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Has anyone ever heard of or had experience with charging an ED off a 12 volt DC charging system? Does the DC to DC converter work both ways? If I set up a few small solar panels at work, could I charge directly to the 12 volt side of the system?


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Has anyone ever heard of or had experience with charging an ED off a 12 volt DC charging system? Does the DC to DC converter work both ways? If I set up a few small solar panels at work, could I charge directly to the 12 volt side of the system?
Converter going both ways, don't think so? Stepping down is much easier than amping up?

A few small solar panels, doubt the juice is worth the squeeze...
 

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Chris,

The main battery is 400V and the charger in the car needs at least 10 amps at 110V to operate. In principle you could do this from a 12V battery - there are "inverters" which will generate 110V for you. But the current at 12V would be around 100amps, so the battery will have to be quite hefty. If you have a solar powered home installation with a good storage battery (such as one from Tesla) then you may be able to do it.

Your idea of a "reversible" charger is one that is being considered by some car manufacturers - it has been realised the most electric cars sit idle and the battery could be used as a reservoir of green energy from solar or wind. It is a burgeoning field, and one that merits monitoring. A simple idea would be to store mains power at off-peak times and then return it to the grid at high peak times. But this is all in the future unless you have the resources to start tinkering.

Let me know if you want some references to the developments.

Frank.
 

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Chris,

The main battery is 400V and the charger in the car needs at least 10 amps at 110V to operate. In principle you could do this from a 12V battery - there are "inverters" which will generate 110V for you. But the current at 12V would be around 100amps, so the battery will have to be quite hefty. If you have a solar powered home installation with a good storage battery (such as one from Tesla) then you may be able to do it.

Your idea of a "reversible" charger is one that is being considered by some car manufacturers - it has been realised the most electric cars sit idle and the battery could be used as a reservoir of green energy from solar or wind. It is a burgeoning field, and one that merits monitoring. A simple idea would be to store mains power at off-peak times and then return it to the grid at high peak times. But this is all in the future unless you have the resources to start tinkering.

Let me know if you want some references to the developments.

Frank.


Thank Frank,

My motivation is that I still keep wishing I could build an affordable solar rig to charge while at work. I was reading about a new EV manufacturer has a 200 watt solar panel in the roof. It doesn’t sound like the results are very beneficial but I keep wishing I could at least do something. Then I started thinking about possibly going 12 volt DC directly to the car and wondered if the DC to DC converter worked both ways. But like you point out, the current would have to be pretty substantial.

Chris


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Hey Chris,

If you want to get a sense of the math behind running a microcontroller (0.33W) off of solar power with a charger and a LiPo battery have a look at this video. You can use a lot of the same math to figure out what you'd need to generate a charging source for the car.



 

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Chris,

The solar panels will keep the 12V battery charged, but that's all. And DC-DC voltage converters most definitely don't work in reverse unless someone specially designed a two-way converter to do such a thing.

Paul
 

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The problem is not insoluble: see https://en.wikipedia.org/wiki/Vehicle-to-grid Bi-directional power transfer is being considered. It "simply" requires two dc-dc converters.
But the power requirements are serious: https://www.theecoexperts.co.uk/solar-panels/1kw-pv-systems estimates that 8 sq m is required for a 1KW output. To charge your car just use an inverter to convert from the panel 12V output to 120V Eg https://www.amazon.com/Ampeak-2000W-Inverter-Converter-Outlets/dp/B0716WT8D5/ref=lp_583328_1_15?s=automotive&ie=UTF8&qid=1523391118&sr=1-15

It is all possible, just expensive at the moment. But watch this space - costs will decline.

Frank.
 

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Fitting those 8 M^2 of panels in the Smart, setting them up and than taking them down would present a problem... Chris wanted a portable system he could take to work!
 
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