Epic fail installing new controller - burned my hands

[LarryHoova]

So I got my new controller today.

Finally figured out how to connect everything, took it for a quick test drive and things were fine with the exception of the speedometer showing 0.00 constantly..

I was thinking as I rode it, I definitely want to increase the shunt on this thing.

Then the power cut out so I wheeled my bike home. Took a look and sure enough the negative wire going to the controller had broken off - no big deal.

So I think to myself, since the negative is not connected, I should open it up and mod the shunt.

So I open it and I see 3 parrallel shunts. I started goobing some solder on them and then decided I should wrap some wire around them.

When I started feeding the wire around the shunt, it created a big spark and I withdrew it quickly.

I could not get my bike to start since then. I think I blew the controller but nothing appears to be fried on it.

So I decide I should remove the controller and bring it inside for a closer look.

I forgot I had the power switched on and dropped a frocking bolt between the neg and pos of the controller wiring harness.

I had 85.5v arc all over my hands. My thumb and finger are burned nice and good - painful stuff.

So I am not sure what happened. Thing is, as soon as I thought I blew the controller I tried turning the back wheel and it turns smooth still.

THEN, I bring the controller inside and I am holding it in my hand. - not connected to anything and I am showing my wife how I put the wire through the shunt and POP it arcs again - without being connected to anything!! It must have charge inside the capacitors or something. I am not going to pretend to understand.

I waited a month for this controller to get here. Walked an hour in the cold to get it. Wasted my Friday night installing it, only to have nothing working now and burned hands.

Please shed some light on what I might have done and what to do next.

 

[LarryHoova]

oops double post

 

[trevc2]

So... you were working on a controller that was still connected to the positive side of your battery?

Apologies if I've interpreted that wrong. It really doesn't seem like you have enough knowledge/experience to be DIY'ing these electronics safely. That sort of power can fry your skin badly enough to require grafts, etc.

So I got my new controller today.

Finally figured out how to connect everything, took it for a quick test drive and things were fine with the exception of the speedometer showing 0.00 constantly..

I was thinking as I rode it, I definitely want to increase the shunt on this thing.

Then the power cut out so I wheeled my bike home. Took a look and sure enough the negative wire going to the controller had broken off - no big deal.

So I think to myself, since the negative is not connected, I should open it up and mod the shunt.

So I open it and I see 3 parrallel shunts. I started goobing some solder on them and then decided I should wrap some wire around them.

When I started feeding the wire around the shunt, it created a big spark and I withdrew it quickly.

I could not get my bike to start since then. I think I blew the controller but nothing appears to be fried on it.

So I decide I should remove the controller and bring it inside for a closer look.

I forgot I had the power switched on and dropped a frocking bolt between the neg and pos of the controller wiring harness.

I had 85.5v arc all over my hands. My thumb and finger are burned nice and good - painful stuff.

So I am not sure what happened. Thing is, as soon as I thought I blew the controller I tried turning the back wheel and it turns smooth still.

THEN, I bring the controller inside and I am holding it in my hand. - not connected to anything and I am showing my wife how I put the wire through the shunt and POP it arcs again - without being connected to anything!! It must have charge inside the capacitors or something. I am not going to pretend to understand.

I waited a month for this controller to get here. Walked an hour in the cold to get it. Wasted my Friday night installing it, only to have nothing working now and burned hands.

Please shed some light on what I might have done and what to do next.

 

[liveforphysics]

We call that a KFF. I wouldn't feel too bad, most guys on here who've been around the block a few times in DIY ebiking have done the same sort of thing if not MUCH worse for some of us... lol


The good news is, if the wheel spun freely with the phase leads mated, and the caps still held charge, then it seems likely the controller is fine, but do carefully scrub off the carbon particles that may be on the PCB's with some isopropyl and a toothbrush, they can sometimes make random arc-flashes otherwise.

 

[LarryHoova]

lol thanks for the kind replies.

these were separate incidents:

1. Without power going to the controller (I have a switch that disables power) AND the negative wire was removed from the switch it arced when I tried to shunt it. It arced when I tried to shunt it in my office here an hour ago connected to nothing.

2. In an effort to get the controller to work after this I switched the power off and on many times. I left it on and thought it was off. I then attempted to open the harness and start removing the controller when I dropped the nut in there. Let's just say from now on, I will be disconnecting one of the poles of a battery before doing anything.

Here is the good news. I realized while I was in the shower nursing my wounds that a few months ago my key ignition wire had come off and the bike was dead. Today I removed the dashboard to see the colors of the wires used for the throttle (they were not standard red, blue, black) - I ran downstairs after my shower and sure enough the ignition wire is off also!!! Yay this means that everything is probably fine and all I have to do is reconnect that wire and everything else now.

I still want to shunt this controller. How long does it take for the charge to get out of the capacitors so I can work on this thing?

 

[d8veh]

It arced without anything connected because the capacitors store charge like a battery. If you shorted one to the shunt, it'll make a big spark, but no harm will be done, but if you short it to any of the 5v part of the controller, there's a fair chance that you've wiped out the CPU and/or other things. The only way to know is to try it. Probability is on your side. I hope you're lucky.

Recently, I was working on a controller, soldering some wires. The PCB was out of the case, and I wanted to rest it on something to do the soldering. There was a tin can nearby, which I thought would be perfect. Zapp! Whoops!. Luckily, it was still OK. I hadn't used that bike for ages and the caps were still fully charged. like you, I wasn't expecting it.

While I think about it, a warning if you ever open a digital camera with a flash. The capacitor in there will give you such a shock if you touch that part of the circuit. It's like someone's bitten your finger. Ebike ones are relatively harmless by comparison.

 

[Tench]

Yep caps can bite!! I once opened up the case of a big meteorological laser that had about a dozen huge 500v rated caps after unplugging it from to the mains 240v, from a sitting position I hit the ceiling and landed in a quivering heap thinking WTF!!

 

[LarryHoova]

damn just got shocked again trying to shunt it lol

ANyone know why my speedometer wasn't working. Is there a 2nd wire I need to attach to make the speedo work?

This is the controller I have: http://www.ebay.com/itm/Electric-Bicycle-Brushless-Speed-Motor-Controller-72V-1500W-For-E-bike-Scooter-/360643164862?

 

[Tench]

What motor have you got and what speedo are you using? we can help but we cant mind read!

 

[LarryHoova]

What motor have you got and what speedo are you using? we can help but we cant mind read!

Its a Daymak beijing -i use the stock dashboard it comes with

 

[LarryHoova]

UPDATE: Everything works I took it out for a spin around the block yesterday.

Even with the shunt mod done, the bike seems to have less torque than before and only hit 40km/h

With my old controller, I had more torque and my top speed as 45k/h and it was limited - I could do 45 going uphill or on flats and never went over 45 going downhill.

With this new controller I should be going 50km+ with the 84v setup I have.

I did NOT connect the 3 speed controller - I assume that if it is no connected, it is in the fastest mode possible.

I am quite baffled why it is slow and why my speedometer doesn't work.

I tested the speed with a GPS based speedo app for my android. Anyone know how accurate those are?

It certainly didn't feel like I hit 45km/h and the torque was definitely less.

Do I have to make the shunt bigger? HELP :/

 

[efMX Trials Electric Freeride]

question for the experts.. :

although i personally may never try to mod the controller shunt etc
i would rather just buy a controller that is up to the task for my needs..

but, is there a way to measure the disconnected controller capacitor voltage
or to drain off any voltage that the caps may still be holding
so that it can be determined if when the controller is safe(r) to work on???


thanks!

 

[Ykick]

question for the experts.. :

although i personally may never try to mod the controller shunt etc
i would rather just buy a controller that is up to the task for my needs..

but, is there a way to measure the disconnected controller capacitor voltage
or to drain off any voltage that the caps may still be holding
so that it can be determined if when the controller is safe(r) to work on???


thanks!

Short the main power input connectors together with choice of conductor to drain them. Pliers, screwdriver, test leads, 150ohm resistor, etc. Obviously, must be disconnected from battery before attempting to drain them.

SOP in the dark ages when working on high voltage DC vacuum tube equipment.

 

[leffex]

Wow... Thats alot of stuff happening in the first day... You are lucky my first month or two was trying to get the wheel turning at all, waiting for a sensorless controller using it daily for two weeks in constant rain to have it explode(stop working ) so... Then the winter came and coldness... Sometimes my throttle started to act weird and give full speed or just stop working .... Figured that out either some lose wire .OR (key ignition cables lose wire) OR brake cutoff wire lose.

Then this year i had a phase wire loss, some stutter and it just stops or something... Connected back works like a dream again.

When the batteries gets older you need to watch them more carefully and even charge one or two at a time rather than all at once. When you get a short like that your cells in some batteries might be damaged...

If you drive fast get some protection dude, a damage in the axle area will take a long time, many years to heal...

Keep safe and continue learning.

 

[zombiess]

I just want to post this since most don't seem to understand the seriousness of what really happened or treat their battery with the respect it deserves. An 84V battery is lethal, it can kill you! YOU MUST TREAT IT WITH RESPECT! Always assume everything is live until you verify it is not, always discharge caps, preferably with a resistor to avoid molten metal splatter from entering your eyeball. If you like sparks, wear safety glasses! Then short away with insulated handles tools and enjoy the show, many of my screw drivers bear the scars of shorted caps. Use gloves if it's a big cap, probably ear plugs too, really big high voltage caps can vaporize a screw driver.

 

[zener]

No its not!
DC Voltage is over 120V lethal!
I self touched a 84V accidentialy with both hands and i am still here. I could feel the electricity and could emidiately detouch my fingers.

 

[liveforphysics]

No its not!
DC Voltage is over 120V lethal!
I self touched a 84V accidentialy with both hands and i am still here. I could feel the electricity and could emidiately detouch my fingers.

I shock myself with 116vdc nearly daily, and often across the chest. No death yet...

However, that doesn't mean even 12v couldn't kill me if the electrodes managed to break the skin, as pokey wire ends often can do. Always best to error on the side of caution with shocks, and SERIOUSLY be careful with arc-flash damage. I've had some very painful burns that took weeks to heal from KFF events.

 

[granolaboy]

I always ALWAYS disconnect the battery before mucking with any wiring in ANY way, and then I turn on the ignition and turn the throttle, to drain anything left.

Once I skipped this step while re-wiring the alarm on my scooter and vaporized a good length of low gauge wire.

I thought it was the amps that killed ya, not the volts...

And don't forget the "one handed rule" if you ever have to work with anything that's live...

 

[zombiess]

No its not!
DC Voltage is over 120V lethal!
I self touched a 84V accidentialy with both hands and i am still here. I could feel the electricity and could emidiately detouch my fingers.

If you seriously think this, then you have zero business poking around inside anything with current flowing. I've met guys who survived 480V and even 3000V mains lines shocks and even one technician that survived racking in a HV breaker explosion, but the odds are against you. I met an electrician who had a buddy that got a small shock from 120V AC on top of an aluminum ladder, guy came down the latter right away kinda joking about it because it's not unusual to happen, seconds later he didn't feel so well and a few seconds later was dead, heart failure, Just because someone else survived it doesn't mean you will.

When you work with electricity it's not a matter of if you get shocked, but when, best to minimize the damage it will do. If you wear a metal wedding band or any rings, take it off, your sudden pull back reflex could have you leaving a finger detatched, bracelets, necklaces, etc should be removed.

 

[amberwolf]

If you drive fast get some protection dude, a damage in the axle area will take a long time, many years to heal...

I doubt an axle will ever heal.

(although you could repair it in a short while if you ahd the equipment and knowhow, probably)

 

[jateureka]

... Even with the shunt mod done, the bike seems to have less torque than before and only hit 40km/h

With this new controller I should be going 50km+ with the 84v setup I have.

I did NOT connect the 3 speed controller - I assume that if it is no connected, it is in the fastest mode possible.

HELP :/

With no speed switch connected, the controller will actually default to the slower mode in most cases.
If you don't want to use the switch then you could hard wire it. Do a search on the forum here for 'speed switch' or contact the vendor to see which wires need to connect together for high speed.

Doing the shunt mod to increase current will increase torque so you get up to top speed faster but doesn't generally increase top speed. If you are using the same battery voltage that you had on your old controller then you wont get any faster.