Expanded scale voltmeter question
04-14-2005, 08:07 AM
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Expanded scale voltmeter question
Hello guys...
I just want opinions about this. I bought an [link=http://www.hobbico.com/fieldequip/hcap0351.html]Hobbico Expanded scale voltmeter MkII[/link]. On their web site...they state "Simulates a very realistic 225-275mAh load for testing batteries..."
I just checked mine and it draw only 180ma on the receiver side (4.8v). I am an eletronic technician so i did some calculations and replaced the 21 ohms resistor with a 15 ohms to get a 250ma load. Now i realized that the resistor i replaced also affected the TX (9.6v) side so i put back the original 21 ohms resistor. Did anyone else ever mesure his voltmeter load ? Should i buy another one or it's not a big deal ? I lost a plane due to a batterie failure so now i am very peeky with my packs. Thx for you advices everybody. [X(]
I just want opinions about this. I bought an [link=http://www.hobbico.com/fieldequip/hcap0351.html]Hobbico Expanded scale voltmeter MkII[/link]. On their web site...they state "Simulates a very realistic 225-275mAh load for testing batteries..."
I just checked mine and it draw only 180ma on the receiver side (4.8v). I am an eletronic technician so i did some calculations and replaced the 21 ohms resistor with a 15 ohms to get a 250ma load. Now i realized that the resistor i replaced also affected the TX (9.6v) side so i put back the original 21 ohms resistor. Did anyone else ever mesure his voltmeter load ? Should i buy another one or it's not a big deal ? I lost a plane due to a batterie failure so now i am very peeky with my packs. Thx for you advices everybody. [X(]
04-14-2005, 10:59 AM
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RE: Expanded scale voltmeter question
Forget the ESV. Use an inexpenive digital multimeter. A flashlight bulb makes a wonderful load and you can see, as well as measure what is taking place.
Nice page on the R/C Battery Clinic for those of you not as veresed in electronics. It's down on the left side of the page, entitled "loaded digital voltmeter, better than an ESV". http://www.rcbatteryclinic.com/
Nice page on the R/C Battery Clinic for those of you not as veresed in electronics. It's down on the left side of the page, entitled "loaded digital voltmeter, better than an ESV". http://www.rcbatteryclinic.com/
04-14-2005, 01:11 PM
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RE: Expanded scale voltmeter question
Since you are an electronic tech, I agree with JR, forget that expanded scale voltmeter who's accuracy is always questionable due to the soft knee on the zeners used. Using a digital meter and a load of your own making (whether it is a light bulb or resistor) your results will be much more reliable.
04-15-2005, 09:24 AM
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RE: Expanded scale voltmeter question
What i don't like about loaded digital voltmeter is that i am pretty new to R/C and i never remember when to stop flying when reading batteries voltage. With the expanded scale voltmeter, i like the colored visual scale and when it's close to the red which is set at 4.75 volt i know it's time to go home. I was just curious if i got a bad one or if they are all innacurate like mine. I did a quick research and i haven't found a more sofisticated expanded scale voltmeter. If anybody can point me to a model that is accurate plz tell me, i don't care about the price.
