These are strange times, strange times indeed. I just used our 2021 BMW i3s to help repair our electric riding lawn mower. Give me a moment to explain. Our electric lawn mower’s 5-year-old batteries decided they were done and our mower no longer would keep enough charge to mow the grass. I called the dealer to ask if they could come pick up and fix the mower. I got a surprising call back. They could not fix it. They said the batteries were backordered for an unknown length of time.

Lead-Acid Batteries Instead of Li-Ion

Faced with a large worthless mower in my shed with no options for help, I asked myself. How hard could it be to fix on my own? So I started taking apart the mower to find out what the batteries look like. To my surprise, they looked like four massive car batteries. Turns out the manufacturer chose to use AGM lead-acid batteries instead of more durable lithium ion batteries like in our BMW i3. Surely I can replace these old school batteries myself.

I decided to call my local battery store to see if they could order the batteries for me. After checking a ton of very specific numbers off the old batteries, much to my surprise, he said four were in stock. The deal with these old-school style lead-acid batteries though is that the battery store wants the old ones in return.

Replacing the Old Batteries

First step is figuring out how to remove these old batteries from the electric lawn mower. Thankfully the manufacturer had published a tech manual online for dealerships. I could read and follow the entire instructions on removing the old batteries and how to install the new ones. Much to my amazement, the layout was incredibly simple. There are four 12 volt batteries aligned in series. The positive end of one battery flows into the negative of the next one and so on. The only trick part was figuring out how to get the last battery under the seat. After a few busted knuckles, I’ve got them all out.

The next day, I loaded the four old super heavy old batteries in the trunk of my BMW i3. The high trunk of the i3 made loading these heavy batteries easy on my back. I was also thankful to have the WeatherTech Trunk liner to place the batteries on. The trunk mat held the batteries securely and gave me peace of mind to protect the carpet, even though these are sealed batteries.

I backed up to the store and the employee came out being very interested in the BMW i3 as he’d never seen (or noticed) one before. After talking about the car’s 180-mile range and easy home charging, we switched the batteries out. I was grateful to note that batteries were literally identical save the new ones had Duracell labels on them versus the lawn mower’s name on the old ones.

Back in 2017, we bought our electric lawnmower with zero research. It seemed a good fit for us with solar panels, electric vehicles and why not add an electric riding mower. Sadly my lack of research on what batteries were used in this mower and COVID shortages would come back to bite me. Much to my amazement, the repair manual was online and a dealer that had these same batteries in stock. These are super common as they were also used in boats and golf carts.

I wish my electric mower had lithium-ion batteries, and were as durable as my BMW i3 batteries. Hopefully there will be some easy way to install 48Volt lithium ion batteries in the future. In the mean time, I am happy to be back to mowing the grass using solar power from our roof.