10000hr Battery Life Bench Multimeter - Page 1
Forum section: electronics / testgear

author: EEVblog
author_rank: Unknown
timestamp: February 02, 2021, 02:15:09 am
content: This really belongs in the test equipment group:

author: floobydust
author_rank: Super Contributor
timestamp: February 02, 2021, 03:12:50 am
content: Feasible but I find it's a MYTH that batteries last decades. Their lifetime spec is theoretical, based on self-discharge not their pissing, leaking package. Hello Duracell "10-year guarantee (5-year guarantee for 9V)".I deployedUltralife 9V LiMnO2(1st generation) 1,200mAh in a fleet of Fluke 87's for low temperature below -18°C use. They lasted from 5-12 years depending on multimeter use. After about 12 years, they die and balloon out quite a bit- but never leaked. The latest are CAD $40 each and appear to have changed from plastic to SS case.TadiranLiSOCL2claiming proven (up to) 40 year life ... they leaked after about 8 years. Laser-welded SS case corrodes and they spew electrolyte all over a PC board and eats traces. Their lifetime claims are not in datasheets, only in marketing wank. Not a believer.I get 2,000hrs on a 9v one of my old DMM's and it's a treat.

author: bdunham7
author_rank: Super Contributor
timestamp: February 02, 2021, 03:34:11 am
content: https://multimeterwarehouse.com/m9803r.html

author: retiredcaps
author_rank: Super Contributor
timestamp: February 02, 2021, 05:57:37 am
content: Dave's meter is an APPA 205.Regarding the JRC NJU9210FF, it's been used in Appa 105 rebranded Tek DMM 252.https://www.eevblog.com/forum/testgear/iso-tech-(appa)-idm105-dmm/https://www.eevblog.com/forum/testgear/tektronix-dmm-252/https://www.eevblog.com/forum/repair/tek-dmm252-multimeter-wrong-voltage-and-current-measurement/

author: SilverSolder
author_rank: Super Contributor
timestamp: February 02, 2021, 04:28:47 pm
content: Quote from: floobydust on February 02, 2021, 03:12:50 amLithium batteries do have good durability - I use them everywhere I can now... (i.e. when rechargeables are not appropriate). I started using them about 8 years ago, and I haven't yet had to change one that died before it was used up. No leaks either. I'm a Lithium fanboy now.

author: MadTux
author_rank: Frequent Contributor
timestamp: February 02, 2021, 11:10:15 pm
content: Well, battery only needs to survive like 50 charge charge cycles. Then you're dead anyway

author: floobydust
author_rank: Super Contributor
timestamp: February 02, 2021, 11:43:34 pm
content: Quote from: SilverSolder on February 02, 2021, 04:28:47 pmWhat brand/size/chemistry?For primary lithium batteries, I'm having good success with Energizer Ultimate Lithium, using them in cold weather rated -40°C to 60°C.L91 AA 3,500mAh Lithium/Iron Disulfide (Li/FeS2) BUT high voltage ~1.8-1.7V typ. about $3 ea.L522 9V ?mAh Lithium/Iron Disulfide (Li/FeS2) voltage ~8.5V typ.Marketing wank :"Energizer Ultimate Lithium™ batteries are 100% leak proof* *Based on standard use", "Holds power in storage for up to 20 years (AA/AAA)"Realistically, Eneloops are great. Charge them once or twice a year, about $5 ea. AAWhy isn't there a solar panel and renewable approach instead of this 10,000hr battery being proposed?

author: MBY
author_rank: Regular Contributor
timestamp: February 03, 2021, 01:38:23 am
content: Funny, I'm currently in a project myself to do exactly what Dave is thinking! My choice of "decent but cheap" bench DMM is the [Noname/Victor] DM8145, a 80,000 count bench DMM with a LOT of empty space.https://www.banggood.com/DM8145-4-7-or-8-Bench-top-Multimeter-1000V-20A-80000-Counts-Digital-Multimeter-tester-Auto-Range-Multimetro-Digital-Voltmeter-Ohm-p-1687590.html?cur_warehouse=CZ&rmmds=searchI think this meter is ideal, as it has a real power switch with an arm traveling to the back where the simple iron core transformer PSU is.I've ordered some micro switches that has yet to arrive. My plan is to mount it in such way that it's actuated by the power switch arm and my goal is to have a seamless switchover between battery and mains use. If connected to the mains, the mains charges the battery, and if power is lost/removed, the battery powers the meter. And the option to use primary cells. Probably with a switch or a jumper. High voltage tolerance is the aim, I think, so one can wack 18650, alkaline AAs, PP3 or whatever in. Some old bench meters often had a battery option, usually like 2-6 Pb-acid D-cells (the Cyclone thing). I think such option is available to e.g. Keithley 177 and 179 DMMs and such.I have an old "Beckmann" multimeter powered by a couple of D-cells, and I think it has the same dry cell batteries as when I got it, in the early 90s. I's very similar to the bench fluke you showed. No mains, just batteries.

author: SilverSolder
author_rank: Super Contributor
timestamp: February 03, 2021, 03:40:58 am
content: Quote from: floobydust on February 02, 2021, 11:43:34 pmEnergizer Ultimate, Ultralife 9v batteries, and Eneloop 2000mAh AAs are the staple diet.

author: Raj
author_rank: Frequent Contributor
timestamp: February 03, 2021, 07:04:56 am
content: Would you buy a bench top meter with hand held meter specs?Naa, I'd just find a meter who's display connect with ribbon cable. Extend the cable length and 3d print a new case for the thing.

author: drussell
author_rank: Super Contributor
timestamp: February 03, 2021, 02:49:30 pm
content: My good old American Reliance model 37 also uses that same JRC NJU9210 controller IC with an external true RMS converter chip. They're only 4000 count, but was actually a pretty slick setup back in the early 90s when I got mine.Mine runs on two AAA cells and it lasts for YEARS on a set of alkaline AAAs. Definitely nice, low power consumption!It has certainly held up and still works well today within its performance limitations.I actually just fully disassembled the ol' Amrel the other day and gave everything a thorough proper cleaning of the button and switch contacts, the LCD zebra strip, re-lube the main dial assembly, etc. and it is back to running basically like new.edit:It took quite a bit of scrubbing with SuperClean (basically sodium hydroxide based) to get the yellow holster clean, I wish I had a "before" photo, as it has been many, many years since I did a real proper cleaning of all the grease and grime from when it gets used in the garage or shop or some dirty worksite or whatever. I was really surprised how nice and yellow and clean it came, or I suppose I was surprised how dirty the whole thing actually was?Oops. I guess it was a tad overdue for proper routine maintenance?

author: drussell
author_rank: Super Contributor
timestamp: February 03, 2021, 03:31:06 pm
content: Quote from: retiredcaps on February 02, 2021, 05:57:37 amAha!!!I'll bet my Amrel was made in Taiwan by Appa! I always wondered who actually made those since it was a relatively short-lived product line for Amrel, who's focus was primarily high-end power supplies and electronics loads and military contract stuff.The Amrel 37 has smooth sides, not the ribs like the Appa 100 series and the dial switch positions are in a different order, as are the buttons (like the blue select button is below the reset/on button) but it is exactly the same size as a Fluke 87 and fits an 87 holster also, etc. My Amrel even came with a yellow holster as this was before Fluke started slapping and smacking other companies around for using yellow holsters.Somewhere at home I have the tilting bale (one of the little pins broke off, I need to repair that at some point) and the plastic protector that goes over the LCD that says "AMREL 37 True RMS Digital Multimeter" that I need to glue back on, but considering the abuse it's been put through in the past 30 years or so, it's holding very up well.I'm glad I bought it a good set of Mueller probes way back in the day, they've lasted for probably almost 25 years. The original ones that came with the meter lasted for a few years, then I think I bought a cheap set once, then splurged on the Muellers that even came with a bunch of screw-on accessories. That was well worth the investment.

author: goaty
author_rank: Regular Contributor
timestamp: February 03, 2021, 03:50:43 pm
content: This one easily lasts longer than 10000hr on one battery.

author: retiredcaps
author_rank: Super Contributor
timestamp: February 03, 2021, 05:30:46 pm
content: Quote from: drussell on February 03, 2021, 03:31:06 pmLook on the pcb backside and see if you can spot 105 on it like in this picture fromthe ISO-TECH (APPA) IDM105 DMM thread.

author: pascal_sweden
author_rank: Super Contributor
timestamp: February 03, 2021, 06:26:21 pm
content: http://www.vicimeter.com/en/product/VC8145

author: drussell
author_rank: Super Contributor
timestamp: February 03, 2021, 07:31:07 pm
content: Quote from: retiredcaps on February 03, 2021, 05:30:46 pmNo, it is apparently a much cheaper design than the 105 and only says "MIC37-1G" on the board. I don't recall seeing "APPA" anywhere on it but I'll check closer the next time I have it totally disassembled. This one is definitely a cost-reduced variant as it doesn't have proper HRC fuses, they're actually just 5x20mm size ceramic. I wouldn't want to go probulating high energy circuits with this one, I have other meters for that, plus you usually want a clampmeter anyway in that kind of situation. The construction just looks very similar to the one that Dave showed in the video, though I suppose it could have been made by some other similar factory still...I know the datecode on the AD737JR is 9246, though... I happen to have written that down the other day when I went looking for datasheets after thinking about multimeters in another thread.When I saw Dave taking apart that GW Instek branded one I was thinking to myself, wow, that construction style looks a lot like the Amrel.

author: wizard69
author_rank: Super Contributor
timestamp: February 03, 2021, 10:31:31 pm
content: Quote from: Raj on February 03, 2021, 07:04:56 amWhy not? This especially if it is easily battery portable. It might not be the main meter on a bench but there are plenty of cases where you don't need high performance and endless resolution.What we are really talking about here is a bench meter that is easier to use than a handheld and I'm pretty confident that we have all used a handheld meter on the test bench at one time or another.

author: wizard69
author_rank: Super Contributor
timestamp: February 03, 2021, 10:42:45 pm
content: This is one of Daves better videos as it inspires and with this thread highlights meters I never knew existed.Actually I'm hoping it inspires one or more manufactures to take some of the ideas expressed by Dave and others in this thread to heart. For one long battery life in a desktop multimeter should be easy with today's technologies. Even if it isn't 10'000 hours, a meter that could remain on for years at a time would be fantastic. The idea expressed above for solar power is pretty good too if the goal is to charge or supplement the contained battery. It is actually surprising to me that manufactures haven't gone this route with handhelds or in cases like this where the device is a "portable" bench top design.

author: Fungus
author_rank: Super Contributor
timestamp: February 04, 2021, 04:20:51 am
content: I recently scored this on eBay France:Looks like the guy had a bunch of them and I got the last one.It's in perfect condition. I had a look inside and it's just a Fluke 27FM in bench format.The footprint is quite big so I've been thinking about chopping the back off. It seems a shame to do it, but... it would make a really small "bench" meter.The main issue with handhelds (or at least, the ones I own) isn't lack of digits, it's that they have auto-power off and start to beep at me after a few minutes sitting idle. A bench meter will sit there all day and be happy.The Fluke 37 has a 9V DC power socket so it would be easy to run off an adapter but it also goes for 1000+ hours on a 9V battery. There's a big storage space in the back for leads/tools so it would be an easy mod to put in a huge battery, eg. 6xAA would be about 5,000 hours use, 6xC cells could be the mythical 10,000.The only downside I see is using a dial to select ranges. Most bench meters use push buttons.

author: EEVblog
author_rank: Unknown
timestamp: February 04, 2021, 08:43:49 am
content: Quote from: Fungus on February 04, 2021, 04:20:51 amNice!

author: EEVblog
author_rank: Unknown
timestamp: February 04, 2021, 08:46:16 am
content: Quote from: wizard69 on February 03, 2021, 10:42:45 pm

author: AVGresponding
author_rank: Super Contributor
timestamp: February 04, 2021, 12:34:07 pm
content: HP 3468/78 have LCD displays, would be interesting to know how much power they use...The only LCD bench meters I have are my Micronta 22-195 which uses 4x C cells anyway, and which runs pretty much forever on them, a Black Star 3225 which ditto, a Black Star 3210MP, which is basically a newer 3225 and mains powered, and should therefore be easy to mod, and a Keithley 197, which I believe may be available with a battery option (mine doesn't have it).EDIT: Forgot the Solartron 7150 I have, but there's absolutely no space in the case for batteries on that, it's properly stuffed, though I suppose if you ripped out the trafo you might have enough room.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 04, 2021, 02:41:06 pm
content: The old 3468 / 3478 (5.5 digit) use quite a lot of part. They are not at all build to be powered from battery. They include and old 5 V powered CPU and thus take a lot of power - expect more like 10 W. 3478 specs are < 25 W.Battery power with a high resolution meter would be more like a thing for rechargable battery and than maybe some 1-3 W and 10 - 30 h for a singel charge, unless one uses a really large battery. It would still makte sense sometimes because of isolation.

author: AVGresponding
author_rank: Super Contributor
timestamp: February 04, 2021, 06:03:14 pm
content: Quote from: Kleinstein on February 04, 2021, 02:41:06 pmThe inputs on these instruments are fully isolated anyway? Not sure what you're getting at there.My Keithley 197 appears to use around 3W, but that's measured using an inline mains power meter. For a better reading I'll have to open it up and get into the DC side, I'd expect to see maybe 2W at that point, but of course that's still a bit much for the purposes of this thread.The Solartron says 23VA on the back, so clearly way too power hungry...

author: thm_w
author_rank: Super Contributor
timestamp: February 04, 2021, 11:19:54 pm
content: Quote from: AVGresponding on February 04, 2021, 12:34:07 pm3478 uses 7.3W

author: wizard69
author_rank: Super Contributor
timestamp: February 04, 2021, 11:43:30 pm
content: Well that was fast. It is one of the great things about this forum, I find out about things that I never knew existed! Now the question is who makes that meter? So far I've found:http://www.all-sun.comhttps://overseas.sanwa-meter.co.jp/products/digital_multimeters/ps8a.htmlThese meters are surprisingly hard to find as a google search for "solar powered meters" turns up a bunch of crap about meters for solar power installers. Honestly Dave I'm surprised you are not offering the Sanwa on your site, it looks like a very green solution. Not a bench top but rather an ultra compact but the PS8A is very interesting to say the least.The funny thing here is that in reading the various manuals they have objections to cleaning with Alcohol. I wouldn't even care normally but lately everything is being cleaned with IPA.Quote from: EEVblog on February 04, 2021, 08:46:16 am

author: MBY
author_rank: Regular Contributor
timestamp: February 05, 2021, 12:23:32 am
content: Quote from: pascal_sweden on February 03, 2021, 06:26:21 pmYep, this is the DMM I mentioned and I think it's a good candidate. Turns out to be easily modded (I've done a mod so the annoying buzzer only beeps in continuity mode, described herehttps://www.eevblog.com/forum/testgear/vc8145-thread-it_s-here-finally/msg3448652/#msg3448652)I've done some preliminary work on it. It have four relays, so it consumes a couple of mA more than Daves GW Instek.PSU---------------------------------------Measured with: BK 2709B DMM.9 Vdc single rail from a 7809. About 13.5V on the unregulated side.It has a "low bat" segment on the LCD and the case has screw towers and suchthat are unpopulated. A battery option is certainly possible, but the "low bat"segment seems NOT to be connected/used as it never comes on.Winding down the input voltage dims the backlight and the LCD starts fading pretty soon.The measurement seems stable and reliable down to 7.55V.I connected a PentaRef (that haven't been calibrated for 5-6 years) set to 3.9001V and the display (Vdc range) showed a stable 3.9009V down to 7.55V, and then started drifting upwards (as expected).-------------------------------------------Current consumption--------------------Measured with: uCurrent on mA range, a BK 2709B DMM.About 11-12 mA in the following modes:mAdc, Vdc, AdcAbout 44 mA in the following modes:Vac, mVdc, Ohm (add 0.9mA on short), Cap, Temp, Out74 mA in:Diode/ContBack-light: add 9,6 mA-------------------------------------------My goal differs a bit from Daves. He wants a primary cell-driven low power DMM that lasts for decades with intermittent use. Li-SOCl2 as Dave suggested is an excellent choice for this and I understand the reasoning. But they are pretty expensive and my own user case is a bit different. So I want a rechargeable Li Ion system anyway (or would have selected alkaline or Li-FeS2 primary cells instead, as the DM8145 takes more power).I've tested to power the DM8145 from a boost converter (this may be critical. There is a reason mains-driven measure equipment always have good old iron transformers and linear regulation) and nothing bad seems to be happening, but I haven't checked all the ranges and scenarios. But I know that many are gonna puke on my "solution" with buck and boost DCDCs, and rightly so. This is just a, eh, shall we call it "design study"?The upper part (circled in red) of the schematics is the real PSU of the DM8145. The lower part is my quick and dirty add on for a 3.7V li ion battery (bank). It's just a sketch, I haven't done all the calculations, tests or other "brain task" necessary. The only practical tests I've done is measure the currents and a superficial test to power the DMM from a boost converter. The relay inhibit the boost converter when mains power is available. It may not be needed, but without it the battery sees a light duty as long as power is on (driving a useless DCDC) preventing some cycling. Without it the thing works like an online UPS with seamless switchover. I decided to stuff in a large cap (C5) to make the switchover seamless with the relay.The case have several screw towers not in use. I've discovered that one was suitable to mount a microswitch for the battery mod. Attached are some pictures. Yes, the "block" used to push the micro switch is a large SMD cap I glued on the power putton steel arm.Edit: It's a bit silly that they have chosen 5V relays (Omron, no less!) driven from a 5V rail, when they have 9V available and of course use linear regulation. 9V relays would draw less power. A mod is certainly possible with either reed relays or driven from 9V, to minimize the power consumption.

author: MBY
author_rank: Regular Contributor
timestamp: February 05, 2021, 12:31:15 am
content: Quote from: wizard69 on February 04, 2021, 11:43:30 pmThe meter Dave posted is an Uni-T UT90x (UT90C perhaps). Don't know more about it, haven't seen it IRL, haven't used it. But Uni-T devices usually is on the range from crappy to almost decent and sometimes really decent. (They are very "hit and miss". Most of my most useless POS equipment has been Uni-T, but also some of my all time favorites, such as my old trusty Uni-T UT-60C. My experience is that I can't take my opinions and knowledge about a particular model and extrapolate to another. It's all about what I call "soft parameters" never stated in a datasheet. The feeling of using, the feel of buttons, etc.)

author: retiredcaps
author_rank: Super Contributor
timestamp: February 05, 2021, 03:20:35 am
content: Martin reviewed the solar Uni-T and killed it.

author: MBY
author_rank: Regular Contributor
timestamp: February 05, 2021, 03:53:40 am
content: Lol! He didn't even try to kill it! I expected the usual studious HV-testing and high energy events to kill a el cheapo meter, but it turns out it could not cope with mains on Freq range (or ohms range), a pretty basic test. This is why I said that Uni-Ts are hit and miss. They are basically all over the place with input protection, ease of use, functions and build quality. You never know from one model how another gonna preform. Edit: Sorry, we are a bit off topic now. Back to battery powered bench meters. Uni-T have some really old "handheld meter in a bench box"-meters that may be very suitable for battery power. If they don't already have it.

author: Dwaine
author_rank: Frequent Contributor
timestamp: February 05, 2021, 06:29:30 am
content: This is the meter for Dave to mode with a 10000hr Battery . It already runs off batteries...https://www.ebay.com/itm/ANENG-AN888S-Digital-19999-Counts-High-Precision-True-RMS-Multimeter-Ohm-N-D/333768482621?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20201210111314%26meid%3D24aa7e46a44741a2945f999f7f26c78c%26pid%3D101195%26rk%3D2%26rkt%3D12%26mehot%3Dco%26sd%3D220336911971%26itm%3D333768482621%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv5PairwiseWebWithDarwoV3BBEV2b%26brand%3DUnbranded&_trksid=p2047675.c101195.m1851

author: EEVblog
author_rank: Unknown
timestamp: February 05, 2021, 07:02:07 am
content: Quote from: Dwaine on February 05, 2021, 06:29:30 amThat runs off two 18650's and is rechargable.May be possibe to nuke the bluetooth speaker crap and just user the meter though.

author: Fungus
author_rank: Super Contributor
timestamp: February 05, 2021, 09:02:03 am
content: Quote from: EEVblog on February 05, 2021, 07:02:07 amNope. That one uses the trendy inverse LCD display so it will suck a lot of power when it's on.(I'm sure you can put in enough batteries to make it last 10000 hours but it's not an optimal choice)

author: Kleinstein
author_rank: Super Contributor
timestamp: February 05, 2021, 09:17:59 am
content: Inverse LCD or not does not make any difference on the energy consumption: it is just a quitestion on the orientation of the polarizer. With some displays the polarizer is a separate filter sheet and can even be fliped to change between normal and negative display. For convenience the direction of the polarizers is often at some 45 deg. So that flipping the polarizer turns the orientaion by 90 deg, so one can use the same parts in both ways.@MBY:For the battery mod with VC8145, one could consider to also change the L7809 regulator. These take quite some idle current (some 5 mA) and with a LDO one would use a lower votlage for the boost converter (e.g. 9.5 V instead of 12 V). This would reduce the power needs quite a bit.

author: Fungus
author_rank: Super Contributor
timestamp: February 05, 2021, 09:35:02 am
content: The only thing I could find on Aliexpress is this:https://www.aliexpress.com/item/33021584962.htmlNot cheap but the paper specs are quite good.Edit: There's some cheaper ones on there but they're all manual ranging. I assume we don't want that.

author: Fungus
author_rank: Super Contributor
timestamp: February 05, 2021, 09:36:19 am
content: Quote from: Kleinstein on February 05, 2021, 09:17:59 amIt does when the backlight is always on.I guess you could disconnect the the backlight but then it's not very readable.Quote from: Kleinstein on February 05, 2021, 09:17:59 amThat would need to be tested.

author: MBY
author_rank: Regular Contributor
timestamp: February 05, 2021, 11:01:22 am
content: Quote from: Kleinstein on February 05, 2021, 09:17:59 amYep. Exactly my thinking. As any mods needs to solder things on the PSU PCB anyways, it seems reasonable to replace the 7809 with an LDO! If the instrument behaves good, you even can have the boost DCDC feed the 9V rail directly, but I thought it would be a extra filtering step to have a linear regulator after the boost.Quote from: Fungus on February 05, 2021, 09:35:02 amThis is the one I'm talking about and it have at least one long thread on this forum:https://www.eevblog.com/forum/testgear/vc8145-thread-it_s-here-finally/It's certainly no HP or Fluke, but it's good enough. I've used it for a couple of months, but the model seems almost a decade old (and that's a good thing, not a come-and-go model from this weeks Shenzhen market but something under active production and with a lot of knowledge about it online). You can argue that it's too expensive for a Chinese no-brand (or "any brand") bit of gear, but I think it's at least reasonable. I would say that the closest thing, if you want a good meter, and the one they tried to copy, is Fluke 45 (100,000 counts), but they are different beasts really (and if you can get a Fluke for that price, the DM/VC8145 doesn't stand a chance of course).But, all in all, with high availability, good specs in general, large mod potential and a lot of empty space, it's a good contender to be a "standard meter for modding". The display is good, the backlight stays on if turned on, it has a good set of features (and some total useless gimmicks such a timer function nobody seem to understand and very limited waveform output) such as RS232 with a speced protocol, delay/peek hold that actually works and seems to be built with decent components, etc. I like it, and I know good from bad (having Flukes, TTIs, Keithleys and HPs, along with a bunch of really shitty gear). So, if it were a vote on "best half decent bench DMM for the masses to do an battery mod on" I gladly vote for the 8145. One thing I hate, and I know a lot of people hate, is it's totally annoying buzzer, but I've fixed mine without compromising away the buzzer when it *should* operate (I've linked to my mod in an earlier post).But, the downside is, 8145 is probably not what Dave intended as it would preform badly on li thionyl chloride batteries. It simply draw too much. We can swap out relays all day long, but I don't think it's gonna beat Daves DMM that does 1.7 mA at 3 volts...Edit: Btw, that Aneng 888 must be some kind of sick joke. I wonder how the design meetings were for that one...

author: Dwaine
author_rank: Frequent Contributor
timestamp: February 05, 2021, 12:07:52 pm
content: Quote from: Fungus on February 05, 2021, 09:02:03 amBut Dave can listen to music when he's in the lab taking measurements.

author: MBY
author_rank: Regular Contributor
timestamp: February 06, 2021, 12:56:34 pm
content: I remembered that I have four D-cells Pb-acid batteries that don't serve any function. I've successfully desulfated three of them, but the fourth is beyond repair. These kind of batteries were once common in backup power for instruments. I know that my Keithley 177 had an option for this (four cells I think) and I've once owned a pretty small CRT-based portable oscilloscope that also used them (two I think). I have a lot of 18650 li ions, but they are kind of useful for other things. So why don't make a quick 'n dirty battery options for the DM8145 using three of those D-cells? That's pretty straight forward and Pb batteries have no problem working in an online setting.Going to build this thing now. I return with some pictures when finished.Maybe I should start another thread? This differs a lot from Dave's idea with a 10,000h battery and is more like a 10h UPS...

author: Fungus
author_rank: Super Contributor
timestamp: February 07, 2021, 10:39:03 am
content: My Fluke 27 is still running the same crappy 9V battery that came installed when I bought it on eBay about 6 years ago.(maybe I should check it for leaks...?)

author: robert.rozee
author_rank: Frequent Contributor
timestamp: February 07, 2021, 01:36:48 pm
content: what about a fluke 77 or similar re-housed in a bench case? with a '77, the selector switch could be desoldered and fitted into a 3-d printed housing, and the LCD could be remoted on a daughterboard wired back to the main meter PCB. the main meter PCB could then sit flat inside the bottom of the case under a battery shelf, with 4 wires going up to new front-panel terminals.the end result would look similar to a fluke 37, although possibly a little smaller. one advantage of using a 77 as the basis is that they seem to turn up here and there with broken cases and LCD mountings, but electrically intact (ignoring the 1k fusible resistor blown).cheers,rob :-)

author: Fungus
author_rank: Super Contributor
timestamp: February 07, 2021, 04:31:40 pm
content: Quote from: robert.rozee on February 07, 2021, 01:36:48 pmI'd definitely prefer push buttons over a rotary switch in a "bench" meter.

author: robert.rozee
author_rank: Frequent Contributor
timestamp: February 08, 2021, 01:53:35 am
content: push button operation could be achieved with bipolar relays - the schematic of the fluke 77 is readily available.serial output could even be added by snooping on the 4-bit bus that runs between the ADC and display driver.the question is: would a 3200 count display be sufficient for such a project?cheers,rob :-)

author: TheDefpom
author_rank: Frequent Contributor
timestamp: February 08, 2021, 04:21:57 am
content: As I posted in the comments of the video, maybe look into the Fluke 45, it has a space for a internal battery already ! AND I am pretty sure I saw you had one already Dave.

author: Wytnucls
author_rank: Super Contributor
timestamp: February 08, 2021, 12:02:57 pm
content: Other contenders are the Fluke 8050A and Keithley 176.Both with 20,000 count and LCD displays.The Fluke lasts for 10 hrs with its NiCad battery pack option (6W)The Keithley lasts for 1,000 hrs with 6 internal C cells.

author: bdunham7
author_rank: Super Contributor
timestamp: February 08, 2021, 04:43:14 pm
content: I have a few Fluke 8050A and I think they draw way too much current for a project like this. My only battery-capable one was ruined by leakage and you can't just put batteries in the ones that didn't come with them--no charging circuit. But I think they draw 50-100mA.What is the lowest current draw anyone has measured on their DMM? My Harbor Freight D830-based freebie draws about 1 mA on most ranges. Resistance draws 1.2mA, 200R and diode draw 3.3mA, all with the test leads open circuit. It uses a 9V battery and the battery low indicator comes on at 7.5V, but the meter works down to 6.0V or even a bit lower. Has anyone measured a meter to draw less?

author: Fungus
author_rank: Super Contributor
timestamp: February 08, 2021, 05:35:47 pm
content: Quote from: bdunham7 on February 08, 2021, 04:43:14 pmWith nothing connected myFluke 37draws about 720 uA in all the AC ranges and 325 uA in the non-AC ranges.

author: AVGresponding
author_rank: Super Contributor
timestamp: February 08, 2021, 06:13:58 pm
content: My Micronta 22-195 uses just under 900uA for DC ranges, and just over 1100uA for AC.To complicate matters, the 4 C cell battery is centre tapped, so a dual rail 3V battery.The hFEfunction that Dave so hates on DMMs uses 2200uA unloaded!The ohms ranges use up to an additional 1250uA, also continuity.Diode test uses 1450uA.I'm going to pull my Keithley 197 apart this weekend if I remember, and see if I can make any useful current measurements.

author: bdunham7
author_rank: Super Contributor
timestamp: February 08, 2021, 06:28:27 pm
content: Quote from: Fungus on February 08, 2021, 05:35:47 pmThat sounds like the winner. If you can pack 6 D-cells in there, you've achieved the 10K hour goal. And they wouldn't need to be alkaline.

author: Fungus
author_rank: Super Contributor
timestamp: February 08, 2021, 06:54:56 pm
content: Quote from: bdunham7 on February 08, 2021, 06:28:27 pm6x zinc-carbon C-cells would be enough for 10,000 hours if you don't do much AC measurement. With alkalines you'd be looking at 25,000 hours.https://en.wikipedia.org/wiki/C_battery#PropertiesWith D-cells you'd be headed for 50,000 hours but I'm not sure they'd fit.Edit: Yes, I just tried it and they'd fit easily!

author: SilverSolder
author_rank: Super Contributor
timestamp: February 08, 2021, 07:13:50 pm
content: Except the Duracells would leak long before the 50K hours!

author: MBY
author_rank: Regular Contributor
timestamp: February 08, 2021, 09:47:00 pm
content: Fluke 37 seems indeed to be a good contender. It need very little power and has a lot of space. The problem is availability and that 2,000 counts are about as low as you can get. I'm thinking along two different lines. A) a somewhat universal solution that anyone can cram into just any low power bench DMM or B) a solution for a affordable bench meter that is still in production and/or have high availability (such as warehouses full of NOS) that can be some sort of "standard DMM" in this context.I hope that Fluke take note and do a updated low cost, low power battery DMM. But on the other hand, what fun is that? This is a electronics forum and the whole point is sometimes to build something yourself!Some has suggested to build a 3D-printed case around a hand held, and that's certainly a possibility but not everyone has a 3D printer or a printer with sufficient space (mine can print max 12x12cm, in practice 11x11cm) and since the market is saturated with handhelds, we probably never can reach a consensus of which meter to use. One thing that would help is a meter with a ribbon or flex cable to the LCD, but that is probably very unusual today.I must find my old Beckmann, as its very reminiscent of Fluke 37, but not identical. I think it is this one:https://www.desmoines-classifieds.com/Madison-County-/Household-Goods-/Beckman-360-digital-multimeter-with-leads-as-is.SHTMLOnly 2,000 counts but have a 20.00 ohms mode. I think it has C- or D-cells (no external power what I can remember) and run for ages and ages. But again, where is the fun in that? It doesn't need any hack to work on batteries.

author: Fungus
author_rank: Super Contributor
timestamp: February 09, 2021, 05:38:53 am
content: Quote from: MBY on February 08, 2021, 09:47:00 pmThere's not a single one on eBay right now.Quote from: MBY on February 08, 2021, 09:47:00 pmSome people havealready done it, it's a lot of work though.The best bet would be to start with something like this:https://www.aliexpress.com/item/1005001638029456.htmlBut that's not a "cool" meter.

author: madires
author_rank: Super Contributor
timestamp: February 09, 2021, 11:00:12 am
content: Quote from: EEVblog on February 04, 2021, 08:46:16 am... was also sold as Voltcraft VC260 (green rubber holster). The power supply is based on a 20F super-cap and an LT1610 boost converter. The super-cap is charged via 9-12V or mains (tiny transformer on board), both protected by a 100 Ohms fusible resistor. The 9-12V input has additionally a two-transistor voltage clamp, and there's a string of diodes to limit the charging voltage. The solar cells are just meant to support charging (the DMM won't run with them alone). That concept works well, but the DMM is crappy (cheap parts, not suited for mains). IIRC, Conrad sold the VC260 for 60 or 80 Euros (DMM, test leads and pouch). BTW, the DMM IC is an FS9721-LP3.

author: MBY
author_rank: Regular Contributor
timestamp: February 10, 2021, 07:47:38 am
content: Quote from: Fungus on February 09, 2021, 05:38:53 amYup! But that version seems inferior to the "Vici" VC8145 or DM8145 with 80,000 counts for about the same price or less. A couple have already mentioned it in the thread and I started a new thread about modifications to this meter:https://www.eevblog.com/forum/testgear/dm8145vc8145-dmm-modifications/To my knowledge it has been around since 2012, and it's still sold, so the availability seems good. And it's a pretty decent meter, I like it. It's reminiscent of Fluke 45 even if you of course should choose a Fluke 45 over 8145 every day of the week if you have the chance. But, unlike Fluke 45, the 8145 is actually a good contender to be battery powered. While not practical for a 10,000h battery, it's certainly practical for a battery that lasts many tens of hours on a charge.

author: Fungus
author_rank: Super Contributor
timestamp: February 10, 2021, 08:24:43 am
content: Quote from: MBY on February 10, 2021, 07:47:38 amI saw those but they were about 50% more expensive.Doesn't matter though, that's really the only sort of meter that could be a donor for this. None of the major brands make anything close.(except maybe Uni-T)

author: scopeman
author_rank: Frequent Contributor
timestamp: February 13, 2021, 04:52:59 pm
content: Hi Dave,Although not a bench meter the Fluke 77 series (the older gray cased ones and the yellow case 23) would run over 1000 hours on a carbon zinc battery. All of the new ones I ever had came with a silver cased Eveready 9V CZ battery. They are still one of my favorite DMM's.Now here is a real question. Are there any alkaline 9V batteries that don't leak? If so I have not found one yet. I have been using the Energizer Ultimate Lithium and thus far they have not leaked but AAA, AA and 9V are the only sizes I have seen. I have an old Triplett 801 TVM that uses 9V and D cells. When I store it I always remove the batteries.SamW3OHMP.S. I used a pair of Lithium Sulfuryl Chloride double D cells (60Ah total capacity) 3.9V per cell in an industrial product I designed. They worked well but the cells were close to $100.00USD each. 60Ah would run your meter for a long time!

author: SilverSolder
author_rank: Super Contributor
timestamp: February 13, 2021, 08:47:50 pm
content: Quote from: scopeman on February 13, 2021, 04:52:59 pmI wonder how much 60Ah worth of leaky Duracell batteries would cost? May not be far off!

author: drussell
author_rank: Super Contributor
timestamp: February 13, 2021, 09:37:10 pm
content: Quote from: SilverSolder on February 13, 2021, 08:47:50 pmThat might be abitof an exaggeration.A single, standard alkaline D cell has about 20Ah capacity at a 25ma discharge rate. Eight ProCell PC1300s here locally is 8 x$1.34= $10.72 CAD for 240 Wh.

author: SilverSolder
author_rank: Super Contributor
timestamp: February 13, 2021, 10:16:05 pm
content: Quote from: drussell on February 13, 2021, 09:37:10 pmAre you including the price of the ruined equipment due to leaks?

author: drussell
author_rank: Super Contributor
timestamp: February 14, 2021, 12:51:47 am
content: Quote from: SilverSolder on February 13, 2021, 10:16:05 pmIndeed, no....

author: David Hess
author_rank: Super Contributor
timestamp: February 14, 2021, 03:52:17 am
content: The standard for battery life of old handheld manual ranging digital multimeters used to be 2000 hours with a 9 volt alkaline battery. For reasons which I do not know, automatic ranging multimeters of the same era had much lower operation life but were comparable to modern meters.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 14, 2021, 09:52:55 am
content: With the old metes with 2000 hours battry life (translates to many many years of normal use) chances are the battery would leak before it runs empty. With shorter battery life the chances for leaking batteries are reduced - so its a feature, not a problem.

author: drussell
author_rank: Super Contributor
timestamp: February 14, 2021, 12:29:53 pm
content: Quote from: Kleinstein on February 14, 2021, 09:52:55 amThat is why Dave's original idea was to use some sort of chemistry that is more likely to be stable long-term than a typical consumer alkaline cell so that it was more like a permanently-installed "lifetime" battery.

author: David Hess
author_rank: Super Contributor
timestamp: February 15, 2021, 12:43:05 pm
content: The only times where I have had 9 volt alkaline batteries leak, the outside case contained the leakage, and it never happened with my 2000 hour multimeters, but maybe that was because alkaline batteries back then were more reliable.

author: Fungus
author_rank: Super Contributor
timestamp: February 16, 2021, 01:15:14 pm
content: Fluke 37 on eBay:https://www.ebay.com/itm/284082673373

author: SilverSolder
author_rank: Super Contributor
timestamp: February 16, 2021, 02:15:01 pm
content: Quote from: David Hess on February 15, 2021, 12:43:05 pmThe pervasive quality problems with alkaline AA and AAA cells that I have experienced personally and many have documented in other threads here on EEVblog has made me give up on alkaline batteries altogether - they are so cheaply made now, it seems, that they are just ticking time bombs... it may or may not be fair to the 9V variety, but why take the chance when the manufacturers (Duracell in particular, but others too) have demonstrated such a low regard for their customers?

author: Kleinstein
author_rank: Super Contributor
timestamp: February 16, 2021, 07:56:00 pm
content: In a benchtop meter one should have space for a container, so that a leaking battery would not do much damage. It is just stupid to mount a battery that is prone to leaking so that the liquid would do significant damage.9 V batteris are a little less likely to leak, but they sometimes also leak.

author: David Hess
author_rank: Super Contributor
timestamp: February 16, 2021, 10:04:50 pm
content: Quote from: SilverSolder on February 16, 2021, 02:15:01 pmI do not really disagree since lithium 9 volt primary batteries are readily available but because of their construction, the alkaline cells in 9 volt alkaline batteries are better protected against cell leakage by the outer envelope. My preference might be for low discharge NiMH 9 volt batteries but there are none that I trust, and I do not trust the rechargeable 9 volt lithium batteries either.We had a discussion here not too long ago about the apparently worsening leakage of alkaline cells and it was postulated that this has to do with the removal of mercury from cell construction.