Servo Current draw
 

Anyone have a link or direct data for the average current draw on JR 8611A servos. I would like to know what a nominal load on my battery could be at a given time in flight. (2100 mah)

RE: Servo Current draw
 

The current draw is very much a function of the load on the servo. I measured the load on my DS 8411 servos at idle (all linkages disconnected) and I think it was around 50 mA. Then I held the output arm stationary and pushed the stick full left. the fully stalled servo drew about 2000 milli-amps as I recall (40 times as much as at idle). Your DS 8611 servo should be similar -- at least in the same ball-park. So how much does it draw in service? Hard to tell from my tests. But I know if I fly my 35% Cap with 8 of these servos, I use up about 25 milli-amp-hours of capacity for each minute I fly. in other words, if I fly 100 minutes, I have used up about 2500 mAh of my on-board packs. This I have measured by cycling the packs after flying. 25 mAh per minute translates to a current draw of 1500 mA (60 minutes times 25). This is a weird unit of measure (milli-Amp-Hours per minute) but it works for me. I know that every minute I fly, I am using up 25 mAh of capacity.

If my plane is using 1500 mA current draw, this implies the average amongst the 8 servos is about 200 mA. (1500 / 8).

In summary, the "idle" servo draws 50 mA, the "in-Use" servo draws 200, and the fully stalled servo draws 2000.

I carry 4200 mAh of capacity (two 2100 packs in parallel)

RE: Servo Current draw
 

Sounds good to me D.

mah consumed/time consumed = average current draw for that time period.

RE: Servo Current draw
 

Excellent information from both of you. Using Joe's formula it would be a simple matter to determine my average flight time between recharges.
DMcQuinn , your info gives me the potential "spike" loads I might encounter I don't believe my little 27% extra will ever stall these overkill servos. But if I took your "in use" loads for your big bird and doubled them as a safety factor, I could assume I might generate a (5x400 mah max ) = 2000 mah max max load. Is such a load acceptable to a single 2100 mah pack? I plan to fly pattern with this plane and anticipate the snap roll to be the most violent maneuver it will do. At that time I might get close to the loads described above. Note: I have a separate battery on the ignition.

An awful lot of "assume'n going on huh....? :-)


Well thanks again.

RE: Servo Current draw
 

I think your 2100 mAh pack will do fine.