How to Store Leaf Blower Batteries Over Winter: Six Steps That Protect Runtime

How to store leaf blower batteries over winter comes down to six habits: run or charge each pack to about half full, wipe it dry, take it off the tool and the charger, keep it indoors at room temperature, check the gauge once around midwinter, and let a cold pack warm up before you charge it. Makers disagree on the exact charge level, so I put their numbers side by side below.

Every December I carry the cordless packs from the machinery shed to the house on the day I clean the blower, because a shed shared with fuel cans and sprayers is a poor place to leave a pack. Below are the steps, the maker figures, the research behind them and the fire-safety limits.

How to Store Leaf Blower Batteries Over Winter in Six Steps

Follow these steps in order. Each one carries the figure a maker prints for it, and the next section lays out every maker’s numbers in one table.

1. Bring the charge to about half. According to EGO’s manual and Ryobi’s manual, a pack stored longer than 30 days should sit at 30% to 50% charge. According to Husqvarna, the figure is 50%. I do the last leaf job of the season with the pack I plan to store and stop when the gauge reads about half.
2. Take the pack off the tool. Ryobi’s manual says to always remove the battery pack before storing the device. According to DeWalt, you should disengage the battery from the tool before extended storage.
3. Take it off the charger and unplug the charger. EGO’s manual calls unplugging the charger and removing the pack when not in use good practice. According to Stihl, leaving the charger connected is a storage mistake.
4. Wipe it clean and dry. Ryobi’s manual says to keep the pack dry, clean and free from oil, gasoline and petroleum-based products. The machinery shed floor is dust, chaff and pruning sawdust, so I wipe each pack and its contacts with a dry cloth before it goes indoors.
5. Store it indoors at room temperature. EGO’s manual gives 50°F to 80°F as the best range and says not to store a pack outside or in vehicles. Ryobi’s manual says the same about outside and vehicles.
6. Check it once around midwinter. EGO’s, Ryobi’s and Makita’s manuals print six months between top-ups, so one check in the middle of a winter is cautious. I write the check date on a strip of tape on the pack.

This routine covers the battery only. The blower itself, and any gas fuel, need their own winter list.

What the Makers Say About Winter Storage

The table quotes each maker’s own document, and the document is named in the first column. The Ryobi 40V pack manual answers how to store Ryobi batteries for winter in one line: 30% to 50% charge, below 80°F and away from moisture, charged as normal every six months.

The disagreement is about charge level. EGO and Ryobi say 30% to 50%, Husqvarna says 50% and Stihl says 40% to 80%. According to DeWalt, a pack that will sit for more than six months should be fully charged first, and if you own a DeWalt pack, follow DeWalt’s advice for that pack. Greenworks, Milwaukee and Makita print no storage percentage in the documents listed above.

The best way to store lithium batteries over winter is to follow the figures printed for your own pack: its charge level, temperature range and top-up interval. Where the document gives no charge level, I store at about half. The figures belong to the document named, and models and revisions differ, so match the label on the pack you hold. I keep the maker’s number on the same tape strip as the check date.

Why Half Charge and Room Temperature Slow Battery Aging

A lithium-ion cell loses capacity even when nobody uses it. Researchers call that calendar aging, and it is the reason the advice on how to store lithium ion batteries over winter looks the way it does. Side reactions slowly use up lithium and thicken a film on the graphite, and both speed up when the cell is full and warm.

What the Lab Tests Found

In one lab test, pouch cells held at full charge for nine months lost about 10% of their capacity at 95°F and about 43% at 140°F, while cells held at zero charge showed almost no loss (1). In a second study, three kinds of cylindrical cells were stored at sixteen charge levels. The graphite electrode at high charge was the main driver of storage loss, and the authors conclude that a high storage charge should be avoided (2).

The zero-charge result does not mean you should store a pack empty. The deep discharge section below explains why.

What They Do Not Show

Both tests used single cells in a lab, not blower packs, and neither gives a figure for a cool house in January. I read them the way I read a field trial from another region: the direction carries over, the exact numbers do not. For storage, the lab results point one way: a pack kept full and hot ages faster than one kept at partial charge and room temperature.

Why a Cold Pack Must Warm Up Before It Charges

The documented risk in a cold shed comes at the charger. The makers that print a charging range put its low end between 39°F and 50°F, above freezing, even though several storage ranges reach below it.

Resting in the Cold

Some storage limits reach well below freezing: Makita’s safety data sheet gives -22°F and Stihl gives 14°F. Even so, EGO’s and Ryobi’s manuals say not to store packs outside or in vehicles, and the makers’ best-life advice is room temperature. I follow the makers’ temperature ranges and keep my packs in the house.

Charging in the Cold

The minimum charging temperatures are 50°F for Makita, 41°F for EGO and Husqvarna, 40°F for Milwaukee and DeWalt, and 39°F for Greenworks. OSHA warns that charging lithium-ion batteries below freezing can lead to permanent metallic lithium buildup on the anode, which raises the risk of failure (3).

The Ryobi, Milwaukee, EGO and Makita documents describe chargers that hold off on a cold pack, but I do not count on that. Any pack that spent the night in a freezing shed comes into the house and warms to room temperature before it goes on a charger. I let it sit and wipe it dry first.

Using a Cold Pack

A cold pack still works. EGO’s manual says the pack may pulse for the first minute to warm itself, Ryobi’s says it runs down to -4°F, and Milwaukee’s says it may buzz for a short time until it warms up. On frost mornings I bring the pack I need into the house first, and a pack straight from the cold shed gives me a shorter run than the same pack from the house.

Self-Discharge, Deep Discharge and the Midwinter Check

A stored pack changes slowly in two ways. It loses a little charge on its own, and a pack left empty can fall too low to recover. Both are the reason for one check in the middle of winter.

Self-Discharge

Lithium-ion packs lose charge slowly at rest. DeWalt says its packs have limited self-discharge, and Milwaukee says its packs hold their charge in storage longer than other pack types. Warmth speeds the loss up: in one lab measurement on cylindrical cells, the self-discharge current at 104°F was several times higher than at room temperature (4).

EGO builds the idea into its packs. According to EGO’s manual, after a month in storage the pack discharges itself to 30% and enters sleep mode, and a pack stored for a month or longer should be fully recharged before the next use. A low reading after a long rest on an EGO pack is therefore expected.

Deep Discharge

A pack stored empty carries a different risk from a pack stored at low charge. The pack’s protection circuit shuts it off when it gets too low, and a pack that sits at zero for months can drift below the point where the charger will restart it. In a lab study, large-format cells discharged far below empty developed an internal short circuit after copper dissolved inside the cell and deposited on the electrodes (5). Those cells were driven much deeper than normal use, so the study gives no figure for a blower pack, but the caution is plain: do not leave one empty for the winter.

The Midwinter Check

Makers print six months between top-ups for EGO, Ryobi and Makita, and about a year for Milwaukee. A typical winter runs four to five months, so one check around midwinter is cautious, not required. I do mine in January, because the blower comes out again in late winter for the twigs and sawdust under the plum rows, and I want one pack awake by February.

1. Press the fuel gauge button in the house and read it against the legend for your pack.
2. If the gauge has fallen to the lowest band, charge the pack indoors to about half, or to your maker’s range.
3. Write the date on the tape and put the pack back on its shelf.

Fire Safety for Stored Battery Packs

A stored pack stays quiet when it is intact, dry and away from heat, metal and anything that burns. Heat, metal on the terminals and damage are the hazards the manuals name most.

• Heat: Milwaukee’s manual says not to store a pack where temperatures may exceed 120°F, such as in direct sunlight, a vehicle or a metal building in summer, and Makita’s blower manual gives 122°F. EGO’s manual warns that temperatures above 212°F may cause an explosion, and Ryobi’s gives 265°F.
• Metal on the terminals: Ryobi’s manual warns that shorting the terminals together may cause sparks, burns or a fire. Makita’s blower manual says not to store a battery in a container with metal objects such as nails or coins, so keep packs out of toolboxes with loose hardware.
• Damage: EGO’s manual says not to modify or try to repair a damaged pack. OSHA lists bulging, cracking, hissing, leaking, rising temperature and smoking as signs that a battery must come out of service and stay away from flammable materials (3).
• Fuel and dust: Fuel cans, sawdust and chaff stay in my machinery shed, and the packs stay on a shelf inside the house, away from anything that burns.

Mistakes That Shorten Battery Life Over Winter

Every mistake below breaks a maker instruction, a safety bulletin or a lab result behind the rules on how to store lithium batteries for the winter. The one I guard against most is the pack left in the blower on the shed shelf, because the tool lives in the shed and the pack is easy to forget.

• Storing it full and warm. Full charge at high temperature cost the most capacity in the lab tests above.
• Leaving it in the tool or on the charger. Ryobi’s manual says to remove the pack from the device, and EGO’s says to unplug the charger and remove the pack.
• Charging a frozen pack. Bring it indoors and let it warm first.
• Letting it sit empty. A pack at zero for months may not wake up.
• Forgetting it for the whole season. The makers who print an interval give six months to a year, so one midwinter look is a precaution and a pack forgotten for more than a year is past every printed interval.
• Keeping it loose with metal. Terminals touching nails, coins or keys can short.
• Parking it in a truck or an unheated shed. EGO and Ryobi both say not to store packs outside or in vehicles.
• Ignoring a swollen or hot pack. Treat it as out of service, as the Stop Sign above says.
• Trusting a generic number over your maker’s. The table above shows the makers do not agree.
• Following another platform’s number. Check the label on the pack to see whose rules apply.

Getting Your Batteries Ready for Spring

A week before the first spring job, bring each pack into a room at normal temperature and let it sit until it feels the same as the room. Check the gauge, then charge it to full indoors, as EGO’s manual advises after a long rest. The night before the first job I charge it again and fit it to the blower.

In late February I compare the first runtime of the season with the last one from autumn, and a pack that falls far short is the one I watch. When it is time to match packs to a blower, the leaf blower guides on this site cover the models. Settle on one routine for how to store leaf blower batteries over winter, and let that February comparison tell you whether it works.

Frequently Asked Questions

Should lithium batteries be stored inside during winter?

Lithium batteries should be stored inside during winter, in a dry room at normal room temperature. EGO’s and Ryobi’s manuals both say not to store packs outside or in vehicles, and a pack that sat in a freezing shed has to warm up before it can be charged.

Is it bad to leave power tool batteries in the cold?

Leaving a power tool battery in the cold goes against the makers’ advice, which is storage at room temperature. Their charging minimums run from 39°F to 50°F, so bring a cold pack indoors and let it warm before it goes on the charger.

How should I store lithium batteries when they are not in use?

Store lithium batteries that are not in use at about half charge, clean and dry, off the tool and the charger, at room temperature and away from metal and heat. If your maker prints a different number, follow it.

Is it safe to store lithium batteries in the house?

Storing lithium batteries in the house is safe when the packs are undamaged, off the charger and kept in a cool, dry spot away from heat, metal and anything that burns. Keep them away from fuel cans, sawdust and direct sun, and take a swollen, hot or leaking pack out of use right away.

Where to store lithium batteries for winter?

Lithium batteries belong in a dry indoor room at normal room temperature, such as a workshop shelf or a closet. Avoid a freezing shed, a hot attic and a vehicle, and keep the pack away from fuel and dust.

References

1. Mao Z, Farkhondeh M, Pritzker M, Fowler M, Chen Z. Calendar Aging and Gas Generation in Commercial Graphite/NMC-LMO Lithium-Ion Pouch Cell. J. Electrochem. Soc. 2017;164(14):A3469-A3483.
2. Keil P, Schuster SF, Wilhelm J, et al. Calendar Aging of Lithium-Ion Batteries. J Electrochem Soc. 2016;163(9):A1872-A1880.
3. Occupational Safety and Health Administration. Preventing Fire and/or Explosion Injury from Small and Wearable Lithium Battery Powered Devices. Safety and Health Information Bulletin SHIB 06-20-2019. US Department of Labor; 2019.
4. R-Smith NA-Z, Moertelmaier M, Gramse G, et al. Fast method for calibrated self-discharge measurement of lithium-ion batteries including temperature effects and comparison to modelling. Energy Rep. 2023;10:3394-3401.
5. Guo R, Lu L, Ouyang M, Feng X. Mechanism of the entire overdischarge process and overdischarge-induced internal short circuit in lithium-ion batteries. Sci Rep. 2016;6:30248.

Safety Note: Leaf blowers throw debris and can damage your hearing. Wear eye and ear protection, read the manufacturer’s manual, and check your local rules on noise and operating hours.