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Re: use of solar panel at spoiler on roof?

Posted: Sun Jun 20, 2010 9:03 pm
by garygid
Maybe an inductive loop to put near the lights? Or, not.

Re: use of solar panel at spoiler on roof?

Posted: Wed Jun 23, 2010 12:34 am
by MikeBoxwell
garygid wrote:Just do not park in the shade.

I can imagine a whole new type of road-rage here, with angry solar car owners trying to keep out of the shade of high sided vehicles as they are driving along, or writing rude notes on the windshields of vans who dare park next to them and leave them in the shade! :lol:

Re: use of solar panel at spoiler on roof?

Posted: Fri Jul 09, 2010 12:55 pm
by bruceha2000
Given that Toyota has said the optional panel on the 2010 roof does not generate enough electricity to be of value charging the traction battery, the small one on the Leaf spoiler would be pretty worthless.

The panel on the Prius only covers part of the roof as it ONLY comes with the 'moon roof'. One would hope that in the back labs somewhere, the engineers ARE thinking about ways to generate usable amounts of electricity from the roof and hood as is done on the EV distance race cars.

Re: use of solar panel at spoiler on roof?

Posted: Wed Sep 07, 2011 12:50 pm
by gregoryjward
I've been attempting to measure whether the solar panels are charging the battery or not. I have full sun on them around noon and am monitoring the 12-volt battery at around 12.62 volts on my digital voltmeter. Covering the panels doesn't change the voltage at all, even after waiting several minutes. Uncovering the panels again likewise does nothing. There should be at least a small change in voltage if the panel is charging the battery.

I also measured current directly. I never saw any reverse flow of current into the battery. In its quiescent state, the car seems to draw on the order of 20 milliamps from the 12-volt, probably to run the clock, keep the nav system memory, probe for the intellikey, etc. It's a very low draw, and it would take months to deplete the battery. Again, covering and uncovering the solar panel made no difference that I could detect even at this low current.

Opening a door and running the interior lights draws about 4 amps(!), then closing it again, the system continues to draw 1.5 amps for a few minutes, dropping to a lower level later on. I suspect that waking the system leaves it in a more alert state, running some computer or probing continuously for the key; who knows? My thought was that if the battery were fully charged to the point where the panel wasn't putting current in, then discharging the battery a bit for a few minutes should make a difference. It didn't seem to.

The upshot is that I can find no evidence that the solar panel is even connected to the 12-volt system, leaving a big mystery as to its purpose, beyond the obvious marketing gimmick.

-Greg

P.S. I read somewhere -- in the manual? -- that the Leaf wakes itself up every week or two to recharge the 12-volt battery from the traction battery using its DC-DC converter, just to make sure it doesn't go dead. The solar panel is really not needed, even for keeping a charge on the lead-acid battery in other words.

Re: use of solar panel at spoiler on roof?

Posted: Wed Sep 07, 2011 2:37 pm
by GeekEV
gregoryjward wrote:I've been attempting to measure whether the solar panels are charging the battery or not. I have full sun on them around noon and am monitoring the 12-volt battery at around 12.62 volts on my digital voltmeter. Covering the panels doesn't change the voltage at all, even after waiting several minutes. Uncovering the panels again likewise does nothing. There should be at least a small change in voltage if the panel is charging the battery.
In the service manual it looks like the solar panel is more-or-less directly wired to the 12v battery. As a result, you're probably measuring "backflow" from the actual 12v battery. The proper testing procedure, according to the service manual, is to disconnect the 12v battery negative terminal, then measure the voltage across the positive and negative terminals. That will effectively remove the battery from the equation...

Re: use of solar panel at spoiler on roof?

Posted: Wed Sep 07, 2011 2:43 pm
by IBELEAF
Forgive me for a dumb question, but I was wondering if you leave your lights with fogs in the sun for 8 hours would the battery die or solar panel would be putting enough charge to keep it alive?

Re: use of solar panel at spoiler on roof?

Posted: Wed Sep 07, 2011 3:29 pm
by TomT
I have directly measured the output of the solar panel. It is about 5 watts in full, mid-day, direct sun. Hardly enough to be of any real use. If you haven't changed out the four incandescent bulbs for LEDS, with the headlights on you have a draw of about 42 watts.

Re: use of solar panel at spoiler on roof?

Posted: Wed Sep 07, 2011 3:42 pm
by gbarry42
gregoryjward wrote:I've been attempting to measure whether the solar panels are charging the battery or not. [...] I also measured current directly. I never saw any reverse flow of current into the battery.
I did the same test, saw the same behavior, and I did see the current go to zero, then negative. The most current I saw going into the battery was around 35 mA. I figure in bright sun, it's almost enough to offset the draw when the system's asleep, on average. Not much at all.

Re: use of solar panel at spoiler on roof?

Posted: Wed Sep 07, 2011 3:51 pm
by EVDRIVER
It's a gimmick, I would rather have seen it gone and have the money toward a better stereo, a few more tablespoons of paint, extra spray on carpet. etc. It is clear a bunch of marketing boobs that it would be cool :lol:

Re: use of solar panel at spoiler on roof?

Posted: Wed Sep 07, 2011 4:19 pm
by gregoryjward
GeekEV wrote:
gregoryjward wrote:I've been attempting to measure whether the solar panels are charging the battery or not. I have full sun on them around noon and am monitoring the 12-volt battery at around 12.62 volts on my digital voltmeter. Covering the panels doesn't change the voltage at all, even after waiting several minutes. Uncovering the panels again likewise does nothing. There should be at least a small change in voltage if the panel is charging the battery.
In the service manual it looks like the solar panel is more-or-less directly wired to the 12v battery. As a result, you're probably measuring "backflow" from the actual 12v battery. The proper testing procedure, according to the service manual, is to disconnect the 12v battery negative terminal, then measure the voltage across the positive and negative terminals. That will effectively remove the battery from the equation...
I replied to this once, but my post got lost(?)

Thanks GeekEV for the tip -- I tried it and indeed the solar panel provides voltage to the system with the battery disconnected. Covering the panel causes the voltage to drop from 12 (or so) down to 1 or 2 volts, proving that the panel *is* doing something.

My faith is restored that it isn't a completely empty marketing ploy, at least.

-Greg