How I Upgraded My Slinger Ball Machine to Use DeWalt 20V Batteries
If you own a Slinger tennis or pickleball machine, the battery is a common headache. Built-in packs wear out quickly, replacements cost about $200 and are often out of stock. Charging takes 5 hours and must be monitored to avoid overheating. Many owners resort to rebuilding the pack by replacing individual cells, which works but requires time, tools, and dismantling the battery.
I wanted something simpler.
The Better Solution
I already own several DeWalt 20V batteries for my workshop tools. They're reliable, easy to charge, readily available, and I always have extras on hand.
While searching for a solution, I discovered a $20 adapter on Amazon that allows modern DeWalt 20V batteries to power older 14.4V DeWalt tools. That got me thinking:
Could this adapter be used to power a Slinger machine?
The answer is yes.
With a few simple modifications, you can convert your Slinger machine to run on swappable DeWalt batteries.
What You’ll Need
Free Laser-cut installation panel (optional) Download laser cutter template
The Modification
The process is surprisingly simple. (video instructions here).
Remove the battery from the front of the machine by removing the four thumb screws.
Detach the two-prong connector from the pack.
Remove the four black screws on the battery pack and separate.
Cut the wires connected to the original battery. Cut one at a time so you don't zap yourself on the charged battery.
Remove the silver two-prong connector from the battery case by removing the threaded ring that holds it in place.
Optional: for a clean install, download the free laser cutter template. Otherwise, you can run a longer wire to the battery connector through the Velcro opening on the inside of the machine and put the battery adapter and battery in the back compartment of the bag. It’s not as pretty, but it works.
Attach the lasercut plate (optional) to the battery adapter by gluing it to the plate, or take the adapter apart (6 screws) and drill two corresponding holes to attach it to the battery adapter to the plate more securely.
Connect the two-prong plug that was cut off the old battery to the battery adapter using blue female spade connectors. Be sure to connect the red wire to the positive terminal on the battery adapter. You’ll need to open up the female spade connectors by sliding a flathead screwdriver in and loosening them up a bit so they fit snugly over the battery terminals.
Attach the battery 2-prong connector from the battery adapter to the plug in the ball machine and install the battery adapter ot he front of the ball machine with the 4 thumb screws
Load a battery, turn on the ball machine, and you’re all set!
That's it.
Once completed, your Slinger machine can run from a removable DeWalt battery pack instead of the original internal battery. You may notice that the low battery red light shows. This is because the battery indicator does not recognize the new battery, but everything runs just fine. I’ve gotten multiple 2-hour sessions out of one charged battery, and it works with the oscillator too!
Why This Upgrade Is Better
This modification solves nearly every battery-related complaint I have with the Slinger system.
Instant Battery Swaps
When the battery runs low, simply pop in another fully charged DeWalt battery and keep playing.
No waiting five hours for a recharge.
Faster, Smarter Charging
DeWalt chargers are designed for quick charging and automatically manage the charging process.
There's no need to babysit the charger or worry about unplugging it at exactly the right time.
Lower Cost
Many players already own DeWalt batteries.
Even if you don't, replacement DeWalt batteries are often easier to find and more affordable than Slinger replacement batteries. Generic Dewalt batteries get great reviews and often cost a fraction of the name-brand versions.
Readily Available
Unlike Slinger batteries, which are frequently out of stock, DeWalt batteries are available almost everywhere—from hardware stores to online retailers.
Future-Proof
If a battery eventually wears out, you're not replacing a proprietary battery system. You're simply replacing a common tool battery.
Taking It a Step Further
After proving the concept, I wanted a cleaner, more professional-looking installation.
So I designed a custom mounting plate that attaches to the front of the machine and securely holds the battery adapter. The result looks much more like a factory-installed solution rather than a quick DIY hack.
If you'd like to build your own version, I've made the design available for download.
Final Thoughts
I love my Slinger machine, but the battery system has always felt like its biggest weakness. Expensive replacements, long charging times, limited availability, and concerns about overheating make ownership more complicated than it should be.
This simple and inexpensive DeWalt battery conversion completely changes the experience.
Now I can swap batteries in seconds, charge them with equipment I already own, and never worry about hunting down another proprietary replacement battery.
If you're tired of dealing with the stock battery system, this might be the easiest and most practical upgrade you can make to your Slinger machine.
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