I'm working on a new antweight design. Its almost finished but as i'm using two modified Hs-81 servos plugged into a 2.4GHz receiver, I don't want to use the 7.4V battery from Little Doris as it tends to overheat the servos, and I gather that the servos aren't designed to be run at this voltage. Can anyone recommend a suitable battery? I'm guessing a voltage of 4.8-6v is the most suitable range, but many of the Lipo batteries i've looked at tend to be too large for antweights (compared to the lipo in Little Doris, which is about 17g or so).
Thanks in advance
Team DisConstructor
Team DC Antweights - Laurie Phillipson, Driver of Little Doris, THRUST, TiNY, Avenger, Avenger 2
You can run a lipo with a voltage regulator very easily: http://www.windisch.co.uk/robots/archives/184
I would advise bolting the regulator chip to a piece of aluminium within the robot or something metal as It can get quite warm if you are running for a reasonable amount of time.
A lipo cell is 4.2 volts fully charged and so the batteries come in multiples of that ie. 4.2, 8.4, 12.6.
There is a tendancy to call them 3.7, 7.4, 11.1 but this is misleading as the charged voltages are quite a lot higher.
As Josh says the best bet it to fit a regulator and I seem to remember Simon had a good description of how to do that on his site.
The lipos I use in my robots tend to be around ten or twelve grams, the Hyperion packs Micron sell seem to be quite good and there have been some even lighter packs discussed on the forums somewhere!
Joey McConnell-Farber - Team Picus Telerobotics - http://picus.org.uk/ - @joey_picus
"These dreams go on when I close my eyes...every second of the night, I live another life"
The voltage regulator solution will work, but beware that the regulators are only rated to 1A current.
Whist the regulator will work well for a receiver and maybe a weapon servo, I would suggest using more than one regulator if you are using servos for drive.
Make two regulators as described on Simon's site.
Connect both to the battery.
Connect one to each drive servo (red and black wires).
Connect the signal (white/yellow) and ground (black) wires from each servo to the receiver (not the red wires).
Connect ONE red wire from ONE of the servos to the receiver.
If you want to use a weapon servo as well, I would be inclined to use three regulators, one for each drive servo and the third for the receiver and weapon. At this point a smaller, cheaper and lighter solution may be to use a 6V NiMH battery pack!
