Can Volkswagen solar battery maintainers be used on other vehicles?

I bought a bunch of these solar chargers to maintain the batteries in cars that may not be driven for weeks or months at a time.
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I tried them for 3 or 4 weeks on 4 different cars (a period of time that any car battery should be able to start the car without a jump) and all the batteries were dead. Even a car with a 2 month old battery.

Is there something special with these chargers that only allow them to be used on VW's?

Comments

  • BB.BB. Posts: 28,083Super Moderators, Administrators admin
    Re: Can Volkswagen solar battery maintainers be used on other vehicles?

    It looks like this version has an ODB II connector (On Board Diagnostic 2).

    I have looked around at getting an ODB II "terminal" for my own vehicles and it appears there should be an unswitched 12 VDC and Ground connection--so even with key out of the ignition and the doors closed, the power should be getting to the battery...

    So, check if the ODBII connector(s) on your vehicle is hot (test it with a small 12 VDC light bulb--not just a DVM--as you want to draw ~1/2-1.0 amp or so to make sure there is a solid connection).

    You also need to make sure the panel is exposed to full sun from ~9am-3pm for maximum charging effect.

    Next, you need to know the load(s) that the car has on it... For example, my in-laws Lexus with On-Star, Lojack, GPS, lots of small computers, etc... draws something like 180 mA (0.180 amps according to the dealer). Their car needs to be run every 2 weeks or the battery runs the risk of going dead (in fact, I am going to be replacing their 3rd battery or so in the next few days--even though I used a trickle charger--but I don't think they would always connect it).

    0.180 amps * 24 hours/day=4.3 amphours per day...

    4.3AmpHour * 14 volts / 4 hours per day of sun = 15 watt minimum panel required for 3 seasons of the year in my area...

    So--your panel may not be connected to the battery, or your vehicle may have a larger drain than you think, or there may be a stuck trunk light (2nd in-law car--replaced battery twice for it because trunk left unlocked)...

    Those are the basic areas I would start looking at...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Can Volkswagen solar battery maintainers be used on other vehicles?

    What about at night, would the battery drain itself if the panel wasn't putting out at least 12V?
  • mike95490mike95490 Posts: 7,967Solar Expert ✭✭✭✭
    Re: Can Volkswagen solar battery maintainers be used on other vehicles?
    atikovi wrote: »
    What about at night, would the battery drain itself if the panel wasn't putting out at least 12V?

    It will, a little bit, and so the solar charger needs to supply enough power in the 5 hours it sees good sun, to replace what is lost the other 19 hours.

    Often, the panels are just junk, barely supply enough power to light their indicator LED, and you find dead batteries in 6 weeks, instead of 5 weeks.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • System2System2 Posts: 6,290 admin
    Re: Can Volkswagen solar battery maintainers be used on other vehicles?

    I was told the square box on the cord should prevent the battery from draining into the panel at night. I think I'll hook one up to a charged battery in the basement for a week and see if it drops in voltage much after seeing no sunlight.
  • BB.BB. Posts: 28,083Super Moderators, Administrators admin
    Re: Can Volkswagen solar battery maintainers be used on other vehicles?

    All that is needed is a small diode to prevent reverse current... The VW solution should have that. If you have a DVM, you can just hook the panel up and see how much current is flowing in full sun and with a dark jacket thrown over the panel.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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