MoTeC Global Forum

Hi all,

I have dummy questions for the smart people to help me out here. I would appreciate your inputs.

A bit of background, I have M150, PDM30, DHB and 2 SPAL brushless fans. I wish to control the fans with DHB but here are my concerns. Each fan would require between 15 to 20 continues amps, that would total up to 40 amps. As I understood from the DHB, it has maximum of 20 continuous amps and this worries me.

According to the instructions as I understood it, it has one input from ECU, one output to the fan and one power input.



Each fan has 4 wires, Black/Red for power, white & yellow for the PWM signal (I guess)




Based on my understanding, the power is connected to DHB, but due to DHB amp limitation can I disconnect the power from DHB and connect Black/Red wire on the Fan directly to the battery?

Second question, the fan has 4 wires and DHB has only 2 output and I guess to yellow and white. Hence, black/red wires on the fan has no place to be connected to DHB. Then why do you need to power DHB since the Fan is powered directly?

Or is this power only to amplify the PWM signal and DHB will always require power not to power the fan, but only to amplify the PWM signal? so in this case, what would be the consumption of the PWM signal for the 2 brushless fans?

Thanks,

Abdulla

Hi,

It looks to me from the information provided that you do not need to use the DHB for these fans. You should have Battery Power supplied to Pin 1, Vehicle Ground to Pin 2, and have Pin 4 wired to the M150 resource that is used to switch the fan. The M150 can then drive the fan using a PWM output signal.

SDean wrote:Hi,

It looks to me from the information provided that you do not need to use the DHB for these fans. You should have Battery Power supplied to Pin 1, Vehicle Ground to Pin 2, and have Pin 4 wired to the M150 resource that is used to switch the fan. The M150 can then drive the fan using a PWM output signal.

SPAL PWM.PNG

Hi Stephen,

Yeah we've thought of this but the problem all of the pins are used on the M150 so we got the DHB. Now in this case, what would be the optimal solution?

Thanks,

Abdulla

So how were you going to control the DHB if all the M150 outputs were used? Are you sure you don't have an unused injector or ign output?

David Ferguson wrote:So how were you going to control the DHB if all the M150 outputs were used? Are you sure you don't have an unused injector or ign output?

We dont have full bridge output left that we can use from the ECU.

You don't need a full bridge output, you can use one of several output types. Try to configure the fan control output resource and you will see a list of available outputs in the pop up list - that will include Half-Bridge, Injector and Ignition outputs. Any of these can be used as the pwm control signal for the Fan.

David Ferguson wrote:You don't need a full bridge output, you can use one of several output types. Try to configure the fan control output resource and you will see a list of available outputs in the pop up list - that will include Half-Bridge, Injector and Ignition outputs. Any of these can be used as the pwm control signal for the Fan.

I think this will make the fun to function as on/off isn't it? I want to make the DHB to function as speed controller. This is what the DHB is made for. If not, then what is the DHB is made for?

The FAN output is a Pulse Width Modulated signal, so you can drive variable speed fans (like the SPAL) that have a PWM input, (or use a DHB where you feed the PWM signal to the DHB -- that's how it works). If you set the Duty Cycles to 0% and 100% then you will get the Off/On behavior you are describing.

To control the duty cycle, you modify the table "Coolant Fan 1 (or 2) Duty Cycle Coolant Temperature. Note that this table can have an axis for the Coolant Temperature and the Vehicle Speed (you don't need the fan if the vehicle is moving fast enough). There is also a table for Duty Cycle Air Conditioner that you may want to tune.

To test the output, you set the Coolant Fan 1 Test Duty Cycle, and then enable the Coolant Fan 1 Test.

Be sure to look at the Help for Coolant Fan 1 (that completely describes the system, which outputs can be used, etc)

All of these parameters can be found in M1 Tune, under Initial Setup, Engine Output tab.

SDean wrote:Hi,

It looks to me from the information provided that you do not need to use the DHB for these fans. You should have Battery Power supplied to Pin 1, Vehicle Ground to Pin 2, and have Pin 4 wired to the M150 resource that is used to switch the fan. The M150 can then drive the fan using a PWM output signal.

SPAL PWM.PNG

Just to be clear about this, Stephen: If the fans did not have a direct connection to chassis ground (which sinks the current when circuit is close), then the DHB would be necessary. Put differently, if this were a two-wire fan, power and ground, then the DHB would be necessary to avoid sinking all 20 amps of current to the ECU. Correct?

--Peter