Hi,
I am using Futaba Tx with the battery came with it. This battery show about 11.4V when fully charged overnight however voltage drops rapidly once at field. I think I can get about 4 flight (10 min./each).

Are there battery available that gives me more time? Same issues with Rx battery.

I do have a Hobbico Field charger which I can use to charge these batteries. Does field charger charge batteries at faster rate then regular wall charger?

Thanks for your help.

Regards,
Sujit Chokshi

The battery voltage will drop rapidly. However, then it should reach a point where it will stay for a long time. What's the voltage that it's dropping to? How old is the battery? You should be able to get way more time than 4 10 minute flights.

Be careful with field chargers, some of them are setup to charge the higher capacity batteries used for electric cars and planes, so they may provide too much current for the typical transmitter battery pack. If it's specifically designed for charging transmitter batteries, it should be ok, but it would be good to know the charging current.

If I am right the stock battery is 600 mah Nicad?
Yes field chargers do charge faster but are not good for the battery.
Nicad batteries will set a memory if not discharged before charging and you will loose capacity.
I recomend a battery conditioner such as a Hobbico Accu-Cycle:
http://www.hobbico.com/cyclers/hcap0260.html
To restore the capacity of your battery.
I replaced my stock battery with a 2100 mah Nimh battery. I only have to charge it about every three or four days and it doesn't have the memory problems of the Nicad batteries.

Schockshi,

Apparently, you have a voltmeter.

What is the voltage after your 4 ten minute flights?

Some of us think you may be quitting too early.

Ken, AMA 19352

G'day Mate
I use an ACE Smart charger I'm sure you can get em easily in the USA, they are a reflex charger that will charge both TX & RX at the same time, & eliminate memory problems & restore older batteries if use with a cycler. I also use an ACE cycler which is a good way of determining your battery capacity. It shows exactly how much capacity your battery has in Milliamps, so you simply charge then discharge & you should have an increase in capacity after a few charge discharge cycles.
Good Flyin Mate
Allan

Voltmeter is built into to the radio. However, I am just worried that voltage is droping faster than I would have expected.
after couple of flights it come down to about 9-9.5V.

That's normal and is around the nominal volatge for the pack. Both Nicd and NiMH have a top charge that leaves quickly as they drop to thier normal voltage which is around 1.2V a cell. After the quick drop, they hang out around the 1.2 for quite some time, then drop rapidly as they die. You can safely fly well into the 8 volt range. Depending upon who you talk to, battery isn't considered "dead" until somewhere between 0.9v and 1.1v per cell, which is still well under your 9V reading, esp considering the meter in the radio may not be terribly accurate. To be sure, use the radio until you normally quit, after 4 flights, etc. Then put the battery on a cycler and discharge to see how much is left. Chances are you still have at least half the charge left in the pack.

Schokshi,

Yes, most of us will stop flying at 9.5! Not many would put it up again if the Transmitter read 9.0. Receiver battery has half as many cells, so cut those in voltages in half.

About 2 years ago, I finally bit the bullet and bought a Peak Charger, Discharger, Cycler, analyzer. I also bought Nickle-Metal Hydride (NiMH)batteries, which have many more milliamperes for the same size than a Nickle cadmium (NiCd). You can buy good NiMH batteries for less money than original equipment NiCds. And I buy them at my local hobby shop (LHS)!! Mine are 1650 mAh, except for the racers.

If your budget won't let you go that route, use your voltmeter as your guide, pay very careful attention, and take the batteries down to 8.8 volts for transmitter and 4.4 volts for receiver. Try very hard not to take them down below 8.0 V and 4.0 V!!!!!!

Then look at your charger. If you have the older equipment with 500 mAh batteries and 50 mAh charger, charge for 18 hours. You can do this discharging after flying, or in the middle of the week. If you have the newer equipment, you have 600 mAh batteries and a charger which charges the 8-cell battery at 70 mAh ( Not terrible) but charges the 4-cell at 100 mAh (Just not right, that's the charge rate for a 1000 mAh battery.) If you have this charger, try to find a real expert at your club to help you rejuvinate your batteries. Or borrow an old charger from an old f*rt.

After you have done that procedure a couple of times, your batteries may have improved in performance and you can charge with the new charger (faster). As long as you do not leave the receiver battery on for more than 10 or so hours, you will be OK.

It is so much easier with MiMH batteries and a good peak charger, discharger, cycler, analyzer, but the old fashioned approach will work, especially if you still have only one transmitter and one plane.

New batteries, NiCd or NiMH, should always have at least their first charge at 1/10th capacity. That is 1000 mAh battery, 100 mAh. 600 mAh Battery , 60 mAh (50 will do). 2000 mAh battery, 200 mAh. After that, they usually can be charged faster, but I stay below capacity for radio batteries.

There is a lot more can be said, but that should be enough for now.

Good luck,

Ken, AMA 19352

The typical curve for a transmitter battery should have it staying in the 9.6-9.8 range for more than 40 minutes. I can get something like 10 flights or more out of mine before it even gets to 9.6. I personally would never fly with the voltage less than 9.4. Suggestions such as "You can safely fly well into the 8 volt range" are dangerous.

Is this a new radio or second hand? If it's new, contact Futaba service and ask them about it. Either the battery is draining too fast or the volt meter is wrong. Either way, something is not right.

"Suggestions such as "You can safely fly well into the 8 volt range" are dangerous." - I routinely fly down to 8.6 volts. Never had a problem, BUT I'll add that my TX actively monitors the battery and sounds an audible alarm when the battery voltage hits 8.6v at load, which means it is time to land now. However you are right Piper, being the beginner forum, most probably aren't using a high end radio that does this level and accuracy of battery checking. My mistake and you are right it could be very dangerous. I guess we all become used to the equipment we personally use... I got lost in that. For a "needle" based voltmeter like found in most beginner radios, assuming it is working correctly, I'd agree you need to stay in the 9V range. Your 9.4V is conservative, but safe which untimely is more important than run time, so no argument there. Cheers.

Charge the TX full up overnight.
Next day, Turn the TX on, grap a bag of chips, a frosty beverage, slip a DVD in, & watch a show.
Every 10-15 mins look at what the voltage is.
After a while, hopefully a long while, the TX will say it's had enough, and start beeping the Low Voltage song.
That will give you a good idea of the condition & life of your batteries, and will help us see what problem if any you have.
(this is for a digital volt meter, not a needle type)

When my TX stops saying over 9 volts, I stop flying. But I leave it on at home to complete the charge/drain cycle before recharging.... sometimes a half hour or more before it beeps. Some folks stop at 9.6, some stop at 9, some at 8.6 - but seems to me the TX itself is set to tell you LOW VOLTAGE from the factory. I doubt they intentionally set the warning 20minutes past safe transmitting.