I have a 600 mah rx battery, when fully charged it reads 5.3 volts.
I have a (Hangar 9) digital volt meter with a 240 mah load for rx batt.The manual says they dont recomend flying under 4.8 volts. Sure seems low. Is that correct or can i be safe to fly at a lower voltage. What is the norm. Thanks in advance.

I assume you are using four (4) cell Nicd battery. It has a nominal voltage of 4.8. However, a freshly charged battery can test at well over 5 volts. I see you are using a load on your tester. Good, always use a loaded tested. You can get false reading otherwise.

When used, Nicd batteries drop rapidly to a ~4.8 volt loaded test. They "hang" in this 4.8V range for a long time, then they drop rapidly to zero. Because of this, I agree with what your manual said, don't fly if they test below 4.8 volts.

If you have a cycler, you can kinda double check this. Fly until you get a volt test reading under 4.8v. Drain the battery on a cycler that can measure capacity and see how much of the pack you have left.

When I do this with my packs, I end up having about 1/3 of the rated charge left in the pack. Technically I could fly until I have 0% of the charge left, but I feel only draining to about 33% gives me a nice safety buffer.

i ran that battery on my trainer plane and it would allow 3 flights on a LA-40 until it ran out of gas all three times. I did not have a timer radio then so i would guess they were 12-16 minutes flights.

A standard battery pack (500 MaH) should be good for 90-120 minutes on a full house .40 powered trainer.

I run a 600mah pack and an LA-40 in the LT-25 club trainer. I typically run a quart of fuel through it on a flight training day. This works out to about 8 10-15 minute flights.

With bigger engines, faster airplanes and more violent maneuvors, you wear down the batteries faster.

Get a expanded scale voltmeter with leads for your brand of equiment,it will check the batteries uder a load to let you know if it is safe to fly or recharge time,price is around $ 11.00,cheaper than a crash.

Thanks guys I guess everyone has a little different idea but i get the picture.

A standard at our club is for a standard battery pack is for 6 ten minute flights and then pack it up. This is flying time from takeoff to landing which doesn't include engine start time, engine adjust time and taxiing to and from the runway. This will also allow a safety margin. We have found that 60 minutes flying time in 1 day is also plenty for a new flyer. More than that and they seem to start to lose concentration. Some new flyers can't handle more than 3 flights before they are burn't out!