Learned something today about my Voltage Meter

R.Boyd · 11-09-2018, 10:27 PM

I've been using a handheld digital voltage meter for years that I got from the home Depot that cost me about $50. Been using it monitoring my battery voltage etc and never thought about it being a little off in it's readings. Been checking the voltage on my US2200 batteries after charging them with my powerwise charger to see how close they come to a full charge. They been reading about 38.3 consistently. Finally got tired of that and bought one of those $10 voltage meters to install in the dash. I do a lot of hog hunting at night with gen 3 night vision and therefore decided to wire it into my 3 position key switch so the cart would be dark in the first on position and I could turn it to the light position and have the meter on. Since it's not drawing really any amps and I don't have lights working it would be perfectly which it did. After some research, I learned that the reading would probably be a little low after running through the switch as opposed to go straight to the batteries. Well, after getting it all wired in and having just charged the batteries I switched it on. Low and behold it was reading 38.6 volts after sitting for 12 hours. 0.3 higher than my hand held meter was showing. I knew that one was or the other was off, so I borrowed a really expensive Fluke meter from work. Low and behold it matches the cheap in dash meter exactly when measuring straight from the battery. All along, that cheap meter has been reading low by .3 of a volt when measuring the whole pack. So the moral of the story is that you can't always trust what your meter is telling you and sometimes it pays to check it every now and then. Guess I should check it on the low setting as well where it measures out to two decimals and see what happens. Just thought I would share.

LukeL · 11-09-2018, 10:42 PM

Thanks. For my personal cart I have one of Scotty’s voltage meters so I never check it with my multimeter. I guess I should tomorrow. Good way to test one or the other!

Club Car DS driver’s club #59

WalterM6 · 11-09-2018, 11:12 PM

That's what we used to call "No tolerance for tolerances". That is less than 1% off.

cgtech · 11-11-2018, 12:35 PM

Quote:

Originally Posted by WalterM6

That's what we used to call "No tolerance for tolerances". That is less than 1% off.

And a difference in measured SOC of about 10%

.

ggroff · 11-12-2018, 08:45 PM

I have one of the free HF meters that is spot on. I also have a free HF meter that is off by a full volt.

My Fluke is off by .5v but the newer Fluke I have at work is correct (It gets certified). Another guy at work has a Greenlee meter that reads about 1% high across all ranges.

If you want to be certain of your meter, you can call a calibration service and see if they will certify it for you. It's not cheap unless you can get it done through your employer, but it will verify accuracy.

Or.....

You can take voltage readings with whatever meter you have and make a chart. Check regularly and record, and watch for any trends. The absolute voltage isn't as important as the consistency.

In the past, I had to maintain a fleet of electric forklifts. We documented time on charge, time off charge, hours run per shift, voltage and hygrometer readings, general cleanliness of battery, and which forklift the battery was installed. We had a charging station with a crane to swap batteries when charge was depleted. This level of care and documentation meant we could get a 7 year life out of an industrial truck battery.

11-09-2018, 10:27 PM	#1
R.Boyd Getting Wild Join Date: Sep 2018 Posts: 96	Learned something today about my Voltage Meter I've been using a handheld digital voltage meter for years that I got from the home Depot that cost me about $50. Been using it monitoring my battery voltage etc and never thought about it being a little off in it's readings. Been checking the voltage on my US2200 batteries after charging them with my powerwise charger to see how close they come to a full charge. They been reading about 38.3 consistently. Finally got tired of that and bought one of those $10 voltage meters to install in the dash. I do a lot of hog hunting at night with gen 3 night vision and therefore decided to wire it into my 3 position key switch so the cart would be dark in the first on position and I could turn it to the light position and have the meter on. Since it's not drawing really any amps and I don't have lights working it would be perfectly which it did. After some research, I learned that the reading would probably be a little low after running through the switch as opposed to go straight to the batteries. Well, after getting it all wired in and having just charged the batteries I switched it on. Low and behold it was reading 38.6 volts after sitting for 12 hours. 0.3 higher than my hand held meter was showing. I knew that one was or the other was off, so I borrowed a really expensive Fluke meter from work. Low and behold it matches the cheap in dash meter exactly when measuring straight from the battery. All along, that cheap meter has been reading low by .3 of a volt when measuring the whole pack. So the moral of the story is that you can't always trust what your meter is telling you and sometimes it pays to check it every now and then. Guess I should check it on the low setting as well where it measures out to two decimals and see what happens. Just thought I would share.
R.Boyd Getting Wild Join Date: Sep 2018 Posts: 96

11-09-2018, 10:42 PM	#2
LukeL Gone Wild Join Date: Jun 2017 Location: Savannah, GA Posts: 6,539	Re: Learned something today about my Voltage Meter Thanks. For my personal cart I have one of Scotty’s voltage meters so I never check it with my multimeter. I guess I should tomorrow. Good way to test one or the other! Club Car DS driver’s club #59

11-09-2018, 11:12 PM	#3
WalterM6 Gone Wild Join Date: Apr 2017 Location: SE TN Posts: 2,226	Re: Learned something today about my Voltage Meter That's what we used to call "No tolerance for tolerances". That is less than 1% off.

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11-12-2018, 08:45 PM	#5
ggroff Not Yet Wild Join Date: Oct 2018 Location: Kimball MI Posts: 66	Re: Learned something today about my Voltage Meter I have one of the free HF meters that is spot on. I also have a free HF meter that is off by a full volt. My Fluke is off by .5v but the newer Fluke I have at work is correct (It gets certified). Another guy at work has a Greenlee meter that reads about 1% high across all ranges. If you want to be certain of your meter, you can call a calibration service and see if they will certify it for you. It's not cheap unless you can get it done through your employer, but it will verify accuracy. Or..... You can take voltage readings with whatever meter you have and make a chart. Check regularly and record, and watch for any trends. The absolute voltage isn't as important as the consistency. In the past, I had to maintain a fleet of electric forklifts. We documented time on charge, time off charge, hours run per shift, voltage and hygrometer readings, general cleanliness of battery, and which forklift the battery was installed. We had a charging station with a crane to swap batteries when charge was depleted. This level of care and documentation meant we could get a 7 year life out of an industrial truck battery.