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Originally Posted by ctgottapee
have you considered a battery warmer wrap? size it to warm battery to optimum temp in the time the pan heats up. it may do nothing but cheap to try.
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Considered it. I actually don't have a pan heater but a coolant heater. I was considering adding a small oil pan heater pad and could fit a battery warmer pad at the same time.
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you might want to make sure those rear windows don't filter UV or any other spectrum like almost all car windows do now.
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Good point. I'll try to find out.
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a vertical mount is probably better than horizontal for most of the year.
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I'm glad to hear you say that. I was hoping it might be the case. I was thinking anyway it would be better to optimise the orientation for winter use as in winter there are fewer daylight hours.
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it depends on the type of converter you use, if it has MPPT or not, and how the cells are wired and deal with shading. if you use the same small inverter for both panels (it will likely only have one input or combine them inside the unit), you'll have to keep both windows in the sun, otherwise the shaded panel will kill the output as the inverter can't cope with that on a single input.
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Not posssible to keep both sides of the car in the sun ;-), so yes, I'd need one charge controller for each panel. (I guess by 'inverter' you mean 'charge controller'.)
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'maybe' and i am doubtful, but you could get away without an inverter with the right type of panels and just wiring direct with that small of size. as long as you have a blocking diode on them and shut them off while you recharge at home (so you don't overcharge or mess with the chargers detection circuitry)
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I wouldn't risk running ANY solar panel without a controller when charging a sealed battery after seeing this video...
...and yes, the controller would be switched off via a relay triggered when the mains battery charger is connected.
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you can't overcharge while driving as you'll use at least that many watts. if the panel voltage ranges are close to vehicle specs, the vehicle should cope; it probably won't care about low voltage. your cpu might trigger a fault code. i don't think the expense is worth it with an inverter, unless you drove long trips and parked shortly. you'll have to cut the panels when parked for any length of time as you can't control the charging.
my little panel is safe as it doesn't put out enough juice to effect anything in a possible overcharge state. plus i tested my car's usage when parked and it's about the same as max solar output. unfortunately the engineers didn't seem to care about the drain in a big car that normally has a gigantic battery. if i keep the radio constant power on (stores settings) then it doubles. i scored it for $10 bucks open box so it was cost effective. I removed the frame and it's barely noticeable on the dash; i had it on the visor flipped down, but passengers got annoyed flipping it back and the wiring connection to the circuit board is fragile without the frame. the dimming strip across the top of the window also cut the solar input so i had to flip it vertical and i would get constant looks like it was a gang symbol or something. 
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Yes, I am concerned about the car drawing attention. I would always prefer that it looks completely standard, but I think panels in the rear side windows could be made to look like those sun-shields people sometimes fit on side windows with the little sucker feet. The sheet metal backplates of the semi-flexible panels could be easily drilled and fitted with sucker feet to attach to glass.
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do you have a link to your changes to reduce your power usage?
i was planning on trying the alt delete with a switch as my alternator comes with a kill wire; you just ground it so no hacks needed. even has a nice male plug blade connector on it. the service manual has many tests the require the alt to be killed so i guess back then they included as a courtesy to the techs.
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Yes, if you click on my fuelly.com link in my signature you can see graphs of my fuel usage over the past several months. A couple of months ago there's a marked jump from 'about 70mpg' to 'about 80mpg' (Imperial gallons) that coincides with when I started plugging in the car every night.
I also have a thread on my alternator delete project and I'll try to link to that. It's quite long but it's all there. Near the beginning I have a list of the power drain of all the various electrical kit on the car...
http://ecomodder.com/forum/showthrea...mod-27179.html
...but what alternator do you have? It would be really cool to have an alternator with a bulit-in 'kill' function. I actually permanently KILLED my alternator last weekend by trying to ground the field wire.
In the first place that didn't work, and in the second place the alternator was permanently ON after that little experiment and was draining the battery even with the engine off. I don't know how but it seems I've blown at least one diode and the field winding is now being permanently energised via the main B+ cable to the battery. In any case I now need a new alternator (grrr) and if I could fit one with a built-in 'kill' facility that would be really cool as what I wanted to do was wire the thing up so that it charged when the brakes are applied. I've been leaving the IGnition wire disconnected, which is just fine for preventing the alternator from starting (well, it isn't now because of the blown diode!) but I have no way to disable the alternator while the engine is running.