What is the go--nogo voltage for a 4.8 and 6.0v receiver batteries. In other words (how low can I go). Thanks

If you are worried about how low you can go with RX batteries, then you have not read many of the threads within this forum.

Get yourself an Extended Scale Voltmeter and it will tell you when to stop flying. You CANNOT use a standard voltmeter for that, you must use one that places a load on the RX battery (and the TX battery for that matter) and gives you a good indication of when it's ok to fly and when you should recharge.

http://www2.towerhobbies.com/cgi-bin...&I=LXWW16&P=ML

But based on your question, it sounds like you are trying to 'push the envelope' and fly on a marginal battery. If so, please make sure your home owners liability insurance is paid up, you are a current AMA member, and that you have a plastic bag with you to collect the remains of your plane after you finish with your suicide flight.

Perfect example happened today... a guy showed up at the field for the maiden flight of his Cap-232 after some repairs. The controls just quit and the plane went in. One of the more experienced guys checked his Rx battery afterward and it was dead. The battery had been put on a charger last night but there have been a few blackouts around here lately, especially last night. The battery did not fully charge. Had it been checked with a meter that applies a load as you mentioned before the flight, the crash would have been prevented.

Another example... I went out flying with a friend of mine after work. He had forgotten to charge the night before so he threw it on for a "quick 30 minute charge". Problem is, he had a habit of this. Right in the middle of a flight, the controls went dead and the plane went in. A gorgeous, one of a kind, scratch built plane was destroyed.

I now keep track of all my batteries, cycling and testing them regularly. The expanded scale volt meter is in my flight box and it's going to get used before every flight. I like my planes too much to lose them to something as stupid and preventable as an under-charged battery.

http://www2.towerhobbies.com/cgi-bin...?&I=LXNK81&P=0

http://www2.towerhobbies.com/cgi-bin...?&I=LXKLF5&P=0

The new Spectrum RX's also appear to be especially susceptable to low voltages. Many owners are using 6 volt packs, due to this, on DX7 planes.

I put a [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXHDJ2&P=ML]Hobbico Voltwatch[/link] battery monitor on all my aircraft. Before and after each flight I move both TX sticks around and watch the monitor... as long as the LEDs stay lit up in the "safe" region, I'm good to fly some more... if the LEDs light up below the safe region, I recharge. I've never lost a plane or heli due to a bad RX pack with this method. However, at least two guys at my club that only use ESVs have lost their planes due to a dead pack. One guy just plain forgot to check it on his first flight... another assumed he was good for 3-4 flights before he needed to check it... and he was finally wrong. The battery monitor is always there and it's always on when you turn on your plane... and if you mount it in plain view, you'll never forget to check it.

You forgot to add, "IF you can find your plane after you lose it..."

If you really want to know your battery capacity, get a digital volt meter and make a plug that you can plug into your reciever. Connect the red and black wires to that plug and turn on the reciever. Now while on the ground, act like you're flying the plane. Monitor and plot the voltage every minute (this is really easy if you can plug your DVM into a computer). Look for the rapid drop off in voltage (will typically happen around 4.65-4.7 volts). Use that plot of time vs. voltage. If you typically fly for 10 -15 minutes, back up from the rapid drop off time 20-25 minutes (safety margin). That voltage should be your no go voltage.

Brad

I really appreciate all the good information. I do not want to push the envelope but When the voltage gets down some I was just wondering how long it is good to fly. I do have a hobbico voltmeter but it only tells you when it needs to be recharged. Let's say it needs to be recharged at 4.6v--but you get a green light at 4.9v. How long from 4.9 to 4.6 is the average time. I know that it is just a guesstimation. Thanks again

For me personally, if it is borderline, I wouldn't push my luck. It's that "one last flight before I pack up" that will get you.

I think I can relate to that one last flight. Always something seem to get in the way i.e., trees, poles, ground. Thanks Chuck W.

One more thing to remember. NiMH batteries voltage drop when nearing the end of their capacity is like a vertical cliff. I use them in my Tx. Once the voltage reads 9.3 volts the low voltage alarm will go off with in 5 minutes and TX shutdown occurs about 90 seconds later.

If you fly a lot buy a field charger and top up between flights or during the afternoon.

Thanks for the info. Was not trying to push the envelope just didn't want to get near it. I will take your advice and buy one. Do you recommend any particular brand?