The Incredible, Flexible, Ryobi 18V Battery

by Ben N on November 29, 2023

We sometimes take things for granted. One of those things is the modern cordless tool battery. Back in the day, we had to make do with CORDED power drills and the like. But a lithium tool battery is SO MUCH MORE USEFUL than simply powering a drill.

Modern lithium batteries are much LIGHTER than lead batteries, contain MORE ENERGY, and CHARGE FAST. They also usually contain safety features to prevent damage due to temperature or even short-circuiting. Because of mass-manufacturing, they are relatively inexpensive and readily available.

So, why just use them for the cordless tools they were designed for?
Cordless tool batteries are an excellent platform for Off-Grid, DIY, and almost any other project you can think of!

Ryobi 18V batteries are an excellent choice. Ryobi has a HUGE selection of tools, and at less cost than Milwaukee, Dewalt, or Makita. Another advantage is that Ryobi NEVER CHANGED their form-factor. They are a “stem” battery. Even very old batteries fit the latest tools and vice-versa. Other brands have changed physical shape over the years, and most now have a terminal setup which makes it harder to easily connect to the power of the battery.

Let’s take a look at a few projects based on Ryobi lithium batteries.

A few years back, I was playing around with low voltage landscaping lighting. Those bulbs typically run at 12V ALTERNATING CURRENT from a small transformer. But they tend to run on Direct Current every bit as well. Because of LED technology (which by its nature is low-voltage) we’ve also seen a boom in lighting that runs on 12V or even just USB.

I had purchased a 3D printer and realized there was nothing stopping me from simply creating a 3D shape which would connect a Ryobi 18V battery to a standard light-bulb base. After a few prototypes, combining some existing open source 3D models, I worked with another designer (who had better CAD skills than I) to create a single solid 3D model. Nickel strips (such as are commonly used in DIY battery projects) complete the electrical path between the low-voltage light bulb and the battery terminals.

Screw in the light-bulb, push the whole thing down on top of the battery, and let there be light!

The bulb provides omni-directional illumination and the battery itself is a solid base. It works just as well for a trouble light under a car as it does a lantern on top of a picnic table while camping.

After sharing my model, quite a few people were interested in buying them, so I started selling them online. You can also download the file and simply 3D print them for your own personal use.

Probably every parent in the United States is familiar with PowerWheels! These compact “ride-on toys” are even child’s dream. Their very own electric car to cruise around the driveway and back-yard!
Unfortunately, parents will soon also realize that the proprietary lead-acid battery is a bother to remove and reinstall, and since the kids never charge the car, that the battery soon dies a permanent death. On top of that, wouldn’t it be fun to soup up the car a little?

That’s where the “PowerWheels Adapter” comes in. It’s a piece of plastic that matches the shape of the Ryobi 18V battery and has a red and a black wire coming off of it.

Simply cut off the electrical connector in the PowerWheels, connect the Ryobi adapter, and slap in a battery! The Ryobi battery will not only last longer, charge faster, and be easier to install and remove, but it will also increase the speed of the car by 50%. The speed of common brushed DC motors is based on the voltage provided to them. Higher voltage means higher speed. (But keep it within reason! No need to melt little kid car motors!)

These adapter work great for not only PowerWheels, but also almost any other project where you want to interface a new battery.

Electric Wheelbarrow/Work Cart
For a larger, more powerful project, how about something that can really help you get work done – an electric wheelbarrow!
This frame would have originally had a gas engine in it, but the company making the gas-powered carts went out of business. I got a “New Old Stock” cart which was never fully assembled. Powering it with electricity instead of gasoline would mean it would be powerful, (it could tow my car!) but also QUIET and since there wouldn’t be exhaust, it could also be used indoors.

I installed a small electric motor from a 40V electric push mower. Of course, an 18V battery wouldn’t power that… which I why I used TWO!
I installed two “PowerWheels Adapters” and connected them in series (+ to -, + to -) to complete a higher voltage circuit. This allowed me to continue to use all the 18V batteries I already had for the more powerful, higher-voltage project.

The project turned out great, and was perfect for tasks such as moving heavy loads of rocks or firewood.

Youtube playlist of Electric Wheelbarrow videos.

In the time since I built the wheelbarrow, I’ve also started purchasing some outdoor power equipment. Those typically run at a higher voltage. Again, I invested in the Ryobi system, based on cost, availability, and variety of equipment.

I absolutely LOVE my electric chain saw, and I’ve even used the leaf-blower as a source of air for a make-shift forge!

These tools use a 40V battery.

Years back, I built an electric bicycle from a kit. That eventually lead me to building an electric motorcycle, an electric car, and then on to all the other DIY projects since then.

A few years ago, I was injured in a vehicle collision, and since my limited range of motion in my knee, I found myself yearning for an electric bicycle again. The electric “boost” of the bike would take up the slack, allowing me to still be able to pedal. Otherwise, I simply wouldn’t be able to bike at all.

I already had a bike hub motor kicking around that a friend gave me. He had decommissioned his bike (powered by three heavy lead-acid batteries.) I could easily mail-order an inexpensive 36V e-bike motor controller, but the expensive part of so many projects is usually the battery.

Again, Ryobi to the rescue.
A 40V tool battery is just about perfect for an e-bike. It’s right within the voltage 36V nominal equipment requires. I already had the batteries and chargers. No need to buy an expensive battery (and matching charger) which could ONLY run the bike.

The Ryobi 40V battery, 36V motor and controller was almost a perfect match. Not just in terms of voltage, but also the physical size and the amount of current the battery can provide.

All I really needed to do was to 3D print a mount to bolt in place on the bicycle frame which would be designed to match the 40V battery.

While doing some research on this project, I stumbled on a paper by engineering students at the University of Pittsburg. Their senior thesis project was to design an inexpensive, democratic electric bike system using readily available parts. The project included research into various batteries and cost per kilowatt-hour ($/kWh), what system voltage to use, and even CAD design for battery mounts.

In the end, their final project design for a simple, inexpensive electric bicycle which anyone could build was NEARLY IDENTICAL to mine!

I downloaded their battery mount CAD file, 3D printed it, and have had a great electric bicycle ever since!

A quick look at my Ryobi electric bicycle.

Over the years, I’ve owned several different brands and battery systems. I ended up with a mix of tools because I got them different ways – a prize in a contest, a great deal on refurbished tools, and even inheritance. Unfortunately, a MIX means that the batteries are NOT interchangeable.
Investing in a SINGLE brand/make/type means I have interchangeability. And the Ryobi brand, is a great combo of affordable/available/versatile.

I’ve loved working on various electric projects using these batteries, and hope that you do to.
If you are an “Off-Gridder”, the batteries can be charged by solar or when you are running a generator anyways. If you are on the grid, but always like to be prepared, these batteries are great for emergencies as well!

I even designed a project that makes a light come on when the power goes out!

Until next time, stay charged up!
-Ben Nelson

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