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DC booster converter strange behaviour

Sanok

Mar 18, 2017
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Its 400W converter with output voltage and current regulation as pictured. Its original mosfet and 15 amp fuse got burned,
however I didn't exceed any ratings. Now I'm trying several different mosfets that are rated much higher amps and volts than this booster can provide and this is what's happening:
On output I have a 12V 60W car globe, when I'm turning up the current potentiometer nothing happens for about 3/4 of the turning range.
(the globe pulls steady 5amps) untill certain point where current starts increasing rapidly and mosfet gets very hot. I'm switching circuit off at 15 amps to avoid burning the mosfet.
When this happens the globe doesn't get any brighter, so it looks like the mosfet is consuming all current above 5amps.
Is that normal behaviour of N-mosfets or there is something wrong with booster's regulation?
 

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(*steve*)

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What are the input and output voltages when the bad stuff starts to happen?
 

Sanok

Mar 18, 2017
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What are the input and output voltages when the bad stuff starts to happen?
input is 12V, output for the globe was between 13-14V, with other loads output can be set up to 50V.
So with any output voltage the input current increases far beyond of what the load needs.
 

(*steve*)

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Does this happen even when there is no load connected?
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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input is 12V, output for the globe was between 13-14V, with other loads output can be set up to 50V.
So with any output voltage the input current increases far beyond of what the load needs.
That is not the way it should work! If the input current for 12 V input is greater than 15 A (causing the fuse to blow) something is seriously wrong. Perhaps the MOSFET switches are shorted. Perhaps the circuit isn't oscillating. Did you accidentally connect power with reverse polarity? This device has no reverse polarity protection. Considering that it costs less than six bux, you might be better off just purchasing another one instead of trying to repair the one you have, which is clearly defective.

I found the below description at this website. If accurate, the device should work just fine with 12 V input to produce 13 to 14 V output, driving your 12 V, 60 W, car globe lamp load with slightly more than about 5 A of current (60/12 = 5). With reasonably high efficiency (more than 90%), the load current should be roughly the same as the supply current, and certainly nowhere near 15 A.

400W DC-DC Step-up Boost Converter Constant Current Power Supply Module

 
Description:

  • 100% brand new and high quality.
  • Features:
    This is a great 400W DC to DC step-up power supply module for electric equipment, digital products, laptop, etc.
    Input and output are designed with screw terminals for convenient wire connection and disconnection.
    High efficiency, the maximum conversion efficiency can be 96% and efficiency is related to input/output voltage, current and voltage difference.
    There are 2 heat sinks that would ensure a better heat dissipation.
    It can also be used as a driver for high power LED lights or voltage regulator for solar panels.

    Output Voltage/Current Adjustment:
    1, Adjust "CV-ADJ" potentiometer clockwise to reduce voltage, counterclockwise to increase voltage.
    2, Adjust "CC-ADJ" potentiometer counterclockwise about 30 circles to minimize the output current before connecting to load(clockwise to increase current, counterclockwise to reduce current). Then adjust "CC-ADJ" clockwise to the current value you need. If you use the module for battery charging, connect to output after battery is fully discharged. Because if the more energy is left in battery, the less charging current will be.

    Specifications:
    Type: Non-isolated boost module
    Input Voltage: DC 8.5V to 50V
    Output Voltage: DC 10V to 60V (continuously adjustable, default 19V)
    Max. Input Current: 15A (please enhance heat dissipation if more than 8A)
    Max. Output Current: 12A (related to the input and output voltage difference, the greater voltage difference is, the smaller output current will be. please enhance heat dissipation when current is over 7A)
    Quiescent Current: 10mA(will increase when convert 12V to 20V)
    Constant Current Range: 0.2A to 12A
    Output Power = Input Voltage*Current
    Operating Temperature: -40° to 85°(if temperature is too high, please enhance heat dissipation)
    Frequency: 150KHz
    Max. Conversion Efficiency: 96% (Efficiency is related to input/output voltage, current and voltage difference)
    Over Current Protection: Yes (if input current is more than 15A, it will automatic reduce output voltage)
    Reverse Input Protection: No
    Size: 6.7x4.7x2.7cm/2.64x1.85x1.06inch
    Quantity: 1 Pc
 

(*steve*)

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Is your load connected to the power source in any way? E.g. is it a light on a vehicle? Or is it completely separate, like 2 wires leading to a globe that's sitting on a wooden bench?
 

Sanok

Mar 18, 2017
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That is not the way it should work! If the input current for 12 V input is greater than 15 A (causing the fuse to blow) something is seriously wrong. Perhaps the MOSFET switches are shorted. Perhaps the circuit isn't oscillating. Did you accidentally connect power with reverse polarity? This device has no reverse polarity protection. Considering that it costs less than six bux, you might be better off just purchasing another one instead of trying to repair the one you have, which is clearly defective.
I have just bought this and started testing it with the globe when it got burned. I'm sure I didn't reverse polarities.
Its original mosfet was rated at 80V/80A. Don't know how it could get shorted when the fuse blew. Now I'm using mosfets rated at hundreds of volts but only up to 30A, because thats what I've got. They are still alive but have burned several 15A fuses.
Will get a new booster and see if same happens, perhaps this one has some other fault.
 

Sanok

Mar 18, 2017
6
Joined
Mar 18, 2017
Messages
6
Is your load connected to the power source in any way? E.g. is it a light on a vehicle? Or is it completely separate, like 2 wires leading to a globe that's sitting on a wooden bench?
just 2 wires from the booster and all is isolated from bench. It must be a fault with current regulation because it only happens when current is almost fully increased with potentiometer
 
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