scottwitting Posted December 18, 2014 Report Share Posted December 18, 2014 Having electrical problems with my lads 12.5 and need some expert advice! Here's the story so far.... The problem is that the drive is very weak and juddery and only a small amount of load on the rear wheel causes it to stall, i.e no torque. My initial thought was the motor brushes. Bike is a 2011 model and has been well used so would make sense. I've had the motor to bits before to do bearings so I set off down the route of checking these. However, I decided to direct wire the motor to the batteries before stripping it - this resulted in the motor spinning up nicely and with loads of torque so I didn't progress the motor strip. I've examined all connections and can't see any that look dodgy. Reading on here suggested throttles are often the cause of problems. Also suggested it is possible to disconnect throttle and short the connections to the controller to spin the wheel up. Despite trying to link all three terminals I have not managed this(?). I stripped the throttle, it did look a bit worn and I did seem to be able to spin the wheel without the lack of torque by playing around with the throttle in bits. Thought I'd solved it - £25 on a new throttle - still the same.......... Reading on here suggests potentiometer can cause problems. Disconnected this as suggested - still the same. The relay provides the live feed to the controller when the key is turned, suspected faulty relay so I linked this out and problem remains. With the key switch on I've measure resistance through the system to the motor connection. Live has no resistance, earth has about 58k ohms with throttle shut reducing to zero when you give it full throttle, kind of what you'd expect if the controller ramps current to vary speed. No clues from this. I'm running out of ideas, tending to think it may be brushes like I originally thought and the direct wire test provides such a initial kick that it masks this? If not then there's only really the controller.........big bucks...... Anybody had similar problems? Any advice on what else to check? Anybody got any reference resistances to test for? Help! Only saving grace is he's just about ready for a bigger one, a 16 Racing is top of his Christmas list and he's been a good boy..........still need the 12.5 running for his little brother though! Cheers Scott Quote Link to comment Share on other sites More sharing options...
proc Posted December 19, 2014 Report Share Posted December 19, 2014 If he's big enough I'd get the mecatecno 20, had a 16 for my lad the throttle was either on or off it was lethal I know they've adressed it now but still not as good as the green machines in my opinion Quote Link to comment Share on other sites More sharing options...
scottwitting Posted December 19, 2014 Author Report Share Posted December 19, 2014 He's not big enough for the T20 yet, I agree they are a better bike than the Oset 20, mainly due to the lithium batteries. So if Oset don't go LiPo before he's big enough that's what I'll go for, otherwise you spend the same money/more buying an Oset and then converting it to lithium. The 16 R that's hiding in the garage attic has a much softer throtlle responce than the 12.5 he's become accustomed to, which is quite vicious, but it's taught him good throttle control, to the point where he can deliberately wheel spin off! I'm worried the 16 will be too soft for him, even on the highest setting! Quote Link to comment Share on other sites More sharing options...
gwhy Posted December 19, 2014 Report Share Posted December 19, 2014 (edited) Hi Scott, sounds like you have tried everything,, here something you can try : disconnect the motor and measure the resistance of the motor, it should be very low then give it a spin via the rear wheel and measure the resistance again ,, it should be the same resistance as before you spun the wheel try this a few times. if the brushes or commutator is worn then this should show up as a high resistance when the motor is stationary.. let us know the readings then we can go from there. or clip a volt meter onto the 2 leads going to the motor then wiht the bike rear wheel off the ground give it full throttle and see what voltage is being delivered to the motor ( it should be near battery voltage ) the voltage shoud not drop to much if you now apply the rear brake a little, if the voltage drops away very fast and there is no torque then its likely that you have a high resistance somewhere in the system, could even be the battery's... do the same test but before the controller if you get the same results then its likely that its not the controller at fault Edited December 19, 2014 by gwhy Quote Link to comment Share on other sites More sharing options...
scottwitting Posted December 20, 2014 Author Report Share Posted December 20, 2014 Hi gwhy, Thanks for the advice. I also posted on the Facebook Oset page and Ian replied yesterday. He suggested checking the fuse/fuse holder for poor connections. Prior to this I had only checked for continuity across the fuse at each end of the fuse holder wire and this suggested it was ok. However, when I removed the fuse one blade was very crusty and the holder had slightly melted. No spares, so I cleaned it up as best I could, back together and hey presto, problem gone! It is obvious that the poor connection was enough to severely limit the high current flow, causing the motor to 'steal' the power to the controller and it to shut down, hence the cyclic, juddery nature of the problem. Kicking myself for not properly checking the fuse sooner, but it's sorted now! Thanks again for taking the time to give me the good advice. Cheers Scott Quote Link to comment Share on other sites More sharing options...
gwhy Posted December 20, 2014 Report Share Posted December 20, 2014 no worries Scott, the second test above would have showed that up .. with any type of fault like this its always best to measure voltage through the system under load, and this will 9 times out of 10 point you to what is causing the problem. glad you now have it sorted.. Quote Link to comment Share on other sites More sharing options...
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