EEVblog #1371 - A 10,000hr Battery Life Bench Multimeter?

Dave is a tad obsessed with making a 10,000hr battery life bench multimeter. It's actually not hard.

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#Multimeter #Hack #Battery

[SeanBZA]

Yes, done that, and the SAFT D cell, despite being now a decade or two past expiry date, it still has not leaked, though it now has an internal impedance that is in the order of around 10M, but still if you use a high enough impedance meter, will output 3V2ish. I would take some high value capacitors, around 15000 uF 16V, in a pretty big can, and put in parallel with the cell, as that will at least give some surge current capacity, and with a low value series resistor in the cell lead, will not damage the cell, but give a good bit of pulse capability. Use a good brand, the leakage in the capacitor is likely to be larger than the regulator current. Resistor any value from 10R to 50R will so, the voltage drop across it at the 1mA current will be near zero.

Had this running a chime clock for around 5 years before the ESR went too high, and the chime would sound sick, and the cell was then already past expiry by a few years. Still got it somewhere, IIRC it expired in 1994, just waiting to see if this thing will ever leak, as it so far is stubbornly refusing to do so, unlike pretty every other brand of cell, SAFT really put a lot of design work into the seals there.

[reps]

Keithley 155! Battery life is not quite up there, but nV sensitivity and 'infinite' 'display' 'resolution' 🥰

[justin.campbell]

2:12 "look at all the crap!"
*points camera at beautiful Rohde & Schwarz Power Supply*

[sec]

Good branding. Saft is German for juice, and we also use that to mean energy.

[sandalcandal]

Maybe an alternative to trying to find a low power bench meter would be taking a handheld DMM and modding it to fit in a custom "Bench" case with a beefed up battery?

[randomelectronicsanddispla]

Anything will run for 10000h on battery, as long as the battery is big enough.

[Tinker]

Just replaced the battery in my DT-9208 for the second time since purchase in 1997... Good enough for me.

[excavatoree]

The 37 is a 27/25/8025a/8025b with the main PCB re-arranged. I think the display/processor board is the same for both, but it's been a while since I've had my 37 apart.

[AndyFletcherX]

10, 000 hour battery life means it could be recharged when you send it off each year for recalibration :)

[moddquad]

Press the yellow back light button to disable the 10, 000 hour battery life feature.

[intstr]

Why not take your EEVBLOG meter guts and have a bench enclosure made for it?
What does the power consumption on your meter look like?

[dreamcat]

This is what older people do past a certain age: they reminisce about the good old days when (in formative years) things seemed better. And there is definately a warm feeling and appeal to those simpler times. Which is in fact a very positive and worthwhile experience to that person. With great health benefits. For Dave here he is remembering the times when he used to devlop those sonar buys (or whatever else) and seal long lasting lithium batteries into them. And then combining that nostalgia with other nostalgies for other past vintage equipment.

However practically speaking, I don't want a really basic lower performing portable bench MM with a hard to read ancient LCD display and a poor backlight. Just for the sake of a long runtime. What is more practical for myself would be: a decent high spec 6.5 digit (or higher) meter such as a keysight 2000+ or whatever else. With a nice display and a good backlight. And then a high quality ABS plastic 3d printed mount for an external power tool battery. Such as an 18v makita. That can be charged and swapped about along with all my other power tools. It will give a shorter runtime, but much easier to get a brighter display, and easier to drive higher current for a better model of professional multimeter. BUT also even much more than a portable multimeter, i need a portable oscilloscope that would also work from the same power tool batteries. And then be a floating scope, without the sensitivity drawback of differential probes. And being portable is practically speaking great for either mains power stuff or taking it to the car for automitive stuff... that is what I want more than a 10000 hour bench MM. Because the only time i would ever user one of those would be in an emergency situation like a power cut. In which case a brymen handheld multimeter is fine for that purpose.

So yeah lithium ion does not last as long. But you could potentially still use internal lithium cells as a battery backup. But only if the bench meter could be modified somehow to disable the power hungry features such as backlight, and active heaters etc. Which quite frankly is not very likely for any of the good ones (keysight / hp / rigol etc) are ever designed for. So it would have to be some set of hardware mods in order to implement such a 'lower power mode' option. Hope it helps understand my position on this.

[ajl]

Man we still use fluke 37's here for simple measuring. The lead compartment is handy indeed! Never lose the leads and can store a grabby probe extra. Still being calibrated and run all year round. Mean box measuring machine!

[ghostman]

at a current draw that low wouldnt a small solar panel also work to make it basically last forever?

[FuzzyOne]

An E-Ink display with a variable deep sleep timeout and update rate would be awesome, maybe some graphing features as well would be awesome :)

[worroSfOretsevraH]

No annoying ads interrupting every couple of minutes. Thumbs up!

[AndyFletcherX]

Wonder how much of the 1.8mA was taken by the 3V regulator

[billr]

I was at an electronics recycling center getting rid of some stuff when I saw a guy toss an old Fluke bench multimeter on a pile. I couldn't let that happen so I grabbed it and took it home. I found it was mains powered but also had big D cell size rechargeable NiCads in it. All dead. I replaced the NiCads and charged it up and the thing works like a top, and will run forever before it needs another charge. Or I can leave it plugged in and use it as a bench meter. It is a 70's vintage Fluke 8000A multimeter, it's very fast and seems to be still reasonably accurate for my simple needs. I use it all the time now.

[szabolcsmate]

I love these empty box meters. I cut out the empty space in the middle of my Mastech MS8040 and now it's no deeper than my nice and slim digital bench scope. :D

[pedro_]

Dave, you should design a gamer bench multimeter, with aggressive looking design, RGB lighting and watercooling and sell to the gamer community.