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good 9V battery

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james_s:
If the battery in your meter is going flat in storage then there is likely something wrong with the meter.

I often use the backlight on my Fluke 87 so I've been using LSD NiMH 9V batteries for years. The first one I got came from Harbor Freight and it works fine. More recently I've bought others from Amazon, I haven't bought disposable batteries in years.

DDunfield:

--- Quote from: richnormand on February 23, 2019, 06:43:40 pm ---before blaming the battery it would be useful to ascertain that the meter has a hard on/off switch that completely cuts off the battery circuit. If not, you will have to measure the standby current.

Years ago I had a cheap LCR meter that would eat batteries, even if I was not using it much. It had a soft "on" switch with an auto-off feature. The culprit turned out to be a leaky electrolytic capacitor that was continuously draining the battery 24/7...

--- End quote ---

The presence of a physical ON/OFF switch does not always mean no "off" power drain. Sometimes this is because the designer wants to make sure the device can "do something" before powering down (or perhaps just power down things in the right order) - so the physical switch is still "soft". Not that uncommon.

But I did run into a case that I just can't fathom!

I got a little bluetooth camera/music remote powered by a CR2032 battery - handy while travelling. Used it on a trip, turned off the physical power switch and left it in my kit till the next time I traveled (about 6 months), and found it completely dead. I thought - ok, they give you a really crappy battery. Replaced it with a new/good cell, everything worked fine ... turn it off, and tried it again three months later and guess what! - it was dead!

Took it apart to see if it was really a soft switch, and it wasn't - but what I found what that the power switch was SPDT, and in the OFF position, it placed a 10k resistor across the battery.
3V/10k = 0.3ma - assuming 250mah capacity of a CR2032 that's 833 hours ... about 35 days ... the battery goes dead in just over one month.

Quick swipe with an X-acto knife and now it does not go dead when turned off.

Can anyone think of a reason why they intentionally would keep a 0.3ma drain on the battery?

Dave

bc888:


I have a bunch of the EBL lithium batteries as well which I moved too when the AA and AAA Duracells kept leaking I went all Eneloops except for the 9V. Bought the EBL charger with them. They charge up to 8.2XX range for me. The fear I have is that they may do an angry Lithium move and explode. I have not heard or read of a 9V lithium battery doing this, but I wonder if it's because they are not widely distributed.

rdl:
I've been using the EBL 9 volt rechargeables for a few years now. They have paid for themselves many times over and I've not had any problems. I just charged a couple and fresh off the charger,
 
NiMH = 10.15 volts
Li-Ion= 8.376 volts

The difference in capacity between the two is obvious.

james_s:
I think it's very unlikely for a small battery like that to explode, there just isn't enough stored energy for a spectacular fireball as you can get with a large LiPo. I've deliberately abused a few old pouch cells in that size range, now granted they were tired which is why I was disposing of them but they still had some capacity. They puffed up like a balloon and spewed a bunch of smoke but
I didn't get any flames.

That said, I'd avoid charging them unattended or near flammable materials. When lithium battery fires do happen it's most often while charging.

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