Hi,

I have a Growatt SPF5000 inverter with a Pylontech US3000 battery installed.

I'm looking to introduce more stable monitor capabilities by using a Raspberry pi and Solar assistant.

The problem I have is that, ironically, I don't have any outlets near where the installation is. Has anyone managed to find a suitable way to power a Raspberry pi from the dry contacts or something similar? Not sure whether that would work.. it would save me a LOT of effort.

TIA

You can definitely find a DC to DC PSU, SA sell one that works great but I'm quite sure if you hunt around you'll find one at a decent price

https://solar-assistant.io/shop/products/dc_usb_psu

 

1 hour ago, madness_za said:

You can definitely find a DC to DC PSU, SA sell one that works great but I'm quite sure if you hunt around you'll find one at a decent price

https://solar-assistant.io/shop/products/dc_usb_psu

 

Thanks for the reply.. I did think about a DC to USB Power supply, but I would have to connect it directly to the Pylontech battery.. 

I'm going to have to be extremely careful not to stuff up my quite expensive battery..

😅

Another option is to use one of these DC to DC backup UPS units, they work very well just plug into a wall outlet and set the output voltage on 5v for the dc connector and then connect to the RPI 3 / 4 via DC Jack

 

 

https://www.makro.co.za/electronics-computers/wifi-networking/routers-modems/routers/gizzu-mini-8800mah-dual-voltage-dc-ups-/p/000000000000436836_EA?gad_source=1&gclid=CjwKCAiA-P-rBhBEEiwAQEXhH6SuCLvaySsES8UThwhcPFae_l2yHvZ8hHD1SEop76n5jZxHTXelGhoCeQYQAvD_BwE

@Will This is avialable at solarassistant

Get a DC - DC Buckconverter to connect to Inverter/battery

Edited December 19, 20232 yr by Chris Louw

34 minutes ago, Chris Louw said:

Get a DC - DC Buckconverter to connect to Inverter/battery

Thanks - I've just ordered the one recommended above from Solar Assistant, hopefully it will be here soon so I can get going. Thanks for the assistance.

I think the one from Solar Assistant is a good choice, one would want the buck converter to be regulated, especially if connecting it to the battery as the battery voltage would fluctuate based on charging / discharging & SOC.

37 minutes ago, PsyCLown said:

I think the one from Solar Assistant is a good choice, one would want the buck converter to be regulated, especially if connecting it to the battery as the battery voltage would fluctuate based on charging / discharging & SOC.

I have not come across any buck / boost regulator that does not regulate the output as adjusted. They all can have a fluctuating input value. This is why they are such great gadgets. 

I'm sincerely hoping that it automatically regulates the output voltage to suit the Pi, seeing as it can handle up to 60V - I'm confident it would be able to do that.

One other thing - do we know for sure that those ring terminals would be able to securely connect to the Pylontech's + and - terminals.. I don't think a loose connection is ideal. Will have to wait and see when it gets here...

Thanks for all the help on this topic..

I'm a little concerned that I can't see any fuse on the input of that 9-60V DC USB power supply.

Presumably they intend the ring terminals to connect directly to the M8 input studs on the inverter (not the terminals on the Pylontechs)? 

I'd add an inline 1A HRC fuse as close to the ring terminal as possible, in case that cable gets squished or cut.

Here's a cautionary tale:  On my first sizeable (48v) off grid install 20 odd years ago, we'd used Steca kit (Power Tarom), which uses the DC lines for communications to things like remote genset switches etc.  I'd run a 2.5mm twin to one such switch (PA15) and grabbed my meter to check the voltage was present, not noticing my meter was set/plugged for measuring current.  😵‍💫

When the smoke eventually cleared and I'd (thankfully) regained most of my eyesight, I managed to sand most of the scorch marks off the board, then covered the worst of it by moving the PA15 down a bit - which worked out well, since a good inch of the cable had vaporised, leaving it (and my meter probes) a little bit too short. 😅

So, yeah.  I'd fuse it.

-

Another note (I'm full of it today, eh?) on cheap buck converters - especially the ones based on the LM2596 chip.  These are only really any good for < 40Vdc input (the magic smoke escapes around 51V), so for 48V systems, you'd need the LM2596HV, which should be good for up to 60V.

The trouble is that the market has been flooded with the non-HV versions that just have 'HV' written on them (and '100V' or '63V' marked on the input caps).  I have a tub full of them, all with a little melty hole in the lower left where the magic leaked out.  I did find a few modules (the CC/CV versions) that were real HV chips eventually, but not many.

That said, even a 'real' LM2596HV' would be running too close to it's max rating powering a Pi.

What about installing a 10A protection and a 230v socket just connected to the inverter output?

2 hours ago, Mauritius B said:

What about installing a 10A protection and a 230v socket just connected to the inverter output?

Theoretically that is an option, but I'm worried about installing any outlets that doesn't go via the main DB in the house... 

I've purchased the DC charger above, and found that my Keto breaker between the battery and the inverter has the PERFECT placement option for the power supply. I just installed it a few minutes ago - and works a charm...

23 hours ago, HedgeSlammer said:

I'm a little concerned that I can't see any fuse on the input of that 9-60V DC USB power supply.

Presumably they intend the ring terminals to connect directly to the M8 input studs on the inverter (not the terminals on the Pylontechs)? 

I'd add an inline 1A HRC fuse as close to the ring terminal as possible, in case that cable gets squished or cut.

Here's a cautionary tale:  On my first sizeable (48v) off grid install 20 odd years ago, we'd used Steca kit (Power Tarom), which uses the DC lines for communications to things like remote genset switches etc.  I'd run a 2.5mm twin to one such switch (PA15) and grabbed my meter to check the voltage was present, not noticing my meter was set/plugged for measuring current.  😵‍💫

When the smoke eventually cleared and I'd (thankfully) regained most of my eyesight, I managed to sand most of the scorch marks off the board, then covered the worst of it by moving the PA15 down a bit - which worked out well, since a good inch of the cable had vaporised, leaving it (and my meter probes) a little bit too short. 😅

So, yeah.  I'd fuse it.

-

Another note (I'm full of it today, eh?) on cheap buck converters - especially the ones based on the LM2596 chip.  These are only really any good for < 40Vdc input (the magic smoke escapes around 51V), so for 48V systems, you'd need the LM2596HV, which should be good for up to 60V.

The trouble is that the market has been flooded with the non-HV versions that just have 'HV' written on them (and '100V' or '63V' marked on the input caps).  I have a tub full of them, all with a little melty hole in the lower left where the magic leaked out.  I did find a few modules (the CC/CV versions) that were real HV chips eventually, but not many.

That said, even a 'real' LM2596HV' would be running too close to it's max rating powering a Pi.

Thanks for the advice - and as it turns out, the image of the power supply doesn't show the fuse, but when I opened it - it did have an inline fuse on the Positive line. This made me a little less worried as I wouldn't want to lose any magic smoke from any of my devices.. They are not only precious, but expensive as well 🙂

Edited December 20, 20232 yr by willie_b

@willie_b Did the DC USB PSU from Solar Assistant above do the job, did you connect it directly to the battery to power your RPI ?

On 2026/05/09 at 9:07 AM, Jaybabe said:

@willie_b Did the DC USB PSU from Solar Assistant above do the job, did you connect it directly to the battery to power your RPI ?

I am using the PSU from SA, yes it's connected directly to the battery and as mentioned it does come with a fuse on the positive side.

1 hour ago, JacoG said:

I am using the PSU from SA, yes it's connected directly to the battery and as mentioned it does come with a fuse on the positive side.

Thanks.