EAGTAC        
Results 1 to 15 of 15

Thread: Any ideas about the most efficient way to charge 18v tool batteries from solar?

  1. #1

    Default Any ideas about the most efficient way to charge 18v tool batteries from solar?

    All of the MPPT controllers that I've seen are made for 12, 24, 48v, or else for odd specific voltages 14.4v, etc, have not seen one made for 18v yet.
    Milwaukee Electric has an 18v charger that runs off a 12v cigarette lighter outlet, that's the closest I've seen so far.
    The brighter the light, the darker the shadow.

  2. #2

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    Skip MPPT. True MPPT costs at least $100 and anything cheaper than that is probably lying. You can get most of the benefit of MPPT very easily however. All it takes is a $20 buck/boost board. Calibrate the buck/boost board to output whatever voltage you need.
    Try the largest, fastest, most flexible flashlight search engine: parametrek.com
    40 brands, 1936 models and still growing!
    NEW: battery search, sleeping pads search

  3. #3

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    I'll look into that, thanks.
    The brighter the light, the darker the shadow.

  4. #4
    Flashaholic*
    Join Date
    Sep 2007
    Location
    MA
    Posts
    2,932

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    You're still going to need a Lithium-Ion charge for the CC/CV/Cutoff charge profile. Since your input source may drop out, the charger circuit should have a nice auto restart/resume capability and not get all confused.

  5. #5
    Flashaholic* Timothybil's Avatar
    Join Date
    Nov 2007
    Location
    The great state of Iowa
    Posts
    3,131

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    I've got one of the standard high quality portable solar panels with USB output. If I ever need higher output voltage I have one of the booster circuit boards that will take USB in and put out up to around 20-25 volts.
    I am of the old school 'separate function - separate device' school. I use my solar panels to charge either my USB power banks or my 12v battery in my large fixed solar setup.
    Remember, Two is One, and One is None!.

  6. #6
    Flashaholic
    Join Date
    Nov 2007
    Location
    Somerset UK
    Posts
    382

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    I do not believe that that there is any safe, simple, and reliable way to charge an 18 volt lithium battery from a PV module.
    Lithium batteries are very particular in their charging requirements and no sort of improvisation can be recommended. Improper charging caries a significant risk of fire.

    I would obtain an "in car" charger for the power tool battery. Power this from a 12 volt lead acid battery that is charged from the PV module. If no in car charger is available for your 18 volt battery, then you will need a standard line powered charger that is worked from the 12 volt battery via a sine wave power inverter.

  7. #7

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    Quote Originally Posted by broadgage View Post
    I do not believe that that there is any safe, simple, and reliable way to charge an 18 volt lithium battery from a PV module.
    Lithium batteries are very particular in their charging requirements and no sort of improvisation can be recommended. Improper charging caries a significant risk of fire.

    I would obtain an "in car" charger for the power tool battery. Power this from a 12 volt lead acid battery that is charged from the PV module. If no in car charger is available for your 18 volt battery, then you will need a standard line powered charger that is worked from the 12 volt battery via a sine wave power inverter.
    you're getting right to the problem.
    There's already a ready made solution for a price in the (12v dc IN, 18v dc OUT) Milwaukee charger... I'm just thinking that not only is that likely suffering from some inefficiencies (panel is closer to 18v really), and it also doesn't allow me to make use of a bunch of batteries that are already paid for.
    I'd like to be able to press some of these packs into service as power storage straight from solar, just as you would 12v or 24, 48v... but "18v" (21v tops), set them up in parallel and use them as storage until they get yanked for cordless tool use... then I would need to charge them independently until they were at comparable voltage with the non drafted batteries so they could be put back into the pool.
    - with a proper controller charging the batteries and also handling excess live loads going out independent of battery charging.
    Last edited by eh4; 05-06-2018 at 05:11 AM.
    The brighter the light, the darker the shadow.

  8. #8
    Flashaholic* MrAl's Avatar
    Join Date
    Sep 2001
    Location
    New Jersey
    Posts
    3,144

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    Quote Originally Posted by eh4 View Post
    All of the MPPT controllers that I've seen are made for 12, 24, 48v, or else for odd specific voltages 14.4v, etc, have not seen one made for 18v yet.
    Milwaukee Electric has an 18v charger that runs off a 12v cigarette lighter outlet, that's the closest I've seen so far.
    Hello there,

    From the other posts i take it that the tool uses Li-ion batteries where some are in series and possibly some in parallel.

    If they are Li-ion, then the only way to do it is to either get an approved 12v charger (as i think others said) or else use a 12v to 120vac inverter for the car and use that with a solar panel and maybe lead acid battery.
    The only other way i can think of is you would have to study the design of the pack to make a safe charger.

    This is not just something we can take lightly because accidents with these calls are really nasty.

    The reason this design would be so particular is because the cells are not charged in series, they are usually charged with a charger that can at least MONITOR each cell individually, that's why there are so many contacts. Each cell may even be charged separately or two at once that are in parallel, but in this case they are hard wired in parallel.

    So the best advice is to use an approved 12v charger or use a 12v to 120vac inverter to power the regular charger. Small 12v to 120vac inverters are not that expensive either.

    Sorry to say all this but if you do it any other way there is a very big risk involved.
    Take care,
    Al
    LED's vs Bulbs, the battle is on.
    My bumper sticker: "I Brake for LED's"
    To err is human, to theorize divine.

    Got Light?

  9. #9

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    You don't need an inverter. Massive waste of power.

    And I didn't mean to imply that you could connect the buck/boost board to the battery directly. Connect it to the charger of course. Doing so will be perfectly safe.
    Try the largest, fastest, most flexible flashlight search engine: parametrek.com
    40 brands, 1936 models and still growing!
    NEW: battery search, sleeping pads search

  10. #10
    Flashaholic
    Join Date
    Nov 2007
    Location
    Somerset UK
    Posts
    382

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    I do not believe that the 18 volt lithium battery can be safely and reliably charged from a PV module, no matter what circuitry may be placed between the module and the 18 volt battery.
    The output of the PV module is too variable, and adding a voltage regulator wont help if the 12 volt input battery charger "wants" more current than is available. I see no option without use of a relatively large 12 volt battery so provide a reasonably steady 12/14 volt input to an in car charger for the tool battery.
    Presuming that an "in car" charger to suit the lithium battery is available, then no inverter is needed.
    An inverter to power a standard line powered battery charger would only be needed if no in car charger is available.

  11. #11
    Flashaholic
    Join Date
    Oct 2016
    Posts
    457

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    Quote Originally Posted by parametrek View Post
    Skip MPPT. True MPPT costs at least $100 and anything cheaper than that is probably lying. You can get most of the benefit of MPPT very easily however. All it takes is a $20 buck/boost board. Calibrate the buck/boost board to output whatever voltage you need.
    You have obviously never built an MPPT controller and I would have my doubts on a buck-boost controller too. Without some mechanism to control output current (or effectively the input voltage), any off the shelf buck/boost, etc. will just collapse the input voltage and it will stop woking.

  12. #12

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    Seems like with a 100w Sunpower panel giving 17.8V at 5.62A for its maximum power point, that there would be a way for an efficient fit with charging 18V batteries...
    Maybe a boost converter involved, but not based upon starting way back at 12V nominal.
    Last edited by eh4; 05-10-2018 at 11:18 PM.
    The brighter the light, the darker the shadow.

  13. #13

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    The batteries are smarter than you are...they will prevent this. Unless you have all 4 ports connected to the correct circuit, they will not charge. There is NO way to charge them directly from any source. I have quite a lot of Ridgid 18v lithium batteries, which are essentially the same as Milwaukee. I've tried using a generic 5 cell 120v > 18v (21v) charger, it won't work. Unless you have the other two ports hooked up to the proper temp sensors they will not allow a charge.

  14. #14

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    Quote Originally Posted by Number21 View Post
    The batteries are smarter than you are...
    I can believe that.
    Thanks for everyone's input.
    The brighter the light, the darker the shadow.

  15. #15
    Flashaholic* MrAl's Avatar
    Join Date
    Sep 2001
    Location
    New Jersey
    Posts
    3,144

    Default Re: Any ideas about the most efficient way to charge 18v tool batteries from solar?

    Quote Originally Posted by parametrek View Post
    You don't need an inverter. Massive waste of power.

    And I didn't mean to imply that you could connect the buck/boost board to the battery directly. Connect it to the charger of course. Doing so will be perfectly safe.

    Hello there,

    He does not NEED an inverter? Only if the charger has a 12vdc input right?

    I was under the impression that the charger only had a 120vac input and so would only run on 120vac. If it has a 12v input then there are more possibilities.

    If the charger has a 12vdc input then the only requirement is a 12v voltage regulator of some sort.

    No matter how it is done though the original charger should be used somehow, not a made up circuit. It is possible to make a home made circuit, but the exact nature of the battery pack must be fully understood and the design centered around that.
    Take care,
    Al
    LED's vs Bulbs, the battle is on.
    My bumper sticker: "I Brake for LED's"
    To err is human, to theorize divine.

    Got Light?

Posting Permissions

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