motor12

I am going to be using 12 servos in total (9 futaba S3305 and 2- S9001 and one tail wheel retract servo) my question is can i run this many servos on the same battery LIPO(2600 mah 2S)with a step down voltagereg.along withmy receiver.Please feel free to make suggestions. Thanks

speedracerntrixie

My Feedback: (29)

Not really enough information to make a call one way or another. Knowing the size of the airplane and the power plant being used would make for more accurate suggestions. My current sport flyer is a 55cc powered Laser 200. I do not fly 3D just IMAC type flying. It has 5 servos and a ignition battery eliminator so the ignition is run off the same battery. I get roughly 90 min of actual flight time on a 3000 mah 2s lipo and regulator setup.

motor12

The airplane is a Top flite FW190 giant scale and the motor is a DLE 55, Thanks

scale only 4 me

My Feedback: (158)

For peace of mind, I'd run a redundant battery share system of some sort.

speedracerntrixie

My Feedback: (29)

I agree ,I don't because of weight but for a warbird I would go with a Smart Fly Turbo reg that has built In batt share and smart switch. Pretty much a plug and play setup.

mattnew

My Feedback: (2)

You'll need to determine if the "common paths" between the 12 servos and the battery can supply the amount of current the 12 servos can potentially/ or rather likely draw. 

speedracerntrixie

My Feedback: (29)

The turbo reg uses a fail safe switch so no current flows through the switch. It has 2 inputs and 2 outputs. The outputs can be plugged into two separate spare channels into the RX. The RX power bus is beefy enough to handle the current of that many servos unless 3 or 4 of them are stalled at the same time.

Zeeb

My Feedback: (41)

Well first off I think I'd reconsider your servo choice on the S3305's as they are classified as "surface" servos. The centering is really loose compared to an air servo and I have used them on an old Funtana when I didn't know any better. They do work on that application but jitter when the A123 battery is first turned on, here's the part of the servo description on Tower's website saying it's for boats and cars:

"FEATURES: Wide usage in cars and boats that require standard size,
high torque servos"

While it's a bit of a personal preference deal (some guys run nylon gears on the throttle servos), I'd ditch the S9001 servos as well since I do not run nylon gear servos on gassers.

Next, a 2600mah LiPo probably isn't going to handle the load once it's run through regulators which limit current flow and then there's the issue of matching up/operating all those servos through a single servo lead connector. Those will only handle about 3 amps continuous.

A PE would be in order unless you're running either JR or Spektrum in which case the big PowerSafe 12 channel rx's will do the job but I would NOT be using LiPo batteries with those rx's since they will take the voltage but the servos won't. In fact, I'd abandon the idea of using LiPo's for the flight pack on any radio system and go for either A123 (my preference) or the LiFE batteries and forget the regulators.

scale only 4 me

My Feedback: (158)

Personally those servos are too slow for my liking, I'd bite the bullet and run hs5625s, same torque but much faster, but everyone is different

I'd set it up for that many servos and a Futaba RX this way,, (RX assumption made since you're running all futaba servos)

2-A123 2300mah packs,, 6.6 volts safe for most servos, plenty of C rate, plenty of Mah
PowereExpander Pro,, for battery share and to step down RX voltage
Pin switch option,, so simple
IBEC,, to eliminate 3rd pack & switch

Then I'd make some sort of hatch for battery connections and field charging

good luck

karolh

Sub

motor12

Thanks for all the suggestions, since reading the replys i have decided to forget using LIPO batterys and go with NICD as recommended by Futaba (per phone call).The servos were on the recommended list from TopFlite thats why i listed the S3305 as servos used. Thanks this has been a big help.

scale only 4 me

My Feedback: (158)

Curious,, What packs did they recomend?

motor12

No recommendations on size or mfg. only told to use NICD with large enough mAH to operate all servos. The guy i was talking to seemed to be in a hurry and was shortwith his answer. Most likely sick of people like me with trivial questions.

MTK

You can do that but you will probably only get2 or 3 15 min flights before needingto recharge. No matter what, you'd have to keep track of your voltage after every flight andrecharge when you read around 7.4-7.5 volts on your pack. Never drive a 2S Lipo to less than about 7.2-7.3 volts. You will have a time getting a charge back in it (chargers will not drive a battery too depleted), and the battery may be damaged......

You may want to go with a 4000 ma 2S LiPo, regulated to5.7 volts. You should be able to drive the dozen servos and ignition for about 5 flights 15 minutes each. I suggest you take a good look at and buy the Tech Aero IBEC for your ignition battery eliminator circuit. It has all the RFI filtering built in. Again, make sure to check voltage every couple flights until you are certain how the battery drops and how the drop repeats over many flights. Actually this is a good practice to get into across the board but especially for the more complex airborne set-ups. I use a small digital volt meter to keep track

In regard to the FutabaTech telling you to use nicads, some Futaba servos get jittery when driven at higher than 6 volts, and it may be that the servos quoted are some that do. I don't fly Futaba so I can help in telling which servos will or won't. The Futaba tech was in the best position to make the call.

However, althougth standard 4.8 V nicads at 4000-5000 ma capacity will work okay, they will be very heavy (basically 4 size D cells in series,about a pound) and use up lots of space. Even 4.8 V NiMH battery of similar capacity will be heavy. LiPO will be much lighter.

You have some choices. As far as V-Regs, Tech Aero has some of the best around....Look up their stuff on-line

motor12

Well i called the futaba service center again this morning and talked to a different guy, who was very polite and seemed willing to help. I told him yesterday i was told i could only run NIMH batteries on futaba servos not lipos or life batteries. I told the service center guy a lot of people are running LIFE batteries and no reg. with no problems. He told me to hold he would check. When he came back he said i would be fine using a LIFE battery set up without a regulator. So that is what i am going to do.

a70eliminator

Ok well thats settled now you have to think about life batteries have unique charging characteristics.
Don't ask me for specifics as my 9 servos run off a 6v nmhd battery charged with a wall wart.

karolh

Using Life batteries is an excellent choice, however their battery technology is completely different from Nicads, NiMh or Lipos, so make sure that you get aquainted with the do's and don't that are associated with their use.

scale only 4 me

My Feedback: (158)

Kinda makes me nervous that he had to check before he could answer such a basic question.

Look into A123 (life) packs too,, you'll be happy once you try them, but it does take a little schooling to get acquainted with calculating how many flights before recharging since you can't just go by voltage. I've been running them for a few years now and swear by them,,,


good luck

Zeeb

My Feedback: (41)

Welcome to Hobby Services....

IF you can get them on the phone, in my experience you get someone who cannot help you with questions about 9 times out of 10.

It took Bax (Bill Baxter over on the Futaba support forum) who runs the USA Futaba service operation for Hobbico, several years to say that A123/LiFE batteries were okay for 6 volt rated servos, even though the voltage on an A123/LiFE is virtually identical to a 5 cell "6 volt" NiCD/NiMH pack.

For the OP; I think the decision to go with the newer chemistry is the way to go but as mentioned, there is a bit of a learning curve associated with using those batteries. One of the biggies is that you cannot volt check 'em to determine charge state and you need to educate yourself on why as well as some other important points about using those batteries....

MTK

A123 Voltage nominal rating is 6.6 volts for a 2S battery. Full charge puts the voltage upwards of 7.4 volts. Compare to a LiPo or Li Ion whose nominal voltage is 7.4 and full charge voltage is 8.4 for the same 2S battery

A 5S NiCd or NiMH has a nominal voltage rating of 6.0 volts and a full charge voltage of6.8 -6.9 volts. It doesn't sound like alot of difference but that's significantly lower than that of an A123 2S battery

Some servos simply can't handle the extra 1/2 volt, especially with freshly charged batteries. JR's servos almost universally can handle it, but that's just JR. FWIW 2 U

One thing that competition pilots always consider is servo output consistency, first flight of a contest to fifth, at the end of the day. That's the reason many of us use LiPo's regulated down to 6 volts usually. It doesn't matter if the LiPo is at full charge of 8.4 or nominal charge of 7.4. The servos see 6 volts throughout the day and perform identically (speed and torque) from start to finish. Airplane response is identical start to finish for the day.

scale only 4 me

My Feedback: (158)

If you used a123 packs you'd know that they fall off that peak 7+ voltage almost instantly and drop to 6.6-6.7 volts when in use and hold that range through the whole discharge cycle.