# Charging 18v tool batteries from solar.



## IronRing (Jul 22, 2017)

Hi,

I'm looking to charge 18v tool batteries from solar panels. I have collected 12v 87w worth of panels, and i'm going to use a 12v vehicle charger to charge the tool batteries (ryobi). i intend to simply get a small pwm charge controller, but what size battry do i need in the system between the charge controller and the ryobi charger?

Thanks


----------



## Murby (May 24, 2016)

12 volts... A motorcycle battery should work fine but a car battery or deep cycle battery would work far better. 

Or even better, a series of 18650 Lithium Ion cells stacked in series and strung in parallel to make a 12 - 13 volt battery.


----------



## IronRing (Jul 22, 2017)

I never considered a motorcycle battery, that's a good idea. I was thinking a smallish AGM battery, something like a 25Ahr or 50Ahr


----------



## mustangglp (Jul 7, 2015)

You will need a inverter. To convert 12v to 120 then you can just pull you charger in.


----------



## IronRing (Jul 22, 2017)

mustangglp said:


> You will need a inverter. To convert 12v to 120 then you can just pull you charger in.


I thought about that, but i figured the 12v vehicle chargers may be the way to go. i read that a lot of lithium ion 120v chargers don't like cheap modified sine wave inverters, and i also wanted to avoid the expense of buying a pure sine wave inverter.


----------



## Gary in ohio (May 11, 2002)

Murby said:


> 12 volts... A motorcycle battery should work fine but a car battery or deep cycle battery would work far better.
> 
> Or even better, a series of 18650 Lithium Ion cells stacked in series and strung in parallel to make a 12 - 13 volt battery.




A motorcycle batter is a poor choice for solar. Its not going to handle the charge cycles. Neither will a car battery. At a minimum get a deep cycle marine battery


----------



## Al Yaz (Jun 13, 2017)

ya i am thinking you need an inverter too. not saying it can’t be done but how would you use your ryobi charger otherwise?


----------



## hunter63 (Jan 4, 2005)

I charged battery drills with a inverter plugged into the dash of my service truck.
My portable set up now.......can be charged with solar/charge controler....or truck....or 110v charger.

Garden tractor battery...same as my garden tractor (can be spare)..in 20mm plastic box...with accessories...........


----------



## ShannonR (Nov 28, 2012)

IronRing said:


> I thought about that, but i figured the 12v vehicle chargers may be the way to go. i read that a lot of lithium ion 120v chargers don't like cheap modified sine wave inverters, and i also wanted to avoid the expense of buying a pure sine wave inverter.


You could, but the 12v charger will wear out much faster and you may cook a couple drill batteries in the process. Ask me how I know!!


----------



## IronRing (Jul 22, 2017)

ShannonR said:


> You could, but the 12v charger will wear out much faster and you may cook a couple drill batteries in the process. Ask me how I know!!


Ok I'll bite. 

I figured these vehicle chargers for my tool batteries would be just as reliable as one for 120v.


----------



## Gary in ohio (May 11, 2002)

I would skip the inverter, lots of wasted power. Just get a buck converter and convert your 12v to 18v. See what the voltage and current your wall wart needs and match it with a converter. See if the batteries have a "mobile" charger available.

I do something similar for my laptop. It takes 19v and is fed from a 12v source via a converter.


----------



## wy_white_wolf (Oct 14, 2004)

None of my AC tool chargers liked the cheap modified sine wave inverter. I went 12v without the inverter and worked great.

WWW


----------

