micp

My Feedback: (3)

I recently purchased the I4C battery tester that provides a load test of .5 amp, 1amp and 1.5 amp. The instructions give the appropriate load to be tested for the size and voltage of the battery but it does not give parameters to follow to make the fly no-fly decision on voltage. In the past I used the hobbico meter that gave you the answer but I got tired of replacing 9 volt batteries and wanted something a little better which I assume the I4c is. Do any of you have general rules for 4.8 and 6 volt batteries for fly / nofly decisions??

Thanks

Tom

exeter_acres

My Feedback: (2)

for me it is 1.2v per cell....

so for a 4 cell pack it is 4.8v
and for a 5 cell pack it is 6v


I use 1.1v per cell on the Tx

BaronSchwab

Ditto for me.

tande

My Feedback: (48)

The manual that came with my "Futaba" 9C says that the trigger point for the on/board batt. fail/safe function (PCM/RX) is 3.8 volts---This function pulls the throttle to idle to give you a warning---by cycling the throttle stick; it resets & you again have throttle control---TIME TO LAND!!---This tells me that the RX will still process a TX signal at 3.8 volts (RX V.)---
(This should be interesting!!)

mglavin

My Feedback: (31)

According to many OEM discharge curves and my own testing you can safely run NiCd and NiMH batteries down to 1.1V per cell and realize the required current potential . A 4.8V battery is comprised of four 1.2V cells, so 4 x 1.1 = 4.4 volts.

6.0V/5 cell battery can be discharged to 5 x 1.1 = 5.5V.
TX can be discharged to 8 x 1.1 = 8.8V.

Static voltage is not an accurate method to decide on when enough flying has elapsed. A LOADED volt meter or ESV is an acceptable method to utilize to determine if you should fly or not fly. However, this is NOT the best method available to determine when to fly or not. The best method is to cycle your battery pack(s), note the mAh capacity, log the elapsed time flown, discharge the battery pack and again note the mAh capacity that was available after the recorded flight time, calculate the consumed power and divide by time flown and you have a KNOWN average power consumption, you can use this info together with the LOADED voltage test data to decide weather it's safe to fly or not.

1400 4-cell battery, cycled and capacity rated at 1420mAh.
After logging 36 minutes flight time, additional bench discharging of the battery netted an additional capacity of 880mAh. Running the numbers reveals we used 540mAh flying. 540 divided by 36 = 15mAh per minute consumed.

1420-880=540, 540/36=15mAh average per minute.

Theoretically you can use the entire capacity of the battery pack; we as modeler's seldom due simply because the voltage level falls below established minimums and the ability of the battery to provide adequate current or amperage is suspect long before the batteries capacity rating is realized. I believe most modelers charge far more frequently than is required, but do so for that warm fuzzy feeling.

A safe NO fly number would be around 50% of the rated battery capacity. At 15mAH a minute you could fly for 47 minutes with a 140mAh battery...

The secret is to log the accumulated flight time, become familiar with your models displayed and LOADED voltage readings, use this info to recognize a prematurely low voltage reading. Low voltage readings recorded/noted sooner than normal are indicative of abnormally high current draw, a bad cell or a battery that’s degrading/loosing its capacity.

Geistware

My Feedback: (16)

What I do is test the average load of my system by running my servos with the 9C's servo cycler until the voltage gets to 5.5 volts (1.1 volts per cell). I then discharge the pack (C/5) to see what is left. This lets me know the average load of my plane.

I find that if you fly large planes or have all digitals, you do not use up the entire capacity of the pack as would be seen at the normal discharge rate. (C/5). If you are using standard servos, you should be OK.

micp

My Feedback: (3)

Thanks Mike: Great info. Don't know if you remember me but I used to fly out a Mather and SAM before moving to Arizona. Name is Tom Schryer.

Thanks

Tom