# Supersized Power Bank Built From An EV Battery

Perhaps one day in the future when our portable electronics are powered by inexhaustible dilithium crystals, we’ll look back fondly on the 2020s when we carried around power banks to revive our flagging tech. Oh how we laughed as we reached for those handy plastic bricks only to find them drained already of juice, we’ll say. [Handy Geng] won’t be joining us though, because he’s made the ultimate power bank, a 27,000 AH leviathan that uses an electric car battery for storage and supplies mains power through a brace of sockets on its end.

The vehicle battery is mounted on a wheeled trolley along with what appears to be either the in-car charging unit or a mains inverter. The whole thing is styled to look like a huge version of a pocket power bank, with a curved sheet metal shell and white hardboard end panels. The demonstration pushes the comedy further, as after charging a huge pile of phones he replenishes an electric scooter before settling sown by a chilly-looking river for a spot of fishing — along with his washing machine, TV, and electric hotpot for a spot of cooking. We appreciate the joke, and as we know him of old we’re looking forward to more.

Thanks [Fosselius] for the tip.

## 25 thoughts on “Supersized Power Bank Built From An EV Battery”

1. MrSVCD says:

How many watts? There is quite a difference between 48v 27kAh and 400v 27kAh.

1. DKE says:

Given typical powerbank ratings, I’d expect 3.7 V @ 27kAh.

And probably less than half that.

2. Paul says:

How many watts?
Surely you mis-typed, and meant to say “How many watt-hours

3. 400V 27kAh = 10.8MWh
48V 27kAh = 1.30MWh
5V 27kAh = 135kWh
3.7V 27kAh = 99.9kWh
I never realized the powerbank Ah ratings could be given in the batteries’ 3.7V instead of the output of 5V. This shows Wh is a better unit, even with “honest” manufacturers, as in USBC-PD where the output voltage may vary.
What are the use cases for using Ah?

1. PWR says:

None! It’s a marketing technique, and quite annoying one:
What you think you get: 5V * 3Ah = 15Wh.
What you actually get: 3.7V * 3Ah = 11.1Wh.

Also, values are provided in mAh, just because the three extra zeroes = better.

Just assume 3.7V. If a new chemistry comes along that has lower voltage (LiFePo4 at 3.2V) then the consumer loses as values will still be provided in mAh, but energy will actually be lower.

2. Tweepy says:

Sure, it would be way better to use Wh(watt hours) for energy storage, but would it be the raw stored energy or the available output one? (about 10 to 30 percent loss in conversion at the end)

3. RÖB says:

The usage cases for Ah is where the voltage is fixed and know or specified.

4. Bob says:

Consider they are all measured in 3.7V they give a reasonably sane value to compare them among each other.

4. Edward says:

Brave of sockets on its end? Brace means “two”

2. X says:

All Tech men carry batteries.

3. Setho says:

OK, this is def tangential – but does anybody else think he is watching ‘White Rabbit’ by the Jefferson Airplane on his TV at around the 6:40 mark on the video?

1. Paul says:

A White Rabbit clip from the Matrix movie.

1. setho says:

Thanks for clearing that up!

4. Paul says:

No cooling system for the battery. No inverter to produce the 240 Vac for the power strips. And the 12V car battery is not connected.

Let’s just say he’s going on style points.

On the other hand, you don’t need an inverter: just feed the 350 Vdc battery voltage directly to the power strips. The SMPS of the phone chargers or TV won’t care. Maybe the washing machine won’t even, if it’s newer electronic one.

1. It is surprising how many appliances are having a bridge rectifier in them directly after their mains filter. Even things people usually think are AC driven aren’t often driven by AC.

Even a fair few heat pumps are getting variable frequency drives these days instead of the old contactor, since a VFD can ramp up more smoothly and ramp down again too, or even adjust the speed of the compressor if the compressor allows for it. In the end, a lot of wear can be removed and those pesky start currents disappears, ending up tripping a lot fewer breakers and leading to a lot fewer customers complaining that “it doesn’t work.”

Downside with feeding in DC to some appliances is that some have capacitive droppers, and those won’t do anything on DC. But capacitive droppers are abhorrent regardless, so this isn’t really a downside.

Though, I have also stumbled onto the rare PFC circuit that complained when feed DC and simply decided to not run continuously. (Since a PFC circuit is technically just a boost converter that has its PWM modulated by the current mains voltage. But some PFC controllers are “smart” and faults out if feed with a continuous DC for some reason…)

1. Eric Weatherby says:

You’re absolutely correct. AC is for *distribution*, and outside of some lights, resistive heaters, and some electric motors, most modern technology doesn’t use AC to actually do its job.

1. abjq says:

I’m pretty sure a resistive heater will also work with DC?

1. RÖB says:

That is probably … no that “is” the worst I have seen.

It doesn’t pass regulation in my country and I doubt it passes regulation there.

2. Filux says:

I’m pretty sure a SMPS would burn and short out because all the transformers on the netside inside would short when suplied with DC. I have not tested this tough.

1. some guy says:

I am afraid you are wrong. Inside an SMPS the first thing (after maybe some filtering and stuff like this) is a bridge rectifier and a big capacitor. Then there is a MOSFET driving the transformer primary. You can feed the thing DC without any problem, altough as said above it might not always work if there is some PFC-stuff involved (i don’t know this part).

1. some guy says:

Uh but if you meant a “traditional” old-style AC power supply with a 50 Hz transformer than you are correct of course, the transformer would burn if feed with DC.

1. X says:

It really needs a Tom Brady compatible power connector.

2. Hirudinea says:

And it won’t fit in my pocket!

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