I made one to charge dewalt and ryobi batteries 20v and 18v lithiums. . I have found 100w is not enough in Ohio. The 12volt chargers I am using pull 6 solid amps at 13 volts. I used 2 x 100 watt panels, a 5 farad capacitor "battery" and a 30 amp mppt controller. It works great. I wired the panels in series so this gives it about 40 volts open circuit. This seems to work well on the half cloudy days. Your old battery will be fine as long as you have enough solar coming in to maintain 6 amps at 13v. Good luck and happy experimenting.
Tradition is not the worship of ashes, but the preservation of fire.
D Nikolls wrote:The quickest method is certainly to buy a 12V car charger for your particular brand of power tools, if available.
D Nikolls wrote:The quickest method is certainly to buy a 12V car charger for your particular brand of power tools, if available. Some brands have one that handles 12-24V nominal input, others only 12v.. and some brands may have nothing to offer.
Douglas Alpenstock wrote:
D Nikolls wrote:The quickest method is certainly to buy a 12V car charger for your particular brand of power tools, if available.
I agree 100%. Battery packs are expensive and vulnerable to damage. In a couple of minutes I was able to track down name-brand DC-powered chargers for Makita, Dewalt, Milwaukee and Ryobi. These would be more efficient (less conversion loss) than a 120V wall charger plugged into a pure sine wave inverter (which would work fine otherwise).
Douglas Alpenstock wrote:You may be able to buy prebuilt circuits on Amazon.
Checking the no-load voltage of the wall wart would also be useful (probably higher than 18V).
It's hard to know if the charger/battery electronics will work properly in an undervolt situation. To avoid that, I suggest overbuilding the DC-DC converter by a good margin, rated for a continuous output of 4-5 A and 20 VDC.
Cade Johnson wrote:a 12V solar panel may well be able to directly charge an 18V tool battery by a direct connection.
Some places need to be wild
Some places need to be wild
Douglas Alpenstock wrote:......In a couple of minutes I was able to track down name-brand DC-powered chargers for Makita, Dewalt, Milwaukee and Ryobi. These would be more efficient (less conversion loss) than a 120V wall charger plugged into a pure sine wave inverter (which would work fine otherwise).
"You must be the change you want to see in the world." "First they ignore you, then they laugh at you, then they fight you, then you win." --Mahatma Gandhi
"Preach the Gospel always, and if necessary, use words." --Francis of Assisi.
"Family farms work when the whole family works the farm." -- Adam Klaus
Some places need to be wild
I think they should change the spelling to Sandy Eggo. This tiny ad agrees with me.
permaculture and gardener gifts (stocking stuffers?)
https://permies.com/wiki/permaculture-gifts-stocking-stuffers
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