Questions re controller behaviour, display switching off, and "linear" throttles

[Alister]

Hi, my wife has a bike with a 36V KZQW22A controller. Based on the date stamped on the controller the bike is only about 18months old, and clearly hasn't had much use (allegedly it has been used and had the battery charged every week or so).

I have two questions.

1. The display loses power or switches itself off occasionally. There is no discernable pattern (i.e. it doesn't switch off when it seems like the motor is operating at full power or anything like that), and it can be switched back on immediately. I would like to troubleshoot, to determine whether the problem is the display or the controller or what.
There is a german guy selling these controllers at https://www.groetech.de/index.php?main_page=index&cPath=44, and he says you can run them without a display: "brown and red must be bridged with a jumper on the display port". I disconnected the display and jumpered those pins and it does seem to work, although I haven't actually ridden it. I am wondering if it is likely to actually be safe if we ride it like that, to see if the motor still switches off (if it doesn't then I guess the problem is the display, or the wiring to it). Or is it possible that the display has a safety feature that is turning it off because of something that isn't quite right, and it will be dangerous to ride without a display?

2. When using the throttle the bike is significantly faster than on the highest PAS assist mode.
The guy selling these controllers says on the pages for the "sinus hall" KZQW22A models that "the system is somewhat slower with PAS than with the throttle, this can be corrected by using a linear PAS sensor". Is this common behaviour, or is it peculiar to these controllers?
The only place I can find a PAS sensor described as linear is also on his site: https://www.groetech.de/index.php?main_page=product_info&cPath=4&products_id=598. It connects to the throttle cable. Are there other options, perhaps that would use the normal PAS connector instead of the throttle connector? Maybe there is another technical term that I should be searching for instead of "linear"? I'm guessing that sensor would work on pretty much any controller with a throttle connector, so even if I don't have the "sinus hall" KZQW22A model it would work?

Thanks.

 

[e-beach]

Hi Alister! Welcome to ES!

Let me start by saying that I can't comment on the PAS question because I don't use one. I want to be able to cruse when I want to and pedal when I want to. Nor do I use a display because I usually know how far I am riding and how much charge I have leaving for my destination. If I feel the need, some times I will put a charger in my backpack and charge somewhere along my route. I ascribe to a keep-it-simple e-bike set up because something is always going wrong with complex setups.

However if you want more information on a PAS, start here: https://www.ebikes.ca/product-info/advanced-pas-kits.html They are also super nice people who are really good with e-bikes so don't be afraid to contact them.

Which brings me to my thoughts on your display. My first notion is something is loose. Either a loose wire connection outside the display or maybe a loose solder joint inside the display itself. Or perhaps the display is rattling around enough to cause the on / off switch to trip.

What I would suggest is to check all your connections very carefully to make sure your connections are well connected. If that doesn't work, depending on your electronic skills, open the display and look for anything loose that connects to the power in part of the circuit.

As for damaging your bike by disconnecting the display, I have never heard of an e-bike being damaged by disconnecting the display. Damage to e-bikes usually comes from things like over discharge of the battery's, over heating the motor, shorting the wiring and crashing. IMO you should be fine riding without a display. Just know your distances and amp hour usage so you don't run out of battery far from home. Around ES the rule of thumb is about 25 watt hours per mile. My usage is about 27 watt hours per mile due to a lot of stop and go riding. Use those numbers as a place to start.