How long should a multimeter battery last? - Page 1
Forum section: electronics / beginners

author: nangalakula
author_rank: Contributor
timestamp: May 04, 2025, 11:28:20 am
content: Hi all,I have an old simple digital meter, I think I have a 9V volt battery in it. I do not even remember when I had to change the battery in it or if I changed a battery in it ever.I recently bought a digital meter with auto range, loz (mainly this is why I bought this specific model), etc... Peaktech 2030. It has a 9v battery. The original battery, I got with the meter, was over within an hour. I thought maybe the battery was old or something like that.I've changed the battery and it is gone again. I do not think I used more than a few hours. Maybe 3-4 hours.Is this normal, expected? Or am I better off sending the meter back?

author: Xena E
author_rank: Frequent Contributor
timestamp: May 04, 2025, 11:42:00 am
content: Either the meter is junk or the batteries are.Use another meter to measure the current drain, if its higher than spec, send it back.X

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 04, 2025, 11:56:55 am
content: The worst meter would be good for about 100 hours per battery. The ones that consume little power the battery can last to 800 hours or so. If your battery only last a few hours then it's either the battery or the meter.

author: nangalakula
author_rank: Contributor
timestamp: May 04, 2025, 12:07:53 pm
content: I've measured it and it consumes ~42 mA when it is on. And I tried a few measures and it does not really change during metering something, may 1-2 mA extra.

author: Xena E
author_rank: Frequent Contributor
timestamp: May 04, 2025, 12:18:42 pm
content: Faulty, send it back.

author: nangalakula
author_rank: Contributor
timestamp: May 04, 2025, 12:27:01 pm
content: I've made some further measurements. It has a function to switch off the backlight. When I switch it off then the power consumption goes down to 2 mA.I bought a nimh 9v rechargeable battery when the very first included battery was over. VARTA Recharge Accu Power, 200 mA.So it has a capacity ~9v x 200 mA = 1800 mah.With backlight on: ~1800 mAh / (42 mA x 9v) = 4.7 hWith backlight off: ~1800 mAh / (2 mA x 9v) = 100 hBut it has a reversed display or called something similar, which needs the backlight to make it visible. So switching off the backlight is not really an option.So the question could be reformed if with the backlight on, is this runtime reasonably expected?

author: Gyro
author_rank: Super Contributor
timestamp: May 04, 2025, 12:32:47 pm
content: If the meter has the backlight on 100% of the time, the poor battery life is understandable. If it needs the backlight on to be able to read the display, it is a bad purchasing choice.

author: Aldo22
author_rank: Super Contributor
timestamp: May 04, 2025, 12:34:44 pm
content: That's a lot.I happened to measure this on my ZT-225 last week.Without backlight: 3mAWith backlight: 10mA (the backlight is not necessary with good ambient lighting).With the 3xAA batteries it lasts “forever”.

author: DavidAlfa
author_rank: Super Contributor
timestamp: May 04, 2025, 12:38:24 pm
content: Inverted LCDs is a really stupid trend...

author: Gyro
author_rank: Super Contributor
timestamp: May 04, 2025, 12:48:44 pm
content: I would definitely return it if possible, in favor of a 'normal' display. A little 9V battery isn't going to maintain its rated capacity when sourcing that sort of current. They are presumably pumping a lot of current into the backlight LEDs to make the small annunciators clearly visible.If not returnable, I would get used to a life of Lithium rechargeable batteries and frequent changes.

author: bdunham7
author_rank: Super Contributor
timestamp: May 04, 2025, 01:02:21 pm
content: Quote from: nangalakula on May 04, 2025, 12:27:01 pmFor that meter, apparently so. But that seems ridiculous for a fairly basic DMM as there are other perfectly usable DMMs that last from 200 to 1000 hours on a 9V battery.

author: Aldo22
author_rank: Super Contributor
timestamp: May 04, 2025, 01:10:02 pm
content: Quote from: DavidAlfa on May 04, 2025, 12:38:24 pmI have a UT123, which also has this, but at least “only” consumes 14mA (2xAAA).https://meters.uni-trend.com/product/ut123-ut123t/

author: nangalakula
author_rank: Contributor
timestamp: May 04, 2025, 01:17:35 pm
content: Which is more funny, it has auto power off. And now as I wired up things to measure its power consumption, now I know what happens when it auto power off.It switches the measuring function off, that 2 mA I measured earlier. And keeps the backlight on, and the power consumption/current stays at ~40mA while it is powered off. And light is visible when you look at the screen from the very side of it.

author: Gyro
author_rank: Super Contributor
timestamp: May 04, 2025, 01:24:38 pm
content: QuoteIn that case, I think you have a good claim against the retailer (first), and the manufacturer, for the product being 'unfit for purpose'.

author: nangalakula
author_rank: Contributor
timestamp: May 04, 2025, 01:31:14 pm
content: In theory I still have time to return.I try to send it back. Thanks for the advice. I bought the rechargeable batteries and the charger for this... maybe I can try to send those back as well (but I thrown out the packages of these so not sure if I can send these back).I try to look for a different model with loz mode.

author: ledtester
author_rank: Super Contributor
timestamp: May 04, 2025, 02:02:02 pm
content: Quote from: nangalakula on May 04, 2025, 12:27:01 pmA small point... when you multiply 9V by 200 mAh you get total energy storage measured in mWh (milli Watt-hours).It doesn't affect your conclusions because to get the run times you divide by 9V, but you could more simply start with the 200mAh and divide by 42mA to get 4.7h.

author: nangalakula
author_rank: Contributor
timestamp: May 04, 2025, 02:30:21 pm
content: Quote from: ledtester on May 04, 2025, 02:02:02 pmthanks, yes it is mWh

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 04, 2025, 02:45:20 pm
content: I would say return it if you can. Such a meter is not useful as I do run into meter like that. Actually it's a Fluke 279FC which Fluke states 10 hour battery time. It comes with rechargeable battery and although I don't use it often everytime I want to use it I have to charge it first.

author: Vincent
author_rank: Regular Contributor
timestamp: May 04, 2025, 03:18:04 pm
content: I've had a Mastercraft 52-0052-2 multimeter for 16 years. First one I ever bought.I'm not even sure I had to replace the battery THREE times total.Despite all its flaws, it's one frugal meter battery wise! Though I only use the backlight when necessary.

author: nangalakula
author_rank: Contributor
timestamp: May 04, 2025, 03:46:13 pm
content: Quote from: BeBuLamar on May 04, 2025, 02:45:20 pmYes, I agree. I have already filled the return form. Lets hope they accept it back.Quote from: BeBuLamar on May 04, 2025, 02:45:20 pmSounds painful, and it costs 1400 $ it must be pretty special to justify such price.

author: radiolistener
author_rank: Super Contributor
timestamp: May 04, 2025, 03:54:00 pm
content: Usually I recharge my Li-Ion 9V (8.4 actually) accumulator in DMM about once per 2-3 month.

author: nangalakula
author_rank: Contributor
timestamp: May 04, 2025, 03:57:44 pm
content: Quote from: Vincent on May 04, 2025, 03:18:04 pmI tend to give up on the loz stuff. It limits the models and especially the availability a lot.I've ordered a EMOS MD-430 finally to replace this peaktech. No reverse display so battery life should be fine. This reverse stuff looked nice, but to replace the battery so often, maybe does not worth the hassle. And it is in stock and cheap compared to the peaktech. It has auto power off as well, and hopefully it really works.It was a really surprise that the paektech APO let the backlit on, which gives the majority of the power consumption.

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 04, 2025, 04:57:30 pm
content: Actually my 3 Fluke meters the 189, 287 and 289 are heavy power consumption. The 189 only rated for 72 hours and the other 2 only 100 hours. I use AA Li-Ion rechargeable and they seem to be fine.

author: mwb1100
author_rank: Frequent Contributor
timestamp: May 04, 2025, 05:35:16 pm
content: Quote from: nangalakula on May 04, 2025, 01:17:35 pmYou've got to be kidding! How could that design failure escape review, much less QA?

author: Aldo22
author_rank: Super Contributor
timestamp: May 04, 2025, 05:55:51 pm
content: Quote from: nangalakula on May 04, 2025, 03:57:44 pmWhy did you choose this DMM? What advantages does it have?I had never heard of it before.

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 04, 2025, 06:20:14 pm
content: Quote from: mwb1100 on May 04, 2025, 05:35:16 pmQA doesn't determine if the product is right or wrong. QA job is to assure that the product conform to specifications. So if the meter was designed to work that way and if it shut off both the back light and power then in fact it shouldn't pass QA inspection. QA people should not decide how to product should be.

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 04, 2025, 10:26:34 pm
content: Quote from: nangalakula on May 04, 2025, 03:46:13 pmWell it's a thermal imager that's why it's expensive but the camera doesn't have focus and very low resolution. My boss bought it and didn't like it at all. I

author: SteveThackery
author_rank: Super Contributor
timestamp: May 05, 2025, 09:35:40 am
content: Keeping the backlight on even when in sleep mode is so extraordinary itmust(mustn't it?) be an actual electronic fault with the meter. It seems inconceivable they woud design it like that.

author: Gyro
author_rank: Super Contributor
timestamp: May 05, 2025, 10:16:25 am
content: Quote from: SteveThackery on May 05, 2025, 09:35:40 amIf the OP can manually turn the backlight on and off, it would have to be a very specific kind of electronic fault (I can't think of a simple single fault scenario that could cause it). I think it much more likely to be a design fault.

author: Psi
author_rank: Super Contributor
timestamp: May 05, 2025, 10:20:23 am
content: Assuming backlight control works fine when the meter is on it might be a missing or bad gate pull up/down resistor on the backlight control fet.It would work fine with MCU GPIO output to gate with MCU on, but with MCU sleeping and GPIO High-Z the gate could float up/down and turn backlight on.

author: Gyro
author_rank: Super Contributor
timestamp: May 05, 2025, 10:26:38 am
content: It depends how 'sleepy' it gets - whether it is actually a tristate output.

author: Psi
author_rank: Super Contributor
timestamp: May 05, 2025, 10:26:52 am
content: Yep, just a guess.I could see that kind of fault being missed in QA

author: Gyro
author_rank: Super Contributor
timestamp: May 05, 2025, 10:33:50 am
content: Unless somebody with the same meter (and revision?) chimes in, I guess we will have to consign it to the 'we'll never know' category, which is always a bit frustrating.

author: Xena E
author_rank: Frequent Contributor
timestamp: May 05, 2025, 12:04:19 pm
content: Listed as a discontinued product with RS.

author: SteveThackery
author_rank: Super Contributor
timestamp: May 05, 2025, 02:33:43 pm
content: Quote from: Gyro on May 05, 2025, 10:16:25 amYeah, possibly, but bear with me. Rambling a bit, but definitely on topic (see later), I've just repaired a radio with the opposite fault (sort of). It uses a push button, not a switch, to turn it on and off. Therefore the electronics around the button switch the power to the rest of the circuit.Except it doesn't quite work like that in this radio. The on/off button circuit powers up the radio and display, but the audio amplifier circuit is separately controlled. There is a continuous voltage supply to a high-side switch transistor adjacent to the amplifier IC, and that transistor is switched on and off by a signal from the microcontroller.This allows the audio amplifier to be powered up and down under software control.*The switching transistor had gone open circuit collector to base, so it couldn't power up the amplifier. HOWEVER,if the transistor had failed short circuit, the amplifier would be permanently powered, even when the circuit was switched "off".This could be the backlight problem: it is obviously software controlled, so maybe the power switching transistor for the backlight has failed short circuit.*I think software-controlled power to the audio amp is used to mute the amp when the radio is searching for stations, or something like that. Also maybe a short delay after power-on to let the radio stabilise.

author: mwb1100
author_rank: Frequent Contributor
timestamp: May 05, 2025, 04:10:12 pm
content: Quote from: BeBuLamar on May 04, 2025, 06:20:14 pmI made the wild assumption that auto power off would be specified to reduce current draw to a minimal value. I believe this is a reasonable assumption.I also made the assumption that this problem is not simply a defect in this particular user's meter (and other posts make it clear that this assumption could well be very wrong).

author: nangalakula
author_rank: Contributor
timestamp: May 05, 2025, 07:04:22 pm
content: I've packed the meter and will be taken tomorrow.I was thinking that this auto sw off, not switching off the backlight is a design problem. But I have a single copy of the device so I cannot tell. I can hardly imagine that I got a faulty one. As it otherwise works as expected, I think.

author: SteveThackery
author_rank: Super Contributor
timestamp: May 05, 2025, 07:07:04 pm
content: Quote from: mwb1100 on May 05, 2025, 04:10:12 pmI totally agree. I can't know for certain, but I am 99.9% convinced that nobody would design a multimeter which kept its backlight on while ever there's a battery in it. Three or four hours on the bench, not even used, and it needs a new battery? Sotwo or three batteries every working day? No chance.

author: nangalakula
author_rank: Contributor
timestamp: May 05, 2025, 07:12:49 pm
content: Quote from: Aldo22 on May 04, 2025, 05:55:51 pmThis one was available in a local store, this was the main reason.I am looking for, if I ever find, one which has loz (preferable) + the backlight can be switched off and on as it is needed, and it is not auto, or switching off after 15 sec and like...I've tried this MD-430 and it is the version which turns its backlight off after 15 sec. So no success yet.Now I looked up the uni-t models. and maybe UT61D+ (or maybe 161D) is such. But it is not easy to get and looks a bit expensive.Does someone have it here. Can the backlight be switched on/off freely (without this 15 sec auto turn off which is everywhere)?

author: nangalakula
author_rank: Contributor
timestamp: May 05, 2025, 07:21:03 pm
content: Quote from: SteveThackery on May 05, 2025, 07:07:04 pmIt can be a design error as well, unintentional design problem. But totally unreasonable.I would not even discover it if Xena E does not suggest to measure the power consumption of the meter. I haven't noticed it earlier while it switched off. You have to look at the screen from the very side to see that the led(s) are still on.

author: nangalakula
author_rank: Contributor
timestamp: May 05, 2025, 07:45:43 pm
content: I have found the uni-t 161D in a shop. The user manual says the backlight can be switched on/off and it does not mention that it switches off automatically after 15 sec or such. And it has the same price as the peaktech.If you have such meter please can you tell if its backlight switches off automatically or not?

author: mwb1100
author_rank: Frequent Contributor
timestamp: May 05, 2025, 09:01:06 pm
content: The UniT UT161D:- after 15 minutes of "no operation" will automatic power off (APO). APO can be disabled by holding SELECT during power on. I believe that "no operation" means no button presses or switch changes. I'm pretty sure the APO doesn't monitor reading changes like a few meters do.- the backlight turns off after 15 minutes (NOT seconds). I don't think this behavior can be disabled, but 15 minutes is pretty generous.Like most multimeters with a backlight, it can be turned on & off freely.I don't know for certain if the UT61D Plus has the same behavior, but I'd be a little surprised if it didn't. The UT61D Plus is essentially the same as the UT161D with lower-rated fuses (and maybe some other protections removed - I can't remember). The UT61 Plus is significantly less money if I recall.Both meters are pretty nice in my opinion.

author: Aldo22
author_rank: Super Contributor
timestamp: May 05, 2025, 09:48:22 pm
content: Quote from: mwb1100 on May 05, 2025, 09:01:06 pmWith the Zoyi ZT-225, the backlight also remains on when APO is disabled.But it still beeps after 15 minutes.

author: nangalakula
author_rank: Contributor
timestamp: May 05, 2025, 10:53:24 pm
content: Thanks a lot, it is not a problem if it turns off after the 15 min as the result of the APO.I tried one before this peaktech and now this MD-430 and both switched off the backlight after about 15 seconds. So if the lighting conditions are not too ideal it is a hassle to re-enable the backlight all the times. And a lot of times it is not defined in the user guide or it is, and nowdays a lot of meter switches off after 15 second or so or they have a kind of auto backlight. And the meter decides if the backlight is switches on or not.So thanks, if the UT161D is such that it keeps it on while the APO is not activated. Than it is perfect (also it has loz) and it seems I can order that one. I try to get one.Quote from: Aldo22 on May 05, 2025, 09:48:22 pmSounds good. I check it out and see if I can order it somehow. It could be nice for a second one without loz.

author: Xena E
author_rank: Frequent Contributor
timestamp: May 06, 2025, 12:00:39 am
content: @ nangalakula...anecdotal comment your academic interest...Ealier today I posted a request on my company groups.io for comment from anyone who has had experience of the Peaktech brand of multimeter that you inquired about in this thread.One reply from a technician who owns one privately, (purchased in Germany), says that he is happy with the meters performance and accuracy, however, it's battery life performance is poor... though not as bad as yours.He claims that his perhaps manages 20 to 30hours on a store brand alkaline battery. It's current consumption is 7-8 mA when measured.It does make me believe that yours was faulty in some way, 40+ mA drain from 9 Volts would be an incredibly bright backlight if that's what caused the drain.X

author: nangalakula
author_rank: Contributor
timestamp: May 06, 2025, 04:34:23 am
content: Quote from: Xena E on May 06, 2025, 12:00:39 amSounds more reasonable.

author: nangalakula
author_rank: Contributor
timestamp: May 06, 2025, 04:43:01 am
content: I've just got a replay from kaiweets about their meters. I've asked them about the 15 sec turn off. And even though it is never mentioned in any of their manuals or data sheets for the meters, their Black and White, their traditional meters, turn the backlight off after 15 sec.Maybe I am the only one who cares about this

author: mwb1100
author_rank: Frequent Contributor
timestamp: May 06, 2025, 05:50:23 am
content: Quote from: nangalakula on May 06, 2025, 04:43:01 amNope: unreasonably short backlight duration drives me crazy. I think the minimum that a backlight's auto off should be is 1 minute.I have also checked on some UT161D backlight behavior that I may have been unclear about in my last post:- if APO is enabled (the default), when it kicks in (ie., the meter turns off) the backlight turns off as well- if APO is disabled and you turn the backlight on, the back light willnotauto off. This behavior surprised me a little, but since I rarely disable APO it's no concern to me.- turning on MIN/MAX or USB data logging will disable APO. I don't think this is mentioned in the manual, but it's common behavior for multimeters.

author: Xena E
author_rank: Frequent Contributor
timestamp: May 06, 2025, 06:42:01 am
content: Be aware that there are brands of multimeter out there that have a slimline form factor that use coin cells for power! Expensive nightmare to own some of them. Just thought of that as Kaiweets were mentioned... unless it is for a pocket multimeter, (I have one that uses two LR44 cells), and it is required to use disposable batteries, there's no real reason tonotuse AA cells ... apart from the higher risk of leakage.It must also be remembered that although a lot of meters share the same annoying functionality of the back light, that is because they also share the actual chipsets...If I were to specify, I would have the backlight turn on and off manually, but of course also turn off after the auto off timeout the meter itself. Modern LEDs also don't need massive drive currents to be effective backlighting either.X

author: SteveThackery
author_rank: Super Contributor
timestamp: May 06, 2025, 08:52:32 am
content: Quote from: Xena E on May 06, 2025, 12:00:39 amThat seems pretty reasonable to me. And it is ten times longer than the OP's.

author: Aldo22
author_rank: Super Contributor
timestamp: May 06, 2025, 09:10:44 am
content: Quote from: nangalakula on May 05, 2025, 10:53:24 pmThe cheapest way to buy Zoyi devices is at Ali Express:ZOYI Official Store

author: MathWizard
author_rank: Super Contributor
timestamp: May 08, 2025, 03:51:14 pm
content: Quote from: Psi on May 05, 2025, 10:20:23 amDid the OP open up the DMM ? Maybe some resistor lead was touching the wrong thing, or even solder balls. My Byrmen235 had some solder-ball somewhere, and I think it used to short something and drain the battery, if the dial was turned a bit too much in some place.But yeah, backlights and reverse LCD screens, not a good combo.

author: nangalakula
author_rank: Contributor
timestamp: May 16, 2025, 01:17:50 am
content: Quote from: MathWizard on May 08, 2025, 03:51:14 pmIt wasn't opened, except the compartment of the battery.I've got the UT161D. And with a backlight which is on when it is needed and does not sw off after 15 sec, what a relief.It came with an adapter with K-R-C +/- signs. The manual does not say anything about it. It only talks about the adapter for the 161E and with the hFE option for measuring transistor magnification (the 161D do not have hFE).I measured the adapter and it connects +/- to the common and to the V/ohm etc. terminal and the transistor poles are not connected. So I guess this +/- part can be used to test diodes. What you can test with the test leads anyway. I tried it with an LED and it works as expected.Do you know what these K-R-C stands for? And how you use it? The user manual does not tell anything about it. Maybe I should just know it...