere.
I've done OK with those blue ones from that vendor. Out of the plastic they are really low at .87 to .94, mine have charged up so far. I'm putting them in my lanterns, mag lites and my tent fan. It sure helps the wallet at half the price of my Tenergy Premiums. :thumbsup:
Yea I figure for $50 for 16 cells it's not too bad, even if there are crappy performers there. I have two XML modified Rayovac Sportsman Xtreme lanterns, each takes 3 D cells. So that's 6 of 16. So even if my worst D cells are 7,000 mah that's still enough runtime on high for the whole night. Then I'd save my best performing Tenergys for the TK70 if I were to use it. Which is 4 of 16. What tent fan do you have? I have seen them and was thinking about buying a small but good D cell one, powered by at most 6 D cells which is what I have remaining.
I am having a bit of an issue with the Tenergy Blue D Cells from that ebay seller. My cells also arrived with a very low voltage. all were in the .9 range. When i charge them via the Maha 9000 the cells will never get to 1.47 volts for them to terminate. The voltage just stays at 1.41 and never goes up. I put 12,000mAh into them and it never went past 1.41 volts. They also never got hot.
After the Maha, i i put the cells on my hobby charger and they terminate right away when the peak delta is set to 5mV. They only discharge to about 7,000mAh.
I'll try to exercise them and see if they open up. Anyone else seen this?
Thanks,
JD
After the Maha, i i put the cells on my hobby charger and they terminate right away when the peak delta is set to 5mV. They only discharge to about 7,000mAh.
I'll try to exercise them and see if they open up. Anyone else seen this?Thanks,
JD
