I just picked up a Hobbico Expanded scale voltmeter. I've had a couple of battery issues and want to be able to test with a load.
This meter has no load switch so it must always apply a " Simulated 225 - 275mAh servo load"

What procedure do you go through to check your batteries before and during your flying day?

I also have a voltwatch on the plane but the batteries are pretty important :-) so I dont want to take any chances.

How low in the green would you still fly? I assume the gap between the red and the green is no mans land? fly there at your own risk?



Thanks

Steve

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Ihave one of the same meters, pretty good little units and it's always under load. Icheck the battery before each flight. Ihave either the GEM 2000 or volt watch units on my planes, they wrok pretty good but the meter tells me exactly what the voltage is. Just a piece of mind thing but checking the battery only takes a second.

If you have voltwatch, perhaps it would be prudent to "measure" with both devices and compare what you get. Although the voltwatch does not give you a meter-like reading, you can compare green to green, yellow to your "no-mans land" and of course, red to red.

I see the voltmeter you have there has 4.9 and 9.6. The voltmeter should have a switch for RXbattery pack you are measuring too.. 4.8 / 6 volts.
Yours does not appear to be able to measure 6 volt packs.

CGr.

in the green fly........ not in the green........i know what your thinking....is that 5.3 or 5.4 volts....in all the excitement I've forgotten myself...but as this is your airplane...and it can be a smoking hole......you gotta ask yourself just one question...do ya feel lucky...WELL DO YA

H'mmm no 6 volt. Hadnt thought of that. I'm using 4.8 now but if I moved to 6 volts this meter would not work....

Which brings up another question.

the merits of 4.8 volts vs. 6 volts OR Spectrum says you can plug two identical batteries into the AR7000 RX.

I have two spectrum Nicads 4.8 v 1100mah I could use.. ( in place of the Nimh 1700mah I'm using now ) which would be better?



Sorry, this battery area is my weakest link.....

Steve

This meter isn't one of the high dollar meters, you just read your 6volts from the 4.8 side, no big deal. Irun two batteries and one battery, 6 volt and 4.8 volt. Sort of what kind of mood I'm in when I'm building and setting up a plane. With two batteries you want two switches and batteries of the same volt and mah. Ieven run one 6 volt battery with two leads going into two different switches. Most the time it's the switch that fails and not the battery. In this case it's a big sub C pack with very high mah with the battery being double wired.
So much has beer writen about batteries and it comes down to the pilots choice. Horizon has come out and stated you should have a 6 volt system in your plane if you are running there digital servos and 2.4., they only give you the 4.8 though.

Yes I thought it strange that they give you the 4.8 Nicad!
I am not using the digital servos now so I guess I'm safe using the 4.8 volt.
My biggest fear is losing control...When the plane doesnt respond right away or if the wind does something to it my heart stops.

Would a 6 Volt pack just be 5 - AA's instead of 4 - AA's?

I did pay extra to get the Spektrum switches hoping I'm getting better quality? They seem heavier duty?

Thanks

Steve

Not necessarily AA batteries. They could be any physical size and still produce 4.8 or 6 volts depending on the cell count but you had the basic idea. Larger cells, such a "A" or "C" will USUALLY have higher amperage capacity but not always. There are other variables. Check the labeling and just make sure all cells in the pack are the same. As far a a 6 v ESV is concerned it's not that big of a deal. The top of scale is over 5.5 volts and you aren't in danger until below 5 just like with a 4.8 v pack. If down to 5.2-5.3 recharge your 6 v pack if you want. All it's going to do is slow down your servos a little and reduce your torque perhaps.

The switches you bought are quite a bit better then the ones I started out with. We had those little guys that come with the cheap flight packs and new radios. After I had one fail I went ahead and started using the heavy duty JR switches with the charge jacks and bigger wire. So far no problems with one of them. I have tried others and the switches were OK but the plastic cases were brittle and tended to break.
Bruce covered the batteries pretty good, Ionly use packs like the sub C for my bigger planes, that's a lot of weight to be dragging around for no real reason on a small 60 size plane. Ialso don't bother with the two packs on a smaller plane. After the 60 size I may use two depending on the plane itself but it's more about the extra cost and the type of plane. A nice warbird that I spent a lot of time building I would run two. Most the time.

The real valuve of having an ESV is to plot your discharge curve. This gives the true health of the battery pack. But the ESV was designed when we mostly flew 4 channel glow models with 500 or 600 ma packs. The load was similar to the current draw of our radios. But now, with 1000 and 1200ma packs and airplanes with 12 or more servos and big servos at that, its difficult to graph the discharge as it actually will occur. Predicting the number of flights and thier duration isn't as easy as it once was. And measuring voltage between flights reveals little about the health of the battery pack.

Do you hear me Hobbico ? Its time for a meter with a variable load !!!! Get on that , will you .

my ESV has a switch where I can read 6 volts or 4.8.......
Popriv.....6V will give you more torque and speed from your servos......for more flight time you want a bigger capacity battery say a 2400 mAh.....
for 2 batteries connected to a receiver  they would be in parallel.....where voltage remain constant and current (mA) is additive....the same as a bigger capacity battery

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Use a resistor in parallel with the meter to simulate load, if you have a 6v battery rated at 2000ma=2amps (then R=volt/current) = r=3 ohm, (volt x amps =12) watts so buy a 3 ohm 12 watt or larger resister to simulate full load. Get one as close as you can at radio shack. If you can’t find the one you want you can add them in parallel or series to get the value you want. In parallel you divide the values in series you add the values.</p></span>

One point I failed to mention is that no matter how many cells you use the idea is NOT to let the pack voltage drop below and average "volt per cell" value which many (but not all) believe should be 1.2 volts per cell. This would mean a 4 cell pack should be recharged at 4.8 volts and a 5 cell pack at 6 volts. A freshly charged pack will read higher than these numbers. This is done for the health of the cells in the 6 volt packs.

good point Bruce...I was taught 1.1 V a cell on a nicad......But then again a Nicad can recover from a total discharge if you're careful charging it back up...where others can't

If they don't reverse, but we don't see that much on our RC cells.

How would I use the ESV to monitor the "health" of the pack?
As opposed to using it to check voltage between flights. ( this use seems pretty straight forward )

I now have this ESV to use and I charge with a Hobbico field charger always at its lowest setting of .2 amps to charge my 4.8v Nimh RX batteries.
I plug a digital Volt Meter into the Hobbico charger and monitor the charge rate.
I have nothing other than a light bulb to drain/cycle packs...

I do have a brand new battery I think I fried by leaving the plane on. how can I test it with the equipment I currently have?

Wife got laid off last week so I really shouldnt buy anything other than Fuel right now .

Steve

http://www.radiosouthrc.com/closeup....8&amp;offset=0

1-20 volts. 500,1000,1500, MAH load tests. Can be used for NIMH, NICD, and LIPO

Bruce, I guess I am one that disagrees with your idea that you charge when the voltage per cell gets to 1.2 Volts. Halfof the batterycapacity remains unusedat that voltage. NiCads hit the knee at about 1.07 volts, where the voltage starts dropping quickly. They work quite safely to 1.15V (loadedvoltage)with plenty of margin.

Popriv, your battery is probably OK. Chances are you just did what is called a "deep cycle" if you are lucky. Go ahead and try to charge it back up and then check the voltages. If the total voltage looks low then try to check the individual cells to find the bad cell. Make sure it isn't just a connection/wiring problem. If problem persists you will need to decide whether to replace the offending cell(s) or the pack.

Popriv....like Bruce says....slow charge your batteries just like you have been doing....for a 1/2 hour or so....make sure the pack stays cool.......that way you won't have a reversed cell......if it stays cool check the voltage for a reference continue to charge