Bosch PCE pump PWM control

[lolimpol]

I want to get some Bosch PCE pumps for my EV conversion (0 392 024 003 or VW P/N 04L 965 567).
However I can't find any information on whether the pump can be turned off using PWM. I know it will run at 100% if there's no PWM on startup, but what does it do if there is PWM on boot, but this goes below a certain percentage after the startup process?
There's an alternative in the PCE 2.0 pumps (0 392 024 050 or Mercedes P/N A 000 500 26 86), which uses LIN control. This pump seems to use a similar control scheme to Pierburg LIN pumps, and can be gotten running using https://github.com/ufnalski/lin_bus_mer ... mp_g474re/.
I can't find any pressure or flow numbers for the PCE 2.0 part number since I believe it is an OEM only part, but they don't matter much for my application. Neither can I find any information on whether these can be turned off using LIN, but Pierburg LIN pumps can, So I think it's safe to assume it is possible.
The PWM PCE pumps however are cheaper than the LIN variant and there's many more available.
I found this document from Cascadia Motion: https://www.benzworld.org/attachments/b ... f.2909783/ Which states the pump turns off below 7% PWM. However this document mentions a "PCE-XL" which I cannot find in any Bosch catalogues. Is this the normal PCE repackaged by Cascadia to earn a quick buck?

Does anyone have any more information on this?

[lolimpol]

I decided to bite the bullet and got some VW pumps from an Audi A3. part number 04L 965 567.
Pumps go at full speed after about 2 seconds Like the wiki states, However they retry 2x instead of the 20x stated in the wiki.

Then I tried driving the PWM pin with an open drain N-channel mosfet setup (Pull-up resistor and pump on source, ground on drain). I generated the PWM with an ESP32 and LEDC. 100Hz frequency and 10 bit resolution (0-1023).
Here are my duty cycle findings (keep in mind the values are reverse because of the driving setup):
Failsafe mode triggers from 950 and turns off below 942.
Below 890 the pump turns on.
Using these values I calculated some percentages:
73 (Opposite of 950) is 7.14% duty cycle.
81 (942) is 7.92% duty cycle.
133 (890) is 13.00% duty cycle.

So at least for the VW pumps the control table looks like this:
0-7% Fail-safe mode,
7-8% Fail safe mode hysteresis,
8-13% Pump off,
13-100% 0-100% pump speed.

Keep in mind I have no capability of testing the higher speeds except sound, so I will not test it.

I'll go ahead and update the Wiki, if anyone would like to check my work that would be great!

[jrbe]

Thanks for working on another pump. I don't have much to add besides the pwm may be inverted with a high side pullup / N-fet. Worth considering /checking before generating too much test data.
LIN could be interesting too, thanks for sharing the link.
PCE-XL is likely just Cascadia's name for it, Bosch uses 0 000 000 000 like numbers for most things.

[muehlpower]

I also use PCE pumps. I think I read that even at a duty cycle of 90%, the pump runs at 100% capacity.

However this document mentions a "PCE-XL" which I cannot find in any Bosch catalogues. Is this the normal PCE repackaged by Cascadia to earn a quick buck?

I haven't been able to find out what XL means. The data sheet for the PCE-XL lists the part number 0392024078, which can also be found in the standard Bosch catalog. 0.85 bar, 1000 l/h. I use VW PCE pumps. I don't know which Bosch PCE corresponds to these, but the plug is different, as is the pin assignment.

[lolimpol]

Thanks for working on another pump. I don't have much to add besides the pwm may be inverted with a high side pullup / N-fet. Worth considering /checking before generating too much test data.
LIN could be interesting too, thanks for sharing the link.
PCE-XL is likely just Cascadia's name for it, Bosch uses 0 000 000 000 like numbers for most things.

The highside pullup DOES invert the PWM, I might not have made that clear. I took that into account when calculating!
LIN would be nice for reducing complexity and wiring (just like why the OEM's do it )
I realised when editing the wiki that the Cascadia PWM scheme does fit +-1%, so it would seem the XL is just a normal PCE.

[lolimpol]

I also use PCE pumps. I think I read that even at a duty cycle of 90%, the pump runs at 100% capacity.

I haven't been able to find out what XL means. The data sheet for the PCE-XL lists the part number 0392024078, which can also be found in the standard Bosch catalog. 0.85 bar, 1000 l/h. I use VW PCE pumps. I don't know which Bosch PCE corresponds to these, but the plug is different, as is the pin assignment.

I would like to see your cooling setup, do you have it posted anywhere?

According to the Cascadia PWM scheme the pump would run at full speed anywhere above 93%, that would make sense since the pump should fail ON, and there could always be a way for the PWM line to fail to 12V, or to GND. Maybe one day someone has the capability to measure the flow. Although realistically it doesn't really matter for most of our applications here.

[jrbe]

The highside pullup DOES invert the PWM, I might not have made that clear. I took that into account when calculating!

You can likely invert the code to invert the signal back to not inverted.

[lolimpol]

You can likely invert the code to invert the signal back to not inverted.

Yes that can be done quite easily in code, like with an 8 bit (255 step) PWM signal:

255 - duty_cycle = pump signal