Micah Toll wrote a great article at Electrek on two factors that threaten the longevity of lithium-ion batteries. While most people understand that high temperatures can shorten a battery’s life, probably a less recognized factor is high voltage. Much of Micah’s article sources a discussion by Professor Jeff Dahn of Dalhousie University where it’s claimed that “high charge levels result in extra performance for a few cycles, followed by a crash in performance and much faster deterioration of the cell”.
In the article Toll writes:
Next, you should aim to charge to lower levels when possible, especially if the car will be resting for a long period of time. While it may be comforting to see your battery meter read “100%”, your battery will be anything but comfortable.
It is important to note that the most damage from high charge levels comes from when the battery rests at such high levels for long periods of time. I’ve heard of many people who freak out after learning about the effect of high charge levels, with some swearing off 100% charging forever.
But 100% charging isn’t a big deal in small doses. If you are planning a long trip and will be heading out shortly after you finish charging, a 100% charge will have very little impact on your battery’s lifespan. However, if you will be leaving your battery unused for many days or weeks, a charge level of between 30-60% is much healthier for the batteries over the long-term.
So in summary, avoid heat and a long-term full charge on your lithium batteries. While some batteries will discharge on their own after so many days of storage, others you may need to discharge to a lower level manually if you have no plans to use the battery in the near future. I’ve seen some recommendations that for long-term storage a charge level of 30-60% is recommended, but some manufactures have suggested a charge level of 80% is acceptable for long-term storage of your lithium batteries.
I’ve included below Jeff Dahn’s lecture entitled, “”Why do Li-ion batteries die and can they be immortal?”
For the past couple years I’ve had an obsession with battery-powered cordless tools. While I’ve bought a number of cordless power tools and even a cordless snow blower…what has been missing in my garage is an all-battery lawn mower. For the past couple years, I’ve had my eyes on the EGO Power+ 56V Lithium-Ion Self-Propelled Mower.
The trigger for me to buy the EGO was Home Depot’s recent price drop of $100 on the LM2102SP mower which brings down the price from $599 to $499. There is some discussion whether this sale price is permanent or not. Last year, Home Depot’s “New Lower Price” dropped the mower’s price by $50 only to go back to its original price within a month or two. I never saw a lower price for the mower at Home Depot the rest of the year.
This year, I didn’t want to take a chance so I bought the EGO mower in March with South Dakota snow still on the ground. The salesman at Home Depot said this was the first mower he personally sold in the 2018 season. Needless to say, I have at least a month to go before I see enough green on the lawn for the first cut of the season.
Before I bought this mower, I was considering a few others based on reviews I found online. One mower I was considering was from the GreenWorks Pro 21-inch 80V line (although the self-propelled version is a hard find). I also considered the Lowes exclusive Kobalt 80V Self-propelled currently priced at $549 (and as far as I can tell is actually a GreenWorks under a different brand name). Another mower on my radar is the Yard Force 22-inch Self-Propelled Mower running on a 120V Lithium-ion battery. Unfortunately, the Yard Force mower is so new that with so little reviews and at a steep price, my wallet said “no”.
For those of you that aren’t comfortable with buying a mower with a “polymer composite” deck, you should consider taking a look at EGO’s 20-inch lawn mowers with a steel deck. Both the 21-inch and the 20-inch mowers come with a 5-year warranty on the mower and a 3-year warranty on the battery/charger. When the weather gets warmer, I plan to review my new EGO mower in detail.
A few weeks ago during my visit to the local Home Depot, I came across the Ryobi RM480E, an all-battery powered electric riding lawn mower. Ryobi claims that you’ll get up to 2 hours of run time or cut up to 2 acres on a single charge. This quiet, smooth battery powered riding mower houses three high-torque brushless motors to support the mower’s blades and drivetrain. The RM480E’s uses four 12V lead acid batteries instead of lithium-ion which given the choice and given the size of the mower so they’re not lithium).
The mower itself has a 38 in. cutting width with a 12-position deck height adjustment. Cutting height ranges from a minimum measured at 1.5 inches to a maximum of 4.5 inches. The mower is capable of cutting in three modes: side-discharge, mulching, and bagging.
I have not reviewed the Ryobi RM480E myself, but overall the mower has received favorable reviews. However, most reviewers recommend that if you have around 2 acres or more you should stick with a gas mower. After 2 acres of mowing, the RM480E will likely require an overnight charge before you can continue cutting the rest of your acreage. The best Ryobi RM480E reviews I’ve read so far are written by Pro Tool Reviews as well as Paul Sikkema over at Today’s Mowers. For the best video review, check out the review by Tools In Actions (embedded below).