How to charge from solar panels on roof while driving

2013 leaf

So I have a portable 2.kWh battery and 2 100 watt solar panels I will put on the roof that will let me charge the car while parked and feed power in from the roof at the same time.

But how can I get power from the panels while driving?

Does the 12 volt battery have the ability to send power BACK to the 24 kWh battery? If so could I plug into the 12 volt power adapter and send power into it to charge the car?

See the replies in the previous topic you asked this in. You could hardwire a connection to the battery for a larger solar panel. You could do what you propose with a small panel putting out less than 10 amps, but I'm not sure it would be worth the trouble. Inflating your tires to 42psi would give you more range, if you are running them at 36 now.

Bollucks said:

2013 leaf

So I have a portable 2.kWh battery and 2 100 watt solar panels I will put on the roof that will let me charge the car while parked and feed power in from the roof at the same time.

But how can I get power from the panels while driving?

Does the 12 volt battery have the ability to send power BACK to the 24 kWh battery? If so could I plug into the 12 volt power adapter and send power into it to charge the car?

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Assuming the 2 kWh battery is a 12V battery?

As far as I know, the DC to DC is one-way to the 12V system, can't back-feed power from the 12V system to the 360V system.

As far as I know, the DC to DC is one-way to the 12V system, can't back-feed power from the 12V system to the 360V system.

Click to expand...

I hesitate to encourage the OP, but...there have been a couple of people who have confirmed that the car will drain the 12 volt battery to get a few more meters of range, incredible as it sounds. My suggestion to charge the 12 volt battery from the solar panels doesn't require that, though: just powering all of the 12 volt accessories like lights, HVAC blower and infotainment center will give a the car a bit more range, by keeping the power that would normally go to the DC-DC converter in the pack. So a larger AGM battery, plus solar panels feeding it when the sun shines, would do what the OP wants, without messing with the high voltage system.

Bollucks said:

2013 leaf

So I have a portable 2.kWh battery and 2 100 watt solar panels I will put on the roof that will let me charge the car while parked and feed power in from the roof at the same time.

Click to expand...

The portable 2 kWh battery is basically useless, it would be cost prohibitive to try to tie that into the main pack.

With respect to the solar panels, realize there's no free lunch with that - the aero drag that roof mounted panels would add would likely more than offset any energy you might collect from the solar panels, unless you drive around at under 20 mph all the time.

Have a look online for electric car aerodynamic drag calculators and you'll soon realize just that, at highway speeds, overcoming the forces of aerodynamic drag will far exceed the 150w charging rate that you might get from your solar panels. Then also realize you need to invert the 12v DC to 120V AC and somehow tie that on to the AC charging circuit.

If you were driving around on the moon, the solar panels might be more useful.

knightmb said:

Assuming the 2 kWh battery is a 12V battery?

As far as I know, the DC to DC is one-way to the 12V system, can't back-feed power from the 12V system to the 360V system.

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An inverter would be required, then the 120v AC would need to be somehow tied into the J1772 port area, to AC charge the pack. Since the LEAF won't charge in ready mode, that would have to be hacked to work too.

The whole idea makes no sense anyways...

How would i hardwire into the battery with 12 volt solar panels?

I’ll post some photos of the flexible panels once they’re flush mounted on. I know about coefficient of drag for those being a drag.

Bollucks said:

How would i hardwire into the battery with 12 volt solar panels?

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You realize that I mean the 12 volt battery, yes? If you can't do that job, then inflating the tires more and slowing down a little are the best ways to increase range.

Bollucks said:

How would i hardwire into the battery with 12 volt solar panels?

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If you mean the high voltage pack, you don't hardwire into that. Not only is it 400V nominal, it's also a sealed pack.

Ignoring aero dynamic loses, and assuming you used an inverter and somehow figured out how to wire that into the 120V charging circuit and got the LEAF to charge while in ready mode, you would be lucky to get a 0.13 kW rate on a sunny day out of those panels.

Further assuming you can drive 1 mile per 0.25 kWh (or 4 miles/kWh), you will be able to add about 1 mile of range every 2 hours.

You are an order of magnitude removed from any kind of useful charging solution.

Now if you REALLY want to generate some alternative power, a windmill on the roof is the way to go!

LeftieBiker said:

Now if you REALLY want to generate some alternative power, a windmill on the roof is the way to go!

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Catenary is also an excellent choice if yo don't mind following buses.

LeftieBiker said:

Now if you REALLY want to generate some alternative power, a windmill on the roof is the way to go!

Click to expand...

That's the follow up project!

alozzy said:

LeftieBiker said:

Now if you REALLY want to generate some alternative power, a windmill on the roof is the way to go!

Click to expand...

That's the follow up project!

Click to expand...

I feel like we are just picking on the OP at this point, but I would like to mention my design to have regen run at the same time while driving so the EV can keep building up energy forever

Save the planet with perpetual motion!

knightmb said:

I feel like we are just picking on the OP at this point

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Just a little light hearted humor. I'm actually trying to do the OP a favor, as he/she has already spent a considerable amount of money on a portable 2 kWh battery pack and solar panels. I've tried to explain multiple ways why it's not a worthwhile project...

Seems to be a nice small "renewable" system for limited backup energy - nothing at all wrong with that. Using it to increase an EV range is a real challenge (IMO).