External power specifications

I am planning on using a larger pump with my pioreactor. With that, it will require the use of an external power supply. The docs on Supplying more power to the PWM channels | Pioreactor Docs state an 18 V maximum. Is there a maximum for the current?

:wave: hi @rafik.n

I talked to my cofounder (our EE expert) about this, and here’s a summary of his opinion.

is actually quite complicated because the allowable current will depend on many things such as:

It’s complicated because the allowable current will depend on many things such as:

  • the inductance of the pump
  • the DC resistance of the pump
  • whether the pump can be back-driven and thus able to act as a generator
  • the stability of the external power supply chosen
  • Amplifier voltage
  • operating temperature of the HAT (colder allows more current)

Do you have a specific pump & PSU in mind + how you plan to use it ? We are open to trying it here on some test HATs we have.

hi @CamDavidsonPilon,

I am integrating the pioreactor electronics on a larger reactor which is why I need a larger pump. I am considering a diaphragm pump such as one of the options linked below. It will be used for dilution purposes (will only be using 1 pump in total). Both are 12 V. Rated for 5 and 6 amps. They cannot be backdriven. If it is risky I can opt for the relay/plugin route.

pump options:

  1. https://www.amazon.ca/VeYocilk-Diaphragm-Priming-Sprayer-Pressure/dp/B0C1H58RFQ/ref=sr_1_3_sspa?crid=3HUTLSKEN7292&keywords=DC%2Bwater%2Bpump&qid=1700796170&s=hi&sprefix=dc%2Bwater%2Bpump%2Ctools%2C89&sr=1-3-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1
  2. https://www.amazon.ca/Diaphragm-Priming-Pressure-Switch-Clamps/dp/B07RZRVSW5/ref=asc_df_B07RZRVSW5/?tag=googleshopc0c-20&linkCode=df0&hvadid=335540902013&hvpos=&hvnetw=g&hvrand=6825094088271922485&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9000833&hvtargid=pla-777955958581&psc=1&mcid=13f53e0ad0c63bd2b4470abd06d44b17

power supply:

60W is definitely too much for the HAT, unfortunately. A possible solution, if you really wanted to use the HAT + software, would be use the HAT to drive the input of a PWM-able DC motor driver. Then that DC motor driver drives the pump.

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Thanks for the advice!