How Long Do Heated Socks and Jackets Last? Battery Life in the Cold

How long heated gear lasts: what makers say

Heated socks, gloves, vests and jackets all work the same way. Thin heating wires in the fabric warm up when a battery pushes current through them. Higher settings send more power, so they make more heat and drain the battery faster.

Here's what makers list for some popular gear. Run times are almost always measured with a fresh, fully charged battery, and many are listed as "up to."

From each maker's product page. ORORO's figures are from an SGS lab test at 14 °F. DEWALT says a 2.0 Ah battery gives up to 9 hours but doesn't say on which setting.

A real-world check: Outdoor Life tested heated socks on their highest setting. Gerbing's 7 V socks ran about 3 hours, ActionHeat's AA socks about 3 hours on fresh alkaline batteries, and Hotronic's XLP 2P almost 10 hours, though that pair stepped itself down a level partway through.

So for a morning sit in the stand, almost anything works. For a full day on the ice or an all-day sit, you'll want low settings, a bigger battery or a spare.

Working out your own run time

Every heated garment is just a small electric heater. The math is the same one an electrician uses for any load:

Hours = battery watt-hours ÷ heater watts

1. Find the battery's watt-hours. Many packs print it on the label. If not, multiply volts by amp-hours. A 7.4 V, 5.2 Ah (5,200 mAh) pack is 7.4 × 5.2 = about 38.5 Wh. Divide mAh by 1,000 to get Ah.
2. Find the heater's watts on each setting. Makers rarely list it, but you can work it backward from their run times. ORORO's 38.48 Wh apparel battery lasting 3.3 hours on high means about 11.7 W on high, about 5.8 W on medium and about 3.4 W on low.
3. Divide, then knock some off for the cold if the battery will be in an outside pocket or hanging off your sock cuff.

The same math explains why voltage alone tells you nothing. A 5 V sock pack and a 7.4 V pack with the same watt-hours hold the same energy. What matters is watt-hours and how hard the gear pulls.

Our Heated Gear Battery Life Calculator does this for jackets, vests, gloves and socks, including the cold.

Why there's no single answer for "how long"

• The setting matters most. On Milwaukee's jacket and ORORO's heated apparel, high uses three to four times the power of low.
• How many zones are on. Milwaukee's jacket has two zones, DEWALT's hoodie three. Turning off the back panel saves power.
• Battery age. Lithium-ion packs hold less after a few seasons of charging.
• Battery temperature. Covered next.

Why batteries die fast in the cold

The chemical reactions inside a battery slow down as it gets colder, so the battery can't deliver as much of its energy. Battery University gives a rule of thumb: a battery that delivers 100% of its capacity at 80 °F will typically deliver only about 50% at 0 °F.

The good news is that the loss is temporary. Battery University notes the reduced capacity only applies while the cell is cold. Warm it back up and the energy is still there. That's why a phone that died on the ice can show 30% again after a ride home in the truck.

Heated gear batteries usually sit in a pocket against your body, so they stay warmer than the air. Sock batteries are the exception. They clip to the cuff, right where your boots and the stand floor are coldest.

Charging in the cold is worse than using in the cold

Using a lithium battery in the cold just costs you hours. Charging it below freezing can damage it for good. REDARC explains that charging lithium below 32 °F causes lithium plating, a buildup inside the cell that permanently cuts capacity and gets worse each time. REDARC's best charging range is 41 °F to 113 °F. ORORO also says to charge its batteries at room temperature.

Getting more hours out of heated gear

1. Charge fully at home the night before, at room temperature.
2. Preheat on high, then turn it down. DEWALT builds a preheat mode into its controller for this reason. Low uses about a quarter to a third of the power of high on the jacket and vest above.
3. Dress like the gear isn't there. Good base layers and an insulated outer layer hold in the heat, so you can run low. Outdoor Life's tester found warmer socks lasted longer because they rarely needed the top setting.
4. Turn it off on the walk in. You're making plenty of heat walking with a pack, and sweat is what chills you later on stand.
5. Keep the battery warm. Use the inside pocket the jacket provides, and keep spare packs in an inside chest pocket.
6. Carry a spare. ORORO recommends it, and it's the easy fix for long days.
7. Don't drain the pack charging your phone unless you have to. ORORO notes that running USB devices off the jacket battery shortens heat time.
8. Store packs at room temperature over the summer and top them up every few months. ORORO suggests a charge about every six months in storage.

And don't count on heated gear alone in the backcountry. Outdoor Life's advice: batteries can fail, so layer as if you had none.

See the jackets, vests, socks and spare batteries we like on our heated gear page.

Keeping your other batteries warm

The same cold that drains your sock batteries goes after everything else in the blind or the shanty.

From Apple support, LiTime's battery specifications, Deeper's support page and Energizer's L91 datasheet.

Bioenno Power's tips for ice fishing batteries: charge overnight at home, bring the battery into a heated shelter or warm truck before charging it in the field, use an insulated bag, and if you use chemical hand warmers, put them near the battery, not touching it.

For more on keeping a flasher running through a cold day, see our fish finder power guide and the Fish Finder Battery Life Calculator. Trail camera batteries are covered in our trail camera guide.

Questions people ask

How long do heated socks last on one charge?

Usually about 3 to 4 hours on high and 5 to 14 hours on low, depending on the battery. Lenz lists 3.5 to 4.5 hours on its highest level and 10 to 14 hours on its lowest with the rcB 1200 pack.

How long does a heated jacket battery last?

Milwaukee's M12 heated shirt jacket lists 8 hours on low, 4 on medium and 2 on high with the CP2.0 battery. A bigger battery from the same tool line runs longer.

Are heated socks worth it for sitting in a tree stand?

For long, cold sits they can be. Your feet don't move much on stand, and boots on a metal platform get cold. Pick socks whose low-setting run time covers your longest sit, and carry a spare pair of charged packs.

Can I use a phone power bank for heated gear?

Only if the gear is made to run on 5 V USB power, like the DSG 5V socks. Gear built for 7.4 V or a tool battery needs its own battery. A mismatched voltage won't heat properly and could damage the gear.

Why does my heated gear die so fast in the cold?

A cold battery can't deliver all its energy. Battery University says about half at 0 °F. Keep the pack close to your body and it'll last much closer to the rated time.

Can I take heated gear batteries on a plane?

In the U.S., the FAA says spare lithium-ion batteries must go in carry-on bags, not checked bags, with the terminals protected. Batteries up to 100 Wh are fine without airline approval. Check your airline, since some set stricter limits.

Can I charge heated gear batteries in the truck?

Yes, once the cab is warm. Charging lithium below freezing can damage it, so let a cold pack warm up first.