Good Day. I was reading through a few other threads in this Forum, and came across one where a gentleman was concerned about how many flights he would get from his 4.8 V 1100mAh Rx battery. Another member replied that he should just get rid of the 4.8 V, and replace it with a 6.0 V 2500mAh battery. I must admit that I know very little about anything electrical. Can this be done without doing any damage to the Receiver? 4.8V to 6.0 V.

Generally the bulk of receivers and servos out there are happy with either 4.8V or 6V batteries. For most trainer and sport airplanes though a 4.8V, 1100mAh pack will be just fine. Depending on the airplane 5 flights should be no problem and possibly more (always check batteries throughout the flying day) The only exception might be if you are using a Spektrum/JR radio since they have had low-voltage reset issues in the past. Even though those problems are supposedly fixed, I'd still use a 6V, high capacity battery to be safe.

6V is also advantageous in some situations where a little more servo torque and speed are desired such as 3D aerobatics. Otherwise there is no need for anything more than 4.8V, definitely not for someone just starting out.

The long lock out has been fixed with the 2.4 JR/DX7 radio gear, now if your battery hits the low mark you only get locked out for a second or so. 6 volt is still something you should give a lot of thought to, a second is a very long time to be out of control. Like Chuck mentioned, most new gear will handle either 4.8 or 6.

KW,
There is always the option of going to a higher capacity 4.8 volt battery.
I fly 4.8 volt 2,000 mAh batteries in my 40 size planes.
The only time I remember being shut down due to low battery was an
unusually long flying day.
Do check your voltages frequently and do it under load.
Good Luck,
KW_Counter

Unless you have a servo binding or try to push your capacity to the limit there shouldn't be any voltage issues with 4.8. If you're worried, put a meter on an extension with half charged battery and push a surface all the way to stalling the servo. That's as much load as you'll ever have, and you can see what you actual reciever voltage is.

Far more important than the capacity of the battery is the quality of the switch and wiring, especially when using any of the 2.4GHz systems. It the wiring between the battery and the receiver has any appreciable impedance, when you draw that momentary rush of current by commanding any high draw servos you will get a voltage drop in that wiring. If it causes the voltage at the receiver bus to drop below the reset (reboot) level, you will get a temporary loss of control. This will happen whether you have a 4.8 or 6 volt battery.

This is very true, I have had one battery short out and two switches go bad, one with a wire short and one with a bunch of dirt get between the poles. Checking voltage with a good loaded meter between flights is a good idea, a lot of people use the volt watch. I do both. I started using a fast field charger some years ago, not always needed but if my batteries run low on a long day I'm not grounded. It's a great tool, I used to fly a lot of giant scale events and be at the field for days on end and the quick charger kept me flying.

Very true about getting a field charger, I always carry my triton JR charger, it will cycle, charge and discharge my batteries and record all the info. I also carry a medusa research meter in my box, it's small and shows realtime draw and voltage on the pack, it can tell me if a single servo is binding or not by moving the surface and watching the current draw. I originally bought it for my electric heli's, but I don't fly them anymore, so I adapted it for my flight packs. The only real way to test your packs is charge them with a accurate charger that records total MAH and discharge them at the same rate. it should be very close to the same time on charge and discharge, as far as the plane goes, a voltwatch is a pretty good tool to have onboard, it's simple and lets you know how everything is doing.

WOW!!! I honestly never imagined this kind of response. Thank-you all very much. It is obvious that my instructor taught me well. I do have a 4.8 volt battery in my one ( so far) plane, but never knew that a 6.0 volt could be used. I also check my battery before every flight ( under load). If the battery is getting low, I use my field charger to top it up. As I said, my instructor taught me well, now I am hoping my brain and thumbs get better aquainted. Although, no scattered plane yet.

Thanks again

The Voltwatch IMHO is far superior to a loaded voltmeter in so far as keeping tabs on your flight readiness situation. It warns you if you are having wiring or switch problems as well as if the batteries are getting low. If you always check it at the end of each flight before turning off the switch, wiggle the sticks and make sure the LED's at the low end (the red one) don't flicker, you are usually in good shape. It is important that you have the Voltwatch attached to the receiver bus, not on the end of Y with another servo on the Y. If you must use a Y (no spare channel) I think it is best to have it Y'd with the throttle servo.

Okay, how about the MPI, combination charge plug, switch, and LED Voltage Display. Will this give you the same information as the Voltwatch?

One thing to remember about 4.8 v 6 volt packs of equal capacity is that the 6 volt pack gives you about 20% LESS flying time. due to the higher current drain.

I have seen them advertised but to date I haven't tried one myself or seen any at the field, they look like a good way to go but ?????? As to the 20% less flight time with 6v over the 4.8?? I have seen it measured with insterments in magazines but in real life I haven't ever noticed it. I run both 4.8 and 6 volts of the same size packs. From lab to field there must be a lot of other factors that figure into the draw difference??

This I do not understand. Remember at the beginning of this thread I stated that I don't really have a great understanding of anything electrical. So, two identical planes, with identical receivers, and identical servos, but one having a 4.8v battery and the other having a 6.0v of the same mAh, will give you different flight times? And the 4.8v battery will actually win out.

Absolutely. With all other things equal(same capacity and same equipment), increasing the voltage will decrease the availble power from the battery. If you want to increase flying time you need to increase the capacity of the battery (milliamps, Mah). The higher capacity will give you more run time. Increasing the voltage will increase the amount of power and speed the servos have.

Ken

Think of your battery as a fuel tank.
6V. is full throttle and 4.8V as 3/4 throttle.

Tim

What can I say? This is certainly the place to learn. So does someone have an answer ( other than practice, practice, practice) for the brain and thumbs thing?
Again, many Thanks

So how do I know my DX7 and Rx's and Rx Batteries are brown out proof? So what I'm hearing is I don't need to go to 6v if I have a 4.8 NiMh 1500 MAh? Really makes no sense to me. For me, 6 v gives me peace of mind.

Bill: The key point here is to make sure you check for and remove any binding in the linkage that could draw th system down. Careful examination of the linkage and the end points will help out and will surely help with the flight time on flying day. And, of course, how you fly too. A lot of overcorrection will quickly drain a battery pack as well.

I've never had a lock-out with my DX7 receivers and I bought mine way back when they first came out. I've used both 4.8 and 6 volt packs. I am using 1200 mah 6 volt packs pretty exclusively now, though.

CGr

In practice the decrease in flight time when going from 4 cell to 5 cell is 4 to 5 percent. A non-issue unless you're trying to get that very last flight out of a pack.

Errr not sure about that. I based my statement on looking at the charge figure on my Prodigy charger. I moved a couple of models, one a jet the other a 120 3D job, to 5 cell packs and noted that I was getting significantly higher figures. I fly 2 flights with the jet and 4 flights with the 3D then charge. I was definitely getting in the region of 15 to 20% more needed to recharge the 5 cell packs.

Nothing very scientific but it was noticeable that instead of 6 -700 mah I was getting 800 plus almost all the time. Both packs were Overlander 5 cell Nimh AA size with a nominal capacity of 1500 mah

Thanks, just curious, thought maybe Spektrum had issue a patch, recall or something. I plan on buying 6v for my giant 19. I like 6v. all my 40 sized planes I'm running 2200 NiMh 6.v. Some guys at the field are running lipos for their giant scales. But the PT 19 is not 3d, so I think I'll be fine with 1500 -2200 NiMh's.

Bill, I believe that the problem was resolved back a couple of years ago. I'm not sure what they did, I seem to recall that they either lowered the threshold voltage or reduced the re-boot time... or maybe both. A properly charged 4.8 volt pack of sufficient capacity should be just fine.

I just happen to like the response of the 6 volt packs so I stick with them, but I could easily use 4.8 volt packs... I'd use at least 1000 mah, though, but only to get the flight time and not for any concern about a re-cycle time for the receiver.

CGr.

I have been using 6v 2500 mAh for some time now. I use them on my DX-7, Airtronics RDS8000. The only 4.8v that I use is on my gas engine for the ignition.

Hey Irish. How is everything going? How is the son-in-law doing? I didn't realize you finished the gasser. Neat!!

Oatmeal with raisins, brown sugar, and fresh nutmeg, a banana, plus Dunky-Do Decaf... ha..

CGr.