Hall throttle - extreme hazard when used with Tadpole Trike

[methods]

First off a disclaimer - You guys know I am no "Captain Safety" so when I use the term "Extreme Hazard" I mean it.

Background: Nearly all throttles on the market are hall effect. Nearly all are plastic. The basic idea is that the plastic grip has a magnet attached(*) which is held close (via a spring) to a hall sensor which is fixed to the handlebar. When you twist the grip you compress the spring and pull the magnet away from the hall sensor. This causes the output voltage of the throttle to swing from something like 1.2V to somewhere like 3.8V. This swing in voltage tells the controller to increase the RPM of your motor.

(*technically there are actually two magnets that straddle the hall sensor and you would think this would create some sort of differential, fail safe signal but it DOES NOT)

Application This is fine for normal bikes. NO EXTREME HAZARD. On a regular bike you re pulling mostly forward and backward , perpendicular to the axis of rotation. This is why you can use slip-on grips etc.... Rarely are you pulling on your handlebars side to side.

On a Kart this is not the case:



Do you see how the handles are pointed nearly straight up?

In a Kart, if you are "getting crazy" you are leaning hard left and right and (especially inexperienced karters such as myself) will find that they are pulling "up" hard on the handlebars to maintain blance.

The Extreme Hazard Since the hall sensor throttle produces a greater voltage when the magnet is farther away, if you remove the magnet you will get FULL THROTTLE.

These hall sensor throttles are not meant to withstand a lot of pressure in the axial direction... in fact, many are assembled with a pressure fit - you "click" them on.

Logic follows that if you are riding a kart aggressively, pulling up on the handles to try to stay on 3 wheels there is a good chance you will yank the throttle right off resulting in UNCONTROLLED FULL THROTTLE

This is exactly what happened to me this morning on my maiden run.





Lucky for me it was a rainy day.

This is a 5305 X5 in a 20" wheel running off of 100V 5Ah
Peak thrust is near 200 lbs
We are talking about a motor that you *CAN NOT* stop with the brakes.
The only thing that saved me was the wet ground - the motor just lit up and starting smoking the tire




I did not have a kill switch. The trike pinned me against the curb (thank god) and the only way I could turn it off was to reach back and under my seat to hit this button:




Solution It is highly recommended that you use a potentiometer based throttle like the Magura pictured below. These are much tougher throttles and although I have not disassembled one, I suspect that they can withstand greater axial tension.

-methods

 

[methods]

Here is a short video to preempt Doubting Thomas.

http://www.deviantmethods.com/MethodsSalePage/KMX_Hall_Throttle_DANGER.3gp

-methods

 

[torker]

That's it I'm mounting a kill switch. My latest mt. bike will have a half twist so I think I'll glue on the other half of the grip. I actually wanted to try a full twist because I think I would like it much better. Not so sure now. What does it take to make a potentiometer style work with infineon? Just the right pinout?

 

[methods]

What does it take to make a potentiometer style work with infineon? Just the right pinout?

Well.... There are two answers to that.

1) To get it working all you really have to do is re-program the Infineon to turn off the Over Voltage detection. This will result in a functional throttle but you will have quite a bit of dead zone at the top and bottom

2) The better way is to "tune" the throttle in by adding a small resistor inline with the power and ground. This will effectually add offsets so that zero throttle is around 1V and full throttle is around 4V (instead of 0V - 5V). Interestingly enough you may find that this gives you *too much* resolution and your wrist may start to hurt from the degree of rotation necessary to change speeds.

I am now thinking that a half twist throttle may be the hot ticket.
I am going to follow your lead and fix the upper part of the grip.
This should solve the problem.

Magura are also $50....

-methods

 

[nicobie]

A couple of cable ties, a bit of hot melt glue and a length of small 2 wire shielded head phone cable...

I had the exact same thing happen to me on my bike. It scared the crap out of me. Hence the kill switch.

 

[docnjoj]

Interesting and scary. I use a thumb throttle but I have considered mounting a kill switch. I only run 36 volts at the moment but I can see the rocket ship with 100 volts and accidentally brushing the thumb throttle. +++ to kill switch!
otherDoc

 

[rscamp]

It is poor technique to pull on the steering bars (or more precisely, do much of anything with the upper body) when pedaling a recumbent. However, with electric power, it would be easy and seem more natural to use the steering to help secure yourself!

Some trikes, particularly those with indirect steering, won't take a lot of load on the steering arms. But thanks for the head's up that if I break the throttle on my QNT that this could happen. It isn't particularly confidence-building that the failure mode is full, rather than zero, throttle. I suppose this is another reason to install the pedal or brake kill switch required by the local Ontario e-bike laws.

 

[dontsendbubbamail]

Do you think a 1/2 grip throttle would be better? It would not help with the durability, but the handle bar rubber grip should keep the throttle from separating.

Bubba

 

[AussieJester]

Methy you really need to have the missus videoing you when you ride
these videos are invaluable for Funniest Home Video Shows...erm... i mean documentation of the hazzards of e-biking..

Seriously though Patrick, Im glad you weren't hurt mate... :wink: your a nutter LoL

KiM

 

[Papa]

Cut-off 1/2" or so of the grip, exposing the tip of the handlebar, then install one of these:

http://www.benscycle.net/index.php?main_page=index&cPath=612_1462

 

[AussieJester]

I went to buy some of them end caps they look neat 30 freakin dollars delivery GEEEET FUUUUCKED...
only 6 bucks a pop and they is aluminium FFS...

KiM

 

[Papa]

I went to buy some of them end caps they look neat 30 freakin dollars delivery GEEEET FUUUUCKED...
only 6 bucks a pop and they is aluminium FFS...

KiM

Well mate, you can spring for one of these (typically called shaft collar):

I bought two 3/4" just last week for $0.89 ea (for a lawn tractor project). Check your local hardware store - you'll need 7/8" or 22mm ID. Not as fancy as Milwaukee's offerings, but at least your grip won't come off.

 

[recumbent]

Methy, definately use haftwist throttles and mount a handle with clamps on the ends witch are also wider and contoured. They cost about $30 a pair but are very confy and safe with half throttle.

 

[mwkeefer]

Methods,

There is another solution... use a motorcycle cable style throttle.

These will stand up to anything you could push (in any direction) and can be made even stronger by drilling set screw thrus into the bars (or divits at least)...

Run the cable somewhere near the controller and setup an actual pot or perhaps a thumb throttle which is actuated by the cable.

Personally... I think the motor cycle throttles are much better suited for eBike use and plan to use them on my next two builds.

In addition... I guess we need to build a small circuit which limits the full travel of the throttle output to 1.2 - 3.8 max... when it goes above 3.8 (to whatever it hit when you pulled the thing off) it should disconnect / interrupt the throttle signal to the infineon. This shouldnt' be too difficult to create its just a voltage follower with a preset trigger. That would in theory function better than a kill or dead mans switch as you may not be able to grab for the kill switch and still hang onto the bike (with WOT condition) and dead man switch doesn't help till your already dumped from the ebike.

-Mike

-Mike

 

[biohazardman]

Moral of the story as he stated always have a kill switch, which is easy to reach. ;^) Next up don’t get in a hurry and see that you have the brake switch hooked up before you go on that first ride. Something I did not do either and I also ran into trouble. If it’s done right when you pull one of the brake levers the motor power is cut. No one should be without this safety feature. Most kits have brake levers with switches installed. If you don’t like them it's not difficult to use a magnet and a reed switch to do the same thing.

 

[amberwolf]

That must've been one scary ride!

I would like to point out that not all of those hall throttles are made in a way that causes full throttle with no magnet. The ScootNGo throttles are not. I had one and it disintegrated when the bike fell over, so I used the pieces to make a magnetic-glove throttle instead, which operated as a safety switch, too, since the average person would have no way of knowing how to turn the motor on and accelerate it--I had the hall sensor under a foam grip. (it was taped on the surface at first). That was on the old DayGlo Avenger. If there was no magnet, it had no throttle output.

I guess it depends on what kind of hall sensor they used?

 

[AussieJester]

Methods,

There is another solution... use a motorcycle cable style throttle.

-Mike

-Mike

OOh -Mike -Mike Methy needs no stinkin' motorcycle throttle a couple of tubes of Araldite
and 5 minutes of peace and quiet he'll have that cheap ass Chinese throttle bullet proof...
But FFS Methy have the missus record the test run this time... sheesh

KiM

p.s YES i am counting on your for the Australian Funniest Home Videos 50k prize make me proud buddy, i 'll split the booty with you if i win ...

 

[AussieJester]

KiMWell mate, you can spring for one of these (typically called shaft collar):

Its not the 'buy price' its the freight, 11 bucks for the item 30 for delivery ... not right IMO

KiM

EDIT.... PLUS 'shaft collars dont have the 'wank value' of the brand name and an extra 3 grub scres ASIF one grub screw will cut it when thers room for 4 evenly spaced grub screws sheesh..ITS ALL about the LOOKS...Get with the program fellas

 

[bigmoose]

That must've been one scary ride!
I used the pieces to make a magnetic-glove throttle instead, which operated as a safety switch, too, since the average person would have no way of knowing how to turn the motor on and accelerate it--I had the hall sensor under a foam grip.

Outstanding idea!! A built in dead-man throttle and anti theft device. Brilliant, just brilliant! Talk to your patent attorney tonight! :wink:

 

[ZOMGVTEK]

I just noticed this thread...

Same thing happened to me on my bike, and it was potentially really bad. Luckily the bike managed to miss a car and tip over putting a large dent in the battery. 4KW is NOT easy to stop!

I managed to find the spring that went flying out of the throttle, and the throttle still works. Its slightly cracked, and now takes even less pressure to fall off and go WOT, but im more careful about it now...