I have a 1000 mah nicad (4.8V] and a 2000 mah nimh {6.0V} on a QQ Yak.
I am trying to buy a good voltmeter as the one I have now is suspect.
I understand voltmeters put a load on the battery to test it's strength.
Question: There are varying products that put different loads on to test battery strength. For instance, the Hobbico II voltmeter puts a 250 mah load whereas www.hangtimes.com voltmeter has a choice between 500mah or 1000 mah.
What is the approriate load to put on the batteries above to test strength: 250, 500, 1000?
Also any ssuggestions on good voltmeters that cover varying degrees of nimh/nicad and varying volt capacities would be appreciated.
Thanks,
Mike

I would say the 250 mA (a load rated is in mA not mAh) load should be OK for both batteries. Just attach the loaded voltmeter, give the battery 10 seconds or so to stabilize and take a voltage reading. If the voltage is still dropping after 10 seconds wait longer until it stabilizes then take a reading.

As far as what volt meter to get, I use a general purpose digital multimeter with an external load, so I am not of much help with regard to RC specific loaded voltmeters.

The appropriate load is not determined be the battery, as much as by the requirements (load) of the equipment in the airplane. The "load" is actually in Ohms. One can calculate the needed resistance (Ohms), that prevent 4.8 or 6 volts from pushing a certain number of mA through it.

Just checked the literature with a new Futaba 3004. There is nothing there about resistance.

Years ago I built an external load for a standard voltmeter. From a tip in a magazine, I used 100 Ohms for flight pack. Ayear ago, when comparing voltmeters, I found that mine showed higher voltages than several commercial models. including the cheap Hobbico ESV. I bought an ESV.

BUT I was only using 4 servos on a light, slow .40 size sport plane. You are using more servos, have larger surfaces, etc., and will draw more current. Therefore, you will want to use a larger "load".


Ken Erickson

You could always measure the battery in the plane with all the servos attached. Use an unused channel and attach an extension to plug your meter into, or a Y cable. This is the way it's done with the on board metering devices.That way you are measuring the battery with exact load placed upon it.