programming a tongshen TSDZ to be legal in Japan

[tensaimon]

Hi,

I'm brand new (to this forum, not to life) and I've signed up to ask a specific question:

I'm very interested in e-assist bikes as a solution to a number of social problems (traffic congestion, global warming, financial difficulties), so I want to start both riding them (I currently ride unassisted) and promoting them (via activism, social media etc). However I live in Japan, which brings 2 problems:

1)
Although there are many very good e-assist bicycles around, they are very "shopping bicycle" - I'd like something a little more capable of longer distances and luggage carrying - so, an aftermarket kit seems like the best solution (I have a bike friday Haul-a-day I want to add an assist to, and I'm toying with the idea of a drop-handlebar BF for longer lighter missions and travelling)

2)
however, in addition to the requirement that e-assist bikes should not move without pedalling, Japan's current e-assist laws are a little odd: the electric assist can be full-power until 10km, then taper down to zero by 24kmh (see the graph on http://criticalcycling.com/2016/10/...6xLzmomshEAwt02v5ovGZtC3EP3jNGgCIo65m5Vg1G5dA.
English wikipedia also describes this: https://en.wikipedia.org/wiki/Electric_bicycle_laws#Japan

This means after-market kits from outside Japan aren't technically street-legal (and I haven't seen any domestic after-market kits). I could go stealth-mode (for example just setting the speed cutoff to 25kmh) as I am unlikely to be stopped, but from a point of view of promoting e-bikes I'd much rather be fully legal.

So I've been researching good kits to use with my HAD and it seems to come down to bafang or tongshen, with the tongshen looking more like what I want (a more natural riding experience due to the tension sensor - I'm happy to be pedaling).

So, my question: can anyone tell me if it's likely to be possible to program the tongshen (or the bafang for that matter) to conform to Japan's requirements?

(I've also contacted tongshen and BF about this, but I'm interested in the DIY spirit of this forum!)

Thanks for any help, much appreciated!

 

[amberwolf]

I don't know anything that specifically does what you need for legality.

You could use an Arduino or other MCU, to intercept speedometer and throttle (or PAS) signals, and perform the necessary checks and calculations to enforce these limits.

It *may* be possible to setup a Cycle Analyst v3 from http://ebikes.ca to do it, by setting a speed limit, but I am not sure there is a way to cause it to ramp down in assist from the lower limit to the upper; it only has one speed limit like that:

I think they can write custom firmware for the CA based on your needs, but it's not cheap.


If ti's helpful:

https://www.ebikes.ca/product-info/cycle-analyst-3.html

SETUP SPEED LIMITS

The CA can be configured with a speed limit to cut motor power when the bike exceeds that limit. This speed limit is implemented as a PID controller and so there are three gain terms that may need to be tweaked to achieve the desired responsiveness when the bike hits the limit point. Surging or oscillation at the speed limit setpoint or power cutouts on hard acceleration (powerful bikes) are indications that speed gain adjustments are needed.

[ SLim->Max Speed ]*
Upper speed limit. The CA rolls back throttle output voltage whenever speed exceeds this setting.
OEM->AbsMaxSpeed determines the maximum value for this setting.

[ SLim->Strt Speed ]*
The minimum starting speed that must be reached before the CA will allow power application. This is useful for RC drives or systems with sensorless controllers that do not work well from a dead start. The rider must pedal the bike up to StrtSpeed before power is applied.

[ SLim->MxNoPdlSpd ]*
The maximum speed at which the throttle will apply power without pedaling in any PAS mode. This feature supports European pedalec legislation which requires pedaling the bike for motor power, but which provides exemption below a certain speed (e.g. 6kph) in which case use of a throttle without pedaling is permitted. Applies only if a PAS device is installed.



[ SLim->Regen Lmtg ]
Chooser to select if Speed Limiting should use regenerative braking to help control the maximum speed.

Disabled: Speed is limited exclusively by reducing power. Above the speed limit the motor power is reduced to zero, but regenerative braking is not applied allowing the rider to continue to coast or pedal above this speed limit. [Default]

Enabled: Regenerative braking is used to enforce the speed limit setpoint. This means that regen may engage automatically when descending hills even without the rider applying the ebrakes. Proportional throttle regen (EBk->PropRegen) need not be enabled. This feature requires a controller with 0.0 - 0.8V throttle regen function (e.g. Grinfineon or Phaserunner).

[ SLim->IntSGain ]
Integral (I) feedback gain for the speed PID control loop. Lower values give smoother control and less likelihood of hunting, but can increase the time it takes for the speed limit to stabilize. This adjusts the correction for accumulated 'past' speed error.

[ SLim->PSGain ]
Proportional (P) feedback term for the speed PID control loop and displayed in terms of Volts / (mph or kph). If set to 0.5V/kph, the throttle output will immediately drop by 0.5V for each km/hr the bike exceeds the set speed limit. This adjusts the correction for the 'present' speed error.

[ SLim->DSGain ]
Differential (D) feedback term for the speed PID control loop. This is used to dampen speed oscillations by determining the ability of the CA to scale back power in anticipation of breaching the speed limit due to acceleration towards that limit. Values in the 100-300 range seem to work well, but lower values are often required for vehicles capable of hard acceleration. This adjusts the correction for 'future' anticipated speed errors.

Alternately, you could find a premade bike system that does what you want, and then move it to your preferred bike. Then just add more battery capacity for longer range.

 

[tensaimon]

Interesting, thanks for the reply! I'll contact ebikes.ca and see what they say. Someone else mentioned an arduino so I'll look into that too .

And interesting idea to just take a kit from another bike, I'll have a look at that tho most of the japanese bikes seem to be mid-drive (which is good for hills), I'm not sure if they are fitting to standard bottom brackets or not, should be fairly easy if they are, but not if they're not....

thanks again!

 

[btslo]

Funny as you can set JAP or EUR mode on the lcd of the TSDZ2. But I don't think they're any different.

 

[continuous_square]

I'm new to this forum and to after market electric motors, so take my opinions with a grain of salt. As far as I understand you could install the Casainho's custom open source "TSDZ2-Smart-EBike" firmware and with help of that restrict the motor to confide to Japanese law. (Looking at Bike Friday's web site they seem to use motors from PSW Power.)

 

[Chalo]

Japan's current e-assist laws are a little odd: the electric assist can be full-power until 10km, then taper down to zero by 24kmh (see the graph on

So there's no electric power limit? Only a defined power ramp down from full power to zero between 10km/h and 24km/h?

 

[amberwolf]

AFAIK they're limited to 250w (dunno if that's input or output, peak or continuous, etc. )

 

[Chalo]

AFAIK they're limited to 250w (dunno if that's input or output, peak or continuous, etc. )

Wow. If that's true, then that would make them the lamest e-bikes anywhere in the world. A full 250W only up to 6mph? Seems like it would be more pleasant to go for a regular bike to save weight and complexity while getting a nicer ride for the money. Most able-bodied people would probably go faster that way. I'm an old fat guy, and I pedal at 24kph without trying very hard at all.

On a pedal bike, I'm usually going 16mph (26km/h) when I pass the "your speed" radar unit on the way to work. It's usually 19 or 20mph on the e-bike, depending on state of charge.