Hello guys, I'm working on an arduino based robot that uses PCA9685 Adafruit servo controlling board to controll 12 HS-5070MH servos.
I'm having a hard time finding the right amount of current that I need to power up my robot.
One servo's no load operating current draw is 240 mA and stall current draw 1300mA.
I'm planing on using an adjustable 4V-12V step-up voltage regulator with a minimum input of 2.9V to output steady 6 - 7.5 V.
Can I use something like Lithium Ion Battery Pack - 3.7V 6600mAh from Adafruit, or should I try to connect by myself LiPO batterie's on paralel to achieve desired current?
Unless you are sure that you know how many servos will be moving at the same time, to be completely safe you should allow for (# of servos * stall current) so 12 x 1.3A = approx 15A.
To get 15A @ 7.5V out of your regulator the input at 3.7V would need to be roughly 30A. The Adafruit batteries I've seen are only rated for 0.5C so a 6600mAh pack can only deliver 3.3A - not much use.
Personally I wouldn't bother with the regulator I'd just use a more modern 2S 7.4V Lipo as used in RC plans/drones/cars. They're usually rated at least 20C these days and may well cost less than the Adafruit version from somewhere like Hobbyking e.g. https://hobbyking.com/en_us/turnigy-5000mah-2s-30c-lipo-pack-xt-90.html
I'm having a hard time finding the right amount of current that I need to power up my robot.
One servo's no load operating current draw is 240 mA and stall current draw 1300mA.
I'm using a 4000 Ma. lipo on a T-Hex with 18 servo's, ping sensor, IRPD, two Xbee's( running continuously) and a cooling fan. I've run for over an hour steady and have juice to spare. I'm not sure how long it will go for but now I'm curious so soon I will let you know the full running time. As for lipo's I read all the stuff about them too : [u]https://hobbyking.com/en_us/turnigy-battery-nano-tech-4000mah-4s-25-50c-lipo-pack-xt-60.html[/u]
And if using any high current battery without built-in protection circuit adding a fuse is an essential safety
measure - a powerful LiPo can easily set all the wiring on fire if there's a short circuit. The fuse is
to protect the wiring.