12V Solar Car Battery Charger

Discussion in 'Electronics & Electrics' started by methodMAN, May 1, 2019.

  1. methodMAN

    methodMAN Member

    Jul 8, 2002
    God's Own
    hey all,

    I have a work car and personal car. Personal car gets a start once or twice a week if lucky and only for short periods of time. Personal car is worth nothing and is cheap as chips to keep on the road - plus its a ute.

    So naturally when starting the car is always pretty lethargic, so someone at work suggested a solar battery charger to keep the battery topped up. I ask for more info and they don't know jack.

    A quick google has millions of answers - but which one is right?

    Any one had any experience with this? or is a straight up waste of money.


  2. slavewone

    slavewone Member

    Jul 9, 2002
    B.Mtns2774 Status:Unhappy
    I haven’t had any luck with a cheap one that fell apart after the plastic went brittle in the sun. I was much more comfortable using a battery charger, but it was much more work.

    I recently got a 20w panel and PWM charger off eBay ($35) and I’m keen to see what the does to a car battery as it’s working really well on a tiny 12v SLA
  3. th3_hawk

    th3_hawk Member

    Jun 4, 2005
    [VIC] Eastern Suburbs
    Do these solar chargers have any smarts so as not to overcharge the battery?

    I did a quick search and hit this:

    From what I can see none of them have overcharge protection and they talk about using them for short periods of time vs what most people with cars not driven much would really want which is a more permanently plugged in solution.

    Of course, there are options, this being nothing more than the first one I saw so there is probably better/different/cheaper/bigger/smaller options out there.

    My car isn't driven very much so is in the back carport hooked up virtually permanently to a CTEK charger. I like the idea of using solar instead, but getting one instead would mean mounting it above the carport roof and running cables, not a hard task but this already works for me
    money_killer likes this.
  4. Sunder

    Sunder Member

    Apr 26, 2012
    Next time your battery dies, invest in a Lithium Titanate oxide cranking battery. They won't run accessories for very long without the engine running, but a 2kg battery half the size of a tissue box will crank a V8 - And better still, their self-discharge is only 1% per month. So as long as your head unit/clock isn't drawing much more than a few milliamps, you could leave it sit for a year or longer, and have it crank first go. (Wouldn't recommend using the same oil after all that time though!)
  5. merlin13

    merlin13 Member

    Apr 12, 2003
    back in BrizVegas
    Funniest thing I ever saw on this concept was encountering the little 4-cylinder buzz-box that Dr Karl had down in Sydney 'waaaaay back when with a solar panel bolted onto the bonnet, supposedly to keep the battery topped up when the motor wasn't running. True story.

    Fitted a few of those maons-powered battery trickle topper-upperers on motorbikes 'n scooters that weren't run regularly, that the batteries used to fade away after not being used for months and months. Far as I can see the basic concept works, at least on smaller vehicle batteries. Heard of similar when I was over in the States on cars 'n trucks in areas that would annually drop well below zero, set up in addition to the heaters used to keep the oil from freezing solid, albeit those being mains powered as well.

    So my 2.2 inc GST cents worth is "something" to dribble power into a stationary car battery can't be a bad thing. At least until you invest in a good one, and/or run the vehicle for longer than a quick trip down the road and back.

    Or invest in a good jump-start box. :)

    As an aside here as well, biggest annoyance with the Yum Cha solar battery topper-upperers is they usually plug in through the cigarette lighter. Apart from lots of modern vehicles not having a cigarette lighter as standard any more, also means that you usually have to leave the ignition switch set to Accessories.
  6. disco frank

    disco frank Member

    Mar 14, 2008
    Had this with a bus i drive, the trailer brakes and imobiliser draw enough current that after 2 weeks the batteries wotn start the bus :(
    ended u with 2 x 10w 12v panels from auto1, wired them in series ( bus is 24v ) then added a $40 solar reg charger from jaycar
    some velcro dots to hold the panels to the window, works MINT , around $100 for 24v less 1 panel for 12v you be around $50

    the OTHER thing you can do is add an isolator switch to the battery that fully disconnects it from the car electrics , BUT anything that needs memory ( clocks radio etc ) will be reset every time
  7. aXis

    aXis Member

    Jun 27, 2001
    Kalgoorlie, WA
    At the kinds of power levels those panels produce, they wont overcharge your battery. They can run fairly safely with no regulation at all.
  8. money_killer

    money_killer Member

    Apr 10, 2010
    Sunshine Coast
    You need a maintenance charger that cycle s your battery so it doesn't get over charged they are normally called a 7 or 9 stage charger. Normally $80-150
  9. Privatteer

    Privatteer Member

    Mar 19, 2006
    When I was parking the ute at airport for FIFO I had one of these Morningstar regs and 2 20w panels in parallel stuck to the roof.
    The 2 panels helped as if one was shaded the other might not be.

    Morningstar are a decent quality brand from my experience.

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