They have an encoder … but I don’t really need an encoder…(not actually sure how to use) can they be run without hooking that up? I plan to use with a sabretooth dual motor controller…
Also… if I have 6 of these… what is my best option battery wise for powering?
I made a 12V version …6 x DC motors without encoders which worked well… but wanting to significantly upgrade the power of the vehicle…
They have an encoder … but I don’t really need an encoder…(not actually sure how to use) can they be run without hooking that up?
Yes, you can use the motors without connecting the encoder.
if I have 6 of these… what is my best option battery wise for powering?
The motor nominal voltage is 24V, so you can use one or more lead acid, NiMh or LiPo battery packs.
The motor’s Rated Current is ~7 A and the Stall current is 24.5 A. For 6x motors you would have around 42A rated and 147A stall (worst-case scenario). You should take these values into account to calculate the capacity and discharge rate, if you are not familiar with these concepts please check this tutorial:
I hope this helps! Let me know if you need further assistance
That battery should work, however, you should take into account how much time you want to use the robot (without having to recharge it) to calculate the needed capacity.
Without much load, that battery would last around 7min
5Ah/(6*7A) = 0,11 hours ~7min
I suggest looking for a higher capacity battery so you can use your robot (without having to re-charge it) for a longer period of time.
gosh, it needs a bigger battery than I anticipated!
Am going with a Turnigy High Capacity 20000mAh 6S 12C Lipo Pack
This should give 25 mins of continuous run time which is OK, in reality the robot will never be under continuous running …so session time will be likely 1 hour which is fine.
I noticed the current POWER MANGEMENT UNIT i have is only rated to 90A. Although the stall current on these motors is 147A.
My thoughts are… (I may be completely wrong): I am comfortable that this will not reach its stall current, as it is massively over powered, and has a torque rating 2 X in excess of what it needs. 60kg/cm (i did the drive motor sizing tool exercise and came up with 26kg/cm)
So in theory if it were to reach 90A thats 45A per channel so 45A / 3 motors = 15A per motor
15A is 61% of 24.5 rated stall current. Which would be 36kg/cm of the 60kg/cm…
So still way over the required torque for this beast.
How much do I need to consider what wire I use to hook up this system?
You should use a wire that can withstand the current drawn.
Is my thinking/planning /design right here?
It is always best to prepare for the worst-case scenario. However, you could fuse the motor leads to protect everything in case they stall, but do not fuse the power leads, here’s the information provided by the manufacturer regarding the use of fuses:
We prefer that you fuse the motors rather than the battery leads, or if for safety reasons you need to fuse the battery that you do it at a much higher current than the motors. The reason is this:
Because Sabertooth is a regenerative driver, it relies on having a battery to put regenerated energy back into when you command a stop (and at other times). If you draw enough power to blow a battery fuse, all of a sudden the Sabertooth has nowhere to put the energy. It will see the fault, though, and try to stop the motor. It doesn’t, however, have anywhere to put the energy (the mechanical energy of the vehicle and the electrical energy carried in the windings and the caps). So blowing a battery fuse will sometimes kill the driver – which we would replace under warranty, but it’s still annoying for all parties.
The better way to do it is to fuse the motor leads. If a motor fuse blows, the motor will freewheel, the Sabertooth will sit there contentedly, and the only thing you will have to replace is the fuse.
Both options should work but I think it would be best to use the 45A fuse. If you were to use a 15A fuse on each motor in case one motor stalls and the others don’t you would have to replace that fuse even if there really wasn’t a concern (because in that case that channel won’t necessarily reach 45A between all 3 motors).
