Voltage Calibration?

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Re: Voltage Calibration?

Postby Kent Osterberg on Thu Feb 17, 2011 10:25 am

I very much appreciate the comments regarding a 6000 count VM. I would welcome any exact make/model suggestions. I must have something I can trust.

Take a look at the Fluke 114 or 115 multimeter, the 115 includes a 10-amp range. At 12 volts they have an accuracy of ±0.08 volt.

Voltage is not a very useful indication of battery SOC. Voltage depends greatly on the discharge current, the battery age, and temperature. That's why amphour based devices like the Flexnet DC are useful. If you set up the AGS to use both the Flexnet DC SOC and voltage, it'll keep the depth of discharge near near the value you want it to be. Getting your battery properly and fully charged will have much more of an effect on its health and longevity than the exact depth to which it is discharged.
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Re: Voltage Calibration?

Postby flyinghigh on Thu Feb 17, 2011 10:31 am

I looked it up.

The 2812 inverter has a DC output accuracy of 2%...or .24 volts at 12v

I could not find that spec for the FM80

If using the 2812 to charge, one could be charging your AGMs at 14.7 according to the mate, but really be putting out 14.94...nearly 15 volts. (That would smoke em good...)

or you could be putting out 14.46 and undercharging them every day.

Basically it is a .48 range of accuracy...nearly half a volt.

The fluke 87 has a voltage accuracy of .05% if anyone is looking for a good VM.
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Re: Voltage Calibration?

Postby Kent Osterberg on Thu Feb 17, 2011 12:35 pm

The 2812 can be adjusted in 0.1 volt steps. The adjustment is a little coarse, but it can be adjusted so that it charges to the desired value within ±0.1 volt. That meets battery manufacturers' requirements.
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Re: Voltage Calibration?

Postby flyinghigh on Thu Feb 17, 2011 1:11 pm

Good point Kent. After I find a VM I can trust I will do that. :grin:

Then I can do the same with the FM80 and I should be good to go.
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Re: Voltage Calibration?

Postby coolness on Sat May 21, 2016 1:12 pm

Can anyone tell me how to calibrate the flexnet DC voltage manually as mine is reading 2.5 V too high
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Re: Voltage Calibration?

Postby coolness on Sun May 22, 2016 11:14 am

coolness wrote:Can anyone tell me how to calibrate the flexnet DC voltage manually as mine is reading 2.5 V too high
I just figured it out now it's
within .04 V accuracy via manual calibration
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Re: Voltage Calibration?

Postby ssiems on Sat Sep 24, 2016 9:37 pm

I can correct the inverter voltage to read the same as I am reading at the battery's and the same as the charge controllers.my charge controllers read the same as what I am reading at the battery's with out correction. The readings as seen by the fndc are high by 1.3 volts. That can be the difference between 100% charge and 80% charge.
could it be that you have to use the full length of the leads that come with the fndc to power it? as I am only using about a foot of the wire. Does the Resistance of the wire enter into the calibration ? as far as I can tell there is no way to calibrate the fndc. with the fndc controlling the charging and discharging I would think errors in this amount could be very detrimental to battery charging and battery life!
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Re: Voltage Calibration?

Postby ssiems on Sat Sep 24, 2016 9:40 pm

I can correct the inverter voltage to read the same as I am reading at the battery's and the same as the charge controllers.my charge controllers read the same as what I am reading at the battery's with out correction. The readings as seen by the fndc are high by 1.3 volts. That can be the difference between 100% charge and 80% charge.
could it be that you have to use the full length of the leads that come with the fndc to power it? as I am only using about a foot of the wire. Does the Resistance of the wire enter into the calibration ? as far as I can tell there is no way to calibrate the fndc. with the fndc controlling the charging and discharging I would think errors in this amount could be very detrimental to battery charging and battery life!
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Re: Voltage Calibration?

Postby ssiems on Sun Sep 25, 2016 6:56 am

OK Guys and Gals hears the scoop on the fndc
This is what 50 years of electrical engineering is telling me.
Most all accurate voltmeters are 100,000 ohms or higher per volt in lay mans terms they do not draw any current and that's why they are very accurate .
when they designed the fndc they used the wires that power it to also tell it the voltage (not a very good idea) what that results in is that there is current flowing in the circuit
any thing in the path on the negative side or the positive side that has resistance of any amount is going to effect the voltage reading that would include the wire and any connection in the circuit.
There probably is no way they can correct it with software changes.
Here is what I would suggest if your voltage readings are low go to a larger gauge wire If your readings are high as mine are insert resistance in the negative power wire .
I will be trying this tomorrow and will post suggestions on what will work.

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Re: Voltage Calibration?

Postby ssiems on Sun Sep 25, 2016 1:03 pm

as I stated in my post my voltage reading on the flex unit were 1.3 volts high I placed a 10ohm 10 turn variable resistor in series with the negative lead of the fndc and was able to calibrate the voltage reading with in .05 volts. If you have a problem of your readings being to low you might try to shorten the power leads it may help also check your connections if your terminal ends are crimped on I would suggest you solder them. I have determined the length of the leads supplied with the unit only measure .1 ohm which would not effect the reading short or long.I had to add about 7 ohms to get my readings correct. If your readings are lower then the battery voltage you will probably have to get a different fndc.



Stan
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Re: Voltage Calibration?

Postby coolness on Sun Sep 25, 2016 4:34 pm

ssiems wrote:as I stated in my post my voltage reading on the flex unit were 1.3 volts high I placed a 10ohm 10 turn variable resistor in series with the negative lead of the fndc and was able to calibrate the voltage reading with in .05 volts. If you have a problem of your readings being to low you might try to shorten the power leads it may help also check your connections if your terminal ends are crimped on I would suggest you solder them. I have determined the length of the leads supplied with the unit only measure .1 ohm which would not effect the reading short or long.I had to add about 7 ohms to get my readings correct. If your readings are lower then the battery voltage you will probably have to get a different fndc.



Stan
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What I did with mine is adjust the one of the pots inside it, it is easy to do I had a 2.5V high reading now it is 0.04V within spec
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Re: Voltage Calibration?

Postby ssiems on Tue Sep 27, 2016 7:18 am

I guess they didn't want us to know about that!
have you noticed if yours is accurate across the range of voltages?
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Re: Voltage Calibration?

Postby David LeBow on Mon Oct 03, 2016 9:36 am

Hi Stan,

Could you please PM me when you get a chance? There seems to be a problem with the e-mail address you have in your forum profile.

Thanks,
David LeBow
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http://www.alpha.com
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