mpuvdd

Hey guys,

Does anyone know if an AR400 Receiver can power 5 standard sized servos off of a 4.8V NiHM battery?

I don't know if I need a BEC or something to avoid brownout on my receiver.

The manual says to run a volt-ohm meter off of one of the receiver leads and load the control surfaces but I am not in town to try that yet.

Thanks for your time,

Seth

Joe Fisher

My Feedback: (4)

The receiver dose not power the servos the battery powers the servos.The receiver only sends the small signal that tells the servos what to do. There should be almost no limit to how many servos a receiver can control. There is a limit on the number of servos that a battery can power. And that is the the current the battery can provide. 2100ma cells can power almost 4 x as many servos as 600ma cells can power for the same time.

kmeyers

I don't think so. Nimh are great little storehouses of energy, but, they are not capable of high current demands. They are best suited to low current over a longer period of time.

So what is the current draw of your servos. They generally list two currents for any servo:
Idle current and current at lock stall.

I have two standard size servos in my hand. One is a 45 in/oz the other is 250 in/oz @ 4.8 v. The max current for each is 180 mah for the 45 and 3400 mah for the 250.

What happens is the current reduces the voltage and receiver reboots if the voltage drops low enough. For this reason most people use 5 cell Nimh packs for safety.

But your specific servos may or may not work based on their current draw.

What servos are we taking about?

A BEC will not increase the voltage. Oh but a voltage booster will, we use them on single cell (usually a lipo) application.

hogflyer

The AR400 is a great receiver (I fly a couple of them) but would not recommend a 4.8v NiMH on a Spektrum receiver, run a 5-cell 6.0v NiMH or 6.6v 2-cell LiFe. While it may perform OK on 4.8v, they have too much history of brownouts in the past.

Are you running this on a glow plane where you'll have dual aileron servos, single throttle, rudder and elevator servos? Or running electric with an additional 5 servos?

I'd recommend getting a LiFe which have many good advantages and they'll take the load you'll put on them. I have several of them and have converted all my glow planes and gliders over - just put an 1100mAh in my Kavalier last night replacing a 4.8v NiMH that wouldn't charge properly (Airtronics receiver's have no issue on 4.8v). You can recharge them and let them sit with no issues.

I have a 1/4 scale Hall Cherokee aero tow glider that runs 7 high torque (192in/oz) servos with an Airtronics 10ch receiver on dual Hobbico 6.6v LiFe 2200mAh batteries (each plugged into it's own battery port on the receiver). They sat for 10 months after I charged the two 2200mAh packs and when I recharged them last week they took only 250mAh each.

Hogflyer

mpuvdd

Thanks for all of the replies guys.

I am running them on a gas plane. 5 servos. Each servo is a Futaba s3003 with about 44 oz-in of torque at 4.8 V. Though I can't find a current draw online, I would estimate that each servo can draw up to 180 mA in low performance flight, for a total of 900 mA.

The battery is a Hydrimax NIMH 4C 4 CELL 4.8V 2000MAH battery.

My local hobby store did recommend this battery with the Spectrum AR400 but I was a little bit skeptical.

Hogflyer: Interesting information regarding LiFe batteries. I will certainly check into that!

j.duncker

My Feedback: (2)

I would move up to a 5 cell pack.

mpuvdd

Will do. Thanks!

hogflyer

With running the Futaba S3003 servos you'll be fine with a LiFe pack - either 1100mAh or 2200mAh. At least that's what I'd run with it.

Also just a note on the servo's - the S3003 servos have the main shaft is supported by plain bearings. For only a couple bucks more you can move to the S3004 which has a ball bearing supported shaft. S3004 servos on a LiFe work fine for up through .60 size birds - had them in my Twist 60. Plain bearing servos will eventually wear and create slop at the output shaft - I have a nice collection of this type servo in the basement for spare parts.

Hogflyer

mpuvdd

Hogflyer,

Spare servos like that are always good for bomb drops!

kmeyers

They sell a conversion kit that comes with a new top and a ball bearing. I once converted 4 servos for 12 bucks. Completed servo = S3004