I ended up doing this (using an old RC pack), but i the end realized the motors were defective internally. I ended up getting a replacement and the robot works fanastic.
See: http://forum.makeblock.cc/t/notification-replacement-of-25mm-defective-motor/917
Thanks I obtained an 8xAA and a 10xAA battery holder and have tried these with both Alkaline (1.5v) and rechargeable Hybrid NiMh (1.2v) batteries and got a really good result with either. My tank now charges around the room at a good speed (and can turn on the spot) so the extra couple of volts seems enough to do it.
I have similar motor issues and even after contacting support, answering their questions and posting videos, no luck.
I even posted a YouTube video and hopefully that helps. But at this point I have a starter and ultimate kit that’s as good as a paperweight. https://youtu.be/jcyFzR7A6pQ
Directly connected to the battery pack that came with the kits here’s the results of the motors. Note the letter refers to the kit. The number to the 1st or 2nd motor in that kit.
1a:180ma
1b: 200ma
2a: 170ma
2b: 190ma
3a: 180ma
3b: 200ma
Note that 1b & 3b are the highest and at points for split seconds hit 210ma.
Voltage of the built in pack was around 8.7v. Using a fresh 9v battery with a metered voltage of 9.2v all the amps above increased by 10ma respectively. This agrees with the posts where people upgraded the battery pack to a 12v to get better results.
@shaiss : just picked up another kit, for a nephew. Pulled out the motors and put them in my original (perfectly functional) kit’s tank to test em. They barely move it, so I guess this new kit has bum motors. What exactly were you doing to get those milliamp results, exactly? Motor to battery pack to …voltmeter?.. I am not much of an electrician and would appreciate a for dummies guide to what exactly is going wrong and how to test for it. When I have the time I am going to set up a torque comparison test between the new and old motors, was thinking about just lifting a series of dead weights on string until the motor gives up…
Here’s some of the photos/videos when I was testing:
None show a good overview of the circuit, so I put this together to illustrate:
You should see your multimeter bounce a bit similar to the video. Note that you are testing at 9V which is misleading since the motors are rated for 6V and the orion board only puts out 6V. SO, if you’re getting 200ma at 9v you’re going to get less at 6V. I haven’t proven this out since I don’t have a working motor. 0 for 6 so far 
Outstanding. I will post some comparison results when I have time to set this up, between my two good motors and my two apparently bad ones. Along with a torque test hopefully.
Just for your reference: my two (good) motors free-running current is about 250mA @9V (workbench power supply). When slowing them down (hold the wheel), current goes way over 500mA.
Resistance measured on the wire leads is 1.5-2 Ohms. Bad motors are probably 30-50 Ohms… I guess this would be easier to test (no battery required).
Joep
Would you be able to share a picture of how your testing the resistance? I’d like to test mine, but as I have no experience with measuring resistance I’d have to figure all the out first.
Hi,
Connect the two motor leads to your multimeter and select the resistance range, see picture.
Note that below 10 Ohm, error of a few Ohms is possible. Make sure you have solid connections and check if the readout of the multimeter is zero when the probes are connected together (without the motor). If not, you can subtract this value from the motor resistance reading.
The resistance measured is an indication of the torque the motor should be able to provide. The supply current is dependent of the turning rate of the motor (and voltage & pwm duty cycle of the supply). And battery voltage will drop when current increases. So for a good comparison, you need supply current, supply voltage and turning rate (at lease some estimate).
Since you seem to have motor that provides insufficient torque to move, it would be interesting to know the current when they are not moving. Use your battery and measure the voltage too (don’t need to measure them simultaniously). If the current is low (with sufficient supply voltage), it’s an electrical problem. If it’s high, you have a mechanical problem. Note that high currents can damage motors, so do not block your motor for this meaurement!
Update: I had a chat with my local supplier and he told me the motor issue is a mechanical one. If this is correct, DC resistance is not usefull to detect the issue, but the no-load running current is.
Spot on!! The tutorials and getting started sections are haphazard and confusing and way too much is left out. Newbies like me find this confusing and waste hours looking for answers here on the forum. Most of these issues should be dealt with in a proper getting started section for each product.
I received my replacement motors. Running on a fresh 9V directly connected to the battery they draw ~170ma with no load. This was consistent across the 6 motors. Installed in the robot and it works as expected. Only thing I see is its a tad slower turning tight than it is left, not sure why, but will keep playing over the weekend!
Got my replacements for the motors in a bad kit here as well, and they work great. To the Makeblock team, thanks for fixing the problem.
Please help me with the motors. I sent a message to @evans_xy concerning the matter. I am new to this so please have patience. This messaging system wont allow multiple messages of the same content.
Thank you,
John
Purchased an Starter Robot Kit for my son on dec. 11 on amazon. Built kit as instructed
but no motor function. Signal is being sent from IR, lights signaling robot working, but,no movement.Checked voltage at electric motor with forward or reverse bottom pressed and get 5.75 volts ( 6 volt system ), Motors are not bound and tracts removed . Motors are defective I think .How do I get 2 replacement motors ?
