Charging over DC?

[bbulkow]

Just checking - my research says no -

Is it possible to charge over DC in a microgrid / offgrid situation? Without intermediate batteries and high cost?

Eg- here's the only product I find - https://www.ampernext.com/products/first-30kw-dc-dc-solar-ev-charger/ Request quote is not encouraging (i did request one)

Willing to (light) mod.... I'm probably not bold enough to roll my own little CCS implementation.

Putting power on the 12v bus, almost certainly, won't fly (right?)

Asking because if I have solar, which is DC, converting back and forth between AC has about 10% loss each way (give or take), and in a mobile solution, that's a little gut wrenching. But if you imagine even two 400W panels, with minimal loss, you can imagine a good solution direct to car.

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[kltye]

Putting 12v over the LV bus won't touch the HVB. It will keep your 12v topped up, though ?.

Here's a product that may or may not see the light of day: https://electrek.co/2024/08/21/dc-to-dc-solar-powered-ev-charger/

I'm also unhappy about all the conversion losses, it might be cheaper to just buy more panels to offset the inefficiencies

 

[ChasingCoral]

Yes. Assuming the voltage of your microgram is over 400v.

However, I know of know CCS chargers on the market that run off DC, so you'd have to build one.

 

[bbulkow]

Putting 12v over the LV bus won't touch the HVB. It will keep your 12v topped up, though ?.

Here's a product that may or may not see the light of day: https://electrek.co/2024/08/21/dc-to-dc-solar-powered-ev-charger/

I'm also unhappy about all the conversion losses, it might be cheaper to just buy more panels to offset the inefficiencies

I saw that. Clicking a few extra links, their "fleet charger" might be $2500, out of my price range.

I'll post back about those bulgarians I found....

 

[superdave80]

Is it possible to charge over DC in a microgrid / offgrid situation?

Probably

Without intermediate batteries and high cost?

Not likely. I doubt any charger would be happy trying to manage a fluctuating input current without some sort of buffer. And I'm sure a DC charger of any type is going to be in the thousands of dollars.

 

[bbulkow]

Probably

Not likely. I doubt any charger would be happy trying to manage a fluctuating input current without some sort of buffer. And I'm sure a DC charger of any type is going to be in the thousands of dollars.

Solar controllers which handle a few panels and are set to output 12v, 24v, 48v (steady enough to charge a battery bank) are fairly cheap, as they are mass produced. They're in small enough packages they don't seem to have much buffer.

While i agree that getting *up* to 400v isn't the same problem, dealing with the variant input of solar seems straightforward tech these days.

 

[AtomicInternet]

So I've recently hooked up those cheap solar generators you find on Amazon to my computer servers to get 500w free solar during the day (the most DC input they'll take).

Most all of them also have 1100 watt AC output, which happens to be what the Mach E takes at 120v charge.

So while it will be PAINFULLY SLOW you could plug a 120v charger into a "solar generator" (giant battery) and empty it into the Mach E. Then solar charge it back up during the day and voila, grid free (maybe 5-10 miles) charging. Sadly the car requires stable power to charge, and you can't just throw the DC leads into the DC port on the bottom part of our CCS.

I also have rooftop 4 kW solar which I can recommend as practical, albeit requiring a huge whole-home battery or being on the grid.

 

[devmach-e]

There's no practical or cheap way to take the DC voltage coming off of your solar panels and directly charge the HV battery. And 800W of solar is less than what you can get out of a standard 120V outlet. Keep in mind that the standard 32A 240V EVSE that comes with the car supplies nearly 10 times that amount.

 

[SpaceEVDriver]

You can't DC charge with less than ~400 Volts unless you incorporate a step-up transformer, at which point it's cheaper to carry a small auxiliary power station that can run a L1 EVSE.

We carry a 5 kWh power station with our Lightning while on camping trips. It gets us about 15-30 miles extra range a day.

600 Watts will provide 1/2 the power needed to run an EVSE, so you'll discharge the auxiliary power station faster than you can charge it. We use solar to fill the power station in the morning and then discharge it in the afternoon and evening.

 

[AtomicInternet]

If your goal is just to be off-grid, I can also recommend my frunk generator solution:

https://www.macheforum.com/site/threads/winter-range-drop-fixed.40786/

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