backchannel: solar generator hoop jumping

I am continually surprised/saddened at the amount of hoop jumping people put into these “convenient” power stations. “It’s so easy and no wiring is required”, they said.

Note: this is a commentary on the “Charge Your Portable Power Station Faster With This!” video. Specs taken from this manual (pdf). Prices are Amazon prices rounded to the nearest dollar and current as of this writing.

OP is fairly clueful but gets sideways on a few points.

buy stuff that meets your needs

First things first: these kind of shenanigans wouldn’t be necessary if people bought gear that met their needs in the first place. Power station, DIY, whatever.

the approach

OP discusses two challenges with his solar generator that he wants to work around:

1. 8A DC input limit for car charging
2. 10A / 126w DC output limit

I support people using what they have and coming up with workable solutions. But it wouldn’t be necessary if he’d bought gear that met his needs in the first place. This isn’t about me, but I will note that my setup cost less than his, charges at ~30A from the alternator¹, and routinely supports 60A loads. It also has 750w of panel instead of 0w.

charging

The idea here is to boost (step up) charging voltage, sidestepping the input current limitation. He does this by running the stepped up voltage into the solar charge controller port with an adapter.

Let’s look at the specs..

• the DC input port can handle 8A at 24v, or 192w
• the solar charge controller can handle 15A @ 11v-60v, for up to 900w although there appears to be a 500w per-port limit.

This will work, and does work. He says he gets 420w-450w of charging this way. (5:55).

nitpicks

efficiency

The Victron 12-24v “doesn’t lose any efficiency” (5:30). There is no free lunch. The description on the Victron’s listing says:

93% high conversion efficiency

Keen eyes will note that 93% < 100%.

wire sizes and currents

I only need to run a wire to the back of my jeep that can handle 15A

No, in his setup the wire to the back needs to handle ~35A because it’s carrying 12vdc. 450w / 14v = 32A. If he put the boost converter under the hood it would be sending that 400w+ at ~30v (450w / 30v = 15A).

If he wanted to go this route he could have put a simpler 12v-48v booster under the hood and run 7.5A to the EF.

DC loads

EF inverter output -> 25A 12v LED power supply -> loads

Well, that certainly got around the 8A output limit. EF doesn’t publish inverter efficienc ratings so we can assume something between 80-90%.

the parts list

charging

• EcoFlow Delta 2 Max, $1,400 on sale as of this writing
• Victron Energy Orion 12/24-Volt 20 amp DC-DC Converter, $148
• XT60 to MC4 adapter, $15

Total $163 for alternator-only charging.

Alternate approach:

• used 250w panel, ~$80
• 24v 8A booster mounted under hood, $18.

Car charging would be reduced but solar charging added. I’d expect better results for less money. And a less-fiddly install.

DC loads

• 120vac -> 12vdc LED power supply, $60

Total $60.

1. 45A this morning, because I ran SoC down into the 20s ↩