Solving a problem using a voltage follower! Thank you!

Thread Starter

dannym8585

Joined Apr 18, 2022
25
Alright guys Im the new guy I have a problem and You guys are way more knowledgeable than me so let me give you a run down of the problem and how I think we can solve it. I just need the hardware that will do it!

Problem: I have a module that controls fuel pressure but it only has the ability to deliver up to 15 amps before is over heats and toasts out. This module is coded to another one and they work in conjunction together so it needs to remain in place. My idea to solve the issue is to use the existing module as a reference signal to a voltage follower that has the ability to deliver 50amps. The voltage needs to be able to range from 6v to 15v does something like this exist?

Thank you for any help guys I appreciate it!
 

BobTPH

Joined Jun 5, 2013
5,496
PWM does not vary the voltage, it varies the duty cycle. It may well be controlled by a voltage though.

You could augment the current by using a MOSFET switched by the existing PWM module.

Bob
 

Thread Starter

dannym8585

Joined Apr 18, 2022
25
HMM Bob you seem like a smart guy, I dont believe im understanding PWM fully, if i were to use just a multimeter when the module was at say 50% duty cycle. If it module was supplied 12v would the multimeter read 12v? or would it be around 6v as its only at 50% dtc?
 

BobTPH

Joined Jun 5, 2013
5,496
The multimeter is designed to read a steady voltage. Depending on its circuitry, it might read the average voltage which would be 6V in your example, but it would not be wrong if it did not.

Some multimeters can measure duty cycle as well, which is really what you would want to measure on a PWM signal.

Bob
 

Thread Starter

dannym8585

Joined Apr 18, 2022
25
From what I can tell, keep in mind I dont know much about mosfets because this runs a motor the mosfets may get very hot due to the channel resistance value? Does that make sense? Would that be an issue?
 

Thread Starter

dannym8585

Joined Apr 18, 2022
25
The multimeter is designed to read a steady voltage. Depending on its circuitry, it might read the average voltage which would be 6V in your example, but it would not be wrong if it did not.

Some multimeters can measure duty cycle as well, which is really what you would want to measure on a PWM signal.

Bob
I gotcha I understand. So more than likely the module in question is actually putting out the voltage being supplied to it, then using pwm to essentially artificially reduce voltage or duty cuty to reduce output of the pump
 

Thread Starter

dannym8585

Joined Apr 18, 2022
25
I wouldnt see a reason for it to reduce the voltage and use pwm would be very redundant and from what ive researched the reason manufactures use pwm is to reduce heat and use less energy instead of using resistors to lower voltage
 

LowQCab

Joined Nov 6, 2012
2,342
Before it's possible to provide You with a solution,
there can be only a very limited amount of guess-work.

It's fine to guess that the Load "may" go a high as ~50-Amps,
OK-fine, that means that You WILL BE running a ~50-Amp Fuse to the Load, right ?
So the new add-on "booster" Controller will never see any more Current than ~50-Amps, right ?
So that part is settled.

But what must be determined as a matter of fact,
is whether your existing Load-Driver, that is connected to the existing Pump
is indeed a PWM type Controller.
You can test this with an old Speaker that You don't care about, ( because You might destroy it ).
Connect a Speaker in place of the Fuel-Pump, then turn-on the Ignition FOR 0.5-Seconds,
if you hear a VERY-LOUD Tone, then it's PWM,
if You only hear a loud "click" sound, it's NOT PWM.

Are You working with a stock GM-Fuel-Pump-Control-Module,
but You want to install a larger Fuel-Pump,
so therefore, You have to increase it's Current-Capacity ?

Does your new Fuel-Pump have a built-in PWM-Speed-Controller, but the
required PWM Frequency that the new-Pump needs is substantially different
than the Frequency that the GM-Controller operates at ?
This is common.

Also, will this "add-on" be mounted inside the Car, or outside of the Car ?
Inside is ALWAYS better.
.
.
.
 

Thread Starter

dannym8585

Joined Apr 18, 2022
25
This is making me excited okay. Can confirm the module is pwm. Its for a bmw they use something called a ekp (just a fuel pump module) Youre exactly right the stock module can only output around 15 amps before they over heat and die. Im trying to run 2 fuel pumps for big power #s so i need something that can deliver up to 50 amps to be safe but 2 walbro 450s which will be plenty will draw at max 40ish amps. The module and add on can be installed inside, its inside currently and there is space to make it fit as long as it can be build relatively compact. The new fuel pumps are very basic and can work on any current just a basic motor nothing special.

Thank you!
 

BobTPH

Joined Jun 5, 2013
5,496
Hey bob do you think using a FET would be a more effective solution because our target current flow is around 50amps?
As you already stated, using PWM is a more efficient method of reducing power than reducing the voltage by adding resistance. The odds are that your current PWM controller is already using a MOSFET. What you probably need is a MOSFET with higher current capacity.

Do you know what the input to the current PWM module is?

Bob
 

Thread Starter

dannym8585

Joined Apr 18, 2022
25
As you already stated, using PWM is a more efficient method of reducing power than reducing the voltage by adding resistance. The odds are that your current PWM controller is already using a MOSFET. What you probably need is a MOSFET with higher current capacity.

Do you know what the input to the current PWM module is?

Bob
Ill need to put a wiring diagram tomorrow to see where the module gets it power from, as far as i know it is just car voltage which would be around 12-14v depending on charge of the battery but I cant confirm that 100% I do know this module doesnt look like it could be modified either way to add a higher flowing mosfet just because of the way it was built everything is very small. But i dont know much about electronics to say it couldnt be let me attach a picture quickly
 
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