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12V Solar Battery Charger

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by Harters, Apr 28, 2020.

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  1. Harters

    Harters Active Member

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    I have searched for an answer, but most reviews I can find are quite old, so I thought I would start this one as technology moves on so quickly.

    Recently my Prius started up fine after being not used for just under 3 weeks, but as the car is just over three years old and with all the reports of people not being able to start their cars due to flat batteries I started looking at portable solar chargers/maintainers. Plus I thought it would be a nice gadget to have.

    I purchased one from Amazon which had good reviews, but I am a little worried now that it could end up over charging the battery. I am not very knowledgeable on volts, amps etc. so I am hoping someone can put my mind at rest.

    Unfortunately the panel is now out of stock on amazon.co.uk so I cannot provide a link, but the specs are below:

    ALLPOWERS 18V 12V 10W Portable Solar Panel Battery Charger Maintainer


    Just found this on the Amazon. com site and it seems to be exactly the same apart from the manufacturer name




    I am confused as to why it says 18V when its for a 12V car battery? I understand from other threads that it could never charge a battery due to the low wattage, which I don't need, so its just going to be to maintain the voltage and maybe top up. It does have a diode to protect reverse charge when there is no daylight, but it does not mention anything about preventing over charging.

    It came with cigarette lighter adapter and crocodile clips which is what I am going to use. The lead was pretty short so I have extended that. I tested the panel by connecting a 12V interior dome light dome LED bulb to the end and it seems very efficient at pumping out power even on a UK overcast day. I attached the panel to the inside glass of my side garage door, but when I placed it outside in full sunlight it went incredible bright. I know a small LED is different to a battery, but I am worried this could provide too much power and end up damaging the battery.... am I worrying unnecessarily?

    Thank you
     
    #1 Harters, Apr 28, 2020
    Last edited: Apr 28, 2020
  2. sam spade 2

    sam spade 2 Senior Member

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    You need to find the "specs" on the charger. Was there an "instruction" sheet with it ?

    Then there always is Google. I just did a search and it appears to be a trickle charger with no "smarts" at all.

    At a bit less than one amp capacity it might be OK but you would need to check the battery water level occasionally.
     
    #2 sam spade 2, Apr 28, 2020
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  3. Mendel Leisk

    Mendel Leisk Senior Member

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    What's your parking situation? I'm assuming you don't have access to alternating current outlet, or it's not secure enough?
     
    #3 Mendel Leisk, Apr 28, 2020
  4. Harters

    Harters Active Member

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    Thanks Sam

    I have checked the paperwork that came with it and it states:

    * Solar Panel: Monocrystalline silicon 18V10W
    * No-load voltage: 18-23VDC
    * Load voltage: 12V
    * Output current: 400mAh-550mAh(Max.)
    * Size: 330 x240x5mm/12.9 x9.5x0.2in
    * Weight:381g/13.4oz

    They call it a battery trickle charger/maintainer. I have seen other reviews where they say that only solar panels over 18W need to have any overcharge kind of protection, but I just want to make sure I am not removing one possible problem and replacing it with another by overcharging the battery.
     
    #4 Harters, Apr 28, 2020
  5. Harters

    Harters Active Member

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    I have access to power as the car is locked in my garage, but I just fancied having a solar panel rather than having something plugged into the mains and didn't want to spend much on it.
     
    #5 Harters, Apr 28, 2020
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    With a secure garage with power I'd go with AC current charger. Solar's finicky. If it's the only option yeah, but not otherwise.
     
    #6 Mendel Leisk, Apr 28, 2020
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  7. Harters

    Harters Active Member

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    I have just checked the small, small print and it states it does not need a charge controller as a 10W panel will not overcharge a 12V battery, but then says for automobile and motorboat always co-ordinate with control modules, so it contradicts itself?

    I would return it, but as I have extended the wires that stops me doing that, oh well it was only £24
     
    #7 Harters, Apr 28, 2020
    Last edited: Apr 28, 2020
  8. sam spade 2

    sam spade 2 Senior Member

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    You should be fine, especially since it will have no output at night.
    But you DO need to get in the habit of checking the battery "water" when you check the oil level.
    You DO check the oil occasionally .........right ?? :)
     
    #8 sam spade 2, Apr 28, 2020
  9. sam spade 2

    sam spade 2 Senior Member

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    Agree.
    I think he made the wrong choice.
    A smart battery tender would be a MUCH better choice and wouldn't cost much if any more.
    It also would cost maybe $1.00 a month to run.......or less.
     
    #9 sam spade 2, Apr 28, 2020
  10. Harters

    Harters Active Member

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    Oh yes, its part of my regular checks, not that it ever moves (y)

    Thank you.
     
    #10 Harters, Apr 28, 2020
  11. Harters

    Harters Active Member

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    It was me just wanting more of a gadget item that made me choose solar, not the running costs, but in this case my sensible head should have ruled my gadget head :oops:

    I will connect it tomorrow and see how it goes, but I will not leave it on permanently like I thought I was going to and I could with your suggested battery tender.
     
    #11 Harters, Apr 28, 2020
  12. Mendel Leisk

    Mendel Leisk Senior Member

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    In the "you can never have too many chargers" vein, I've been thinking about an on-board style charger, where you just have a power cord poking out through the front grill. This one seems interesting; I believe it's what @MSantos is using:

     
    #12 Mendel Leisk, Apr 28, 2020
  13. Harters

    Harters Active Member

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    Looks a bit too complicated for me, but very interesting.
     
    #13 Harters, Apr 28, 2020
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  14. Mendel Leisk

    Mendel Leisk Senior Member

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    Complicated? One end connects to the 12 volt battery, other end plugs into the wall outlet, likely with an extension cord. There's no buttons on it, nothing.
     
    #14 Mendel Leisk, Apr 28, 2020
  15. davecook89t

    davecook89t Senior Member

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    For me, solar panels to maintain our cars' 12V batteries was the best choice, owing to our habit of leaving one of our cars parked at a different location for months at a time. I bought 2 of these:


    which have been working well with the amount of winter sunlight we get in either downstate New York or Southwest Florida. Like you appear to be, I am a person who is interested in trying out the newest technology, especially when it points the way to a lower carbon future, but I am also wary of paying too high a price for what I'm getting, or in the case of battery charging, risking damaging the battery with something that is unproven. My first attempt at using solar panels to keep 12V batteries charged was a "fail". I bought 4 of these:

    1.5 Watt Solar Battery Charger

    because I needed 2 for each car. 1.5W from one panel was not enough to keep a battery fully charged in the winter, although it was adequate during the summer. Unfortunately, 2 of the 4 stopped working after a month or 2, so I bought 2 of the 5W panels referenced above and they have been doing the job for a couple of years now.

    To be on the safe side, I also bought a charge controller from Harbor Freight for about $25, which worked adequately but was eventually found to be unnecessary, particularly since neither of the locations where are cars are parked get direct sunlight all day long (maybe 4 hours during the winter or summer, but the angle is more direct in the summer, of course).

    With the 10W total power under the most ideal conditions that you have, I would think I would want to have a charge controller. The one I bought from Harbor Freight no longer seems to be available, but I see similar ones on Amazon for about the same price. Why not try one of those rather than throwing away the money you spent on your solar panel?
     
    #15 davecook89t, Apr 28, 2020
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  16. Harters

    Harters Active Member

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    I meant the technology of it and having to connect it to the car physically :unsure:
     
    #16 Harters, Apr 28, 2020
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  17. Harters

    Harters Active Member

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    Interesting, I will have a look into that, thanks.
     
    #17 Harters, Apr 28, 2020
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  18. sam spade 2

    sam spade 2 Senior Member

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    So.....you asked the question......and several people here told you that it is a small enough size that it will NOT be a problem......and yet you still seem to worry. Why is that ??
     
    #18 sam spade 2, Apr 28, 2020
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  19. Harters

    Harters Active Member

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    Mainly because I am naturally cautious and I didn't get a reply that stated what you have just said above, that it will 'not' be a problem.

    Now I have had more time to take all the information and your latest reply, I feel more confident using it, so thanks to everyone for all your input and help (y)
     
    #19 Harters, Apr 28, 2020
  20. Harters

    Harters Active Member

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    Hi Dave, Its me again :unsure:

    Is this the kind of thing?



    The diagram they show looks to be more complicated than what my needs would be, but would it just be a case of + & - of the panel in and + & - from the output terminals to the battery?

    There was another simpler looking one, but I noticed it said for solar panels 20w-130w so as mins is only 10W its not suitable I guess.

    Thanks
    Steve
     
    #20 Harters, Apr 29, 2020
    Last edited: Apr 29, 2020
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