High Capacity NiMH D batteries

[txwest]

I had seen them mentioned here, but never noticed if anyone has done a run test. I bought (3) 9000mAh D batteries from C.Crane to go with my DD Triple Blaster Wayne is supposed to be sending me. He said at 4.5V he had measured one of his pulling 1.7 amps. I'm guessing that at 3.6V it will pull around 1.2, so I'm running a test right now with my 3D Mag & Mag-Star lamp, which I believe is 1.2 amp draw. For some reason, the package this bulb came in says not to use rechargeable batteries. Anyone know why?

Last night I ran it nonstop for 4.5 hrs. Didn't check the batteries then, because it was 11:30. I tested them with the C.Crane charger when I got home this afternoon, & was supprised at the outcome. The C.Crane charger tends to be conservative on the "power level" of the batteries when you test them. I can take a C battery I know is less than 1/2 "used" & the charger will show no bars of "power" left. So after 4 1/2 hrs on this load, I expected the "bar" level to be showing low. To my supprise, the power level was showing the max of 5 bars on all 3 batteries, & all showed 1.3V. I turned the light back on at 5:00 & it is almost 9:00 now. No noticeable change in the light output. If anyone else has experience with hi-cap D's, let me know. TX

 

[lemlux]

txwest:

I've never read that a Mag labeled bulb was rated better than a Carley Krypton Star or Xenon Star. As all Krypton Stars for alkalines are rated for 0.7 A (other than the 0.8 A 2-cell) I suspect your bulbs are 0.7 A.

If Mag does offer a new line of premium bulbs as they today suggested, I doubt if they'll break tradition and inscribe any specs on the bulb beyond the number of cells to use.

Nonetheless, your charge life preliminary data is still very encouraging.

 

[Saaby]

Ok couple things...

Disclaimer: The following statements refer to NiMh batteries, which I assume you are using.

Why they say don't use rechargables on things has always perplexed me too. Some people claim that it's because if their slightly lower voltage...maybe, I use them anyway, I use them in everything BUT flashlights.

Why don't I use them in flashlights? Because it's bad to discharge them very deeply and flashlights, esp. LED lites, are quite efficient at that.

Part of the meter mystery may have to due with the fact that NiMh tend to be, er shall be say, eratic for their first few cycles.

Now, want to give us more details on this charger? I like my current charger plenty but it only does AA and AAA.

 

[txwest]

Ryan,
Try this link. Most of the people here are farmilar with the C.Crane charger. http://www.ccrane.com/quick_charger.asp

lemlux,
I was under the impression the Mag-Star was the Carley Krypton Star. May be totally wrong. If I don't know the bulb amperage, I'm hot sure what I'm finding out here. Oh well, I need to run down the batteries for another charge, as this is their 1st use from there 1st charge. That's another reason I'm supprised they're lasting so long.
TX

 

[Saaby]

Thanks!

 

[lemlux]

Txwest:

I think the MagStars are made by Carley, and they have the same shape. They may or may not have the same gas pressure or brightness.

Carley seeks to differentiate their brand name Krypton Stars by claiming that a higher level of precision in either production or inspection is used to reduce ugly beam distortions caused by filament alignment. Maybe MagStars are Krypton Star seconds??

In any event, 0.7 A is a good bet. (edit) a good bet as to the amperage of the Mag Stars.

 

[txwest]

If it were a Krypton Star "2nd", wouldn't it be the same amperage? I'm just surprised, as the 2 for $1.50 Ray-O-Vac's are .75amp. I would figure this Hi-Dollar lamp would be more. TX

 

[txwest]

Update on battery test:

We now have 10 hrs burn time on the batteries. 2 of them have (1) power bar, 1 has none. All are over 1.2V. Putting them back in the light, it seems about as bright as it was 9 hrs ago. I'll probably get 1 more hr tonight, then have to continue tomorrow evening. TX

 

[lemlux]

Txwest:

Yes, it would be the same amperage which, as II could have stated more clearly, is 0.7 A. (I just edited for clarity) The Mag Star and the Krypton Star each have lens tips that tend to partially counteract the Mag black hole in flood focuses. I also suspect that the Mag Star and Krypton Stars may be more pressurized than the Ray-o-Vac.

I'm not real familiar with these alkaline lamps, however, as I use the higher amperage Krypton Stars for rechargeables.

For example a 3.7 V 0.7 A Krypton Star puts out 2.7 CP or 33 Lumens while a 3.7 V 1.7 A Krypton Star puts out 7.5 C or 93 Lumens. As soon as Lampgirl24 gives me the cost of potting higher amperage bulbs in PR bases I expect to run a Carley #1122 3.5 V 2.3 A T-1 1/2 Halogen bulb rated at 11 CP or 136 Lumens in my Mag 3C and at least one of my Mag 3D's. I also expect to run a 4.8V 1.6A Xenon #807 bulb potted into a PR base that generates 13.4 CP or 166 Lumens in my Mag 4C.

These are the type of bulbs that will make your considerable investment in 9000 mAh NiMH's really pay off. I still have a total of 14 4500 mAh and 5000 mAh NiCAD D cells that I move between Mags and a UKE 1200. They are several years old, but work well enough that I haven't succombed to the desire to buy high capacity NiMH D's. It is a PITA to run these NiCADs through a discharge cycle before recharging, however.

 

[**DONOTDELETE**]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Saaby:
Why they say don't use rechargables on things has always perplexed me too. Some people claim that it's because if their slightly lower voltage...maybe, I use them anyway, I use them in everything BUT flashlights.

Why don't I use them in flashlights? Because it's bad to discharge them very deeply and flashlights, esp. LED lites, are quite efficient at that.<HR></BLOCKQUOTE>

I think thats a common misconception. I'm pretty sure that NiMHs and NiCDs cells aren't affected by deep discharges. Only SLA batteries shouldn't be discharged.

As for why people don't recommend rechargables... I say its a conspiracy to buy more disposables.

The voltage isn't a problem since most alkalines drop below 1.5V very quickly while NiMHs stay around 1.25V

I use 2x AA NiMHs in a cheap Eveready Rubber torch with its original bulb and it is actually brighter with rechargables. While its nowhere near as bright as the Scorpion, its infinitely cheaper to run!

 

[Jonathan]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Someguy:
I think thats a common misconception. I'm pretty sure that NiMHs and NiCDs cells aren't affected by deep discharges. Only SLA batteries shouldn't be discharged.<HR></BLOCKQUOTE>

NiMH and NiCd _cells_ are not particularly damaged by deep discharge. But a battery is a string of cells in series, and bad things can happen if you try to deep discharge a battery. Since each cell is slightly different (different capacity, different self discharge rate, etc.) it is quite likely that one cell will discharge before the others. When this happens, the other cells can continue pushing current through the circuit, and _reverse charge_ the cell that discharged first.

Reverse charging NiCd and NiMH cells kills them quickly.


<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>The voltage isn't a problem since most alkalines drop below 1.5V very quickly while NiMHs stay around 1.25V<HR></BLOCKQUOTE>

Some flashlights depend upon this voltage drop, and since NiMH cells have lower resistance than the nominally higher voltage alkaline cells, it is even possible that NiMH cells will result in running the lamp at too high a voltage.

-Jon

 

[Ron Schroeder]

Hi,

A simple single cell discharger for nicads or N-MH is a resistor in series with a silicon diode. The diode will prevent the cell from discharging much below .7 volts. A good resistor value would be 1 to 5 ohms.

Cheap and dirty but it works and will not over-discharge the cells if you forget to disconnect them.

 

[Saaby]

How big a problem is overcharge anyway? I had a charger, which will remain nameless here but I'll give you 2 guesses as to which one it is, where the charging got momentarily interupted and confused the charger. Charged my AAs for around 9 hours (overnight...I went to bed) instead of 3! Stuff I've read seems to indicate that overcharge once can heal itself but if you do it over and over you'll fry 'em. What is the current wisdom here?

 

[Al]

I have run NiCd's & NimH's AA's, C's, D's for years in both low & hi drain devices. I prefer NimH's especially in flashlights and digital cameras regardless of "shelflife". Being aware of the limitations and managing the batteries with a good intelligent charger precludes any problems for me.

As for deep discharge, I usually force the NiCd's down to 0.5V before recharge. The NimH's are conditioned occasionally when I get the urge. I have one set of four NiCd AA's which are used in a small portable radio. Life span at this point: approx. 8 years. Radio isn't used much, so recharge is about once/month.

Whatever works ...

 

[txwest]

OK,
Continueing the test. 1st night was 4.5 hrs. 2nd night, 6.5 hrs. Checked the batteries again. I have 1 with no bars & 1.22V. The other 2 were 1 bar & 1.24V. Light may be a little dimmer, it's hard to tell as it won't be dark here for several more hrs. TX

 

[txwest]

1 hour & 20 min more. The light finally went dim. Checked the batteries as soon as they came out of the light. 2 batteries were just under a volt, one was down to nearly 0. That happened on a test I did on some C cells. One took a dive before the others. After setting for 30 min, they are all over 1V now.

So what did we accomplish? (3) 9000 mAh batteries ($10 ea, shipped), brand new, 1st charge. Put on a load we think is .7A, ran with good light for 12 hours. I'm pleased. The should do well in my DD 3 Blaster. TX

 

[lemlux]

Impressive first charge result.

Be careful about voltage reversal on your weakest cell. When multi-cell NiMH's dim appreciably it's prudent to recharge.

 

[txwest]

In real life, I'll be useing them in my DD 3 Blaster, probably less then 2-3 hrs, & will probably top off charge before useing. TX