Solar Charging Solution

[fwhite42]

I'll preface this entire post by saying that I am the furthest thing from an engineer or really a mechanical/electrical guy at all...

 

So, I read an article today about a new C-Max concept car that Ford has been showing off that is essentially the current C-Max with solar panels on the roof. This made me think that the same thing should be possible and forthcoming for the Fusion as well, and that got me thinking about a near-term solution.

 

Obviously, without major electrical wiring, you can't just throw some panels up there since there's no way to connect them. However, there are plenty of mobile solar systems avaliable that charge into a small battery that can then power various electricity-consuming devices.

 

Now, to be really portable, the battery storage is only about 600 watts, which wouldn't do much for our cars. But, my non-engineer brain wondered if the panel went into the battery and the car plugged into the battery, wouldn't the car keep exhausting the battery and the panel keep charging it, essentially turning the battery into a converter? The panel I have in mind is 85 watts (I'm assuming that's per hour), so for a full day at the office, I'm looking at about 750 watts. Then if I charge the battery off my house electric overnight, I'd have a total of about 1350 watts into the car from the time I parked in the morning. That is likely the difference between a full EV roundtrip commute and having to go hybrid a little.

 

Am I crazy?

 

This is the unit I'm thinking about (but I'm open to any):http://store.sundancesolar.com/85-watt-plug-n-play-solar-energy-kit-with-duracell-600-powerpack/

[murphy]

That 85 watt panel is only going to produce 85 watts when aimed directly at the sun (no clouds).  It takes 6 to 7 kWh to charge the battery.  That's 6000 to 7000 watt hours.  The car's battery is around 300 volts DC.  A single solar panel like the type on the roof of my house puts out around 35 volts in full sunlight.  The only provision to charge the car's battery is with 120 or 240 volts AC.  Your solar panel would have to charge a 12 volt battery which is running an inverter to provide 120 volts AC.  The inverter would have to be rated to produce around 1400 watts at 120 volts AC.  That means it would be drawing over 117 amps from the battery.  A standard 12 volt car battery would not last very long with a 117 amp load on it.

 

IMHO the Ford concept car will only be practical in the sun belt where the sun is overhead most of the time.

 

I have 40 solar panels, rated at 250 watts, on the roof of my house.  The system is rated at 10 kW (10,000 watts).  Yesterday was a very cloudy day with a snow storm approaching.  My system generated 4 kWh of energy yesterday.

[rtshinn]

So, at .08/kwh that's about 32 cents worth of electricity. Ugh..

 

Overall, how do you like your solar power setup? I live in Ohio, so we don't get a heck of a lot of sun

 

 

That 85 watt panel is only going to produce 85 watts when aimed directly at the sun (no clouds).  It takes 6 to 7 kWh to charge the battery.  That's 6000 to 7000 watt hours.  The car's battery is around 300 volts DC.  A single solar panel like the type on the roof of my house puts out around 35 volts in full sunlight.  The only provision to charge the car's battery is with 120 or 240 volts AC.  Your solar panel would have to charge a 12 volt battery which is running an inverter to provide 120 volts AC.  The inverter would have to be rated to produce around 1400 watts at 120 volts AC.  That means it would be drawing over 117 amps from the battery.  A standard 12 volt car battery would not last very long with a 117 amp load on it.

 

IMHO the Ford concept car will only be practical in the sun belt where the sun is overhead most of the time.

 

I have 40 solar panels, rated at 250 watts, on the roof of my house.  The system is rated at 10 kW (10,000 watts).  Yesterday was a very cloudy day with a snow storm approaching.  My system generated 4 kWh of energy yesterday.

[murphy]

So, at .08/kwh that's about 32 cents worth of electricity. Ugh..

 

Overall, how do you like your solar power setup? I live in Ohio, so we don't get a heck of a lot of sun

My electric rate is 16 cents per kWh.  They were installed at the end of September.  For the month of October I generated 1 kWh more than I used.  It's been down hill from there with the days getting shorter and the low sun angle.  The best days so far were October 15 and 21 when I generated 43 kWh each day.  I expect the high sun angle and longer days in the spring and summer will work very well.  At the moment there is 4" to 6" of snow on the panels so even with bright sun they are only generating 11 watts. 

[fwhite42]

Murphy: I live in South Florida and get pretty good sun exposure...and, I'm totally willing to step outside my office and adjust the panel(s) throughout the day to maximize angle. And, again, my goals aren't lofty here. I'm not trying to get anything like a full charge, I'm just looking to get whatever I can get from the sun during the work day and extend my range home ever so slightly.

 

So, that said, would something like this unit work better than the Duracell unit I linked to above? http://store.sundancesolar.com/xantrex-xpower-portable-powerpack-1500/ I'm not sure if it meets the specs you mention, but it looks feasible to my untrained eye.

 

If that unit is capable of charging the car at all, then I could charge the unit at home over night to fill its 1500 watts, then theoretically (optimally) add another several hundred watts from the solar panels.

 

Thoughts?

[murphy]

Something doesn't add up.

 

ELECTRICAL SPECS Inverter Max Power (10 min): 1500 Watts
Inverter Max Power (continuous): 1350 Watts
Surge Power, Max: 3000W Max DC current draw: 12 Amps@12V Battery: Sealed, non-spillable 60 amp-hour AGM battery

 

"1350 watts continuous from the inverter."

To get 1350 watts from the inverter would require 1350 / 12 = 112.5 amps if the inverter was lossless.  The inverter is no more than 80% efficient and probably closer to 50%.  At 50% efficiency the current from the battery would be 225 amps.  No battery that you can lift without a crane or a forklift is going to supply that much current for very long.  It's a very inaccurate calculation but a 60 amp-hour battery will supply 60 amps for 1 hour, 120 amps for 1/2 hour, 240 amps for 1/4 hour.  You might be able to charge the HVB for up to 20 minutes.  The solar array to charge the 12 volt battery in a reasonable time would be large.  60 amp-hour x 12 volts = 720 watt-hours.  Ignoring charging ineffiencies an 85 watt solar array would take at least 8.5 hours of full sun to charge the 12 volt battery.

 

I also find the fact that under Warranty it says "null" disturbing.

[fwhite42]

Thank you for continuing this discussion, and my education.

 

Assuming the portable charger was at full charge (1500 watts) from being plugged in at home the previous night, and then I plugged the car into it, considering the math you did to show that it would charge for about 20 minutes: how much actual charge would be transferred to the car in that 20 minutes? And, would the portable charger then be totally exhausted and need to be recharged before it could be used again, or would it simply be in a "rest" period and then could be used again without recharging it to transfer whatever remained after that 20 minutes?

 

Forgive the basicness of some of these questions, but I just don't understand the difference between amperage and voltage and wattage with regard to energy transfer. All I know is that I'm reading that the portable charger can power a small refrigerator over 120V AC for several hours, so that SEEMS to indicate that it could transfer at least SOME power into the Energi.

 

And, I get that the solar array wouldn't necessarily totally recharge the portable charger, but if it even partially recharged it (say, several hundred watts), could that then be transferred to the car through the portable charger, or would there simply be too much loss in inneficiency to really put anything back into the car?

 

To put a finer point on it, what I've discovered in my limited driving thus far (car has only about 300 miles so far), is that I can make my workday roundtrip so long as I don't need the A/C and the traffic breaks just right (which is what happened today because it's mild out), but I can't quite make the roundtrip when I do need the A/C and/or traffic isn't quite right. So, if this portable charging thing can make up that little bit of difference, I'll be pure EV for my commute year-round instead of only some of the time.

[murphy]

Ford says it takes about 7 hours to do a full charge with the 120 volt charger so 20 minutes is 20 / (7 * 60) * 100 = 4.8% of a full charge.  4.8% of 21 miles is 1 mile.

There are so many inefficiencies in this process that it's impossible to calculate accurately.  You could gain 1 mile by fine tuning your braking and accelerating skills.

Once the battery is discharged it has to be recharged before it can be used again.  This process only works with an AGM battery.  Fully discharging a standard wet cell starter battery can destroy it.

 

The motor in a small reffigerator only draws a couple of amps when running.and they don't run 100% of the time.

 

You might be able to add some charge to the HVB.  It depends on how low the 120 volts can go before the charger aborts due to low voltage.

 

You can never be pure EV year round.  The oil maintenance process will force the ICE to run eventually.  Also if the gasoline in the tank gets close to 18 months old the car will run the ICE to burn it all to get rid of it.

 

I had to check where you live with the mention of running the A/C.  It's 16 degrees F here at the moment.

 

The only inverter I have is 150 watts so I can't do any testing to see what the real world numbers look like.

 

If you can afford the unit without upsetting you budget give it a try.  Even if it doesn't prove useful for charging the car it is still a source of emergency power.

[fwhite42]

Oh, I'm fine tuning my braking and accelerating, for sure...if MFM would report my numbers right, I'd be top-10 in my region for Renaissance Man. My car is showing 96% overall driving, but MFM has it at 91%...and that's with taking a hit because it was god-awful for the 39 miles it was driven at the dealership. Right now I'm averaging about 28 miles per charge with no A/C, a little under 25 with A/C. I'm purposely taking surface streets as opposed to freeway/turnpike, which only adds about 5 minutes each way on my commute, but adds quite a bit of range.

 

I'll never get to pure EV because I use the car for more than just my work commute (I'd have gone Leaf or Focus EV, otherwise), so I don't have to worry about the oil maintenance or stale gas burns. But, I'd love it if I could stay 100% EV year-round on just my work commute.

 

I may pull the trigger on the portable solar charging unit just for grins, but it bums me out a little to think that it might only gain me 1 mile...I was hoping for more like 3 to 5.

[Quatro40]

fwhite 42, this is what you need to achieve what you want with the energy

 

One Xantrex xpower powerhub 1800 watts - http://www.xantrex.com/power-products/backup-power/xpower-powerhub-1800.aspx

8 Solar Panels

1 Wind Turbine Generator

 

If you live in Florida these set up will provide the required power to charge your Energi battery in 4.5 hours and if connected to your house will provide back up power.