Anyone use NiMH D cells, and any good LSD brands of C and D cells?

[the86d]

I got some LED upgrade for the lady's Navy issued "Moonbeam" (Fulton "U.S." "MX-991/U") and ordered one of my own (as I cannot find my USMC issue) and her D batts are dated '15 for good until. I have plenty of other lights and such for power outages, and dark garage corner use, but wanted to tinker with some "upgrading some oldies to new tech".

This got me thinking I have not seen many D or C cell flashlights(, as I am not one of the MagLite fanboiz), and there are plenty of other options.

1) Do you use C or D cell NiMH batts, and chargers, or stick with AA/AAA LSD NiMH with adapters?

2) Any "makes" of good LSD C and D NiMH batts and chargers (non-AA/AAA adapter )?

Please advise.

[sonofeugene]

You'd have to have an adapter custom made, but I'd convert it to a single 18650 lithium ion battery. Then get rid of the crappy incandescent bulb and replace it with an LED bulb. You'll still have a crappy reflector but it would still be far better than what you have. Perhaps one of these upgrades would fit:

http://lightstarproducts.com/products/led-conversion-kits/

That said, I'd not modify it and keep it as a curiosity and momento. Be sure to store it without batteries in it. Then get one of these:

https://www.fenixlighting.com/product/mc11-fenix-flashlight/

And even better, get this:

https://www.fenixlighting.com/product/fenix-hp25r-rechargeable-headlamp/

I just got one and I've never been more impressed with a headlamp.

[the86d]

You'd have to have an adapter custom made, but I'd convert it to a single 18650 lithium ion battery. Then get rid of the crappy incandescent bulb and replace it with an LED bulb. You'll still have a crappy reflector but it would still be far better than what you have. Perhaps one of these upgrades would fit:...

That said, I'd not modify it and keep it as a curiosity and momento. Be sure to store it without batteries in it. Then get one of these: ...

And even better, get this:...
I just got one and I've never been more impressed with a headlamp.

Headlamps sure are handy, especially when you come home to a busted water-pipe, and the sun is going down by the time you get back from the hardware store after work.

I am not sure I'd go with a $23.99 LED upgrade bulb @ 50-300 lumen, when a you can get that or better from a $1.39-$4 bulb, straight 'outa Chino.

I'll probably get a gen'u'ine Sidewinder sometime this year, just to have, but I am thinking I can make some emergency lights with pretty-high output of a Joule Thief variety(/varient).
Tinkering will tell.

Per some research I was doing, I was really thinking I want some NiMH C or D cells, as the power would last a longer time:

...but with that, you are right about 18650's, as they can store about 2000-3000mAH ea, which would probably be a better option, even in a conversion (w/ maybe a resistor).

I've got enough 18650 lights, I buy at least one/year, but my questions were really regarding (which is why I numbered them):

1) Do you use C or D cell NiMH batts, and chargers, or stick with AA/AAA LSD NiMH with adapters?

2) Any "makes" of good LSD C and D NiMH batts and chargers (non-AA/AAA adapter )?

[gorn5150]

I use the adapters for my C and D battery lights. If you go that way make sure to get the adapters that hold two AA batteries each. It makes a huge difference. These are the ones I use for D. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[the86d]

I use the adapters for my C and D battery lights. If you go that way make sure to get the adapters that hold two AA batteries each. It makes a huge difference. These are the ones I use for D. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I came across this regarding upgrading these to protected Lithium Ion batts with those same same adapters (and they are cheaper from eBay @$0.80 ea):

https://youtu.be/lweb4Z0IBEc

[the86d]

I use the 3xAA for D cell adapters.

4 x Parallel AA Battery Adapters Switcher Cell 1.5V AA To D Size Convertor White

https://www.ebay.com/itm/162276781890

...

That's a pretty good deal considering the lowest I can find those is about $1/ea.

This give me an idea...
Use an adapter/dummy cell and drop a Lithium Ion protection board into it, and run an adapter with say a set of unprotected (cheaper) 14500's in the other (the ones Gorn posted).
(Yes there are risks with running Lithium Ions in parallel (or even LiFePO*'s in series), but... eCig users like myself have been doing it for YEARS, they tend to equalize voltage, if they start right off the charger together.)

I have also used the cheapie 3xAAA adapters that come with most run of the mill (OTC at every retail store's front-counter) LED aluminum flashlights with a Tenergy 3v RCR123A (which I have a good QTY of, and don't use in my eCig mods [Prodigy v2 and v3] any more), and they run these aluminum flashlight pretty-well under-running at just over 3v on a full charge, lower than the 3xAAA or 3x1.61(new 1.5v batts)=4.61v.

Time for some tinkering.

HOWEVER, QUESTION:
Would the switch on just about any 3v (1.5vx2) flashlight's switch's lifespan take issue with about 6v (2x LiFePO[4])?
These are the way most of these Tenergy LiFePO4 batts were run in the Prodigy series of eCigs for many years (before China regulated mods took over), but the switch was beefy brass rings, as I recall.

[gorn5150]

I use the 3xAA for D cell adapters.

4 x Parallel AA Battery Adapters Switcher Cell 1.5V AA To D Size Convertor White

https://www.ebay.com/itm/162276781890

When those $15 off $75 or $10 off $50 eBay coupons come around I buy cheap junk like this as filler items to get to the coupon required min purchase. But it takes a long time to show up from China.

Thanks for posting this. I didn't know they made these. I will be getting some.

[gorn5150]

HOWEVER, QUESTION:
Would the switch on just about any 3v (1.5vx2) flashlight's switch's lifespan take issue with about 6v (2x LiFePO[4])?

There shouldn't be any problem running a 3v switch on 6v. If I remember the specs from my high school electronics class back in the early 70's a 3v switch should not have any problems up to 24v if not 120v or so.

[the86d]

Since there were really no responses regarding C and D cell batts. I think I am going to try some Amazon Basic, as they were one of the top brands to buy via recommendations of people on here on Calguns, other than Eneloops.

In another thread La Crosse, eneloop, and EBL were all highly recommended, so I am sitting here wondering if those are China rebrands of China-makes...

Other than what I mentioned, what are the good names in chargers, as I cannot seem to find Amazon-branded C and D cell chargers?

Any brands to stay away from?

[the86d]

Kids toys, remotes, and such you just can't convert to 18650's.

I have been looking on Amazon, and it seems that Ansmann seems to be a good brand, but are these just a rebranded China brand?

Any good China Brands, like the good luck I have had with Anker is for USB?

(I would like to stop paying for 9v batteries in my smoke detectors, so I am really looking for one that does those too, even if I have to change the batts more often, so I am limited in choices.)

[gorn5150]

La Crosse chargers are highly rated. I have a couple of them and they do a good job.

[67Cuda]

C & D batteries are fading away. Flashlights have gotten more efficient, brighter, and smaller, hence AA & AAA batteries.
Any C & D flashlights I have has been sidelined because I don't want to purchase the batteries for them, which are the only things left using them.
What are the things people use the larger batteries for nowadays?

[Dubious_Beans]

I like stuff that takes C's & D's.

An alkaline D cell costs about twice as much as a AA but contains about 5 times as much energy. They are a much better value.

[Dubious_Beans]

This got me thinking I have not seen many D or C cell flashlights(, as I am not one of the MagLite fanboiz), and there are plenty of other options.

1) Do you use C or D cell NiMH batts, and chargers, or stick with AA/AAA LSD NiMH with adapters?

2) Any "makes" of good LSD C and D NiMH batts and chargers (non-AA/AAA adapter )?

Please advise.

I have designed and built NiMH chargers and have spent many dozens of hours reading battery manufacturer data sheets and application notes so I'll give an opinion on why C & D cell NiMH batteries are not very common or popular.

In a nutshell: C & D batteries tend to be quite hard to charge correctly to get good service life.

NiMH batteries are a little difficult to determine when they are fully charged without overcharging, and cells that get overcharged have poor life span.
Lithium batteries (and lead acids) have a voltage curve that rises as they charge and when they get up to a certain voltage you stop charging. Easy peasy!

With NiMH batteries the voltage rises as they charge, but when they are fully charged the voltage actually DECREASES very slightly and then rises again as the cell overcharges. The actual cell voltage during charging depends on the charge rate, the type and age of the cell, temperature, and a bunch of other factors so you can't just look at the terminal voltage and know when to stop. You have to look for that slight voltage dip when they get fully charged.

NiMH chargers typically use one (or more) of 3 methods to terminate charging.

1) Watch the voltage and look for the voltage dip.
The catch here is that they need to charge fairly fast for the dip to be noticeable enough to see.
0.5C to 1C is usually ideal, so for a cell rated at 2000mA/hr, you need to charge between 1000mA and 2000mA.
If you charge them slower the voltage dip won't be noticeable so the charger will never stop and will overcharge the cell.

2) Watch the cell temperature.
When charging, most of the energy is used in the chemical reaction of charging and very little energy is wasted as heat. Once the cell is fully charged then that energy is no longer used up doing the chemical dance and then it IS wasted as heat.
So you look for a sudden increase in temperature rise and terminate charging when the rise becomes aprox 2 degrees C per minute. Note that you aren't looking for a specific temperature, it's the *rate of rise* you are watching for.
Again, this only works well when the charge rate is fairly high... 0.5C to 1C. And it also requires a temperature probe in contact with the cell.

3) Time.
Cheap chargers just charge at a very slow rate and terminate charging after a certain amount of time. They rely on a very slow charge rate to avoid overheating the cell, but it is a crappy way to do it and usually (almost always) results in a certain amount of overcharge which can greatly reduce cell life.


A really good charger will use all 3 methods.
Watching for the temperature rise is most accurate and if done correctly results in very little overcharge.
Watching for cell voltage dip is good too, but the voltage dip occurs slightly after the temperature rise (it's actually caused by the temperature rise) and may result in slight overcharging.
A timer is used as a last resort fail safe so if you miss both the temperature rise and the voltage dip they don't just sit there and cook all day.

The problem with C & D cells is their volume to surface area ratio.
If you charge them at the correct 0.5C to 1C rate to detect the temperature rise or voltage dip then they get really hot inside because there isn't enough surface area to dissipate the heat and the center of the battery overheats before the outside gets hot enough to detect the temperature rise.
A D-cell rated at 8000mA/hr needs between 4 and 8 amps of current to charge and that makes a lot of heat to dissipate!
You can use reduced charge rates to eliminate the heat build up, but then you can't reliably detect when they are fully charged using voltage or temperature so you have to rely on the timer method which is way less than ideal and life span is greatly reduced.

If you don't mind rather short service life and can tolerate slow charge rates, C's & D's are fine. If you want fast charge rates and/or long service life then AA & AAA are much better.

The chargers I designed (for AA/AAA) use all 3 methods. They watch cell temperature and voltage and also have a timer as a last resort fail safe. It's complex and costly but can fully charge a dead cell in less than 90 minutes (60 minutes to 90% charge) with very good service life.

That probably doesn't really answer your question, but may help explain why C & D NiMH aren't more commonly used

Life is full of trade offs...

[the86d]

C & D batteries are fading away. Flashlights have gotten more efficient, brighter, and smaller, hence AA & AAA batteries.
Any C & D flashlights I have has been sidelined because I don't want to purchase the batteries for them, which are the only things left using them.
What are the things people use the larger batteries for nowadays?

I have been doing some Joule Thief tinkering, and the massive capacity of 6000mAH (Wikipedia: C NiMH) to 8000-12000mAH (Wikipedia: D NiMH) compared to AA NiMH @ about 2000mAH, or AAA@about 800mAH is substantial difference. A single cell to light a bank of LEDs with only a single 1.5 cell is really nice to have as a light source. Mind you this is a temp-solution.

In the real world, "replaceable" (non-pouch Lithium) 3000mAH 18650s are still 1/2 the capacity of D cell NiMH it seems, and much higher than that in an 18650 is most likely a lie, unless paying through the nose AND unless you tested real-world capacity yourself. I don't look much for low drain 18650's/26650's, but the dead-notebook-freebies are all about 2000-2500mAH.

I haven't seen many US purchased camping/emergency lanterns that take replaceable 18650s. Modification (to an external power source?) is always an option, but would have to be done ahead of time, before the power goes out. With kids you want something that can light a bathroom (take a shower, or make sure aim stays w/in the porcelain, grab TP, get dressed for school/ready for bed, etc.) which isn't a directional flashlight.

I have an elliptical that uses C batts for it's fancy electronic portion.

The MX-991/U is just one device I would like to use with D cells if power was out for days, like San Diego was.
I'd have to check run-times, but a 8000mAH (Tenergy is what I am looking at) set of D cells, with an LED bulb (again have to test some things that are in the mail) seems like it might be the longest-running flashlight I'd have, w/out having to buy yet another light.

D cells are about the same price as your run-of-the-mill high-drain 18650s, but hold a bunch more.

2 protected 17670's, run in parallel fit in this MX-991/U... hmmm.

Maybe I'll buy the 9v, or 7.5v LED for this, or a dummy D cell to test size constraints with an 18650 shim.

An Opus BT - C3100 V2.2 battery charger/capacity tester is in the cart now, and just paid for a used Ansmann Energy 8...
eBay's scripts on every page are making their site unusable these days.