Tuesday, 28 October 2014

Brush/Bearing wear on the Kostov K9!

Ok so here comes another tale of woe due to my own inexperience of EV related matters, I was driving to work the other day with my daughter to drop her at school, on the short divergence to do the school drop I have to pass a lane with a large regular flood puddle and being an EV driver I always take it slow through this puddle, it is not enough to swamp the motor thankfully but if I hit it with any speed it would give it a damn good wash, Still on this particular day as soon as I had passed the puddle a new and very disconcerting noise appeared and sounded distinctly like brush failure!
So I limped it home and took the fat fryer to work, Guessing that there was more than a clean going to be required here I dropped it down to my mechanic and waited for him to have the time to investigate, a few days later I had the bad news “new brushes required” and the following day a call to say that one of the bearings was also failing (the one outside nearest the wheel).
After thinking over the issue for a day or two and during a chat with a friend the penny dropped, RPM Sensor! I Still have no RPM sensor “WHAAAT” I hear all you EV experts shout, Yes I am a fool and have been driving the little Honda Beat EV for over a year with no RPM sensor and no sensor means no RPM limiting, So now the penny has dropped it seems almost obvious that if you don’t limit the revs somehow then at some point you will be over-speeding the motor, And on a similar note I also have no motor temperature monitoring either.
So I guess the key words here are MONITORING and LIMITING!
So a new set of brushes and bearings are on order and my EV sits looking sorry for itself waiting for the parts to arrive from Bulgaria!

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