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Solar Charger Voltage Production

Discussion in 'Gen 2 Prius Audio and Electronics' started by efusco, Apr 27, 2004.

  1. efusco

    efusco Moderator Emeritus
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    In another thread I mentioned that I'd installed a solar charger for the 12v battery in my Prius. This stirred more interest than I'd anticipated. Part of the interest was how much voltage my charger produced while in the back of the car.

    I took out the multimeter today and checked a few different circumstances:

    Car in garage, charger in hatch (very shady): 2.5v
    Charger in direct sunlight: 23v
    Charger in hatch where sunlight was shining: 22v-23v
    Charger in shaded area of hatch (no direct light): 6v

    My charger (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...943333&tc=photo)

    Does have a built in diode to prevent battery drain during those lower light/night periods so it should be safe to leave in plugged in at all times. I have some mild concern about overcharging the battery with this charger and thus, do not leave it plugged in at all times. It's a back-up for when the car will be parked for a period over 1 week at a place such as the airport parking lot.
     
    #1 efusco, Apr 27, 2004
  2. richard schumacher

    richard schumacher shortbus driver

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    Can you provide details of the installation?

    I'm surprised that few Solar chargers have a built-in voltage regulator set for the charging voltage of a 12V lead-acid battery (14.4V, I think?). That plus a reverse protection diode would make it safe to leave them connected continuously.
     
    #2 richard schumacher, Apr 27, 2004
  3. efusco

    efusco Moderator Emeritus
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    There really aren't any details to provide.

    The charger I linked above came complete with the solar panel, a cigarette adapter plug, and some battery terminal sized alligator clips. You interchange the connector you want via a little plug built into the wires. Plug in the one you want to use to the wire coming from the charger.

    I accessed the 12v battery in the Prius, attached the alligator clips to the battery terminals, ran the wire out through one of the access ports (the one behind the tail light to be specific so that about 8" of wire with the charger-side plug are visible. I keep the solar panel itself in my Handi-tote. To use it I just plug it in.

    The only issue I'd like to figure out is a way to attach some suction cups to the 'sun-side' of the charger so that I could stick it to the hatch window to maximize charging since the sunny area on the floor of the hatch will change depending on the sun position. I'll probably end up putting up the toneau cover and setting the charger on top of that to get it closer to the glass.
     
    #3 efusco, Apr 27, 2004
  4. riskable

    riskable Junior Member

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    A simpler question would be: Does it improve your gas mileage at all? I would assume that it doesn't since the alternator generates electricity for the 12V battery pretty much the whole time the car is on.

    So does it help at all?
     
    #4 riskable, May 6, 2004
  5. efusco

    efusco Moderator Emeritus
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    I haven't actually used this thing yet. I don't plan to plug it in unless I'll be leaving the car parked for longer than 5-6 days.

    And no, I can't imagine that there would be any measureable improvement in gas mileage since it only charges the little 12v battery. There must be some finite gain, but it can't be much.
     
    #5 efusco, May 6, 2004
  6. sparkymarvin

    sparkymarvin Member

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    My guess (and any expert Priuser please speak up)

    Is that fuel economy would be improved by a few MPGs in the first five minutes of driving the car,
    after starting it up from sitting for a somewhat-long period of time.

    PS. The Prius does not have an alternator. It has multiple inverters and converters that regulate energy in the electrical systems.
     
    #6 sparkymarvin, May 6, 2004
  7. newts

    newts New Member

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    A couple of points:

    It is a trickle charger and puts such a tiny charge on the battery that you should worry about over charging any more than you should worry about the pilot light on your water heater boiling your water away.

    The total amount of energy put into the 12v battery will not have any noticable effect on the milage.

    What it is good for is leaving the car for a long period. You probably don't need to worry about turning off the smart entry with the solar charger.

    I want one of those solar fans you close in the window while parking. When sunny and hot it ventilates the car. At night or cloudy it doesn't run.

    jv
     
    #7 newts, May 7, 2004
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