MP5 Motor Cutting Out Randomly

[jmeaghan]

Hello everyone I have posted here a few times about different issues and have had excellent help from people.  I have had my MP5 for over a year with no problems what so ever.  Recently it has started cutting out (loosing power) randomly.  Sometimes it runs for a good distance and other times it cuts out right after I apply throttle.  I check all the connections for moisture and I have checked the output of the batter with a volt meter.  Neither of these appear to be the problem.  After it looses power I simply disconnect the power and reconnect it to get the bike operational again.  Then a short time later it looses power again.  Aside from checking the connections to make sure they are tight and have no moisture, and testing the battery output voltage the only other thing I have noticed is the batter contacts are quite worn (oxidized).  I was considering taking some steel wool or sandpaper and trying to clean them up a bit. Has anyone dealt with this or hear of this before, or have any suggestions?  It would be greatly appreciated.


Cheers.

[Papagino]

Hello jmeaghan, I wouldn't recommend using a steel wool or sandpaper to clean the battery contacts, as this could remove the plating on it and this would allow for premature oxidation afterward.

I would recommend using a pen eraser, the type that comes with a brush like the one attached.

I have a background in electronics and this is one of the best ways to remove oxidation on contacts without damaging it.

Spraying the contacts with WD40 after the cleaning will prevent moisture and oxidation.

Anyway, just my 2 cents

Cheers
Dan

[jmeaghan]

Thanks Dan I will try this suggestion tomorrow.  I appreciate the reply.


Cheers

[Papagino]

Hello again jmeaghan, I forgot to ask, does your battery have a switch or contactor, or is it plugged in straight to the motor?

If it is plugged in straight to the motor, then every time you plug it in, arcking or spark is generated because of the controller's capacitors being charged. If this is the case, then the contacts of your battery and battery connector will form a black residue and could be the cause of your motor cutting out.

If this apply to your case, then using a precharge resistor can solve this problem.

See this post for more detail on how to build one:

http://goldenmotor.com/SMF/index.php?topic=6065.msg34016#msg34016

Cheers
Dan

[jmeaghan]

Hello Dan thanks again for the reply.  You hit it right on the head.  The battery is plugged directly into the motor and I have heard/seen arching before.  I will review the link you sent.  Thank you kindly for your help it is greatly appreciated!

Cheers

Jeremy

[jmeaghan]

Hello Dan one more follow up question.  Do you know where I can purchase these items?


Thanks again.


Cheers


Jeremy

[Papagino]

Hello again Jeremy, well it depend where you are from... Canada,US...

If you want to buy online, there is Digikey or Amazon or eBay, otherwise, you can easily find the switch and resistor in an electronic repair shop or in a RadioShack if you are in the States. Remember that the push button switch is a momentary switch, and not an ON / OFF switch.

And for the pen eraser... any office supply stores should carry them.

Hope that help...

Cheers
Dan

[jmeaghan]

Hey Dan & Papagino thanks again for the prompt replies and all the info.  Would you kindly let me know if this is what I need?


Thank again for all the help!


Cheers


Jeremy

[Papagino]

Yes this should work, however, I would rather use one 30 ohms 5 watts resistor than four 30 ohms 1/4 watts.
This will provide 5 watts of heat dissipation instead of only 1 watts with the four 30 ohms 1/4 watts resistor as shown in my link above.

Here are an example of the 5 watts resistor on Amazon.
https://www.amazon.ca/700V-Metal-Oxide-Film-Resistors/dp/B0087ZE2LS/ref=sr_1_1?ie=UTF8&qid=1474996073&sr=8-1&keywords=30+ohms+5+watts+resistor

Be careful if you order from Amazon, make sure the items are not shipped from China or other Asian countries as it will take over a month before you received your items.

If you order from Digikey.ca, it will cost $8.00 for shipping and it will only take 1 or 2 days to receive your items.

Hope that helps..

Cheers
Dan