Why does my multimeter sometimes say zero when measuring the voltage on my car battery?

[Muse]

Drives me nuts. I got a new battery installed in my car a couple weeks ago by AAA affiliated local company. Seems to be fine. Using two multimeters, one a Triplett (bought online, around $50) the other Ames (bought from Harbor Freight, not one of their cheapies), either often says 0.00 volts DC.

The Ames MM has V as AC/DC, either. The other I set at 20volts DC max.

Sometimes they do show the voltage. I got one today to say 12.63v for a bit. Or it goes immediately to 0.00 again. I have tried moving the dial back and forth between detents, thinking some contact(s) aren't making a good connection. That's worked sometimes. The other day pulling out the leads and reinserting has fixed the problem. Today, neither fixed the issue. I'm pressing the probes onto the top of the battery posts, which are clean metal and with force, of course.

I have a Fluke MM but am afraid to even try it thinking it may affect the device, but I assume it would work.

Is it that the battery has too much power?

AI is no help.

 

[pcgeek11]

Is there a reason you think the battery has issues?

If you are making good contact with the battery terminals, the meter leads are not damaged / plugged in correctly to the meter and the battery starts the engine I would venture to guess you have two shitty meters.

Why not try the Fluke Meter? That is what it is made for. Set it to DC Volts and hold the red to the positive terminal and the black to the negative terminal. Most are auto-ranging. If no auto-range set it to the largest voltage expected.

I doubt your battery is overcharged.

 

[Red Squirrel]

Maybe a dodgy rotary switch, maybe it's not always contacting properly when you switch it to volts. When it does that, test a 9 volt battery or something just to confirm if it's the meter.

 

[Muse]

Maybe a dodgy rotary switch, maybe it's not always contacting properly when you switch it to volts. When it does that, test a 9 volt battery or something just to confirm if it's the meter.

I took it inside and it read a small 12v remote battery fine, same MM that read 0.00 on the car battery.

 

[Muse]

Is there a reason you think the battery has issues?

If you are making good contact with the battery terminals, the meter leads are not damaged / plugged in correctly to the meter and the battery starts the engine I would venture to guess you have two shitty meters.

Why not try the Fluke Meter? That is what it is made for. Set it to DC Volts and hold the red to the positive terminal and the black to the negative terminal. Most are auto-ranging. If no auto-range set it to the largest voltage expected.

I doubt your battery is overcharged.

I'm only testing the car battery because I want to keep tabs on it. I sometimes don't drive for 1, 2 or 3 weeks at a time. I sometimes keep a charger on the battery. I had reason to suspect I had a battery drain issue, maybe constant, maybe occasional. One day about 3 months ago I came to the car and it wouldn't start. A MM read 0.00. I now think maybe that reading was faulty, but the car wouldn't make a peep when I turned the ignition key, so I thought it was dead. Got a jump from neighbor and drove a while, brought car to shop who said battery and alternator were OK. I decided battery drain. Also had issues to security system, which would sometimes work, sometimes wouldn't and in recent times wouldn't work. Had that ripped out and a new one installed a week or two after the battery appeared to go dead. All this has me wanting to keep tabs on the battery so I've been taking readings most days since the new battery was installed. The AAA guy who installed it tested my old battery and said it was a goner.

Yeah, maybe both MMs have issues. Dunno.

 

[pcgeek11]

I'm only testing the car battery because I want to keep tabs on it. I sometimes don't drive for 1, 2 or 3 weeks at a time. I sometimes keep a charger on the battery. I had reason to suspect I had a battery drain issue, maybe constant, maybe occasional. One day about 3 months ago I came to the car and it wouldn't start. A MM read 0.00. I now think maybe that reading was faulty, but the car wouldn't make a peep when I turned the ignition key, so I thought it was dead. Got a jump from neighbor and drove a while, brought car to shop who said battery and alternator were OK. I decided battery drain. Also had issues to security system, which would sometimes work, sometimes wouldn't and in recent times wouldn't work. Had that ripped out and a new one installed a week or two after the battery appeared to go dead. All this has me wanting to keep tabs on the battery so I've been taking readings most days since the new battery was installed. The AAA guy who installed it tested my old battery and said it was a goner.

Yeah, maybe both MMs have issues. Dunno.

I would use the Fluke Meter. Their meters are very robust and are known for quality.
I always check a known voltage source before checking the questionable source. That way you know the meter is working as it should. I personally wouldn't trust any meter from Harbor Freight.

In my many years working in electrical and electronics I have always been able to trust my Fluke Multi Meter. They also make a doohickie to plug into the DC port for a cigarette lighter that will display the voltage.

Amazon.com : voltage display for car

 

[Red Squirrel]

You should set up a charger then plug it in when you get home. You can also add a battery disconnect switch and turn it off when you don't plan to drive for a while.

Had to do that with my truck as it barely lasts 12 hours idle now, I need to figure out what's eating up the battery, it's just been too cold to start messing with that.

 

[pcgeek11]

Had to do that with my truck as it barely lasts 12 hours idle now, I need to figure out what's eating up the battery, it's just been too cold to start messing with that.

That could just as well be an internal battery issue as in a partially shorted cell.

 

[olds]

Two bad meters or operator error. No offense, but I'd guess the later.

I have a truck I don't drive often; so, I have something like this plugged into the cigarette lighter: https://www.amazon.com/SUNAPEX-maintainer-Portable-Motorcycle-Snowmobile/dp/B07QB3N2PW

 

[nakedfrog]

Try measuring from the terminal connector instead of directly on the terminal, if that's what you're doing currently?

 

[Muse]

Two bad meters or operator error. No offense, but I'd guess the later.

I have a truck I don't drive often; so, I have something like this plugged into the cigarette lighter: https://www.amazon.com/SUNAPEX-maintainer-Portable-Motorcycle-Snowmobile/dp/B07QB3N2PW

I have two types of battery maintenance devices. A cheap trickle from Harbor Freight (actually several), which does really work to maintain charge but is slow compared with my at-the-time ~$30 higher performance battery maintenance charger from Kragen.

Operator error, sorry pal, I know how to use a multimeter. I have at least 7 of them and have used for a couple decades.

 

[Muse]

Try measuring from the terminal connector instead of directly on the terminal, if that's what you're doing currently?

Yeah, I will. Seems the top of terminal, solid metal, would have to work but yeah, I'll try that.

 

[Red Squirrel]

That could just as well be an internal battery issue as in a partially shorted cell.

Brand new battery, I originally replaced it because I thought it was the battery but then it did it to the new one too. I did put my meter on it at one point and found that it was drawing about 0.6 amps idle, just need to investigate further to see what the draw is, by pulling one fuse at a time to try to narrow it down. If it's something that's not important like the radio or the auto starter I'll just leave it out, otherwise I'll bring it to the shop. My mechanic told me I really shouldn't put much more money into this truck though so I really should try to start looking for another. There's just not much on the market, and trying to find one with an 8 foot bed is going to be very hard, probably have to even give up on that idea. Vehicles are so retarded expensive now so new is just out of the question, at least until the mortgage and credit line is paid off, even then it's hard to justify to put basically half the money I paid for my house towards something that I will get MAYBE 20 years out of if I'm lucky. .

 

[Muse]

Brand new battery, I originally replaced it because I thought it was the battery but then it did it to the new one too. I did put my meter on it at one point and found that it was drawing about 0.6 amps idle, just need to investigate further to see what the draw is, by pulling one fuse at a time to try to narrow it down. If it's something that's not important like the radio or the auto starter I'll just leave it out, otherwise I'll bring it to the shop. My mechanic told me I really shouldn't put much more money into this truck though so I really should try to start looking for another. There's just not much on the market, and trying to find one with an 8 foot bed is going to be very hard, probably have to even give up on that idea. Vehicles are so retarded expensive now so new is just out of the question, at least until the mortgage and credit line is paid off, even then it's hard to justify to put basically half the money I paid for my house towards something that I will get MAYBE 20 years out of if I'm lucky. .

I thought I'd have to bring it to a shop to ID the drain if I decided there is a drain but I did a search and some great YT videos popped up showing how I can find a drain myself. I thought I bookmarked them (in my personal data) but can't find them. An internet search on parasitic drain of car battery will bring them up.

I miss my old Town and Country because it had big trunk and more than that a roof rack. I could tie down 4x8 pieces of plywood on that.

 

[William Gaatjes]

Yeah, I will. Seems the top of terminal, solid metal, would have to work but yeah, I'll try that.

Have you tried this ?
Turn on your car radio while measuring the battery. If there is music but your measurements are still not between 10V and 13.8V, you have a clue where too look . And try using the fluke multimeter. Of course, set it to DC not AC.
Also, be aware that during cranking the engine, the battery voltage of the lead acid battery can drop easily as low as 6V.

 

[snoopy7548]

Are you using the same leads between meters? You could have an intermittent connection. Try measuring lead-to-lead resistance while moving the wires and see if it remains at <1ohm or jumps around.

 

[jmagg]

Are you using the same leads between meters? You could have an intermittent connection. Try measuring lead-to-lead resistance while moving the wires and see if it remains at <1ohm or jumps around.

Bingo. Cheap multi meters are notorious for broken leads.

 

[Muse]

I conclude that pressing lead tips into terminal tops is an iffy proposition. Somehow I get discontinuity sometimes. Maybe it's the leads. I haven't dug into that. Seems more likely that conduction from terminal top isn't happening although pressing lead tips firmly into top. The terminal tops show prominent dents from previous actions. It's not very hard metal, have no idea what the composition is but obviously it's chosen to be conductive.

Went out to car this morning, popped hood. Brought 3 multimeters:

Fluke 15B+

Ames (Harbor Freight ~$25 MM, AMES INSTRUMENTS DM600 Compact Digital Multimeter This is rebadged Mastech 8238C from European market, where it's disappeared. Auto-ranging and tests 1.5v and 9v batteries under load, has most other features of my new Triplett 1101-B MM, and Klein MM400 (which don't have under load battery testing AFAIK) ~$25

Triplett Compact CAT II 1999 Count Digital Multimeter - AC/DC Voltage, AC/DC Current, Resistance, Temperature, Continuity, Diode Check, and Transistor Check (1101-B) $35.47 off Amazon, Dec. 2021

Also brought a small remote battery, 12v
- - - -
First tried the Ames on top of battery posts set to read DC volts 20v range, read 12.61v

Then tried the Triplett and it read 0.00v using the DC volts detent. Applied its leads to the small 12v battery, it read 12.36. Then pressed leads to metal collars, not the post tops and it read 12.61v.

Then tried the Fluke on the post tops using the DV volts detent and it read 12.61v.

 

[olds]

I conclude that pressing lead tips into terminal tops is an iffy proposition. Somehow I get discontinuity sometimes. Maybe it's the leads. I haven't dug into that. Seems more likely that conduction from terminal top isn't happening although pressing lead tips firmly into top. The terminal tops show prominent dents from previous actions. It's not very hard metal, have no idea what the composition is but obviously it's chosen to be conductive.

Went out to car this morning, popped hood. Brought 3 multimeters:

Fluke 15B+

Ames (Harbor Freight ~$25 MM, AMES INSTRUMENTS DM600 Compact Digital Multimeter This is rebadged Mastech 8238C from European market, where it's disappeared. Auto-ranging and tests 1.5v and 9v batteries under load, has most other features of my new Triplett 1101-B MM, and Klein MM400 (which don't have under load battery testing AFAIK) ~$25

Triplett Compact CAT II 1999 Count Digital Multimeter - AC/DC Voltage, AC/DC Current, Resistance, Temperature, Continuity, Diode Check, and Transistor Check (1101-B) $35.47 off Amazon, Dec. 2021

Also brought a small remote battery, 12v
- - - -
First tried the Ames on top of battery posts set to read DC volts 20v range, read 12.61v

Then tried the Triplett and it read 0.00v using the DC volts detent. Applied its leads to the small 12v battery, it read 12.36. Then pressed leads to metal collars, not the post tops and it read 12.61v.

Then tried the Fluke on the post tops using the DV volts detent and it read 12.61v.

So, operator error?

 

[KLin]

PEBVAC

Problem Exists Between Voltmeter and Car.

 

[Muse]

Jerks drop gaslighting.

When I press metal leads into the metal battery terminals I expect the conduction of electricity if there's a major difference of potential. WTF is that so hard to understand?

 

[Red Squirrel]

Is there some kind of coating on the battery terminals? Maybe they sprayed some sort of conformal coating or something so you don't get good contact. Get some alligator clips and go from the multi meter tips to a PC fan and then probe the battery, if the fan also doesn't turn on when you get 0 then it might be that you're not getting good contact, if the fan turns on but you still get 0 volt it's an issue with the meter, maybe the socket where the leads plug into or the rotary dial, or maybe even the probe tip itself is loose internally where it connects to the wire.

 

[Muse]

Is there some kind of coating on the battery terminals? Maybe they sprayed some sort of conformal coating or something so you don't get good contact. Get some alligator clips and go from the multi meter tips to a PC fan and then probe the battery, if the fan also doesn't turn on when you get 0 then it might be that you're not getting good contact, if the fan turns on but you still get 0 volt it's an issue with the meter, maybe the socket where the leads plug into or the rotary dial, or maybe even the probe tip itself is loose internally where it connects to the wire.

The battery terminal tops don't look coated and I jam the pointy tips of the leads into them. It really is weird. Sometimes the MM digits jump but don't display anything coherent. I'm going to keep bringing a bunch of stuff out there not just one of my middle-quality MMs, which are the Ames and the Triplett. I'll bring the Fluke too and one or two small batteries. I used to use the cheap cheap Harbor Freight MMs, I think they gave them away almost, they were so cheap. I still have several. They are relatively tiny. They used to work for me most times reading the voltage on my car battery. I used them for AAAs and AAs too around the house. Mostly now I use the Ames or the Triplett. The Fluke I have but it's so big it doesn't fit in my tool drawer in the kitchen, kind of the focus of my house, my kitchen is. I rarely use the Fluke, just when I really need some certainty.

 

[lxskllr]

Maybe oxidation on the terminals. Try hitting them with a file.

 

[snoopy7548]

Just don't place the file across both terminals at the same time...