Peak current of 7A outputs

[Werwolf25565]

Hello,

can someone tell me how much peak current the 7A outputs of the PMU 24 can take?
With the 15A outputs it nicely states.

Thank you

[mkuklis_ECUMASTER]

Hi,
The peak current for 7 A outputs is 70 A.
This information is available in the pinout document.

Ecumaster

PMU-24_Pinout_v1.3.pdf

[Werwolf25565]

Thank you very much. I only looked in the manual.

If i see correctly all 7 and 15A outputs have flyback diode. And of the 25A outputs only O1 and O16 have flyback diode. The other 25A outputs don’t have any flyback diode? Is that correct?

I’m no expert in this. But all electric motors and big coils and so on should be equipped with a flyback diode right?

The fan is shown as an example in the manual somewhere. => so either use one of the 15A outputs or O1/O16 right? (or if you use one of the other 25A outputs, set an extra flyback diode up)

• What about the starter solenoid? That one should have a flyback diode right? So O1/O16 for sure. Right?

• what if i use O1+O2 together? Will the flyback diode on O1 do it’s job?

• what about the fuel pump? Do i need flyback diode?

• what about the vacuum pump for brake support?

Only exception to this: if i use an output with flyback diode but PMU is overheating (because of PWM for example) then i set up an external flyback diode additionally which will do the job outside of PMU to get the load outside. Correct?

Thank you again.

[mkuklis_ECUMASTER]

@Werwolf25565

If i see correctly all 7 and 15A outputs have flyback diode. And of the 25A outputs only O1 and O16 have flyback diode. The other 25A outputs don’t have any flyback diode? Is that correct?

Yes, that’s correct.

@Werwolf25565

I’m no expert in this. But all electric motors and big coils and so on should be equipped with a flyback diode right?

Not necessarily a flyback diode.
Switching any inductive load (coils) requires a flyback path.
That path can be achieved in multiple ways.
Outputs that don’t have a dedicated flyback diode have an alternative flyback path.

@Werwolf25565

The fan is shown as an example in the manual somewhere. => so either use one of the 15A outputs or O1/O16 right? (or if you use one of the other 25A outputs, set an extra flyback diode up)

• What about the starter solenoid? That one should have a flyback diode right? So O1/O16 for sure. Right?
• what if i use O1+O2 together? Will the flyback diode on O1 do it’s job?
• what about the fuel pump? Do i need flyback diode?
• what about the vacuum pump for brake support?

The most general rule is that you need a flyback diode if the output overheats without it.
This can happen with PWM, frequently switched big inductive loads, or big motors. A big load can be described as a load with a current closer to the maximum current of the output.

Diode of O1 will do its job when used in parallel with other outputs.

@Werwolf25565

Only exception to this: if i use an output with flyback diode but PMU is overheating (because of PWM for example) then i set up an external flyback diode additionally which will do the job outside of PMU to get the load outside. Correct?

That’s correct.
As I explained above, this is also the case for outputs without a diode.

[Werwolf25565]

That is a very informative answer. Thank you very much.

So that means i can connect my fan to any of the 25A outputs since all of them have some sort of flyback protection and then i keep an eye open on temperature/problems.

[Werwolf25565]

Another question: I have a fan/pump with 13A and I only use it full speed (so no PWM needed).
All my 15A outputs are in use already.

Do I just use a 25A that i still have left over with no flyback or do I put something even smaller (like my horn that’s on a 15A) on a 25A so that I have the flyback of a 15A output available for my fan/pump?

Thank you for you help once again.

[mkuklis_ECUMASTER]

You can easily put them on a 25 A output without a diode.
It will work just fine.

[Werwolf25565]

Will do. Thank you.