All AAA Batteries Are Not Created Equal

[xrunner]

Replace 3 AAA batteries in a flashlight - simple task? Nope. 

The original AAA batteries were from China, named "Malt Max". Malt Max? Ummm, whatever ...  sounds like some sort of Quick Stop branded beer ...

Replacing with new Duracell AAA, flashlight did not turn on. Thought  - did I put them in backwards? Nope. Checked with DMM - seem good.

Dug back out the weak original batteries from the trash can, put them back in, and presto - flashlight works!

 

Lets compare side-by-side. Ohhhhh, what have we here! As you can see in the close-up, we have a difference in not only positive pole mechanical design, but the overall battery length is not the same (in the close up the other end of the batteries has been set equal).

From what I can tell (I can't get the other part of the flashlight off - yet) The 'Malt Max" batteries work because the positive end fits farther into the assembly due to it's longer positive tip (even though the battery is really shorter - this is compensated for by the spring at the other end). There seems to be some sort of plastic molding down there that only lets the positive pole extend down to the electrical tab.

This what I love about standards - there are so many to choose from. 

[IanB]

From what I can tell (I can't get the other part of the flashlight off - yet) The 'Malt Max" batteries work because the positive end fits farther into the assembly due to it's longer positive tip (even though the battery is really shorter - this is compensated for by the spring at the other end). There seems to be some sort of plastic molding down there that only lets the positive pole extend down to the electrical tab.

This is the reverse polarity protection, designed to protect a device from batteries inserted backwards. Many battery operated devices have this feature. It seems this particular flashlight is not well designed. If you can get the head off, you might be able to file down the plastic ridge a bit to fix the problem.

[IanB]

For a temporary workaround, try getting some "super heavy duty" batteries from a dollar store. They will be designed more like the original batteries you are replacing.

[Seekonk]

Consumer Reports in a test rated COSTCO AAA batteries a best value. I think they are made by Duracell. Side by side they appear to be identical in construction with the little nipple that doesn't make contact with a lot of products.  Worse than that they aren't banded on the positive end, I always get at least one in backwards.

[xrunner]

For a temporary workaround, try getting some "super heavy duty" batteries from a dollar store. They will be designed more like the original batteries you are replacing.

Well I'll have to admit in public that I was not aware that the "super heavy duty" AAA batts were made a little differently (referring to the mechanical design of the positive tip). Thank you. Learn something new every day here! 

Consumer Reports in a test rated COSTCO AAA batteries a best value. I think they are made by Duracell. Side by side they appear to be identical in construction with the little nipple that doesn't make contact with a lot of products.  Worse than that they aren't banded on the positive end, I always get at least one in backwards.

I can't ever remember running into this AAA nipple issue before. You just never know what's around the corner in this hobby. 

[IanB]

My current best buy in alkaline batteries is the Sunbeam brand from Dollar Tree. I have not had a contact problem with the positive button in any devices I own.

[amyk]

For a temporary workaround, try getting some "super heavy duty" batteries from a dollar store. They will be designed more like the original batteries you are replacing.

Well I'll have to admit in public that I was not aware that the "super heavy duty" AAA batts were made a little differently (referring to the mechanical design of the positive tip). Thank you. Learn something new every day here! 

"super heavy duty" is zinc chloride, which has the outer can - and the + terminal is isolated from it. Alkaline is the opposite construction.

According to IEC 60086-2, the positive terminal must be at most 3.8mm in diameter and protrude at least 0.8mm.

[Brumby]

.... and here I was thinking we had a manufacturer allowing for the use of Batteroo sleeves.

[xrunner]

Got the top off the light, and so you can see why one type of battery works and the other doesn't. Never run across this before.

[Tomorokoshi]

The AAA is approximately 40 mm long. It looks like the cheap one is about 2 mm short. This way they get to save about 5% in material cost.

[darko31]

A dab of solder on the positive terminal of the flashlight looks like an okay bodge to me.

[IanB]

Yup. You can also attach a small magnet to the positive button of the battery.

[Quatrerwin]

I found that I've had problems with all Duracell batteries except their 9V for the past few years. They don't seem to make contact in quite a few electronics anymore.

[SingedFingers]

This doesn't surprise me. I have a number of 8xAA holders I use for "extra power supplies". If you put Duracells in and drop the holder a couple of inches they all fly out everywhere. Sometimes it just happens spontanously. GP Ultra/Energizer: no problem like that.

[amyk]

You can measure the height of the positive terminal to see if it's the battery or the device that's not following spec. I'm leaning towards the latter.

[StillTrying]

"A dab of solder on the positive terminal of the flashlight looks like an okay bodge to me."

Yep, that's what I do.
Carefully clean just the very top so that the solder is less tempted to flow down the sides.
If you need to increase the height by more than about 0.5mm it's better to do it with the battery held upside down.

[madires]

Based on IEC-60086-2 the minimum height of the positive "button" is 0.8mm and the maximum diameter is 3.8mm.

[xrunner]

"A dab of solder on the positive terminal of the flashlight looks like an okay bodge to me."

Yep, that's what I do.
Carefully clean just the very top so that the solder is less tempted to flow down the sides.
If you need to increase the height by more than about 0.5mm it's better to do it with the battery held upside down.

Yea I tried that and no sooner did I touch the soldering iron to the metal the plastic underneath separated, couldn't take the littlest amount of heat, very cheap. So, it's basically trashed. No big deal it's a piece of crap anyway. But the battery issue was my main interest, I was under the impression that the case dimensions were set in stone, but I was mistaken. 

[CJay]

From what I can tell (I can't get the other part of the flashlight off - yet) The 'Malt Max" batteries work because the positive end fits farther into the assembly due to it's longer positive tip (even though the battery is really shorter - this is compensated for by the spring at the other end). There seems to be some sort of plastic molding down there that only lets the positive pole extend down to the electrical tab.

This what I love about standards - there are so many to choose from. 

This was and possibly still is a pretty common problem with Duracell, when I was doing domestic good repairs we regularly got battery powered 'stuff' brought to us that didn't work when fitted with Duracell cylindrical cells because the pip on the positive terminal was wider, shorter, had less pronounced sides than other brands.

Fit a different brand, Energiser perhaps and it worked.