Charging car from small solar system

[astrowunder]

This is probably kind of silly, but I'm thinking of charging my car using a 100 watt solar system that I have. I've got it set up all the time and I've been using it to charge my wife and my electric bicycles- works great for that.

I'm mostly curious if it will work, but I obviously don't want to damage anything in the process. I have 70ah total lead batteries hooked up to the solar to store power and a 750w/1500w peak inverter. I was thinking about setting the car's max amps to the lowest setting and then plugging it into the 110 connector. Maybe I can counter the phantom drain with this configuration, I'm not expecting anything else.

Thoughts?

 

[StellarRat]

I can't think of any reason why it wouldn't work. You might even be able charge the car all the way up in a couple of weeks if you don't drive it much. What's the min. amp setting on the Tesla? I've never looked.

 

[astrowunder]

I think it can go as low as 5.

I did some rough calculations. If I had non-stop sun here in Wisconsin (ha), it would take about 6 months to add 300 miles to the car! That's also assuming no phantom drain. Still, I'm currently just wasting perfectly good photons that could be put to at least some use I think.

 

[SabrToothSqrl]

i priced the Harbor Freight 100W panel and laughed at the ROI, given that power from the grid is $0.11 kWh.

 

[mongo]

Is it a true sine wave output from the inverter? Charger may not like it otherwise.

 

[astrowunder]

It's modified, unfortunately. Generally electric chargers don't mind that- its usually computer electronics that have issues. OTOH, don't really want to mess with a $60k+ car

 

[ewoodrick]

This is probably kind of silly, but I'm thinking of charging my car using a 100 watt solar system that I have. I've got it set up all the time and I've been using it to charge my wife and my electric bicycles- works great for that.

I'm mostly curious if it will work, but I obviously don't want to damage anything in the process. I have 70ah total lead batteries hooked up to the solar to store power and a 750w/1500w peak inverter. I was thinking about setting the car's max amps to the lowest setting and then plugging it into the 110 connector. Maybe I can counter the phantom drain with this configuration, I'm not expecting anything else.

Thoughts?

Let's say that you want to charge fro 40% to 80% on the LR battery. That would be a total of 40% of the 80 kWH battery, or 32 kWh (32,000 Wh)
If the cell was always working at 100% efficiency (even at night) then that would take 32,000 / 100 = 320 hours to charge.

But your batteries do help. Your 70 amp of Lead Acid batteries (which by the way should NEVER be drained to 0% and should always be closely monitored by a charge controller, and will emit nasty sulfuric acid gas) have a capacity of 70Ah*12V= 840 watts. Your 1500 watt inverter will completely drain them in just over 30 minutes.

To take it another way, for 8 hours of sunlight and 32 kWh of charging, you would need 32 kWh / 8hr = 4,000 watts or 4,000 watts / 100 watt panel = 40 panels.

So, uh, probably not going to work.

 

[astrowunder]

Let's say that you want to charge fro 40% to 80% on the LR battery.

That's not at all what I had in mind. I'm hoping to just counter-act (or partially) the phantom drain of 2-3 miles per day. At 270 watt-hours/mile, that would come to 540-810 watt-hours, which is in the ball-park of what my system provides.

 

[StellarRat]

Let's say that you want to charge fro 40% to 80% on the LR battery. That would be a total of 40% of the 80 kWH battery, or 32 kWh (32,000 Wh)
If the cell was always working at 100% efficiency (even at night) then that would take 32,000 / 100 = 320 hours to charge.

But your batteries do help. Your 70 amp of Lead Acid batteries (which by the way should NEVER be drained to 0% and should always be closely monitored by a charge controller, and will emit nasty sulfuric acid gas) have a capacity of 70Ah*12V= 840 watts. Your 1500 watt inverter will completely drain them in just over 30 minutes.

To take it another way, for 8 hours of sunlight and 32 kWh of charging, you would need 32 kWh / 8hr = 4,000 watts or 4,000 watts / 100 watt panel = 40 panels.

So, uh, probably not going to work.

The math doesn't look too good. But, at 5 amps set on the charger (the min.) that's a draw of 5a x 120v = 600w. So, to run at min. power you'll have to increase your array to probably a min. of 7 x 100w panels (allowing one extra to cover system losses) and only charge when they're producing nearly max. power if you want to don't want to drain your batteries. If the charger could be reduced to a minimum setting of .75 amps, you might be able to work with what you have. It would take a long time at that rate.

If you charge all through the Spring and Summer you might have enough power to get Ma in the M3 and take a trip to town to lay in supplies for the winter.

 

[StellarRat]

That's not at all what I had in mind. I'm hoping to just counter-act (or partially) the phantom drain of 2-3 miles per day. At 270 watt-hours/mile, that would come to 540-810 watt-hours, which is in the ball-park of what my system provides.

Maybe... BTW, I don't like the term "phantom" drain (not that you invented it). A lot of people don't seem to know that Li batteries lose power constantly even with no load on them. That's just the nature of the beast. Granted EV's also do stuff even when "off" for maintenance so that makes it worse (what I consider to real phantom power), but like I said you'd still see power loss no matter what.

 

[BerTX]

Maybe... BTW, I don't like the term "phantom" drain (not that you invented it). A lot of people don't seem to know that Li batteries lose power constantly even with no load on them. That's just the nature of the beast. Granted EV's also do stuff even when "off" for maintenance so that makes it worse (what I consider to real phantom power), but like I said you'd still see power loss no matter what.

What you say is true, but you don't put any numbers with it, so could be misleading. Li-ion batteries lose 3-4% per month, which would work out to about a third of a mile of range a day.

 

[StellarRat]

What you say is true, but you don't put any numbers with it, so could be misleading. Li-ion batteries lose 3-4% per month, which would work out to about a third of a mile of range a day.

Yes, I didn't put any numbers to it. It is a low number. I just wish there was a different term for it, maybe "vampire drain" is better. That's what they call losses from devices on "stand-by" that aren't truly off.

 

[BobAbooey]

Let's say that you want to charge fro 40% to 80% on the LR battery. That would be a total of 40% of the 80 kWH battery, or 32 kWh (32,000 Wh)
If the cell was always working at 100% efficiency (even at night) then that would take 32,000 / 100 = 320 hours to charge.

But your batteries do help. Your 70 amp of Lead Acid batteries (which by the way should NEVER be drained to 0% and should always be closely monitored by a charge controller, and will emit nasty sulfuric acid gas) have a capacity of 70Ah*12V= 840 watts. Your 1500 watt inverter will completely drain them in just over 30 minutes.

To take it another way, for 8 hours of sunlight and 32 kWh of charging, you would need 32 kWh / 8hr = 4,000 watts or 4,000 watts / 100 watt panel = 40 panels.

So, uh, probably not going to work.

Wow you know ur stuff...

 

[buddhra]

If you check out some videos of people trying to charge an EV from generators, you'll see that you're going to have issues with grounding as well. What you're proposing isn't really that smart from a financial perspective, but from a "I want to tinker and learn something" perspective, I'm on board.

I'd do it using a standard solar panel (https://amzn.to/2SXTZo7) and a grid-tie inverter (https://amzn.to/2DaQjtG). A typical 60-cell panel is going to have the highest output/$ you can find just due to the quantity they're built in. You'd connect it to the inverter and then the inverter to a 120V outlet in your garage. Then just plug the car into the same outlet and set the car to charge at 5A. That way the grid can make sure the car can always charge and maintain a stable voltage and proper grounding and the solar can just supplement as best it can. If you put 2 panels on you could even come close to meeting the full 5A during peak sun.

 

[Glamisduner]

Small solar system? Are you counting Pluto or not?

 

[JeffK]

Small solar system? Are you counting Pluto or not?

This!

I came to this thread to learn about tiny planets and a tiny sun powering a Tesla.

 

[Dana1]

This is probably kind of silly, but I'm thinking of charging my car using a 100 watt solar system that I have. I've got it set up all the time and I've been using it to charge my wife and my electric bicycles- works great for that.

I'm mostly curious if it will work, but I obviously don't want to damage anything in the process. I have 70ah total lead batteries hooked up to the solar to store power and a 750w/1500w peak inverter. I was thinking about setting the car's max amps to the lowest setting and then plugging it into the 110 connector. Maybe I can counter the phantom drain with this configuration, I'm not expecting anything else.

Thoughts?

More trouble than its worth. Let it charge the bikes and set up an effective charging scenario...read the threads on cold weather effects on batteries.