jmartindale

I'm new to this hobby and need help. I'm building a Sig Kadet LT-40, my first plane. I'm putting a OS Max SF46 on it and using a Futaba 7C TX with a FrSky TFR6 RX and two S3003 and two S9001 Futaba servos. What RX battery pack would work well with this setup? Thanks in advance for the help.

JohnBuckner

My Feedback: (1)

http://www3.towerhobbies.com/cgi-bin...&I=LXNHS4&P=ML

John

Rodney

If you have the proper charger, then one of the 2 cell LiFe (not LiPo) batteries would work well.

Ken Erickson

J Martindale,

The 2 cell LiFe batteries can be purchased from the same place you got your receiver. You will also need a matching charger. I, and many of our club, have been using those for some time now. We use 700 mAh for Club 40 racing. I use 1600 mAh for Buddy-boxing. Note: Your transmitter sold with a 600 mAh NiCd.

Ken

jester_s1

Do you have a module in your radio to work with the FRsky?

jmartindale

Jester_s1 - no module in my radio. It was my understanding that the radio and receiver were compatible based on both being faast protocol. Is that wrong?

Rodney

Not wrong, FrSky's FAAST receiver works well with the Futaba transmitter using FAAST.

jmartindale

Thank you Rodney.

JohnBuckner

My Feedback: (1)

If you go with any of the Life types in your glow powered LT-40 you need to understand Two things and that using the Life's is going to be a lot more labor intensive and no one ever mentions this part.
First Life's require balance charging with a capable Life charger system every time. Every time you charge there are now two umbilicals that are connected to the charger. Typically with most glow planes the batteries get buried underneath the nose area and are a royal pain in the butt to dig out. which you will have to do each charge or find some sort of balance plug adapter and extension.


Bottom line it is more work every time you go flying and I have had number of folks buy Life's thinking it the next greatest thing only to return to Nimh.


The pack I linked above in post #2 will serve you well with many long flights and remember Nimh is not old dead technology.


John

Ken Erickson

After I posted the recommendation of LiFe, I realized I should have mentioned my great respect for John Buckner.

What he says in his recent post is true.
` ` ` Need LiFe capable Charger.
` ` ` I keep the Balancing leads close to the wing opening and use an extension on the charger, easily and inexpensively available from the same source as the FrSky receivers.
` ` ` NiMH is not old tech.

One thing he did not mention is that, if a LiFe Battery is discharged beyond a certain voltage, the LiFe compatible charger will not charge it. (LiPos have this same trait.) Let that happen a couple of times and you have a supply of leads to use to extend the battery lead. Serendipitous???

So, with all that, why in the world did I recommend them?
1) They have worked very well for us at our club and for clubs in the area, even without the extra mods mentioned above. Guys keep them easily removed to charge or use the inexpensive extension on the charger.
2) The same battery works in our chargers, purchased in the last 4 years. (Not in the 7C)
3) When I cycled all my NiMH packs this winter, they ALL failed!!!! Not the old NiCds, just the NiMHs.

I do have a pair of Futaba 6EX transmitters, which are used for buddy-boxing. NiCds work just fine for both Tx and Rx.

Ken

Tom Nied

I agree with John B. Go with the 2000 mah NIMH battery. Easy, and lots of flight time. But don't get over confident, use a Voltwatch or voltmeter as you fly.

TomCrump

For a novice, I would agree that it's best to keep things simple. A 2000mah NIHM will be a much easier route than learning how to deal with a more complicated battery/charging system.

There is nothing wrong with Ken's suggestion. I'm in the process of switching to LiFe packs, myself. I just prefer to keep things easy for beginners.

jetmech05

Geez why not keep it simple go with a NiCad 700 mAh. You can get 4 or 5 flights out of that but after your thrid flight monitor battery voltage and you consider the battery fully discharged at 1.1V a cell or 4.4V on a 4.8v a pack.
I like LiIon batteries but they require a good charger and a voltage regulator in your plane. Takes forever to charge but you only charge every 2 to 3 weeks.
again you must monitor battery voltage and charge at 7.1 V a pack

Tom Nied

My Kadet that I learned on had a NiCad 700 mAh battery , and it worked fine. As long as I monitored its health, it was good. That's why I like the VoltWatch. Seems like most of us are agreeing on one thing. Checking and monitoring is important no matter what battery you are going to use. I eventually bought a Hobbico Field Quick charger, great when I go for that 5th, 6th "Last Flight" of the day.

JohnBuckner

My Feedback: (1)

Here in the first picture is the battery that I use the most it is the Tenergy (not to be confused with the Turnigy batteries) 2000 mah 6volt Nimh. I buy them in bulk anywhere from five to ten at a time and these are what I use in the vast majority of my fleet and they have proven to be very robust.

I Absolutely do not use four cell Nimh for any 2.4 system and I believe the five cells types offer a much better safety margin. The only exception to this is I do have a few controlline airplanes that I do use fourcell types with 2.4 but those airplanes most have only one or two small servos and are never more than sixty feet away

Now I do use other technologies where its appropriate for instance I use two cell Life's for my diesel fuel pump pictured and the are ideal for pumping large quantities of fuel. The last picture is a three cell Life that supplies my turbines pumps and computer.

Heck I even use fourcell Lipo's for my daily starter having experimented with just about every possible type over the years and perhaps some might remember the many variations I have posted and pictured over the years.

John

TomCrump

With standard analog servos, I have no issues with running a 4.8 volt pack, on 2.4. I think the 700 mah pack suggested above would suffice.

krokodyl

A 5 cell nimh is easy to use, and plenty for a trainer. I would go with this over a 700 mah nicd, as they don't cost tooo much more, and you don't have to worry about voltage after 3 flights. I always check voltage after every flight, since it's easy enough to do.

I switched to life, mainly because you can fast charge them. I often forgot to charge the nimh until it was time to go. I'm pretty sure that a life is safe to charge at 1c, while doing so on a nimh can greatly reduce flight time. Since the battery is always past 50%, at 1c it will charge by the time I'm all set up. Of course I still try to charge a few hours before anyways. The same goes for field charging, you can safely charge in just a few minutes. The balancing is annoying, so I plan to have a extension running just outside of the airplane, and then another from my balance board, which should make it easy enough.

Hubert

Ken Erickson

J Martindale,

There is not any bad advice in this thread. Unnecessary is not bad, per say. However, you have received lots of different advice from people a long way from where you are wanting to fly RC.

When we have a person asking about learning to fly, the most common answer is something like, "Go to local clubs (or your local club) and learn who are the members who assist the new people." I highly recommend that approach to you for answers to your battery question. After hearing what they have to say, make your decision.

Of course, you still have what you received here.

Best to you.

Ken Erickson
Your

jmartindale

Thanks to everyone for all the good advice. After visiting with a local club member and considering the posts here, I've decided on the NiCM 6V, 2000mAh battery pack. That may a bit of overkill, but I want to stay on the safe side for now. Thanks again to everyone for your input.

JohnBuckner

My Feedback: (1)

Excellent choice in choosing to stay with the 6 volt types Nimh/Nicd and it is most definitely not overkill to use the 6v (5 cell) versions of either with your 2.4 system.

There is another good reason why the 5 cell over the 4 cell (4.8v) types is a good choice and that is simply put, speed! You will find that there is a very slight speed advantage in the servos. Now why is that an advantage to me you might say, I'am not fancy aerobat or perhaps just a new flyer. Well yes its true a relatively new flyer will likely never even notice the difference, However I have seen it time and time agine a newbie will do perceptively better and smoother with faster servo response ever though He may not notice. Indeed that slight servo speed is an advantage to pilots of all skill levels. Back in the day when electric servos were first used they were so slow it was like having 100% expo on at all times.

So even before 2.4 there was good reason to choose the five cell types over the four cell types.

John

Desertlakesflying

My Feedback: (28)

On 72mhz that is fine, but not on as 2.4 ghz system.

Don't do the 700mah nicad if you want to keep you plane more than a few months if that. Go with the 2000mah nimh battery in the link above.

TomCrump

I respectfully disagree.

krokodyl

I don't fully agree either. While a 5 cell is safer, a 4 cell will work, aslong as it is fully charged. Most receivers brownout below 3.5 volts, and if your'e battery is that low, then it's not exactly charged... Especially since the servos probably won't put too much voltage drop. IMO, more than 3-4 flights on a 700 mah battery is pushing it. On my 2000 mah nimh, I always topped it off after 6 flights or less. On my life, I top it off every 3 flights if I have another plane to fly in the meantime, since they are much quicker to charge.

Having said that, the 2000 mah 5 cell nimh is the better choice.

Hubert

jetmech05

How ever did we fly years ago on a 4.8V 700mh battery? While agree that 6V is better it is not a requirement. Please remember there is no put it in and forget it battery. The larger the mAh battery the longer to charge

TomCrump

I think that "preferable" becomes "must have' after awhile. People lose sight of what is actually required.