I have a TX and RX which have 9.6V and 4.8V respectively. What is the safe range of volts that can fly without any problems?

I don't fly with my TX less than 9.8V or the RX less than 4.8V.

NiCads are considered discharged at 1.1v.

Dr.1

A safe cut off point for a 4-cell NiCad pack is normally considered 4.8v. Fully charged they will read somewhere around 5.4 volts. Some Futaba receivers will drop the throttle to fail-safe with a momentary voltage drop to 3.8volts. Batteries will recover when at rest and the best flight pack test is immediately after the flight.

Occasionally I have flown Futaba computer radios down to 9.2 volts. A transmitter with voltage display can be continuously monitored and flown safely closer to the edge. Without a voltage display 9.8v would be a good cut off point. Some transmitters will start beeping vigorously at 8.8v. I have only seen one occasion of a transmitter beeping vigorously while the airplane was in the air but the pilot landed safely.

The knee on the voltage curve for NiCad’s is about 1.1 volt per cell. Stay away from the knee or the voltage will fall off the cliff.

Bill

Most of the better transmitters have a meter to show you the battery level. For keeping an eye on the reciever batterys I buy something called "Voltwatch". They are inexpensive and you check the led indications before and after every flight. They work very well and at the price, I install them in all my new planes. Follow the link below to check them out. I checked and see that you are in Canada. For buying in Canada the best placew to buy from is called Great Hobbies. There prices are very good and good people to deal with. [8D]
http://www2.towerhobbies.com/cgi-bin...&I=LXMZ56&P=ML
http://www.greathobbies.com/

On my 9.6 volt Tx I fly down to 9.6 and it seems to stay there for a good while. Since it has a voltage display I keep an eye on it. When it drops to 9.5 I charge it (I have accidentally let it get gown to 9.2). My 4.8 volt Rx packs are the same way. I can still get a couple of 10-12 minute flights in at 4.8 reading. Once it gets down to 4.7 the voltage falls off quickly so I charge.

When your TX reaches 9V you better be down really really fast. Its not safe to take off when the RX is at 9.2V, at that level the battery will discarge really fast, I think you can reach 9V from 9.2V in like 3-4 mins.

You can take the TX down to 8.8 volts.
I would not take the RX below 4.8 volts

What about NIMH receiver battery?? Is it the same principle as Nicads?

I always rechage at 9.8 on the transmitter and 4.8 on the receiver. I don't think pushing the pack is worth the risk.
Dennis-

NIMH are treated the same as NIcads as far as as charging and voltages are concerned. NIMh are a better battery and have less memory problems than NIcads. If you have a choice of battery packs of the 2 different types, get the NIMH.[8D]

That's what I did 1650 MAH for my trainer... should be good for 20 flights...

I have switched to 1400 mah NIMH packs in my planes. I fly all weekend on one charge!

I have a question, it may sound silly but why do they ask you to cycle the batteries before first flight?
How do you run them down if you dont fly?