calibration issue between instruments mppt-fluke

akskiffer

Member
Do you have matching readouts from charge controller to voltmeter? I am installing a new rover 20a mppt charge controller and using a fluke 10 multimeter. I have yet to add the true sine wave inverter into the mix.
My two differ on volts by close to two V.

the fluke is nice and its manual offers no calibration. The rover is new and its manual offers no calibration.

Any similar experiences?
 

john61ct

Adventurer
Fluke gets sent in for calibration.

I never trust readouts on charge sources, even ones that cost thousands
 

jonyjoe101

Adventurer
I would also check for voltage drop between controller and battery. I get a .5 voltage drop on my system, I have to increase the mppt controller bulk setting by .5 volts to compensate otherwise it would charge at 14 volts ( almost float voltage) instead of 14.4 volts.

It goes without question the fluke is accurate, you can use a cheap voltmeter and see if they are similar to the fluke.

Most controllers have small opening where you connect the battery wires, which limit how thick of wire gauge you can use, also distance to battery might be an issue. I use 10 gauge wire and even then it barely fit on my controller.
 

J!m

Active member
I have a Fluke 10 as well, and it is the bottom of the line.

Nice enough meter, but when I sent mine in for repair, the only option was replacement. I do not believe it is available with a cal cert as it is not able to be calibrated.

I don’t need that high accuracy currently but now that my continuity beeper died, I’ll be going for an upgrade.

PS make sure the battery is fresh. I was working on a project and low battery was giving inaccurate voltage readings on mine...
 

DaveInDenver

Middle Income Semi-Redneck
I have a Fluke 10 as well, and it is the bottom of the line.

Nice enough meter, but when I sent mine in for repair, the only option was replacement. I do not believe it is available with a cal cert as it is not able to be calibrated.

I don’t need that high accuracy currently but now that my continuity beeper died, I’ll be going for an upgrade.

PS make sure the battery is fresh. I was working on a project and low battery was giving inaccurate voltage readings on mine...
It's a low end Fluke but not a bad DMM at all. There is a procedure listed in the service manual for a performance test and if it fails how to calibrate it. It may be old enough and being discontinued that Fluke cannot repair them anymore, don't know about that.

The first hit in a cursory Google search listed a company who'll cal a Model 10 for $55: https://www.custom-cal.com/ModelInfo.aspx?kn=9060&srv=Calibration

100% agree on replacing the battery. Generally speaking I'd trust a Fluke that hasn't been abused or opened to be close enough even if it doesn't have a current calibration. The discrepancy is probably in how the OP is measuring or expectations.
 
Last edited:

J!m

Active member
I had mine replaced probably 15 years ago, maybe 20 now... basically felt like it was a disposable item.
 

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