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schneller
Starting Member
USA
12 Posts |
 Posted - 02/17/2010 : 8:19:48 PM
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I just bought a used Sig Mayhem 3D which will be my first glow plane. It came with everything including the receiver battery pack which is a 6v sub C 1800 NiCad pack. I was a little surprised to see sub C cells. Is this normal? I have no idea how old this pack is and want to be safe and replace it. Any suggestions? The plane has a 72 inch wingspan, weighs around 9 lbs and has 3x HS-605BB, 1x HS-6545MG and 1x Futabo S3004 servos.
Thanks,
Bryan |
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Garret H
RMM President
USA
14 Posts |
Posted - 02/18/2010 : 7:49:38 PM
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Hey, Bryan --
I use sub-C NiMh batteries in my 100cc plane, but they are about 3 years old. They have a high capacity, but they do come with a hefty weight!
I would recommend going with a NiMH pack in that large of plane. You will be much happier with the longevity of each charge and the overall life of the pack. In my GP 25% Giles (which used 6 servos), I ran a JR Sport 4.8v 1500mah NiMh battery, which is a good pack. 6v batteries will give you better servo torque and faster servo speed, but sometimes they are overkill if you do not have enough servos drawing them down. We ran a 6v battery in a .40-size plane with 5 servos once (all analog servos) and the surfaces jittered badly. I think a high-capacity 4.8v pack should be fine, unless you want the extra torque! I run 6v batteries in my 100cc plane, but I am running six very high torque digital servos to draw them down!
I am not sure if you have used NiMh batteries before or not, but there is one thing to be aware of: the first few charges often result in a "false peak" -- the same can happen if the pack has been sitting for a while. You simply need to pay attention when you are charging the battery to make sure the full amount is going into each battery. NiMh packs often like to tell the charger that they are full before the entire capacity is put in; this causes the charger to shut off early.
I definitely prefer NiMh packs over NiCd's any day!
Garret |
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Garret H
RMM President
USA
14 Posts |
Posted - 02/18/2010 : 7:54:30 PM
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I just thought of something: what radio system do you use? If you run Spektrum, then you will need to use a 6v setup...
Garret |
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schneller
Starting Member
USA
12 Posts |
Posted - 02/19/2010 : 10:45:24 PM
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Thanks Garret. I will be using a Spektrum receiver.
Now I just need to get out there and try to fire her up.
Bryan |
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Garret H
RMM President
USA
14 Posts |
Posted - 02/20/2010 : 6:12:44 PM
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Yeah, I have heard it is not recommended to use 4.8v battery packs in nitro planes that use Spektrum brand radio systems -- because the receiver's minimum input voltage is quite high, you can have a lock-out once the battery gets drained down a little ways (if the RX has to re-boot)...I have read several posts on RCGroups.com describing this problem. One guy said that all was well on the first flight of his new plane (with 4.8v battery and Spektrum); on the second flight (on takeoff), the receiver shut off because the battery was drained just enough to keep the RX from re-booting. Everyone says running a 6v battery setup is the simple fix...
Garret |
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Receiver batteries
