graggy

Hi, I just bought some futaba servos (s3010) and on the box it sats nicd use only. I have a 4.8 volt 1500 MaH NiMH battery in my plane I'm using these servos in. Will they work with this battery or should I purchase another battery? Thanks for your help

BarracudaHockey

My Feedback: (11)

That battery is fine. Thats a hold over from the days when NiMH first came out and had high internal resistance. Digital servos can pull a lot of current so with the high resistance the voltage would drop under load and the reciever would shut off.

Newer generation cells are fine.

flhyr

So, I have some hydrimax cells from 2006, do you think those are new enough to be safe?

JohnW

My Feedback: (6)

It's not really how new they are, it is dependent upon the battery capacity and internal impedance of the battery.

Good luck on finding the internal impedance. I think the Hydrimax cells are made by Panasonic, but not sure. Anyway, I looked for quite awhile on Google and couldn't find any impedance data for the cells. However, I can almost guarantee they will have a high impedance, which is not what you want. Another reason why I buy batteries that have clearly published specification so I know what I’m getting. I suggest http://www.hangtimes.com/index.html

The only way to really know is to hook up a volt meter to your setup and measure what happens when you stall servos (might also be nice to know how much current you are pulling so a current meter may be in order too.) Stall some servos and note the voltage drop. If the voltage drops to a unsafe level, the battery is not up to the task. You may want to recheck this across the discharge cycle to determine at what pack voltage you need to stop flying.

BarracudaHockey

My Feedback: (11)

Excellent point.

A.T.

Answered also at crosspost futaba servos

Futaba Battery FAQ
Last item quote
Q. "I purchased a new servo that has a warning label on the back that says it can only be used with NiCd batteries. I use only NiMH, will I be okay?
A. The reason for this warning is that the servo can produce high-current draw from your batteries. If you are using NiMH or Li-Poly batteries, make sure they are capable of delivering sufficient Amps to the servo."
On all large model instalations with NiMH rx packs, suggest use of two packs to provide better protection, not only current but if one pack fails, unlike Nocad which simply drop a cell, NiMH fail completely. Refer to:
Dual (Parallel) Battery Operation = Reliability & More Flight Time -
Never add useless lead to balance a model, increase battery capacity even building a battery box in front of firewall or behind wing as needed for correct CG.
Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links