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Battery to battery charging

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  • Battery to battery charging

    I currently have a 12v Solar setup 1x120AH Gel Leisure battery and a 80w Mono Solar Panel i have 40w of 12v Led Lighting and 60w of 240v lighting powered by a 1000w Pure sine wave inverter which i use on the odd occasion when i work on my motorcycle at night, I am looking for a way to keep my motorcycle battery 12AH maintained via a quick release cable. i use this motorcycle to get to and from work so it will rarely be in the garage during daylight i only travel 2 miles to work its not enough to charge the battery via the alternator hence the need for some sort of charger i have seen battery to battery charges but they cost in the region of £200-£300, i have also thought about using a trickle charger off the inverter but it seems like a inefficient way; is there any otherway to do this cheaply?

  • #2
    The simple answer is just plug a maintainer into the PoCo line. If you don't have grid power, you might build a small DC input charger.
    Search an adjustable (up) converter something like
    150W DC-DC Boost Converter 10-32V to 12-35V Step Up
    and adjust the output to your end of charge voltage. Put a 12V lamp in series to limit the peak current; it will drop to very low resistance
    to allow finishing at the set voltage. Adjust lamp size or in parallel to get the peak current you want. Bruce Roe


    • Leechadwick
      Leechadwick commented
      Editing a comment
      Thanks Bruce I will give this a try as it seems like a good project, I have also purchased a dc to dc charger as listed below thanks for your commemt

  • #3
    This is EXACTLY what you are looking for. Although I'm not a bike racer trying to keep my race bike battery healthy while in a trailer on long trips, I use it for other mundane things - like charging a utility vehicle out in the back-40 where there is no ac, so I drag the donor battery along for the monthly maintenance I do to it:

    Tecmate Optimate TM500 dc-dc charger.

    It will definitely keep your bike's battery healthy if I understand your needs right.


    • bcroe
      bcroe commented
      Editing a comment
      That should do it, for $81. But maybe the OP is gone. Bruce

  • #4
    Thank you for the suggestions that optimate seems ideal I have just ordered one for £65 alot cheaper than the ones I found and it should keep my battery maintained through winter thank you!


    • #5
      Lee - I'm sure you'll enjoy it. Note that the link is direct to the manufacturer, but like anything, can be found elsewhere.

      The pre & post testing, along with the charge algorithm that differs a little bit from the bog standard cc/cv are what got me interested years ago. Of course that would mean nothing if the build quality and QC was crap - which it isn't.

      Put it this way - I liken the use of Tecmate-Optimate's to the level of trust I place in my Fluke multimeters. Pick the right one for the application at hand of course. It is also one of the few chargers that I will allow to touch expensive Enersys / Odyssey agm's. I actually use the larger models for battery commissioning and testing to make sure retail hasn't done any unforeseen damage to them. Usually this is a weekend-long procedure, as the larger versions have more extensive test features. All without pushing any buttons unbelievably. Unless you have the test gear, willingness and knowledge to babysit batteries under charge, the Optimates have established an all important level of trust - similar to owning a Fluke multimeter.

      Enough of the salesmanship. Well, maybe not.

      If you are interested in a small solar-maintainer, then once again, only ONE charge controller is allowed to perform this function with my dinky 5 and 10 watt panels on expensive batteries like Enersys/Odyssey.

      These guys are smart. Kind of like they actually care about batteries. Remarkable in this day and age.

      Highly recommended for newcomers to solar with small battery projects to make sure they get off to the right start with the typical battery sitting around in retail.


      • bcroe
        bcroe commented
        Editing a comment
        Its claimed to be the worlds most efficient, which implies its an MPPT type input. Bruce Roe

    • #6
      Heh, yeah I suppose but we're still dealing primarily with a dinky panel. Far better to beef up the panel, and stay pwm if need be to get that current up. Personally, I'm about to throw away (recycle) any panel under 20 watts. It's just not worth it, especially with winter coming.

      A lot of small stuff works great in summer, but when winter rolls around, a lot of my screwball stuff goes to the recycler.