Auto-off devices that draw more than a milliamp in their off state.

I have a Coleman LED headlamp that has a rubber covered pushbutton switch that cycles among several modes, including OFF. But the batteries would be drained in a few weeks. I found that it was drawing about 500 uA when supposedly OFF, so I have to leave the batteries out until I use it. Stupid design. And this was not cheap - IIRC it was about $20 on sale!

Paul

That is excessive. Allowing about 10uA to flow through one of the LEDs makes them much easier to find in total darkness after a power cut. Once fully dark adapted you can see to move around with that little light.

Anything under 50uA should be broadly comparable with the internal leakage in the battery and won't noticeably affect battery life.

They are in league with battery makers to sell more batteries!

DAB radios are my pet hate for battery abuse.

If you ever needed to use one in anger in an emergency it would last about 24 hours of runtime on batteries if you were lucky. The humble classic transistor radio power consumption is dominated by the output stage but with DAB most power is consumed by the signal decoder.

What is it?

Scales.

Sylvia.

I have a multimeter like that. It has a mechanical off switch that does what it should, but it also has an auto-off feature which turns off the screen but wastes about as much current as when it is on, but has the bad side effect that it looks off so I didn't notice that I had not switched it off with the mechanical switch.

I guess they just told the contractor doing the firmware that it has to have this auto off feature with various selectable time-outs, and they did the minimum that was in their requirements document - it looks off.

I've modified the offending device using an RC circuit, a momentary switch and an FET. If the FET specs are to be believed the off current should drop to a microamp.

I also have a multimeter that consumes batteries at a rate, and am halfway through modifying it (can't reuse the existing 9V battery contacts, so need to buy another one).

Sylvia.

I modified my multimeter ( that ate batteries if left on) to use a small

I have somewhat the opposite problem, a Temna DVM which has a perfectly good auto-off function. But it also has an opto-coupled RS232 output, would be very useful for long-term logging of data to computer. Except that the auto-off turns it off after about 3 mins...

Or just lack of attention to detail. Clearly, it needed the ability to disable the auto-off.

Sylvia.

Lol, it's 2017 yet we're still plagued with these sort of trivial screwups

NT