AA battery connected to step up modular (5v) can power a 5V DC cooling fan BUT
if a DC centrifugal radial 5V cooling fan is connected then its not working
The DC radial fan works fine with 5V mobile charger

 

The step-up module is not supplying enough current to start the fan.

 

The step-up module is not supplying enough current to start the fan.

Thanks, but similar 5v DC cooling fan is working fine. This one is 5V radial. What can be done to fix it?

 

similar 5v DC cooling fan is working fine. This one is 5V radial. What can be done to fix it?

It would appear the radial takes more current than the other cooling fan.
Images of them don't tell us much.

Do you have the current requirement specs for both?

 

It would appear the radial takes more current than the other cooling fan.
Images of them don't tell us much.

Do you have the current requirement specs for both?

The standard fan 4010 with mobile charger (5v) OR 3 AA batteries (4.5) shows 90mA BUT with 5v step up module it shows 550mA. This fan works fine.

The DC radial fan with mobile charger OR 3 AA batteries (4.5v) shows 130mA BUT with 5v step up module it just jerks and does not spin. While at that moment of minor spin the current reading shows 770mA.

 

The DC radial fan with mobile charger OR 3 AA batteries (4.5v) shows 130mA BUT with 5v step up module it just jerks and does not spin. While at that moment of minor spin the current reading shows 770mA.

The radial fan appears to require more than 770mA to start.
What is the output current rating of the 5V step-up module?

 

The radial fan appears to require more than 770mA to start.
What is the output current rating of the 5V step-up module?

with 1 AA (1.5v) battery the step up module output shows 44mA
with 2 AA (3v) battery the step up module output shows 1.03A

 

The DC radial fan’s ACTUAL current consumption is….
Hmmmm.
My crystal ball is having poor Wifi reception.

To the TS: can you please provide the value as read on the fan’s label.

 

Love this game of 20 questions.
So what is the 5V module's output voltage when it is delivering 770mA to the radial fan?

 

There is no mystery here. To boost from 1.5V to 5V at 770mA you need 2.5A if it was perfectly efficient. That is simply too much current for the AA to provide and we know the motor not start at that current.

 

The DC radial fan with mobile charger OR 3 AA batteries (4.5v) shows 130mA BUT with 5v step up module it just jerks and does not spin. While at that moment of minor spin the current reading shows 770mA.

This is EXACTLY WHAT HAPPENS when you attempt to operate a motor that draws too much current from a switching power supply. The motor starts to spin, then the switcher shuts down because the current draw is too great. Then the process repeats.

The radial fan rotor has more mass and interia than the rotor of the axial fan, so it makes sense that the starting current is higher. The starting current is the key point.

Sorry this does not conform to your desires.

 

You'll have to purchase AA-Batteries in bulk quantities.
.
.
.

 

How long do you expect the fans to run on batteries before battery replacement?

 

there you go

 

The DC radial fan’s ACTUAL current consumption is….
Hmmmm.
My crystal ball is having poor Wifi reception.

To the TS: can you please provide the value as read on the fan’s label.

Not available. Its standard model 4020. Current reading not available on web

 

60 amps it have no problem running your fan

 

There is really no ambiguity. Your boost converter can supply enough current to start the fan. The fix is to get a new one that can do the job. But there is a mysterious part—why are you trying to run these fans from AA cells?

 

I believe you meant:

There is really no ambiguity. Your boost converter CAN'T supply enough current to start the fan.

 

Quick test, put 2, 3, or 4 AA batteries in parallel. As mentioned, you may need 2.5A input and due to internal resistance of battery the input voltage is dropping to the DC/DC causing it to shut down. Then with load removed, voltage rises and DC/DC turns back on, etc.

BTW, pictures are cool, but real designers work from datasheets and that requires part numbers. How about part numbers for fans and DC/DC?

 

Not available. Its standard model 4020. Current reading not available on web

Do You mean that the label attached to the unit itself doesn’t have any electrical information at all??