Results 1 to 13 of 13
  1. #1
    mtbr member
    Reputation:
    Join Date
    Sep 2005
    Posts
    10

    Solar Charging and Magicshine

    Hey all. I'm setting off cross-country in a few weeks, and planning on bringing my Magicshine 900 along. I was hoping to figure out some solar charging solution for the light, since I'd like to not bring a separate charger for every electronic doodad I bring on the trip, and I may not even be near electricity for extended periods.

    I'll likely be taking the solar panel/charger model found here on the trip, due to its ability to charge when out of direct sunlight to USB devices from AA batteries. The manufacturer's website lists the charger as putting out 1.5 Watts at 3.6V, if this is helpful. Essentially, I'm wondering if it's feasible to adapt this to charging my light's battery, and was curious if any of you gurus knew what sort of current and voltage the battery likes to snack on.

  2. #2
    mtbr member
    Reputation:
    Join Date
    Jan 2007
    Posts
    754
    To charge the magicshine pack, the voltage should be limited to 8.4 volts and the current should be limited to 4.4 amps. The current can be limited to lower values, the current limit will be a factor in how long it takes to charge the pack. The magicshine default charger is limited to less than 4.4 amps, but it is safe to charge up to that rate.

    It'll take a pretty good size solar panel to make much progress on charging the magicshine pack. The total energy density of the magicshine pack is about 32 watt-hour. So if you wanted to fully charge the pack in say 6 hours, you would need a 5.3 watt solar panel.

    Something kinda like this
    http://www.harborfreight.com/cpi/cta...emnumber=41144

    and you would still need some electronics to do the voltage regulation. The panel will effectively limit the current for you.

  3. #3
    mtbr member
    Reputation:
    Join Date
    Feb 2007
    Posts
    107
    Your best bet would be to use a car charger with a 12v panel.

    http://www.batteryspace.com/smartdcc...ingndrive.aspx

    Unfortunately this one is out of stock, can't seem to find a similar one anywhere.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Sep 2005
    Posts
    10
    Thanks all, this is exactly what I was looking for. I won't be using the light daily, so charge time is a non-issue. The panel I'm interested in operates at 3.6V and puts out 1.5W. Does that mean it outputs ~416 mA? I'm using the Wattage = Voltage*Amperage equation (this is the very outer limits of my electrical knowledge, btw) to make this assumption.

    To charge the magicshine pack, the voltage should be limited to 8.4 volts and the current should be limited to 4.4 amps. The current can be limited to lower values, the current limit will be a factor in how long it takes to charge the pack. The magicshine default charger is limited to less than 4.4 amps, but it is safe to charge up to that rate.
    Since both the amperage and voltage of the charger are below the limits stated, is it safe to assume that if I can make everything connect nicely, I should be okay to charge my battery?

  5. #5
    mtbr member
    Reputation:
    Join Date
    Feb 2007
    Posts
    107
    You'll need at least a 9v panel, as the pack's full voltage is around 8.4v.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Jan 2007
    Posts
    754
    Quote Originally Posted by Stubb

    Since both the amperage and voltage of the charger are below the limits stated, is it safe to assume that if I can make everything connect nicely, I should be okay to charge my battery?
    No, the pack won't even start to charge until the voltage gets above 7.4 volts and you really need to be much closer to the 8.4 volt nominal charge voltage before you'll make much progress on charging.

    The charger maxtheheathen mentioned combined with the solar panel I mentioned should work. The charger is basically the electronic regulation I said would be needed.

  7. #7
    Lets RIDE!
    Reputation: Jim Z in VT's Avatar
    Join Date
    Sep 2007
    Posts
    1,548
    There are flexible/rollable solar panels available that would be easy to carry, but they're pricier than the one Macgyver mentioned.
    It's not about speed, it's about lack of control.

  8. #8
    mtbr member
    Reputation: Cat-man-do's Avatar
    Join Date
    May 2004
    Posts
    3,905
    Quote Originally Posted by maxtheheathen
    Your best bet would be to use a car charger with a 12v panel.

    http://www.batteryspace.com/smartdcc...ingndrive.aspx

    Unfortunately this one is out of stock, can't seem to find a similar one anywhere.
    I'll second that recommendation. I use a small power inverter that I bought from Radio Shack ( 75watts ). This should work fine with most chargers. The one I'm linking to is not the one I have but similar. This one has an extra CL plug opening. Nice to have if you have a GPS and want to charge your battery and use the GPS at the same time. Just make sure that if you charge your light batteries to make sure you let the car run a little after a couple hours. You wouldn't want to overly-drain your car battery. Most bike light chargers don't draw big current loads so you should be fine. ( * You might want to experiment prior to your trip to see how well your car battery responds to the inverter power drain. Better safe than sorry. I'll be doing the same. )

    Link .> http://www.radioshack.com/product/in...lickid=prod_cs

  9. #9
    mtbr member
    Reputation: Cat-man-do's Avatar
    Join Date
    May 2004
    Posts
    3,905
    Quote Originally Posted by Cat-man-do
    I'll second that recommendation. I use a small power inverter that I bought from Radio Shack ( 75watts ). This should work fine with most chargers. The one I'm linking to is not the one I have but similar. This one has an extra CL plug opening. Nice to have if you have a GPS and want to charge your battery and use the GPS at the same time. Just make sure that if you charge your light batteries to make sure you let the car run a little after a couple hours. You wouldn't want to overly-drain your car battery. Most bike light chargers don't draw big current loads so you should be fine. ( * You might want to experiment prior to your trip to see how well your car battery responds to the inverter power drain. Better safe than sorry. I'll be doing the same. )

    Link .> http://www.radioshack.com/product/in...lickid=prod_cs
    I just had a brain storm. Update from my post above which I am quoting....If you wanted to go solar here's a great idea. Buy one of these > http://www.solar-batterycharger.us/a...y_Charger.html
    and use it with the inverter I mentioned above. No, it won't power the inverter alone but what it will do is keep the battery drain on your car battery down to bare minimal. My bike battery charger for my 600L draws about 13.5watts. I'm not sure how much power the inverter draws on stand-by but since it is being powered by the car battery that is not a big issue. The solar panel easily compensates for the power drain of the bike battery charger ( with some left over ) . That should minimize the power drain on the car battery. As long as you have good sunlight you should be good...**just let it charge all day. The bike battery charger stops charging when full charge is reached. After that all output from the Solar panel goes to charge the car battery...That could work. **note...you should use a solar charger monitor if charging a battery for an extended time. Over-charging your car battery would not be a good thing. If you don't get a monitor just use common sense and you should be fine.
    Last edited by Cat-man-do; 04-29-2010 at 02:38 AM.

  10. #10
    Lets RIDE!
    Reputation: Jim Z in VT's Avatar
    Join Date
    Sep 2007
    Posts
    1,548
    I could be wrong, but I don't think there's a car involved here, is there? I read this as a cross-country trip by bike, since Stubb was asking about solar charging. But I just re-read the 1st post and now I'm not so sure.

    JZ
    It's not about speed, it's about lack of control.

  11. #11
    mtbr member
    Reputation: Cat-man-do's Avatar
    Join Date
    May 2004
    Posts
    3,905
    Quote Originally Posted by Jim Z in VT
    I could be wrong, but I don't think there's a car involved here, is there? I read this as a cross-country trip by bike, since Stubb was asking about solar charging. But I just re-read the 1st post and now I'm not so sure.

    JZ
    Now that you mention it I see what you mean. If he's taking a CC trip by bike this would require another kind of strategy. I'd be thinking Dynamo or perhap just use torches. A P-7 torch on medium runs for over 3hrs. and works great. Couple with a smaller XRE R-2 or XPG torch on the helmet and you should be fine. Just carry as many spare 18650 cells as you think you might need. I mean "Just how much riding at night are you going to do on a Cross-Country (self-supported? ) bike ride"?

    I think Stubb needs to get back to give us a couple more details of just what he plans on this CC ride. Need to know questions: How much Night riding are you going to be doing? Will this be all road type ( self-supporting, saddle bags and racks) touring or are you traveling by car? How long will this ride last?

  12. #12
    mtbr member
    Reputation:
    Join Date
    Sep 2007
    Posts
    3,332
    I'd put a XPG Torch on the bars, useable in Medium mode, 5hour run time and a XP-E on my helmet with no other lights around thing Medium and 5hours to ( and use for only faster sections so all night )

    You MIGHT be able to charge a 18650 cell in a day, maybe 2.

    Or get something like a C3 which runs off AA's which you can hopefully source on ride ??

  13. #13
    mtbr member
    Reputation:
    Join Date
    Jan 2009
    Posts
    2
    Hi Stubb,

    For multi-day backpacking and canoe trips, I've used a Xantrex XPower PowerSource Mobile 100 along with a Sunforce 12 watt folding panel. The Xantrex has a 4 Ah battery in it and a built in 12/120 volt inverter so you can use a regular house battery charger (as long as it doesn't draw too much power...) with it. Perhaps not as efficient as having a charger that runs off of 12 volts, but I have some camera batteries which I can only find 120 volt chargers for...

    Anyway, charge up the Xantrex during the day, go riding at night, recharge your light batteries as you sleep.

    BN.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •