12v to 5v 3a step down power module for USB (1 Viewer)

Oct 26, 2021
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I have used a number of £2 buck converters from eBay based on the LM2596 chip for various projects. I compared one to the reference design on the data sheet and it was an almost exact copy. See "Buck Converter LM2596 Step Down DC-DC Adjustable Power Supply Voltage Regulator". To be on the safe side I would add a line fuse and put it in a plastic enclosure. Note that the -ve rail on the output is tied to the -ve rail on the input, so take care not to short the +5v to the van chassis.
 

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Sep 20, 2020
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I got a pair of 12v to 5v 3A buck convertors to power a MiFi and a Pi. They are potted, so should cope better with movement and vibration. No heatsink though. Only been running for a couple of months, so I can't tell you much about reliability.
Amazon product ASIN B08Q34TYV5
I've used these before with good results, many of the cheaper ones give out masses of RFI and electrical noise making them useless. I've only drawn milliamps out of them though for a dashcam, at full current might be a different story
 
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Diabalo
Oct 14, 2007
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I'm using a couple of these to power the Rasp Pi's on our van.

They have remained stable and accurate going by the LED readout and are easy to set the output voltage via the trimmer, plus the seller is UK and in the UK. (y)
Mine are on 24/7 and have been for the past 6 months or so.

<Broken link removed>
I would assume the voltage trimmer is necessary when using it with the Rpi, not sure how accurate the 5v would be with the ones without it. I think the Rpi is susceptible to under voltage.

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Two on Tour

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My Pi's are piggybacked onto 7" touch screens which with the extra current draw of the touch screen brings up the under voltage/current warning arrow on the screen, so I
tweek the trimmer until the warning arrow stays off, which is about an indicated 5.3 volt on the LED readout of the PSU.
 
May 19, 2020
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My Pi's are piggybacked onto 7" touch screens which with the extra current draw of the touch screen brings up the under voltage/current warning arrow on the screen, so I
tweek the trimmer until the warning arrow stays off, which is about an indicated 5.3 volt on the LED readout of the PSU.
How do these devices work with the variations in voltage you see in a Motorhome i.e is the output a constant set voltage?

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How do these devices work with the variations in voltage you see in a Motorhome i.e is the output a constant set voltage?

I don't know if the PSU is regulated or not, but the Pi's have been running fine on the van. The PSU's are boxed and behind a panel in the van, so not able to check the
output voltage at different input voltages, but a have a spare PSU, so I'll hook it up to one of my other Pi's and see how it fairs. (y)
 
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Diabalo
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While carrying out my research into buying one the output voltage is very stable, which is what is needed for running a Raspberry Pi.
 

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How do these devices work with the variations in voltage you see in a Motorhome i.e is the output a constant set voltage?

Okay, I have done some tests on the 200W 8A DC-DC Step Down Buck Converters I'm using at various input voltages.
I used the same setup as I have in the van, that being the PSU powering a Rasp Pi piggybacked on a 7" touchscreen.
I initially powered it up using a 2A plug in the wall power brick which under the load of the Pi had a 12.2v output to the PSU. The output of the PSU to the Pi was 5v on the nail.
Next, I powered the PSU via the lithium battery on our van which was showing 13.2v and the output of the PSU to the Pi was 5v again on the nail.
I then powered the PSU via an AGM battery which was on charge and showing 14.6v to the PSU and again the output of the PSU to the Pi was 5v.
Lastly going to the silly end of the scale, I powered the PSU via a scrap lead acid battery which was initially showing 11.5v to the PSU but quickly reduced to 8.6v, and still the PSU output to the Pi was 5v.
I'm more than happy with the performance of the 200W 8A DC-DC Step Down Buck Converters I'm using going by the results I got. (y)

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May 19, 2020
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Thanks for that Paul, that’s an excellent effort. I might invest in a few of these, do you have an example of a suitable case/enclosure
 

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Thanks for that Paul, that’s an excellent effort. I might invest in a few of these, do you have an example of a suitable case/enclosure

I used a junction box from Toolstation.

 
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Diabalo
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When Venus OS is loaded on the Pi does that mean it can't be used for anything other than Victron kit?

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Diabalo
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I use one of these to power my Huawei B535 router via the 12volt outlet and that leaves the usb for something else.
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I went with one of these in the end, I have set it up at home to run a Raspberry Pi 3 B+ with Victron Venus OS installed and to power my MiFi. I used the USB to power the Raspberry and the output terminals for the MiFi, so far no issues with power.
I have setup my Victron VM portal account and made up the VE Direct leads, just need to install it in the van now. It will be very handy to be able to see what's going on with my system remotely.
 

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