NiMH D cells

AirTrainer

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My Tenergy NiMH D cells are nine years old and don't hold a charge anymore. It's time to buy some new ones. Please let me know if one brand is doing a particularly good or bad job with their products. I'd like to avoid buying crappy batteries.

I'm considering buying D-size adapters that would use my AA Eneloops, but I'm a little leery of putting 4 sets of 3 AAs in parallel in my 4D Maglite. I also have some doubts concerning the build quality of the 3AA to D adapters I see offered for sale; are they an electrically-sound choice? I don't know. I'm not sure I would trust those with the Malkoff XM-L drop-in I installed in the light.

If I could find a D-size adapter that puts 2 AA in series, I would probably use it with 3 single AA adaptors just to get the flashlight up to 6 volts.

The one thing I do know is that I'm quite fond of my Maglite.
 

sween1911

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Don't have much in the way of NiMH D-cell wisdom, sorry.

However, just out of curiousity, is the Malkoff module you have the one that's marked "4 NiMH"?
I have that particular one in a Maglite. I asked Gene Malkoff about it and he said it would work great on a single li-ion. I have it running on a single 26650 in a PVC spacer and it works great.
 
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bridgman

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I have been using EBL C and D cells for quite a few years now with good success... don't think I have had any crap out on me yet. I am not using them for very high current loads yet (a couple of amps at most) but that should change when my 6D Mag host arrives.

Before that I was using Powerizer C cells - the last one just stopped taking a charge but IIRC I had several years of use out of them. Don't think they retained charge as well as the EBLs do though.

There are a couple of scary reviews of EBL D's on Amazon that gave me some doubt before re-ordering, but I went ahead and the latest cells seem as good as the older ones so far.

I found similarly bad reviews for all the other major brands - I think the issue is that D cells are too big to do effective functional testing so occasional bad ones probably will slip through, but vendors seem good about replacing bad ones.

I have some Eneloop adapters for C and D. They seem like a great way to keep a light ready for use without having to worry about alkaline leaks, but for anything I expect to use heavily I would still want full size cells, particularly for D lights.

I don't know if lithium AA's (eg Energizer L91) fit into the adapters yet but that's my next experiment for a year-round car/truck emergency light... I figure a 3000 mAH lithium AA is close enough to a 5000 mAH NiMH to make up for the wider temperature range and longer life.

EDIT - I make fairly heavy use of serial AA-to-D adapters but have nagging doubts about leaving a bunch of cells hooked up in parallel for a long time. No good reason - I guess I'm just old enough to believe in the inherent orneriness of anything more complicated than a rock.
 
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alpg88

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Get new Tenergy premiums or centura. regular blue ones are not as good. If you running stock bulb, and the load is less than 1A, pretty much any adapter will handle it, even cheap ones. IF you using a different bulb and running current is 2A or more, you want high quality holders, like five mega holders. or use D cells.
 

AirTrainer

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Don't have much in the way of NiMH D-cell wisdom, sorry.

However, just out of curiousity, is the Malkoff module you have the one that's marked "4 NiMH"?
I have that particular one in a Maglite. I asked Gene Malkoff about it and he said it would work great on a single li-ion. I have it running on a single 26650 in a PVC spacer and it works great.

I haven't pulled the head off of the flashlight since installing the drop-in. The module is marked "Malkoff 3-4D NiMH U.S.A."

As it happens, one of my chargers works with 26650s. Thank you for the idea. I hadn't considered that.
 

idleprocess

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I also have some doubts concerning the build quality of the 3AA to D adapters I see offered for sale; are they an electrically-sound choice?
I've got a bunch of them in the following style, purchased on the 'zon. They've never given me any trouble. The maximum current I've demanded from them is ~2A; seems like they'd be good for more but I can't say for sure.
 

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sween1911

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I haven't pulled the head off of the flashlight since installing the drop-in. The module is marked "Malkoff 3-4D NiMH U.S.A."

As it happens, one of my chargers works with 26650s. Thank you for the idea. I hadn't considered that.
NICE! That's a SWEET module. I bought mine on here from Jay (LiftdT4R). I originally bought it without a clear idea on how I was going to run it! I reached out to Gene Malkoff himself on what kind of batteries would work with it and he mentioned it was designed for 3 or 4 NiMH's or a single Li-Ion. I was golden after that. I had it chugging on a single 18650, then went for the hicap 26650 and it runs great. Plenty bright! Large PVC pipe to center it in the light, and an aluminum rod spacer to take up the extra space.

Details on the layout (this is when I changed from a Terralux to the Malkoff and ran it on a single 18650)
 

AirTrainer

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NICE! That's a SWEET module. I bought mine on here from Jay (LiftdT4R). I originally bought it without a clear idea on how I was going to run it! I reached out to Gene Malkoff himself on what kind of batteries would work with it and he mentioned it was designed for 3 or 4 NiMH's or a single Li-Ion. I was golden after that. I had it chugging on a single 18650, then went for the hicap 26650 and it runs great. Plenty bright! Large PVC pipe to center it in the light, and an aluminum rod spacer to take up the extra space.

Details on the layout (this is when I changed from a Terralux to the Malkoff and ran it on a single 18650)

What are the black pieces that help to center the PVC and the aluminum rod? Were they miscellaneous items you had around that fit the purpose?
 

alpg88

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I've got a bunch of them in the following style, purchased on the 'zon. They've never given me any trouble. The maximum current I've demanded from them is ~2A; seems like they'd be good for more but I can't say for sure.
I had those adapters, they are good for 1A, they will work with 2A as well, but springs will heat up, there are some voltage loses, anything made for consumers with coil springs, especially with thin wire springs is only good for 1-1.5A.
Once i ran 4 nimh AA in a 4aa holder, to power an xml with a 8 amc driver, springs got so hot they melted plastic holder housing, and it was only 2,8A
 

idleprocess

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Once i ran 4 nimh AA in a 4aa holder, to power an xml with a 8 amc driver, springs got so hot they melted plastic holder housing, and it was only 2,8A
I did the same once with an 8xAA flat holder except my error was shorting the output terminals - took all of about one second for the strongest spring against the weakest part of the plastic to melt through. Was a different, weaker, cheaper type of plastic than these holders and as 3x parallel adapters the current through each AA contact will be ⅓ the total, however I will defer to experience.
 
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sween1911

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What are the black pieces that help to center the PVC and the aluminum rod? Were they miscellaneous items you had around that fit the purpose?
Just wraps of electrical tape. Not too high tech. 😁 If you go that route, don't stretch it as it will deform over time (you can kind of notic it on the PVC pipe, it starts to slide over itself). Gorilla tape is a little thicker and doesn't deform as readily.
 
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