Duracell branded flashlights drain when unused

[y_p_w]

I've been looking for replacements for the original AAA cells in a Panny cordless phone system that are worn out. They old, and last just barely long enough on a call with significant hold time.

Last time I looked at IKEA's cells, there were Japanese, but it has been a while so I don't know if that's still the case.

The price of genuine (if true) Eneloop AAA cells from Amazon is just a bit higher, per cell in a multi-pack, but one won't know the whole story until they're delivered.

I also have the old Sanyo set, originally bought for a game console controllers, and not seen a lot of use, but too lazy to test their capacity.

I've got a bunch of the old Sanyos. Some were Costco-exclusive in the blue AA and green AAA. Some in the original white I'd used the blue AAs in a Siemens Gigaset phone. Those have been the only Eneloop (or equivalent) I've ever seen leak. And the leak was pretty mild - just a little bit of white powdery stuff coming out of the + terminal. I don't think that phone necessarily had the best charging system.

I don't know how this is supposed to be specifically for cordless phones. It does say 750 mAh, which is way more than I remember from my parents' Panasonic phones. They still use a couple of the originals, but I gave them two pair of LADDA to put in there for the ones they might leave off the cradle for extended periods. They've been working really well for them in a Panasonic DECT phone.

https://shop.panasonic.com/products/cordless-telephone-aaa-rechargeable-batteries

The originals weren't anything special. NiMH made in China. I grabbed them to use in remotes after installing the LADDA. Looking at them, theirs were made by Yiyang Corun. Rated at 300 mAh, which seems really low. I have a scale and they weighed between 8-9 grams, while the Panasonic/Sanyo/LADDA AAAs also weighted 11-12 grams. I know the accuracy and rounding errors might be a factor, but they're definitely heavier.

 

[y_p_w]

It all depends on the design and execution of the driver. The lower the price, the higher the risk that it might have some abnormal level of parasitic draw, or some other quirky or buggy behavior.

I've never worked on anything that was a specific flashlight design. Our group did make electronics that were expected to be semi-powered so that they could wake up, but not drain heavily if it was battery powered. They key was to not power on the electronics but put it in a deep sleep mode where all clocks were gated off. Some of the electronics I worked on would start up again with a pulse. I just integrated/connected a design from a vendor so I didn't exactly know how it worked. In electronics terms restart would take quite a while (one of my simulations could take a couple of hours to simulate milliseconds), but that time would be imperceptible to a human.

I'm pretty sure some similar electronics is how the better electronics do this. I've got Cateye bike lights which I'm sure have electronic mode selection. I've put a light away for over a year and it still powered on.

Honestly it shouldn't be that expensive to do it right. I'm not an expert on microcontrollers, but it shouldn't take anything more complicated than an 8-bit microcontroller with simple firmware that can shut off almost everything while it goes into a deep sleep mode. Hit the button once and it should restart the controller and power on the light. Then everything is active until it goes back to sleep mode however it's programmed (cycling, holding down the switch, or even a timeout).

I suspect they had some sort of microcontroller do the switching where there was a free-running clock and it was constantly monitoring for the button to be pressed without going into any kind of sleep mode.

 

[PandaBear]

I think it really depends on the electronics. I remember a cheap Kodak digital camera back then will absolutely not use NiMh and will only take either Li-Ion or Alkaline. It seems to me they are cutting the electronics voltage a bit too close to the threshold and just bad engineering. Needless to say this is how Kodak go from an OK company to out of business if that's their attitude in quality and engineering. If I also remember right they also exit the Europe market when the warranty period is mandated to minimum 2 years. Guess they can't even get 2 years out of a camera after cutting so much quality.

I would spend a bit more and buy from a more reputable company (reputation in flash light, not battery).

 

[Carmudgeon]

I've never worked on anything that was a specific flashlight design. Our group did make electronics that were expected to be semi-powered so that they could wake up, but not drain heavily if it was battery powered. They key was to not power on the electronics but put it in a deep sleep mode where all clocks were gated off. Some of the electronics I worked on would start up again with a pulse. I just integrated/connected a design from a vendor so I didn't exactly know how it worked. In electronics terms restart would take quite a while (one of my simulations could take a couple of hours to simulate milliseconds), but that time would be imperceptible to a human.

I'm pretty sure some similar electronics is how the better electronics do this. I've got Cateye bike lights which I'm sure have electronic mode selection. I've put a light away for over a year and it still powered on.

Honestly it shouldn't be that expensive to do it right. I'm not an expert on microcontrollers, but it shouldn't take anything more complicated than an 8-bit microcontroller with simple firmware that can shut off almost everything while it goes into a deep sleep mode. Hit the button once and it should restart the controller and power on the light. Then everything is active until it goes back to sleep mode however it's programmed (cycling, holding down the switch, or even a timeout).

I suspect they had some sort of microcontroller do the switching where there was a free-running clock and it was constantly monitoring for the button to be pressed without going into any kind of sleep mode.

To give you an idea, the ATTINY 85, 1616, and 1634 are commonly used in some of the more capable flashlights with the Anduril UI.

 

[andrew_j]

I usually remove batteries because they tend to leak before the next usage.