Rebuilding a Ryobi 18v NiCad Battery

This was one of those unscheduled projects that I really had no intention of doing but when you have a persistent 9 year old that wants to take apart and rebuild a battery for some Ryobi tools, sometimes, you just have to give in.

I did purchase a bunch of NiCad 2200 mAhr C-cell batteries with tabs some years back with the intention of rebuilding my batteries when the time came. In that time, I changed tool platforms and went with Lithium Ion as the capacities are greater and the packs lighter, so the batteries sat along with some dead batteries.

I don’t use Ryobi batteries but have cordless Ryobi tools that I use with DeWalt Batteries. Doing that was easy, I just bought an adapter, popped it into the tool, slid on the DeWalt battery and I was off to the races, or at least, in many cases, off to burning my hand at my lack of attention paid to the hot end.

Sure, it looks a little goofy, but the benefit of having only one battery is quite substancial in keeping life efficient and simplified. By having one battery system, I am always ready with a cordless tool… But that is not what this is about, at all.

What started me down the path of this was that I needed, or rather wanted, a chemical sprayer for my garden to spray fertilizer or insecticide around the house and the like. Since I live in Michigan, bugs are a plenty and I use it to keep away things that will eventually infiltrate the house, like ants. I have a manual sprayer, but that is, well manual, so I bought this Ryobi One+ 18v Chemical Sprayer in an effort to enhance efficiency. My intent was to sell the battery and charger on Ebay but for whatever reason, my oldest took a shining to this system and made a case for why we should keep it. Although I didn’t fully agree, I appreciated the effort and we agreed on his active involvement with certain chores if I keep it. Ultimately worth the $40-ish I would have made from it on Ebay.

That same day, I was at my workbench riffling through the things littered about. It has a lot of my fix-it projects at various states where my kids put things that they break. They seem to expect whatever they place there to magically heal so I have to stay on top of that. I pulled out an old dead Ryobi NiCad battery along with a few other brands of battery packs I have been hording. I also had some 2200mAh cells in some boxes so my boy begged me to rebuild an old Ryobi battery.

This was not anywhere on my plan for the week or month but he insisted, I again struck a deal with him where he obligated to other various tasks if we were to do this. So, the project began. He started taking apart the battery and exposed the innards hidden away in its plastic tomb.

Once figuring out how they were chained together. I was able to replicate it with some “new” NiCad cells.

Building was tedious and since I don’t have the proper equipment, I used a lack-luster soldering iron and the tabs that were already welded in place. The soldering job is absolutely embarrassing so to ensure I never get a job soldering, here it is under construction.

Unfortunately, I misread the pack and thought that minus meant minus so I did have to rewire the connectors after I was finished soldering it. I could have probably handled it better but the battery is together and functional.

My son did help me put together the final bits and he finished screwing it together. Unfortunately, after putting it together, I discovered that I do not have correct Multi-chemistry charger for it so I had do charge it the brute force way. Regardless, it was a success, it holds a charge and seemingly operates as one would expect.

The Glue gun looks almost as silly with this battery as it does the DeWalt battery on an adapter. I don’t know how long this battery will last and if was worth the time it took to make but it was certainly educational. I don’t see myself making any effort to use this but it is amazing how excited a 9 year old can get fixing a 12 year old battery

Final Thoughts

Power tools are another nerd hobby of mine. I am amazed by the amount of power and capability you can get out of a plastic casing hand tools. Tearing them apart and seeing what is inside and fixing them, certainly, gives you a sense of accomplishment. It does make your tool much more yours.

Though I don’t see myself using the fruits of this exercise very much, what I do hope it sparks in my son is the desire to not just use but understand his tools, whether they are power tools, computers or any other electronic or mechanical device. That is ultimately why I did this with him. Strike while the curiosity iron is hot. I have also given my son a sense of ownership. Not only does he suddenly want to care for these tools but also use them properly. I see it as a great step forward in his growth.


Ryobi One+ Cordless Chemical Sprayer
Tenergy Batteries

4 thoughts on “Rebuilding a Ryobi 18v NiCad Battery

  1. You should have included the craft paper sleeves from the original. The plastic shrink wrap on the cells will melt in an overtemperature condition leading to a short circuit.

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