Fri May 28, 2010 12:28 am
The panel is so small on the LEAF that it would maintain the 12v battery, but probably would not even charge it up. Assuming it is a 100Ah 12v battery pack and the car was parked up and not used, you could expect the pack to lose around 5-10% of its charge every month - so lets say that equates to around 90 watts.
A 6 watt panel (assuming that is what it is), flat on the roof of the car, would provide around 36 watt-hours of energy per day if the car was parked in sunlight, assuming it is a Californian summer, or around 4 watt-hours of energy per day if the car was parked in sunlight, assuming it is a British winter.
So in a Californian summer, it would take around one month to recharge your 12v battery pack from flat (assuming an 80% depth of discharge), whilst in the depths of winter in the United Kingdom, the solar panel would only just maintain the existing charge in the battery.
What you can do with 36 watt-hours per day of energy in a car (Californian summer)
There is some guesswork going on here, but this is what you can do with the 36 watt-hours of energy you can generate in a Californian summer with the built in panel:
Constantly run two small extractor fans inside the car to extract the heat from the cabin when the car is left unattended
Recharge a mobile phone, an iPod and a hand-held sat nav system all at the same time
Run the in-car sat nav system for 1½ hours
Switch on the headlights for around 15 minutes
Listen to the radio for around 45 minutes, or play a CD for around 25-30 minutes
Run the heating on max for around 50 seconds
Run the air conditioning on max for around 25 seconds
What you can do with 4 watt-hours per day of energy in a car (English winter)
Just about charge up a mobile phone if you leave it plugged in all day and don't use it
Half-charge a hand-held sat nav system (again, if you leave it plugged in all day and don't use it)
Run the heating on max for around 5.5 seconds
A few years back, my cigarette lighter packed up in my car. Because I relied on the cigarette lighter socket to power my hand-held sat nav system and I was in a hurry, I quickly rigged up a 12 watt solar panel I had lying around with a car cigarette lighter adaptor that I also had lying around, and put it on the rear parcel shelf. It worked a treat for keeping my mobile phone and sat nav running.