Solar Battery chargers

Discussion in 'Electronics' started by Finals2land, Aug 4, 2008.

  1. Finals2land

    Finals2land New Member

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    Hi people, i have an slk55 but do not use it enough and hence the alarm and tracker soon flatten the battery. My question is i have seen several different types of solar chargers (mainly from Maplin) which might be the answer to my prayers. Primarily the model i looked at was http://www.maplin.co.uk/Module.aspx?TabID=1&ModuleNo=99760&doy=4m8 dont know if this is good enough or not....Over to you guys??:D
     
  2. BTB 500

    BTB 500 MB Club Veteran

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    Presumably the car is parked in the open then, and a mains charger is not an option?

    The best you can do is probably a small panel that goes on top of the dash, which might generate enough power to keep the battery alive. Those 'briefcase' ones are physically too large.

    How quickly is 'soon' btw? How old is the battery? If the car is only used for short runs it may never get fully charged, regardless of 'parasitic drain' when parked.
     
  3. OP
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    Finals2land

    Finals2land New Member

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    Hi, usually dead within about 3 weeks, less in the winter. Its an 05 plate and its on its 2nd battery last year. The one i saw in maplin was about 53 x 67 cm. I have not measured but i thought it would fit.
     
  4. rf065

    rf065 Hardcore MB Enthusiast

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    I recall some magazine or other testing solar chargers for car batteries a few years ago, and unless they have drastically improved lately, don't waste your money on them.

    You can buy a battery conditioner/trickle charger that can be left on for long periods for £30 or £40, if you have a driveway or garage to park in.

    Russ
     
  5. OP
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    Finals2land

    Finals2land New Member

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    Unfotunately no axs to mains, thats why looking at solar powered. Was just wondering if any body had used them.
     
  6. BTB 500

    BTB 500 MB Club Veteran

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    Measure up inside your car and see what will fit. You'll then have to devise a way of connecting to the battery (which I'm guessing is in the boot if it's like my SL?). The cigarette lighter socket will probably be isolated when the ignition is off.

    I have a similar issue with my car but use a wall-mounted charger in the garage to keep it at full charge.
     
  7. rf065

    rf065 Hardcore MB Enthusiast

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    Unless anyone else can vouch for them, I believe the technology is sound but in practice, for a car battery anyway, they just don't work. Probably ideal for a mobile phone battery though.

    Russ
     
  8. BTB 500

    BTB 500 MB Club Veteran

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    The small/cheap panels only have a peak output of 100 mA or so. That's in decent bright conditions, over a 24 hour cycle you're probably looking at an average charge current of just 30-40 mA. That will barely keep a battery from self-discharging, without any load.

    Let's assume an SLK55 battery is 100 Ah. To flatten in 3 weeks means a constant drain of 200 mA.

    So a solar panel rated 10W would just about be OK, that'd have a peak output of about 650 mA in bright daylight (but obviously nothing overnight!).

    10-15 W panels aren't mega-expensive, basically you pay a premium for more efficient cells that give a more compact panel e.g.

    10W, 39.7 x 27.8 cm, £110: http://www.maplin.co.uk/Module.aspx?TabID=1&ModuleNo=96897&doy=4m8#features

    13W, 67 x 52.5 cm, £50: http://www.maplin.co.uk/module.aspx?ModuleNo=99760&doy=4m8

    So it's down to how much you want to spend, and how much room there is on the dash. And how you will wire it up to the battery so it can easily be connected/disconnected.
     
  9. benztech

    benztech Member

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    An Slk should have a drain of max 0.09milli amps with a tracker expect 0.16 upwards depending on the tracker fitted.
    You should be able to leave a veh. with no tracker for up to a month and it will restart on its own. With a tracker 2-3 weeks
    When you lock any modern MB the alarm and clock should be the only things draining the battery and a tracker if you have one.
    The best thing to do is iddeally get a Mercedes Benz trickle charger for about £75 but mains being a problem you will need to plug it in.
    You could buy a JUMP PACK leave it in the boot
    You could also fit a isolator switch - but that would switch you alarm off - if your car was to get knicked then you insurance would be void.
    Finally every two weeks if you have not used the car make yourself a cup of tea and a paper go and sit in the car for ten mins with the engine running. The alternator will top the charge up.
    I see these solar chargers and i still go out to people with flat batterys.

    Also it does not look that sightly sitting all over the dash especially in an AMG.
     
  10. benztech

    benztech Member

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    The Slk's are fitted with a 74 a/h battery regardless whether an AMG or not:)
     
  11. BTB 500

    BTB 500 MB Club Veteran

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    Blimey that's not very big for a 5.5 litre engine!
     
  12. BTB 500

    BTB 500 MB Club Veteran

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    I think you mean 0.09 amps, i.e. 90 milliamps? And 160 milliamps with a Tracker.
     
  13. OP
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    Finals2land

    Finals2land New Member

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    Hi guys. Thanks for all your help, the concensus does seem to be they are not that great. Also something that i had not considered was how to connect it to the vehicle. I was going to plug it into the cigarette lighter socket but that may be isolated according to you guys. The battery is in the front under the bonnet.
     
  14. Shude

    Shude MB Club Veteran

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    Either yourself or a workshop could move the wiring for the cigar lighter from switched to permanent live in the fusebox. That requires no parts and is probably under an hour of labour.
     
  15. glojo

    glojo MB Club Veteran

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    Hi Finals,
    I am always the odd one out here and I actually have a solar panel connected to our 'stretched limo' (Sprinter van:)) To say the vehicle is hardly used is an understatement.

    My wife took me to hospital on Friday and this was the first time the vehicle has been used in three months. I have a solar panel that connects to the vehicles axillary battery and keeps it topped up. This battery is an extremely heavy duty item that is used to operate the flotation stretched, winch, stretcher lift, fans, alarm systems etc etc. Before we purchased this panel the vehicle used to drain the battery after about four weeks and this in turn caused further problems.

    My wife took our vehicle to a car electrical specialist who fitted a cigar lighter connection solely for the panel and we swear by this gizzmo. Two years of use so far and the only time we have suffered a flat battery was when 'the boss' forgot to connect the panel. I have no idea of your situation, or the vehicles location, all I can say is this system works for me.

    regards
    John
     
  16. lil.smartie

    lil.smartie Hardcore MB Enthusiast

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    We use Sealey ones here for sales cars and they work fine, crocodile clips on to the batter and they sit on the dash.

    Kate
     
  17. OP
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    Finals2land

    Finals2land New Member

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    Ahh there is an upsurge of people with them after al. I think i will get one and give it a try. Give me a couple of months and i will report back on my findings. Thanks again.
     
  18. glojo

    glojo MB Club Veteran

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    Just make sure the panel gets connected to the battery:eek: ;)

    Good luck
    John
     
  19. BTB 500

    BTB 500 MB Club Veteran

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    And make sure the panel is powerful enough. 10W minimum, 15W better.
     
  20. CMR

    CMR Active Member

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    I was hoping glojo would reply to your question as I know he finds them useful. I use this one Maplin Link.
    It can sit easily on the front dash or rear parcel shelf. Get an additional socket wired in, (in case you use it for anything else - best make sure it has an inline fuse even though the charger has one). I had a socket fitted fitted in the plastic panel in the passenger side footwell area (under glove box).
     

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