At what voltage do yo recharge your TX battery and your 4 or 5 cell RX battery?

With nicads the minimum safe voltage is above 1.1 volts per cell. So 4.4 volts loaded on a 4 cell pack and so on is the absolute lowest you can be landing with.

I don't let mine get that far. I never let the Rx batteries go below 4.7V, and the Tx below 9.4V. You run the risk of erratic (unreliable) behavior from the system. I like to use a Voltwatch on the Rx, (hobbico, about $9), shows at a glance when you're getting low, just plugs into a spare place on the Rx.

same levels with Nmh?

Yes, the radios are stupid. They don't know what kind of batteries are installed, they just sense the voltage. It may take longer for the Nmh to drain but you are on borrowed time. Sort of like driving your car with the gas tank reading empty. You know it is gonna quit, just not sure when. You might cross the railroad track (or land the plane) but do you want to bet on it???? [:@]

Use a loaded voltmeter (ESV) like the ones you can get at Tower for about $15. I recharge when the Receiver pack gets to 5.0 volts, but 4.8 is safe. For the transmitter, I usually recharge at about 9.9, but wouldn't let it fall below 9.8.
Dennis-

I was refering to cogburn, because he said "With nicads the minimum safe voltage is above 1.1 volts per cell" and i wanted to know if it applied with nimh's also.

What is the lowest you will take off with?

Nicads drop off pretty fast below 1.2 volts per cell. I have taken some short flights at 4.6v takeoff. Depends alot on how much load your radio setup has. And the capacity of your batteries. Lately i have been using 1800mah nimh battery packs so i haven't really had much problem with it. Nimh discharge curves are pretty flat and yes 1.1 volts is the absolute minimum landing voltage. Here is a link to a discharge curve for nimh.
http://www.digibattery.co.uk/nimh_tech.html
And a battery guru's take on it.
http://www.rcbatteryclinic.com/ (look in the loaded digital voltmeter section).[&:]

edit: individual radio systems may not work at that level-it's up to you to test it on the ground.

Personally since I fly mainly digitals, 5.0 is bare minimum and that will be a very short flight. 4.8 and it's recharge time. Even small low to mid torque digitals will suck a lot of power out of most any batt.

Granted, the larger the number of MaH, the longer it will last, but down at 4.8 volts and mainly below you are really risking receiver dropout no matter what servo type you are using. The other item that no one has mentioned is the way the plane is flown. A sport flyer up doing pattern work at 4.8V may last a little longer than a 3D plane doing 3D aerobatics at 4.8V because when flying 3D all the servos are most likely doing something all at the same time, as in a hover so the drain will be faster. And that is not even worriing about digital versus non-digital

A quick once around the pattern may be fine at 4.8V but as I already mentioned, receiver dropout is a very real possibility.

I agree with this statement 100%. I would HIGHLY recommend that you not attempt a flight once your receiver pack hits 4.8 volts. Many receivers will start glitching at just below this voltage, and moving a couple of sticks at the same time will pull the voltage down quite a bit, even though it may come back up a little once you stop moving the sticks.

It just ain't worth the risk!

Stay safe.
Dennis-

I'll add just a tad more to this. Most receivers once they drop out will not recover the signal no matter if the voltage goes back to 4.8V. Once the dropout occurs, it's time to hunt down the garbage bags. If you see the plane glitching in the air due to voltage then your chances of getting it back are slim to none considering you have to land and if it's any way windy or breezy you will be moving all of the sticks at the same time.

I agree, it's not worth the risk for any plane from a safety standpoint

Here is a link with futaba's recommendations.
http://www.futaba-rc.com/faq/faq-receivers.html

On my 4c pack I fast charge at 4.9... I lost a plane once due to
the battery... If I can help it.... Never again!!! Tranny, once my
meter shows mid scale, I never really looked at the voltage...
I do carry an extra battery for my tranny, So I just switch it
out and slow charge at home... A few members have said you
can get a few more flights out of that, I say for the amount of
time it takes to fast charge, or chance losing the plane... I'll
go the fast charge route....

for volts on my tranny it goes 0-100 so what would i stop at?