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Quick answer
Take the battery off the charger, bring it indoors, and store it somewhere dry at room temperature. That much every brand agrees on. They disagree on charge level: EGO says 30 to 50% charged, while DeWalt and Greenworks’ 40V manual say fully charged. Ryobi’s 40V manual is the strictest on temperature. It says never to store its packs below 50°F, which rules out most unheated garages and sheds in a northern winter. Check the manual for your own battery, and use the table below for the four big brands.
A gas mower needs winterizing. A cordless mower needs almost nothing, except for its battery, which is often the most expensive part of the kit to replace. Consumer Reports’ outdoor equipment lead, Dave Trezza, put it this way: “Even without a gasoline engine to winterize, you’ll need to take other steps” to protect the batteries.
The problem is that the advice online is inconsistent, because the brands themselves don’t agree. So we went to each brand’s own manual. MowReview quotes no prices and hasn’t tested these batteries. How we research explains why.
What each brand’s manual says
| Brand | Charge level | Temperature | Other rules |
|---|---|---|---|
| EGO 56V | 30 to 50% for storage over 30 days | Below 80°F; optimum 50 to 80°F | Full charge every six months; unplug charger and remove battery |
| Ryobi 40V | Not stated in the US manual (Ryobi NZ: 30 to 50%) | Never below 50°F or above 100°F | Don’t store outside or in vehicles |
| Greenworks 40V | Fully charge before storage | Normal room temperature | Room temperature if unused for 3 months or more |
| DeWalt | Fully charged | Cool and dry, away from excess heat or cold | Store out of the charger |
Sources: EGO G3 56V battery operator’s manual; Ryobi 40V operator’s manual (RY40860) and Ryobi New Zealand support; Greenworks 40V battery owner’s manual (LB40A010); DeWalt instruction manual (DCD471, 60V MAX). Older or different batteries may have different instructions.
EGO
EGO’s G3 battery manual is the most detailed. For storage over 30 days, it says to “store Lithium-Ion battery packs in a 30%-50% charged condition” and below 80°F, with 50 to 80°F given as the optimum. EGO batteries also look after themselves: the manual says they automatically self-discharge after a month in storage, then sleep at about 30% charge. Fully charge the battery every six months of storage, and again before first use in spring.
Ryobi
Ryobi’s 40V manual sets a hard floor: “Do not use, store, or charge battery packs in locations where the temperature is less than 50°F or more than 100°F.” It also says not to store packs outside or in vehicles. Oddly, the same manual says the pack can be used down to −4°F, so cold mowing is fine but cold storage isn’t. Ryobi’s US manual doesn’t give a storage charge level. Ryobi’s New Zealand support site says partially charged, at 30 to 50%.
Greenworks
The Greenworks 40V battery manual we checked says to keep the battery at normal room temperature, to store it at room temperature if it won’t be used for three months or more, and to “fully charge before storage.” Consumer Reports, writing in 2018, reported different advice from Greenworks: charge fully every two months in storage, then drain back to about 40%. If your manual differs from both, follow your manual.
DeWalt
DeWalt’s manual says “the best storage place is one that is cool and dry, away from direct sunlight and excess heat or cold,” and to “store the fully charged battery pack out of the charger.”
Why the garage is usually the wrong place
Consumer Reports says most batteries do best between 40 and 80°F, and Ryobi and EGO both point to 50°F as the bottom of the comfortable range. In much of the northern US, an unheated garage or shed spends the winter well below that. A closet, basement or utility room is a better home. Keep batteries dry, away from heaters and direct sun, and out of children’s reach.
Robot mower batteries are different
A robot mower’s battery is usually built in, so the whole mower comes indoors. The brands’ rules on charge level and temperature are in robot mower winter storage, and robot mower batteries in cold weather covers late-fall mowing.
A five-minute winter routine
- Check your battery’s manual for its storage charge level.
- Set the charge: run an EGO or Ryobi pack down to about half; top up a DeWalt or Greenworks pack.
- Unplug the charger and take the battery off it.
- Bring the battery indoors to a dry spot that stays above 50°F.
- Brush clippings off the battery terminals and the mower deck before putting the mower away.
- Set a reminder for a mid-winter check, and charge fully before the first spring mow.
The picks
For tidy indoor storage
StealthMounts battery mounts
- FitsBrand-specific versions, including EGO, Ryobi and DeWalt
- MaterialABS plastic
- MountingScrew-mounted, any spacing
Wall mounts that hold batteries the way the tool does, so a utility room or closet wall becomes winter battery storage. Batteries stay off the floor and away from damp.
Good for
- Owners with several batteries across tools
- Indoor spaces with a spare stretch of wall
Less good for
- Mixed brands: each mount fits one battery platform, so buy the right version
- Quick grabs: the batteries only release by pressing the button on the battery itself
To check your storage spot
ThermoPro TP50 indoor thermometer and hygrometer
- MeasuresTemperature and humidity
- UseIndoor
- PowerBattery
A simple way to find out whether your storage spot stays above Ryobi’s 50°F floor and below EGO’s 80°F ceiling, and whether it’s dry. Leave it there for a few cold nights before you commit.
Good for
- Checking a basement, closet or attached garage
- Spotting damp storage areas
Less good for
- Outdoor sheds: it’s sold as an indoor monitor
- Remote alerts: it shows readings on the unit, not on your phone
If you’re choosing a battery platform
EGO Power+ 56V battery
- Storage charge30 to 50%
- Self-maintenanceDischarges to about 30% after a month
- Charging range41 to 104°F
Of the manuals we checked, EGO’s is the only one that describes a battery managing its own storage charge. If you forget to run it down before winter, EGO says it discharges itself after a month and holds about 30%. Consumer Reports reported EGO saying its gear doesn’t need a mid-season charge.
Good for
- Owners who forget battery chores
- Households building one tool platform for mowing, trimming and blowing
Less good for
- Warm storage spots: EGO says to store below 80°F
- Long storage without checks: EGO still says to fully charge every six months
Questions
Should I store my mower battery fully charged or partly charged over winter?
It depends on the brand. EGO’s manual says to store its batteries 30 to 50% charged, Ryobi’s New Zealand support site says 30 to 50%, while DeWalt’s manual says to store its packs fully charged and Greenworks’ 40V battery manual says to fully charge before storage. Follow your own battery’s manual.
Can I leave my mower battery in the garage over winter?
Often not. Ryobi’s 40V manual says not to store battery packs anywhere below 50°F or above 100°F, and not outside or in vehicles. EGO’s manual gives an optimum storage range of 50 to 80°F. An unheated garage in a northern winter is usually colder than that, so bring the battery indoors.
Should I leave my battery on the charger over winter?
No, for the brands we checked. EGO’s manual says it’s good practice to unplug the charger and remove the battery when not in use, and DeWalt’s says to store the charged pack out of the charger.
How often should I charge a stored mower battery?
EGO’s manual says to fully charge its batteries every six months of storage. Consumer Reports reported that Greenworks recommended a full charge every two months, then draining back to about 40%.
What temperature should a lithium mower battery be stored at?
Somewhere cool, dry and above freezing. Consumer Reports says most batteries do best between 40 and 80°F. EGO says below 80°F, ideally 50 to 80°F, and Ryobi’s 40V manual sets a floor of 50°F.
Does EGO’s battery discharge itself in storage?
Yes. EGO’s manual says its battery automatically self-discharges after one month of storage, then enters sleep mode holding about 30% charge. EGO says to fully recharge it before next use.
The short version
Off the charger, indoors, dry, and above 50°F. Set the charge your brand asks for: about half for EGO and Ryobi, full for DeWalt and Greenworks’ 40V packs. Check it once mid-winter, and charge fully before spring. Ten minutes in October can save you from buying a new battery in April.
Packing up the yard for winter?
The rest of the end-of-season jobs.
