Battery fully charged voltage of a Vapex Instant Tx 8 cell pack 2100 mAh

[Myron Beaumont]

Just dug out a 6 month old Tx Vapex battery pack from one Tx to another (meant for dry cell batteries in a plastic holder -no go area for me ) .Its voltage is 10.41 V now. The question is, how long should I put it on charge to achieve what is fully charged voltage ?.There is no delta peak detection system on my Tx charger,only for the Rx. The charger gives out 150 mA constant current for the 9.6V nominal Tx pack.(FusionNX83).

Timbo will know -& a belated, just remembered, a happy 60th birthday I believe a day or so ago

Free bus pass ?

[Tim Mackey]

Cheers Myron, yup, "back to the sixties" it was on Friday

You had a birthday recently too yes??

Anyhoooooow, back on topic.

If its at 10.4V now, thats around 1.3V per cell.

so just about "half full" between 1V and 1.5 - 1.6V.

You dont state the capacity, but assuming 2000m/a, you therefore need to pump in around 1000m/a, and at 150m/a per hour, that about 7 hours allowing for losses.

Of course, you should monitor the pack to ensure it gets no more than "warm", and perhaps check the voltage after a couple of hours to make sure we are on track.

Unfortunately, I find NiMhs a right pain to charge correctly, and even delta peak detect chargers are often incorrectly triggered.They also have a very steep discharge curve, so voltage state is not always a good indicator of SOC ( State Of Charge ), as they can appear to be high, and almost ful for a long section of the discharge curve, then abruptly drop to almost empty in an instant.

'Orrible things - Give me good old safe and easy to charge LiPos any day.

 

[Ross Clarkson]

Don't intend on hijacking, but woohoo, happy belated from me as well Tim.

[Tim Mackey]

Thanks Ross - bus pass application to be collected tomorrow

[Myron Beaumont]

Hi Timbo

Yes ,it was my birthday on the 11th . 68 th ,I can't believe I'm so old

My Rx battery cut out charging ,delta peak, at what became 5.63V after a rest.This naturally leads me to believe that the Tx battery (same make and cell capacity) should be at 11.26V. BUT! Having monitored the charging every half hour,I stopped its charge when it started to get very slightly warm as you suggested.The voltage on disconnection was11,64V. On leaving it overnight,it has settled down to 11.05V ie 1.38V per cell -nowhere near your 1.5 to 1.6 that you suggested .Should I put it back on charge for an hour or so until it gets really warm ?..If I make up a special lead ,I could do a mAh check with my wattmeter but want to go out today and run in a couple of engines and have a flight as the weather is good here .

Myron (by the way ,the capacities are 2100mAh per cell as stated in the title )

[Tim Mackey]

Only new cells in excellent condition will likely hit the 1.5 - 1.6V mark on full charge, so I wouldnt worry too much about 11.64V. My 6 month old 8 cell tx eneloops rarely get past 11.5V on charge these days, but it still allows me to fly all day and more.

[Lee Smalley]

never seen my tx at more than 11.3V !!!

[Myron Beaumont]

Thanks Timbo .Mine are about a year old so I won't worry too much now.The pack in question is going in my/hers Tx ,a basic Etronix which has a bright flashing red LED when the voltage drops to about 9.5 volts. Lovely mechanical trims as well and a fail safe throttle cut if I switch off the Tx .

Edited By Myron Beaumont on 17/08/2011 17:38:31