Topic: Rechargeable batteries

[ts]

Any reason why rechargeable AA's would all of a sudden stop working in a device that they used to work flawlessly in? Alkaline's still work. No menu on this device so no way to select battery type. It's a self powered monitor that also can run on AA's.

[dyneq]

Do you know the age of them? I have had some refuse to work after 8-10 years. My charger will give me some rudimentary health signs, but I did have a 9V that died suddenly (after a long period of storage).

[ts]

Only a couple years old. Panasonic Eneloop and I have many. Also tested every one of them. They all have a full charge and work fine in other devices.

[dyneq]

In that case, focus on the device. Are the device's battery contacts pushed down and/or weakened? I have brought back a few devices with intermittent power by gently bending the contacts outward toward the battery such that the battery can barely move once inserted.

[ts]

Everything is as new. Plus alkalines and lithiums work. Just/doesn't like rechargeables anymore.  The monitor takes 8 AA's.

[Fatah Ruark (aka MIKE B)]

Could the rechargeables degraded to not put out enough power to keep the device happy? Measure the voltage on the suspect batteries.

Replacing with a "known good" set (aka new) might also be a good next step.

[ts]

Could the rechargeables degraded to not put out enough power to keep the device happy? Measure the voltage on the suspect batteries.

Replacing with a "known good" set (aka new) might also be a good next step.

That's what I thought. I tried 4 sets of rechargeables at 8 batts per set and none would fire this up. All batts are relatively new. On the flip side I can throw in random alkalines and it fires right up.

[vanark]

As far as I know, rechargeables are approx. 1.25V whereas alkalines are 1.5V (to start). Most devices are fine at 1.25V but apparently not your batteries are starting out a little less and your device does not like lesser voltage (is my guess.)

[ts]

As far as I know, rechargeables are approx. 1.25V whereas alkalines are 1.5V (to start). Most devices are fine at 1.25V but apparently not your batteries are starting out a little less and your device does not like lesser voltage (is my guess.)

Yea that's the only logical explanation. It liked them for awhile though and that makes no sense. I see that Lithium AA rechargeables put out 1.5 volts. 8 with charger costs about the same as 8 Eneloops.

I wonder if something failed internally that allows the monitor to operate on a lower voltage. 

[ts]

Rather than mess around with buying more Eneloops (I have 20 already) I picked up some Tenovolt 1.5V rechargeable Lithiums. Problem solved! I guess my device frowns on less than 1.25 volts per battery and I probably have a few Eneloops that have dropped below that even when showing fully charged.