Power Buddy




Introduction: Power Buddy

About: I am an automation engineer but I will give anything a go. I don't know if you call if pessimism or just being an engineer, but I look for problems everywhere, then I look for some weird, left field way to s...

This little case is a handy way to get power where it wouldn't normally be available. It has a 12W 12V solar trickle charger and a 230V mains charger. It outputs 230V @ 200 or a single 12V vehicle accessory plug. I was going to add a USB charger but with converters being so handy and cheap I just included a 230V to USB plug top.

Please note this instructable deals with high voltage and power tools, I assume you know what you are doing if you attempt this. Please observe all safety precautions and follow local wiring regulations.

Step 1: Equipment List

This instructable uses:
1 aluminium flight case (I had this one laying around but they cost about €25)
1 12V to 230V 200W inverter (http://uk.rs-online.com/web/p/dc-ac-car-power-inverters/0597497/)
1 solar regulator (http://www.phocos.com/datasheet_cc_cml.html)
1 12V accessory socket (http://m.ebay.com/itm/291489345195)
2 12v 22Ah UPS batteries
2 6V 12W solar panels(again I had these last parts laying around)

You will also need assorted wire and fittings.

Step 2: Solar Panels & Regulator

Mark out the locations for the solar panels, I centred each of them with the lid and drilled a centre hole to pass the wire through.
Each panel was then drilled and fixed with 4 x 5mm rivets.
The regulator was bolted to the inside of the lid.
As my solar panels are 6V and my regulator 12V, I wired the solar panels in series to get 12V at 12W.
These were then wired to the solar input on the regulator.
The last image shows a test where the solar panels are put in the sunlight and the controller powers up. It shows as an error because no batteries or load are present.

Step 3: 230V Outlet

The location of the inverter was marked on the outside of the box.
I used a dremel to remove the square section and then filed the edges to remove the sharp burr.
I needed to fox the inverter in place but also needed to be electrically safe so I opened the inverter to find spots on the face I could drill and rivet without causing an electrical short.

Step 4: 12V Outlet

The 12V outlet was quite easy, this is a kit so all that is required is a 30 mm hole, pass the socket through and screw on the back nut.

Step 5: Wiring

2 batteries are fitted and wired in parallel, this maintains 12V but adds the Ah together to get 44Ah. This will give a longer run time. These are wired back to the battery input on the regulator.
The inverter and 12V outlet are wired together to the load output on the regulator. Please make sure all connections are correctly insulated to prevent electrical short and possible death.
The inverter has are third wire for are switch, this was tied to positive to keep the inverter always on.
The setup was tested powering my dremel and all was good.
I have shown the 230V to USB plug, this came with my phone.

Step 6: Mains Charger

I added a wooden divider to retain the batteries and to give me a spare to store the USB plug and the mains charger.
The mains charger is a standard car maintenance charger, to use it attach the crocodile claps to the terminals of ONE of the batteries and plug into the mains.
The final image is of the complete unit closed up and ready for use. All in the unit weighs about 20 kg.



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    9 Discussions

    Do you have any issues with heat? Do you only run it with the case open?

    1 reply

    No the case is always closed. The inverter doesn't produce any heat worth reporting. The 1000W unit in my other instructable does heat a little but the metal battery box acts like a heat sink

    Thanks, this looks great! I'm building something similar right now but I'm trying to figure out the best method for adding fuses. Looks like something that you are not worried about? Have you had any problems with burning out your charge controller? I keep hearing that I should add fuses but then I keep seeing projects without them.

    4 replies

    Fuses or DC breakers are still very important even if people keep ignoring those ... 200 watts at 12 volt is still 18 amps, so a 20 amps fus could do, also 4 qmm or awg 10 would be required as wiring

    thanks techie66, I will keep adding fuses to solar projects. Its really not the difficult or expensive, I'm just surprised how often this step is skipped. Working on a project that has underwater aspects so think a fuse might be extra handy.

    Agreed, but as stated this regulator is a fused unit. if you use a cheaper regulator (or no regulator at all) then an in line fuse should be applied.

    True, however the 12v socket should not exceed 10 amps and fuse accordingly, if you drain 15 amps, it will slowly melt.
    Batteries might have a max current (short circuit) of over 300 amps when put in parallel, I would prefer a fuse any day over a charge controller.

    at 200W I'm not too worried as the controller can handle 20A. I have a new instructable for a bigger 1000W unit check my profile for power Buddy Senior, this unit is fused with a 20A automotive blade fuse. please let me know what you build I'd be interested to see.

    1 reply

    Most of my stuff is on www.tinyoffgridliving.com I have made one instructable, on the website is more gathered information about fuses, breakers, batteries and wiregauges for example, maybe you will find somethings you like.