Electric bike building "DOH" moments

[moostrodamus]

Anyone interested in confessing bonehead things you've done in the interest of saving others doing the same?

I'll start:

Got home from a long day at work, somehow managed to rip the anderson power pole connectors off the battery lead catching on the end of the carrier box...was tired, had to pee, but just thought i'd stick them back on..."PAFF", hooked them on backwards, big arc and smoke. Nothing worked.

I wrote to Justin at ebikes and he said "Check the fuse, the controller is probably ok"

I replied "Fuse?"

Blew up controller, had to take bus for a week...DOH!

Doh Moment Tip:

Don't try to repair anything on your bike when you have to pee or are really tired. Always hook a fuse up between your battery and controller.

Anyone?

 

[dogman dan]

Done similar things to waaaaay too many chargers. Somehow checking three times for polarity when putting on a connector is still not enough for me, eventually I cross wires and poof.

 

[dak664]

About a year ago I made the first of several cables with Anderson connectors both ends and three wires spliced into the middle with banana plugs for Harbor Freight multimeters. This allows convenient switching between volts and amps:

Charger/PV  +  <____________________________________> Battery +
                                \
                                /  4.7 Kohm
                                \
                                |
Charger/PV  -  <_______         |          ________> Battery -
                       |        |         |
                       |        |         |
                       v        v         v
                    Common    Volts     10 Amps
                    --------Multimeter--------

The connections are securely heat-shrinked against any possibility of a short, so I just have to remember that the red wire is for the voltmeter. The other day I put an ammeter on the 200ma scale, plugged in the black and blue, and blew the fuse. Since the current should have been right at 200ma, I assumed it was a transient and moved the plug to the 10 amp socket. Turns out this was a prototype that I had forgotten about, the blue wire was for the voltmeter, it lacked the 4.7K resistor, and I had a 50/50 chance of putting a direct short on the battery. The resulting arc fused the plug and socket and tin-plated my thumb!

 

[vanilla ice]

Pretty standard but, "This controller should take a few more volts no problem.. DOH!"

 

[Lessss]

Don't try to repair anything on your bike when you have to pee or are really tired. Always hook a fuse up between your battery and controller.

... and your dc to dc converter if you have one
... and between the controller and motor in case the wires going into the motor arc with a crash if that entry isn't protected by a cover.



Trying to find the right phase order for a new controller motor combo. Pedals start moving backwards - - right into your K N E E - - (OW!)

 

[deardancer3]

not so good: not having a written check list.

very good: Having a written check list

Not so good: Assuming an empty checked box is just an admin error, checking and proceeding. (final torque down of wheel nuts)

Another not so good: "I know that this charger never turns off when done, but I will remember to check it after one beer."

Now very good: Shop closed before finding a beer.

NOt so good: "I can make one more stop before this sprinkle turns into a heavy rain".

very good: installing the new fenders the minute the box arrived.

 

[spinningmagnets]

Brake pads were worn, but "I'll just be careful until I get around to fixing that"..fast forward to a long steep downhill, halfway down there's an intersection, and I had forgotten about worn pads. Brakes don't work, YIKES!, Light turns red, cross traffic starts flowing, I contemplate wiping out on purpose, notice big break in cross traffic, and I sail right through between the cars...heart beating 100-MPH. That was 35 years ago, and to this day I still dont screw around with tires and brakes.

I have many scars, but now the scars are covered by a helmet and gloves when I ride....

 

[jag]

When debugging (power) electronics good practice would be to shut everything down, attach oscilloscope or multimeter probes etc, then power up.

My typical practice: equipment is powered up, move probe tip to different components to measure. OOooooooooops, slip and short something. Typically happens when trying to measure one of the three legs of a TO220 type transistor on the component side. Probe slips and shorts two legs, smoke, burnt traces ...

Had a summer job building a 3 phase motor controller for a paper pulp cooker years ago. Managed to blow numerous then super expensive 400V power FETs. Once even managed to vaporize all the copper on the circuit board. This was in the good old days where one made the circuit board oneself. Make masks on OH paper from printouts in copier, then UV expose, and into the etching bath...

btw Circuit board CAD program ran on a Zilog Z80 processor, if anyone on the forum remembers those.

 

[317537]

Hooked up two battery to a chargers reverse polarity twice in a row, I thought everything was dandy until I discovered my mulitmeter wires were plugged into the opposite colours.

 

[torqueon]

I have heard that your bike can go to full power if a potentimeter wire breaks. I chose to verify, so I diconnected the chain and 1 by 1 pulled wires, and yes it will go full. I fried a mosfet by touching the circut board.

I have learned much from E.S. I am greatfull

 

[AussieJester]

Anyone interested in confessing bonehead things you've done in the interest of saving others doing the same?

I'll make sure i've had a pee before reading Methods response that's for sure, from his charred finger tips to front wheels parting company with the bike (numerous times) and brakes rubbing on the rim (unbeknown to Patrick) making it hard for the poor chap to pedal :-S hehee Brilliant mind with electronics nooot soo good with bicycles i think LoL ..Personally cant think of any that i have done myself...

KiM

 

[Grinhill]

..Personally cant think of any that i have done myself...

KiM,

Haven't you learnt yet? Never, ever mess with Murphy's law!!!

I hope we don't read about your misfortunes tomorrow....

 

[AussieJester]

..Personally cant think of any that i have done myself...

KiM,

Haven't you learnt yet? Never, ever mess with Murphy's law!!!

I hope we don't read about your misfortunes tomorrow....

hahah true but i did say "i can't think" of any doesn't mean they haven't happened LOL..

:: crosses fingers and prays to "fabrication Gods" along with the daily prays to the " Gods of Speed" that nothing will go wrong today::

KiM

 

[1of3]

Too new @ e-bikes for anything yet. (week)

But, I'll be posting here for sure....Electric bike building "DOH" moments

 

[amberwolf]

I've had more than a few; can't actually remember enough details about most of them to be helpful right now, though.

One I do recall that I had within the last month or so:

First, you have to know that on the CrazyBike2, the dropouts can't actually be directly seen except partially from the top and partially from the bottom, looking either down or up between the big metal cargo pod boxes. Also, it's a regular old diagonal-dropout rear frame, with the derailer type that bolts into the dropout with the rear wheel, rather than to a separate spot behind the dropout on the frame itself. The left side dropout has a gap above the axle bolt since there's no derailer bolted there, and so it can slip upward if not tightened down properly, especially since this thing weighs 150 pounds *by itself*.

During some test rides after reinstalling a rear wheel, and especially after the test rides and a trip to the store that loaded CB2 up with 40 pounds of dog food plus more weight in other stuff, I kept having problems with the left side being "loose" enough to push up into the dropouts more, and cause the tire to rub on the left chainstay. I kept stopping and fixing it, pulling it a bit more back down each time.

The last time I did that, the whole wheel just slipped out of the dropouts!

I could not see it because of the cargo pods being in the way, but it was actually the *right side* that was loose and being pulled *down* and *out* of the dropout, even against the weight of the bike plus me, by the torque on the chain from the motor and my pedalling!

Turns out this was caused by the derailer fitting a bit too close to the right axle nut for me to get the wrench to stay on the nut while tightening it, but because it bound against the derailer as it slipped off the nut it *felt* like it was tight, and it *was* tight enough for a normal bike. But not for CB2, since it's so heavy that to quickly start it moving it takes a *lot* more torque and pull by the chain in a much shorter time span than a regular bike would.

So I had the left side cranked down fine and it really wasn't ever moving except when *I* moved it, so by misunderstanding the problem, I made a much worse problem.

To fix the problem required taking the rightside cargo pod *off* the bike, which with the load in it I really didn't want to do on the side of the road in the dark at night. Especially since it was no more than 100 feet from where I had been mugged in 2003. So I got the wheel shoved back in the dropouts just enough to stay there if I got off and walked the bike, and went the 1/2 mile or so home like that.


Moral of the story: Understand the problem you have BEFORE you try to fix it!