Dc buck converter fried already?

[Barbar0ssa]

I picked up a 24v 30a dc-dc buck converter to drive a pond aerator (100w) off of a solar panel and inverter without batteries. The solar panel had 22.1v the buck converter showed regulated 12.2 out. I plugged it into the inverter which beeped, saying it turned on and then nothing. There was no load on the inverter. Now I see no voltage on output of the converter. Are there any tricks I should know or did I just get a dud?

 

[Bud Martin]

I picked up a 24v 30a dc-dc buck converter to drive a pond aerator (100w) off of a solar panel and inverter without batteries. The solar panel had 22.1v the buck converter showed regulated 12.2 out. I plugged it into the inverter which beeped, saying it turned on and then nothing. There was no load on the inverter. Now I see no voltage on output of the converter. Are there any tricks I should know or did I just get a dud?

What is the spec of this 24V to 12V buck converter? 12V output up to 30A? What is the spec of the Solar panel? What is the spec of the pump?

 

[Barbar0ssa]

Solar panel was 150w 12v panel putting out 22.1v open in the evening sun.

The converter is this:

https://smile.amazon.com/dp/B08DK1XLCB/ref=cm_sw_r_cp_apa_glc_fabc_H9J1HWNNGM28MWD33DS6?_encoding=UTF8&psc=1

There was no load on the inverter when it turned on and then immediately turned off. After that, no output voltage on the converter at all.

 

[Bud Martin]

Per Amazon:

About this item​

• Input Voltage Range: 18-36V DC (Typical: 24V) ; Output Voltage: 12V ;Output current: 30A; Output power: 360W.

Your panel has Voc of 22.1VDC. What is the Vmp of the panel? More likely to be around 16~ 17V or so, not really enough to feed the bcuk converter, beside the output Voltage will vary with sun input.
You can verify if the buck converter is sill working or not by connecting it to 24V source to test.

 

[Barbar0ssa]

I'm pretty sure I killed it because when I plugged it into the solar panel I was getting a 12.2 volt output. Then after plugging it into the inverter I haven't seen a 12.2 volt output again. I was hoping for a secret knowledge such as "if you short it everything will just magically work." ?

 

[Barbar0ssa]

I might try 2 panels in series tomorrow. I am pretty demoralized with the darn thing.

 

[Bud Martin]

I'm pretty sure I killed it because when I plugged it into the solar panel I was getting a 12.2 volt output. Then after plugging it into the inverter I haven't seen a 12.2 volt output again. I was hoping for a secret knowledge such as "if you short it everything will just magically work." ?

Oh I did not catch the 'Inverter' part. so This Buck converter output is feeding the 12V inverter that puts out 120VAC, correct? The inverter has large filter caps that act like short circuit when inverter DC input is connected to the powerr soucre, it will draw very large surge current, you will need to put the resistor to charge the capacitors first then you can dircetly connect the DC soucre directly the inverter DC input. There are many thread about pre charging the inverter input to prevent damage the BMS.

 

[Supervstech]

Yup.
What size inverter?
you could easily have exceeded the buck converter amp load.
I WISH inverters all came with a soft charge circuit built into them...
I agree though, the single panel likely doesn’t have the volts to run the buck properly.

 

[Barbar0ssa]

500w inverter.

Can the 150w panel really provide enough power to kill a 360w converter?


https://smile.amazon.com/dp/B07MQY1...abc_ZA44055250ACF1EH1PQ9?_encoding=UTF8&psc=1

 

[rickst29]

500w inverter.

Can the 150w panel really provide enough power to kill a 360w converter?


https://smile.amazon.com/dp/B07MQY1...abc_ZA44055250ACF1EH1PQ9?_encoding=UTF8&psc=1

I will SWAG that your problem was actually the reverse: the 150w panel was insufficient to power your Converter, when the Converter load became momentarily large. Even with no 120-VAC load attached and active, your 500w inverter starts up by drawing a small "whoosh!" of input power from the 12V input side (which mostly charges up some Inverter Capacitors). Even if the 12v demand side is not over the Buck Converter's maximum output capability, the Source Side must also be "big enough" (in watts) to keep the Buck Converter "well fed" and running smooth.

An excess of panel power (such as 2 or 4 panels, which must be wired in Parallel to stay below 36V) is harmless, even desirable. But an insufficient source is a possibly deadly thing. You probably let out all of the magic blue smoke. You might not need a bigger Buck Converter, but you certainly need more panel power -- and under clouds, you need an alternative OR you must shut down at the Inverter. I think you need to be looking at a normal solar controller and a battery, rather than a mere Buck Converter.

 

[Steve_S]

I NOTE about Buck Converters which I am surprised no one mentioned.
BEWARE of the Max Voltage Input Rating !
A 24V Battery system can take a Charge up to 30V - The BUCK Converter MUST be capable of 30V Input (for when batteries are being charged) otherwise it will melt down ! THE DEVIL IS IN THE DETAILS !

For 24V you need a 30V Stepdown Converter, for 48V system, 60V Stepdown.

 

[Supervstech]

I NOTE about Buck Converters which I am surprised no one mentioned.
BEWARE of the Max Voltage Input Rating !
A 24V Battery system can take a Charge up to 30V - The BUCK Converter MUST be capable of 30V Input (for when batteries are being charged) otherwise it will melt down ! THE DEVIL IS IN THE DETAILS !

For 24V you need a 30V Stepdown Converter, for 48V system, 60V Stepdown.

The specs he listed for the converter state 18 to 36V, so he should be ok with a pair of 18V panels in series.

 

[Barbar0ssa]

I have 3 of these panels that have been in a shed for 7 years, originally purchased for a skoolie project so using 2 panels is possible.

If the source being insufficient can destroy the converter then wouldn't every cloud have a chance to destroy equipment?

I am trying to reproduce what @Will Prowse did here:

 

[Ampster]

Are there any tricks I should know or did I just get a dud?

Is it wired correctly? I had one like that and made an assumption about black and red wires that was wrong. I am not clear were the inverter fits in here if this is a DC system.

 

[rickst29]

If the source being insufficient can destroy the converter then wouldn't every cloud have a chance to destroy equipment?

Having finally watched the video, my previous SWAG seems partly wrong: Within the video, the Inverter dropped output Voltage, provoking Inverter shutdown before destroying the buck converter.

But in your case, the initial "capacitor loading" inflow for the Inverter blew the Buck Converter, more quickly than the Inverter "saw" that buck Converter output Voltage had dropped too far. Between the single panel and the sustained-for-too-long Inverter load, your Buck Converter fried. But I now think that the mis-switching Inverter startup (it should have "given up" a lot faster) combined with insufficient output filtering capacitance in the Converter, reachingback to destroy the switching components. (Your 24v--> 12v likely contains less output filtering than Will's 48-->12 model, which must smooth out the 12v side from a much higher differential of Voltage versus the input side.)

 

[Supervstech]

I have 3 of these panels that have been in a shed for 7 years, originally purchased for a skoolie project so using 2 panels is possible.

If the source being insufficient can destroy the converter then wouldn't every cloud have a chance to destroy equipment?

I am trying to reproduce what @Will Prowse did here:

Notice, will hooks to 400W of panels...
He also shows how even a slight shadow drops out the inverter.
He is using a small inverter here, yours got connected to the already powered converter.
I think it was the instant capacitor charging that fried your converter.
I doubt the weak panel had any play in the issue.

 

[Will Prowse]

Yeah, over paneling is a must when running anything direct from solar without a battery.

 

[Supervstech]

Also, looking at your converter vs. The one will recommended in the video... his were 48V converters.
Your 24v simply cannot be used this way.
The single panel won't output enough volts, and in series it will have too high a VOC, which will likely fry it.
When replicating something Will shows in a video... it is a good plan to use the items he lists in the description...
And pay attention to ALL of his information in the videos.
He states 400 to 3000w of panels, he states VOC must be less than maximum voltage of the converter, and he shows how shade drops out the converter immediately.
I hoped he mentioned the inrush capacitor charging, but he didn't in that video.

 

[Barbar0ssa]

The other video had 1 tiny panel charging a laptop at 19w. I will try again with fuses and precharging the inverter. For this project, I'll do 2 in series with a beefier converter.