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lipo battery in a nitro plane?

#1
Hi, I Have a h9 piper pawnee 40 and love this plane, but I can only get about 2 flights in because im afraid the old NiCad battery isn't all the way charged, and in more than one case, it hasn't resulting in less that perfect landings. So my question is, is there any way that I can ise a lipo battery to power the servos and receiver? I think this would be a much better option because I could use a balance charger and be sure that the batt. was fully charged. If anyone has any ideas or has done this before, please write! It would help a lot!
Thanks
 

Montiey

Master Tinkerer
#2
You can use a cell checker to check the batteries voltage, and this way you can see how long it lasts while your flying it. Just land it every 4-5 mins and check it. when it gets low, charge it and repeat. Soon you will have a basis for how long it lasts. I have seen people use LiPos with gas planes, but it is really only necessary if your servos are CRAZY huge and draw something like 3 amps (and i'm talking like a 60% size hardcore 3D Sbach or something insane like that). Basically, if you servos are drawing to much for a NiCd (insufficient flight time), then use a LiPo, or a bigger NiCd.

:)
 
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pgerts

Old age member
Mentor
#3
Nixx packs are somewhat strange as you cant se the individual cells.
The way to "balance" is to charge with 0.05 C in about 2 days.
The "over" charge dissapeares as heat and is not dangerous if yoy only charge at 0.05C for NiHm or 0,1 C for NiCd.

I am using 2 cell Lipo for my nitro planes since many years.
You can use a 5 cell Nix battery and fresh from the charger it can have as much as 1.6 volts per cell = 8 volts.
The 2 cell LiPo might have 8.4 volts fresh from the charger. I have never had any problems with old or new servos BUT - dont do this if you do not know your equipment and how to do preflight checks.
The "normal" pre flight check and range testing is normally enough to get down the fresh top voltages to a more "normal" levels.
 

stay-fun

Helicopter addict
#4
Get a new RX pack if you don't trust the old one. Check how many mAh you put back in the pack after a flight, that'll give you an estimate on how long you can fly it.

A new RX pack can be NiMH, like your old one, or use a lipo, maybe in combination with a BEC if you need to adjust the voltage to what your receiver/servos can handle.
 
#5
I have been using a little cheapo ubec I got off eBay with great results. It's in an old Avistar, and I fly it with two 500 mAh 2s lipos. I have gotten more than 20 flights off of a charge. It's only running 4 servos and it's only a .40 size plane, but it has worked great. My only complaint is that I have to remove the batteries to charge them. All my planes with nimh, I just charge through the switch and leave the battery in the plane.
 
#7
Some receivers have a secondary voltage regulator for protection. This is often just a zener diode to clamp the voltage at around 5v max. It is hard on this type of circuit to operate constantly over voltage so you should use an external BEC if you use a 2S lip or similar. This will ensure that you don't let any of the magical smoke out of your receiver or servos. This would hold true for any of the lithium battery chemistries available to us as they all will be over the 5 - 6v that most receivers and servos are designed to operate at.
 
#8
I use 2300mAh NiMH packs ... 4 cell in all my fuel jobs. Basically because not all servos can take the 5 cell packs voltage. I have no trouble with 4 celll despite some peoples tales of hell and damnation you read on some forums. You think they are sales reps or something !!

My NiMh packs are all over 3yrs old and still delivering the goods. I charge at 1/10th rate .. that is ~ 250mA or if I need quickly - then I use 1A .......... Whenn sitting at home and not used for a while - then I use my old 1980's 50mA chargers to top up.
Most NiMH now are Low Self Discharge - so they can be left months without losing too much.

The main point is to make sure all hinges / surfaces are nice and free to move .. no sticky binding controls etc. This way amp demand is kept well within range of the packs. Foam hinges are a pig in cold weather - so they can lead to higher power drain. In fact many hinges can load up more in cold weather.

Use of LiPo needs careful checking of servos and gear - to make sure they can take the raw voltage or need a BEC to regulate to 5V or 6V ... some BEC's can be switched 5 or 6 ..
There are some servos that can take full 7.4v from a 2S ... but not so many.
LiFe at 6.6v (note these are nominal voltages - so full charged is higher) can be too much for various servos as well .. so again a careful check to make sure.

You will always be safe if choosing 5v ... even for a HV servo ... but of course some people want the higher soeed / torque the higher voltage gives.

Finally - DIGITAL servos will incur greater power drain when pushed to limits .. siginificant increase. I'm actually one who believes Digital only when necessary. I can have as fast ... as good zero resolution and LESS power drain from an analogue servo ... Not only that but I do not suffer central flutter as many high speed digitals exhibit. My EF Extra 300 58" when I bought it had digital elevator / rudder servos ... I tried all the tricks like pads of velcro .. etc. to stop the surface oscillations when trying to centre. The surfaces were fluttering so fast - they were a blur ! I ripped then out .. fitted same model servos but analogue. Instant cure ... measured LESS power draw ... and just as good control, and accurate centering.

Nigel
 
#9
I have been using a little cheapo ubec I got off eBay with great results. It's in an old Avistar, and I fly it with two 500 mAh 2s lipos. I have gotten more than 20 flights off of a charge. It's only running 4 servos and it's only a .40 size plane, but it has worked great. My only complaint is that I have to remove the batteries to charge them. All my planes with nimh, I just charge through the switch and leave the battery in the plane.
 

Bricks

Master member
#12
L
LiFe all the way. I like them because I can balance charge them and check them with a lipo checker, plus they’re compact.

2 cell Life batterie's are the way to go if replacing batteries in a IC plane it is all I will run in my IC planes ( unless it has old servos that cannot take 6 volts ). Only bad thing about Life batteries is voltage drops very quickly when taken to the limits of low voltage they drop quick.