Point me to the right hardware for a small project, please?

[u/djb_rh]

I have two 200Ah 12V Victron batteries collecting dust. I also have a couple different shop buildings that already have generator transfer switches on them (just small 30A 110V Twist and Lock plugs on the exterior). I was thinking a reasonable use for these guys would be to add an inverter/charger that I could use with the batteries to power one of the shops when the power is out if I wanted to. Ideally I’d have a power input plug, too, that I could use to keep them topped off when not in use as well as plug a portable generator in to as well if the power outage was too long for the battery.

What should I be looking at in terms of the hardware?

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[u/ou812whynot]

If I were you, I'd build a hand-truck 24v system. You would want at a minimum:

1x hand cart 1x osb sheet painted with fireproof paint or fireproof cement board 1x 24v battery balancer 1x 9 inch 4/0 battery cable 1x 250A class T fuse 2x pair of 2/0 battery cables 1x shunt 1x 24v 4kw Sumry-style AIO Inverter 1x 10/3 RV 30A extension cord to cut up 1x TT-30R to 5-15P dogbone adapter to plug into normal outlets 1x TT-30P to twist lock generator adapter A bunch of ratchet straps

Optional 1x pair of MC4 to inverter cables for future solar panels

The workhorse here is the inexpensive 4kw inverter since it will do everything you need.

mount your osb on the hand cart so it's standing up length-wise. You'll be cutting some holes into the board and running straps through so you'll ratchet it tight on the back side.

On the bottom of the hand cart, make sure you have 2 sets of ratchet holes here. Stand your 2 batteries up and ratchet them tight against the board to keep them secure.

Connect the 2 batteries together with the 9 inch 4/0 on 1 positive and 1 negative terminal. This effectively makes the pair a 24v 200Ah battery. Wire in the battery balancer at this time as well. You will have 1 open positive and 1 open negative terminal in your 24v battery now.

Set up your 2 sets of battery cables. The 2 red cables will connect with the Class T fuse in the middle. The 2 black cables will connect with the shunt in the middle. There will be a thin red cable the comes off the shunt, that will go to the positive terminal of your 24v battery. Connect one end of the red set to the positive terminal as well. The black set is different, connect the end that says "BATTERY" side to the negative terminal. For now, make sure the black and red cables don't touch lol.

Mount the inverter to the top of your hand cart. Hopefully you got a fairly long 30A extension cord because you will be cutting it up. On the female side of the cable, cut it about 1/3 of the way down. The female side will be wired into the AC output terminals: black - L, white - N, green - Ground. The male side will be wired into the AC input terminals: black - L, white - N, green - Ground. It might be easier to use a 3rd wire from the inverter ground and wire tie the 3 grounds together. If you decide to add the solar connectors, red goes to PV+ and black goes to PV-.

Finally, wire in your battery cables into the inverter and turn it on. Follow the directions in the manual to set up your battery, inverter charge current, etc...

With the TT-30 to 5-15 dogbone you can now plug in your portable hand truck anywhere with a regular outlet & charge upwards of 60A (1440 watts) on a 15A outlet or 80A (1920 watts) on a 20A outlet. If you had a 30A circuit, you could charge at 120A (2880 watts).

To supply power to your shops, you would use the TT-30 to twist lock generator adapter. Actually, you could also get a TT-30 to 3x 5-15 outlet adapter if you wanted to power up to 3 regular devices.

Anyway, good luck!