I am currently designing a small autonomous robot, and was planning on using the qik 2s12v10 serial motor controller to run two High Powered 30:1 Micro Metal Gearmotors. For the power supply, I was planning on using a 9 Volt 600 mAh Li-ion Rechargeable Battery. My question is whether a 9V battery can reasonably cover the stall currents of the HP geared motors (1.6A each)?
Because of size constraints the 9V battery would be best for my application, but I have heard that AA and AAA batteries can supply more current; so would this be a better option to try and work towards? I need to be able to supply 8V-9V for at least 600mAh or more.
Also, I was originally planning on using the TB6612FNG dual motor driver but switched to the qik 2s12v10 for better coverage on the 1.6A stall current (each), not sure if this is necessary but it seemed like a better move (at the cost of more $$$). If I were to try and use the TB6612FNG with a heat sink would it be adequate enough to handle the load?
I am anticipating that the stall currents should only be momentary for my design (only during starting and stopping) as the robot itself should be pretty light… Does this mean that for the most part I should be more concerned with the free running current, or is the stall current still a large factor that I should design around?
Thanks for the help
I think the TB6612FNG (and the qik 2s9v1, which uses that driver) should be able to keep up if your stall times are low and you have a heat sink. However, that stall is at 6V, so at a higher voltage, you’ll be past 2A, which might be pushing it too much.
I expect a lithium-ion battery to have multiples of 3.6 or 3.7V, so your 9V battery unit might only be 7.4V. Many “9V” NiCd packs in that form factor only have six cells for a 7.2V nominal voltage. So, the real voltage is one thing I’d look into if you really need 8 or 9 volts. Your battery should also have some kind of spec. for the discharge rate, which is usually specified in terms of capacity. A 10C discharge rate on a 600 mAh battery pack would be 6A, which would be more than enough for your two motors. 10C is not that high lately, but keep in mind that a 10C discharge rate means a dead battery in a tenth of an hour (and probably less than 5 minutes since the capacities tend to be specified at more favorable discharge rates).
I looked around a bit for 9V lithium ion batteries and didn’t see many specs. You might have to measure your battery voltage to figure out what it really is. Over discharging li-ion batteries can kill them, so that’s another thing to look out for.
Thanks for the response, it was very helpful. I am going to try my luck with the TB6612FNG and heatsink. I was actually accounting for the voltage drop which was why I was wanting a higher voltage to guarantee at least (a regulated) 6V , so no problems there. I also realized afterwards that the TB6612FNG has a 3A peak, should have caught that earlier.
Thanks again for the help, much appreciated!