Shimano SC-EM800 display information

[Asamson]

Does anyone know what is the exact information that the ''power'' graph on the display means. I'm not sure if it's the torque output (Nm), assist ratio, power output (watt) or whatever.
My Boost mode is setup all max-out. When I start pedaling (low RPM), the graph goes right up, but then it starts going down as my RPM increase above 70ish. Pushing harder on the pedal doesnt seems to do anything on the graph.
Do you guys experiment the same thing, or does it stay up top as long a you put some force in the pedal ?

 

[B1rdie]

It shows the level of assistance that the motor is providing, if its in terms of wats or torque I do not know.
The more power you input, the less assistance the motor gives to keep moving at the same pace, so, to have the battery lasting longer I try to keep that graphic at the lower part.

 

[Asamson]

It shows the level of assistance that the motor is providing, if its in terms of wats or torque I do not know.
The more power you input, the less assistance the motor gives to keep moving at the same pace, so, to have the battery lasting longer I try to keep that graphic at the lower part.

I'm not quite sure of the part : The more power you input, the less assistance the motor gives to keep moving at the same pace... I don't think it is suppose to figure out at what speed you're suppose to go...

My best bet was that it gives a torque % in Nm relative to the maximum 85. The engine is able to produce 85 Nm at low cadence, but the faster you spin, the torque starts to decrease as shown on the graph below (even if it's an old one, the principle remains the same). So altough i try to push harder on the pedal, it make no difference.

In terms of assistance, it would do a similar effect, as the assist X factor can't always be match by the engine. For example, if i push 40 Nm and use a 4X multiplicator (which is the maximum setting) the motor would need to push a additionnal 120Nm, which it can't. Therefore, the fastest I spin, the less torque the motor can give, so an available motor torque of 60Nm (at 80 RPM for example) and a 40NM leg input would give a 2,5X on the display graph.

This evening I will try something with the setting, I'll lower the Torque but keep the assist level to maximum. If the graph never show maximum, then I'll have my answer.

The main reason I'm asking is, if the graph show the available power of the motor, then I have a problem with mine. At first I tought that the graph was the equivalent of a ''trottle'' display and i was expecting to see it at max when i'm shuttleling on boost. It appears it is not...

 

[tomato paste]

Wondered this as well, but haven't looked into it. Thanks for the reminder.

 

[mark.ai]

If the graph correlates with the assist percentage/level that the motor is giving, then I noticed something similar recently when viewing the values directly.

If my cadence was above 80 then the highest assist I got was 45. But by dropping cadence to 60, then the assist would go to up to 65. This was with a EP8-RS motor though.

 

[Gary]

The motor will continue outputing 100% assistance right up to a cadence of 120rpm an any mode if you're prepared put the effort in.
It's not controlled strictly by cadence alone.

 

[Asamson]

If the graph correlates with the assist percentage/level that the motor is giving, then I noticed something similar recently when viewing the values directly.

If my cadence was above 80 then the highest assist I got was 45. But by dropping cadence to 60, then the assist would go to up to 65. This was with a EP8-RS motor though.

I think the principle remains the same, I think the EP8-RS simply limit the amperage but the voltage is still the same. The motor torque curve should remain similar, just 20 Nm lower overal.

 

[RustyIron]

Graphs without defined values piss me off. I've searched for answers regarding the Mystery Meter, but Shimano offers little clarification.

Shimano says the meter "displays the assistance," which doesn't tell us much. I REALLY don't think the shape of the graph is related to anything at all, other than some committee's notion of what would look cool to consumers. In all probability, the Mystery Meter is probably measuring something like the gain that turns on some scr's, which doesn't directly correlate to newton meters or anything else. It's somewhat arbitrary, but gives the rider a general idea what's going on.

 

[B1rdie]

Its what shimano believes will help the rider know how much batterie is being drained at the very moment one looks at that.
Why would someone look at that totally undepends on what shimano believes.