*Volt Meter Drops Below 13 Volts*
 

It started pouring down rain today so my yard project came to a halt. I made a trip to Harbor Freight and picked up a multimeter just to see what my charging system is doing as my in-dash meter (Classic Instruments) was showing below 13 volts at times with the AC on. This time the meter showed about the same as the multimeter. It never dipped below 13 volts. Probably need to check it next time I see it drop below 13 volts to see if its the gauge which I suspect or my charging system. What do you guys think about the numbers I'm seeing?

Pic #1 - Engine running, electric fuel pump, and electric fan
Pic #2 - Engine running, electric fuel pump, AC on with blower on high
Pic #3 - Engine running, electric fuel pump, AC on with blower on high, radio on, headlights on

Re: *Volt Meter Drops Below 13 Volts*
 

I only see one picture, but nothing is wrong with any of those 3 voltage readings, charging system is keeping output voltage well above battery voltage..

Re: *Volt Meter Drops Below 13 Volts*
 

I'm wondering where you're sensing wire is attached?

Re: *Volt Meter Drops Below 13 Volts*
 

I agree and where you take your readings is important too. you want to check voltage at the load to see if you are getting plus 13 at the main junction. You say you've seen below 13 with the accessories on. its important how your alternator output wire is ran too. if you've run it directly to the battery positive, you might not get full voltage to your accessories.

Re: *Volt Meter Drops Below 13 Volts*
 

Thanks guys. Not sure where the sending wire is attached. That may be something I need to check out. My readings where taken at the battery. All I was looking for was to see if there were any readings below 13 volts. Before I took these readings I was thinking the in dash gauge was maybe off a little.

Re: *Volt Meter Drops Below 13 Volts*
 

Where the readings took with the motor just idling are reved up? If it was just idling rev it up and see how they read. If they go up a little I see nothing wrong with it. If it drops below 13 every now and then it could be the AC cycling on/off causing it while under a heavy load. If it only drops for a few seconds I wouldn't be to worried. I see nothing wrong with it as is.:chevy:

Re: *Volt Meter Drops Below 13 Volts*
 

Thought I would recheck the charging system again today in hopes of seeing the in-dash volt meter reading below 13 volts and it did. I wanted to make sure I'm still getting good reading across the battery while the in-dash meter is showing low. I feel better now. I was afraid the wife and I would drive somewhere and get stranded with a dead battery. Whatya think of these reading on the multimeter vs the in-dash meter? I don't know if there is any way to adjust the in-dash meter as sometimes it reads correct and some times it's a little off as the pic shows.

Re: *Volt Meter Drops Below 13 Volts*
 

Is it possible to take a voltage reading on the terminal post of the meter itself and compare it to the reading on the dvm?? Varying voltage indications on the dash meter could be due to varying loads that affect the actual charge voltage..

Re: *Volt Meter Drops Below 13 Volts*
 

Can't get to the back of the meter. I'm just Glad the reading across the battery is not below 13 volts. The battery that was in the truck when I got it was about 5 years old so I'm guessing the PO wasn't having any battery issues.

Re: *Volt Meter Drops Below 13 Volts*
 

.
FWIW,

Mine does the same thing...Volt meter consistently reads ~1 volt lower than actual measurements at the battery. I rewired my entire firewall forward charging/starting/accessories to try and fix but no luck. I have peace of mind though due to my testing just like you, now I am confident that when I see 12.5 on my dash, I can be certain it's 13.5+ at the battery ( this is when everything is running full blast ( blower motor, lights, cooling fans, etc ).

-klb

Re: *Volt Meter Drops Below 13 Volts*
 

I hear ya. Ive been reading about a lot of temp, oil, volt gages that don't read correctly. You would think what we have to pay for these gages that they could at least do a little better at quality control. I'm running Classic Instruments.

Re: *Volt Meter Drops Below 13 Volts*
 

Haven't you heard?? It's the Chinese Free Enterprise System in action.. Make it as cheap as you can and sell it for as much as you can..

Re: *Volt Meter Drops Below 13 Volts*
 

Yup you and me are basically running the same...

-klb

Re: *Volt Meter Drops Below 13 Volts*
 

Too duplicate the meter reading you need to measure from the same points
Measurements from different will cause difference in readings as wire lengths and load differences in different spots will vary the readings

And a 20 dollar harbor freight meter are not that reliable it will give you a ball park reading but will not be as accurate or quickly reponsive as a Fluke meter

Re: *Volt Meter Drops Below 13 Volts*
 

Never heard of Fluke...until today. When I have a spare 350+ bucks I think I might want to pick up this fine bit of kit...

Fluke 117/323 Electricians Combo Kit, Digital Multimeter and Clamp Meter
https://www.fluke.com/en-us/product/...ke-117-323-kit

-klb

Re: *Volt Meter Drops Below 13 Volts*
 

Thanks for the info but Man....at $350 that Fluke meter better be able to fetch me a cold beer while I'm taking the reading ☺. I'm not looking to really drill down and get the exact reading with the best meter on the market....just wanted a ball park reading to see if my in-dash gage was reading low and it is.

Re: *Volt Meter Drops Below 13 Volts*
 

I am not saying buy the good meter you need to understand a cheap meter is more a good ball park and may not have fast resolution for an instant reading

A good test i found on a truck for how fast a meter reads is test your trailer receptacle with a meter

I have a 800 dollar meter from the snapon guy that fails this test

Re: *Volt Meter Drops Below 13 Volts*
 

My mother in law bought me a Fluke for Christmas a few years ago, I never looked back.

Re: *Volt Meter Drops Below 13 Volts*
 

As others have mentioned, the lower reading at the gauge is at least partly due to the length of wire and how ever many joints are in that wire between the gauge and the battery where you are attaching the meter. It would, IMO, be a waste of time trying to run a heavier direct wire just to try to get the gauge up to what the meter reads.

As someone said, realizing that the gauge reads 1/2-1 volt lower than actual battery voltage should give you enough peace of mind.

Re: *Volt Meter Drops Below 13 Volts*
 

Again no reason to be worried. It could be the AC cycling. It could be a number of things but if it's reading 13 and above you should be ok. Do the lights go dim when you let off the gas. It could be belt slipping even.
Then again it could be the gauge but as stated you would need your meter hooked up where it's connected to see.
As long as the battery is getting 13 are more volts when everything is running your fine.:chevy:

Re: *Volt Meter Drops Below 13 Volts*
 

As long as the dash guage stays around 13V, and the battery voltage when running is ~13.5 or so I wouldn't worry.
As far as a DMM is concerned, Fluke is great. Mine was last calibrated in 1989. You can pick up a good meter from CL for example for less money. Just make sure you test all functions before buying.