Hi,
I would like to power the L6 arm totally of batteries. I have the scc-32 and the bot-board.I guess im going to power those 2 boards with a 9V battery each,right? How about the servos? Is this good enough?–> (7.2 Volt Ni-MH 2800mAh Battery Pack). How many amperes should I charge this battery with?
Thanks very much.
You can power both boards VL with a single 9vdc battery. Remember to remove the VS=VL jumpers on both boards. 7.2vdc is a little hot for servos. I highly recommend 6.0vdc for them. You can charge the batteries at 1C, but they will last longer and take a better charge at .5C.
What if I power everything from this 7.2 Volt battery? Wouldnt the voltage drop to about 6V if the bot-board and ssc-32 are connected to that battery and thus the remaining voltage be more tolerable for the servos?
It doesn’t work like that. You could however put a voltage regulator in your circuit to convert the 7.2V battery to a lower voltage before connecting to the servos. (But that still wouldn’t be quite as efficient as just using a lower voltage battery.)
If you do end up powering everything from the same battery, the SSC-32 already has a 5v regulator on it’s servo power rail if you use the correct jumper configuration. (It’s limited in how much current it can supply though, so you couldn’t connect too many or very powerful servos.)
You might want to check out this older post from Jim: lynxmotion.net/viewtopic.php?t=2401 .
The Bot Board and SSC-32 will only draw a few tens of milliamps. No real load there… Your logic is reversed. A 7.2vdc battery will be higher than 7.2vdc when charged and drop to 7.2vdc when current is drawn from it.
I told you the 6.0vdc battery was recommended, not due to some mathematical interpretation of some specs, but from real experience. 7.2vdc batteries are too much for most servos. 475 and 645 get jittery at the higher voltage. Micro servos go nuts. The 422 seams to tolerate the higher voltage better than most.
You have to realize 7.2 from 6 is a 20% increase over the maximum recommended voltage by the manufacturer.
Short term you could go to Radio Shack and get some rectifier diodes to put in series for power to the servos to drop the voltage to the servos by ~.7v per diode.
