Trimetric voltage reading

icarus · September 2007

I have a Trimetric meter that I love. The one problem is that the less than fully charged voltage reading is off by about .4 volts. When I check the batterys when the meter is saying 90% charged (according to the inputed crieterion) the voltage on the trimetric reads 12.3. My Fluke hand held reads 12.6. My batterys Sg tests out 90%+ at the same time. I am waiting a response from Bogart Engineering, but maybe you guys out there are smarter and quicker.

All the rest of the meter functions are spot on, eg amps, amp/hours %full etc. I don't know enough about shunts to think that perhaps that is the problem.

Any thoughts?

Icarus

niel · September 2007

Re: Trimetric voltage reading

the trimetric sounds like it's inaccurate on its voltage readings. it is possible something like your wires or the shunt is awry, but i doubt it. did it ever read correctly?

icarus · September 2007

Re: Trimetric voltage reading

It has never read properly. I am in the middle of a re-vamp of the entire system which will move the metering system nearer the batterys. Also moving the loads nearer as well. (My problem now is the loads (inverter, 12vdc are 75' away.) The meter shunt is at the battery bank however. After I get this all done I will worry about it,

Icarus

Windsun · September 2007

Re: Trimetric voltage reading

Shunts will not affect the voltage reading, that comes directly from the battery. Been ages since I set one of those up, so I can't recall if there is a way to adjust it or not.

mike95490 · September 2007

Re: Trimetric voltage reading

Windsun wrote: »

Shunts will not affect the voltage reading, that comes directly from the battery. Been ages since I set one of those up, so I can't recall if there is a way to adjust it or not.

Shunts are adjusted by using a Constant Current power supply, at about 1/3 the rating of the shunt, and then using a file, making a small notch in it, to accurately set the shunt resistance. Only a Cal Lab has accurate enough stuff to do this. We do it in a vat of thermal oil.

Send the Trimetric either to get calibrated, or to Ebay. If you know it's wrong, don't keep trying to use it, thinking it will be right somehow.

--
A broken clock is right twice a day.

tnhunter · September 2007

Re: Trimetric voltage reading

I have the same issue with my TriMetric metric except it has consistently meausred voltage .6 to .7 volts lower than any other meter. My inverter, charge controller and volt meter can read 50.4 volts and the Tri-metric will read 49.7 to 49.8 volts.

I have learned to take this into adjustment.

niel · September 2007

Re: Trimetric voltage reading

imo, there isn't any excuse for those meters to be off that much from the getgo with the price tag they come with. i have one and it read ok, but i didn't like the guessing games i would've had to play in reading %full and my sb50 does have a meter for both volts and amperes so the trimetric is not needed by myself and it just sits collecting dust. maybe i'll add this to my for sale list with my generator in the energy use and conservation section.

crewzer · September 2007

Re: Trimetric voltage reading

Here (in part) are the troubleshooting and Vcal instructions for the Trimetric:

2.3.3.1 If accurate digital meter doesn't agree with TriMetric--:If "amps" reading is OK, and volts are still incorrect (with an error of less than 1 volt), meter may have became uncalibrated. (This shouldn’t happen on its own. Possibly someone accidentally readjusted it.) Either return to factory to be calibrated for most accuracy, or if you are sure your multimeter is accurate, connect it between "SIG" and "+" terminals at TriMetric terminal block, NOT at the battery. Then. use small screwdriver to adjust the screw on the square blue or gray "pot" located on TriMetric circuit board until voltage reads correctly. This should make it accurate to within 0.1 volt or better if you are careful.

Here's a link to the entire Troubleshooting manual: http://www.bogartengineering.com/TROUBLE2.pdf

HTH,
Jim / crewzer

icarus · September 2007

Re: Trimetric voltage reading

Crewzer,

Thanks for the info and the link. I suspect that Bogart will get back to me with the same info. I want to double check my fluke meter just to confirm. then I will try to adjust it, or maybe send it back to Bogart for calibration,

Once again, thanks for all the input,

Icarus

RCinFLA · September 2007

Re: Trimetric voltage reading

If you have confidence in your Fluke meter accuracy and it is a 'true RMS' responding meter then go ahead and recalibrate it yourself.

Depending on the type of charger the waveforms for the voltage and current can give you variations in reading. If the Trimetric unit does not have a true RMS converter it is set up to measure a voltage average assuming a certain waveform.

For example, the Trace DR series uses the transformer in reverse, with rectifier diodes to charge the battery with a full wave rectified sinewave. This creates short current pulses at the peaks of the rectified waveform with zero current over a significant portion of 120 Hz half sinewave voltage swing. The Trace SW series with its syncronous transformer stacking has a charge current profile that more closely follows the full wave rectified voltage with actual current into battery having a half sinewave waveform. These two different type charging systems would read different currents on an averaging meter for the same RMS actual current.

The battery voltage measurement has the similar waveform problem. The voltage waveform looks like bumps over the average DC voltage of the battery, where current only flows during the 'bumps'. The RMS voltage reading will be much closer to the DC average then the current pulses of charging.

You might have to choose whether you want current or voltage reading to have the best accuracy.

icarus · September 2007

Re: Trimetric voltage reading

As I have said before on this site,,,I'm no electrical engineer. When you begin to talk about wave forms and peak rms voltage I begin to get out of my element.

Having said that, as my system has gotten more sophisicated over the years, the ability to monitor it has as well. In the old days, I could just measure at rest voltage and Sg. Now I can measure almost every thing. It may be coming under the catagory of too much information.

My batteries are ten years old and seem to be holding up well. I can use all the amp/hours a day and almost always fully charge the next, so I'm happy.

I am going to monitor this situation and see if it is meter error, or human error. Quite possibly the latter. (I just got a new hydrometer that I was convinced was bad,,,,until someone pointed out that the reason it always read low was I had to much acid in it, so the float kept hitting the top of the bulb!)

Some times were smarter than our stuff, other times the stuff wins!

Icarus

icarus · September 2007

Re: Trimetric voltage reading

As stated before, I'm no electrical engineer, no genius either! As it turns out, my problem was a combination of opperator error, and a dieing cell in the battery bank. (I was testing the voltage with the hand meter in on point and the trimetric was reading the entire bank)

It turns out I had a cell that was just starting to go south, and now a week later it has failed completely. I will post another thread about a battery question as a result.

Thanks to all for your help, and to Bogart for responding quickly and accurately,

Icarus

Trimetric voltage reading

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