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Reviews > Clothing > Socks > Gerbing 7v Sock Liner > Owner Review by Bob Dorenfeld

Gerbing 7v Heated Sock Liner
Owner Review By Bob Dorenfeld
December 8, 2013

Tester Bio
Name: Bob Dorenfeld

I'm an active hiker, snowshoer, skier, backpacker, amateur geographer and naturalist. Home base is the Southern Colorado Rockies, where I usually journey from 7000 ft (2100 m) to above treeline, with occasional desert trips to lower altitudes. Six to 12 miles (10 to 20 km) hiking in a day is my norm, including elevation change of as much as 4000 ft (1200 m) in a day. Most of my backpack trips are two or three nights, sometimes longer. Often I hike off-trail on challenging talus, snowfields, or willow brakes, with occasional bouldering.

Email: geartest(at)sageandspruce(dot)net
Age: 55
Location: Salida, Colorado, USA
Gender: M
Height: 5' 6" (1.68 m)
Weight: 135 lb (61 kg)

Product Overview

Manufacturer:    Gerbing
MSRP:    US$199.99
Material:  Lycra
Power:  7V 2.2 Ah lithium ion battery (per sock), rechargeable
Maximum Heat:  135 F (57 C) @ 7.7W
Replacement battery:  US$25.99
Included Accessories:   Battery charger (for 120V receptacle)
Battery pack weight, each:  4 oz (110 g)
Sizes:  xs, s, m, l, xl, 2xl

 Alt Text
Photo: Gerbing
battery with holderThe Gerbing sock liner is a pair of heated socks for keeping feet warm in cold weather.  Despite the designation "liner" it can be worn by itself, or under another pair of non-heated socks.  On LegThe upper (black) part is made of a thin stretchy Lycra, and the bottom (red) section is a thicker, non-stretch Lycra.  The bottom section contains what Gerber calls "microwires" (tiny wires that I'll refer to as micro wires) that conduct heat to all parts of the foot - bottom, sides, and top, and is therefore more durable than the top stocking.  According to Gerbing the sock liner both insulates and wicks moisture, in addition to the heat function. 

A round power cable 1/8 in (0.3 cm) thick starts at the middle side of the foot, then runs along the back side and up the leg, terminating in a plug for the battery.

The 7V battery rests in a fabric case which is held to the calf by a hook-and-loop strap.  The cable is easily detached from the battery for recharging and for putting the socks on and taking them off.

Field Performance    

Ah, warm feet - who doesn't want to keep toasty while snowshoeing, skiing, or on any outdoor adventure?  Especially for those of us who's feet tend to get cold outside, a little bit of technological assistance is welcome.  I found the Gerbing heated sock liners about three years ago, and initially balked at the price.  But after trying out less expensive heated socks and discovering that they either didn't keep my feet warm, or were uncomfortable to wear, or both, I gave the Gerbings a shot and have been very satisfied with them.  I am now in my third winter wearing them for day trips of snowshoeing and skiing, where I am exposed to outside temperatures as low as -15 F (-26 C).  All told I've put some 150 miles of walking/Nordic skiing on these socks, plus about twenty days of alpine skiing.

While searching for heated socks I found that motorcycle and hunting specialty retailers tend to have the best selection.  Gerbing makes a large line of heated clothing in addition to their sock liners, some of which may be of interest to me as a non-motorized outdoorsman.


Since the socks are made of rather delicate Lycra, I slip them on very carefully to avoid tearing the stretchy upper calf portion.  Usually I roll the tops down to avoid snagging on a toenail (I also make sure my nails are trimmed), then gently slide into the foot, tugging the heel backwards into position, and finally pulling up the black tops to just below my knees.  The power cable goes on the outside of the foot, but otherwise the socks are not made for left or right.  I'll wiggle the cable a bit to make sure it doesn't sit too far down into the instep: ideally it should come up along the foot's outside, then across the ankle and up the outside of the leg.

Battery with holderI usually have the battery holder detached from the cable before putting on the socks.  Then, using the hook-and-loop strap I'll attach the battery holder (photo at left) at about the thickest part of my calf and pull the strap fairly tight to keep it in place, having routed the cable underneath the battery case.  It's easy to readjust the strap later on the trail if the case slips down or feels too tight.  Finally, I'll plug the cable connector into the top of the battery and secure it with the small fold-down hook-and-loop strap.  If I'm wearing long underwear I'll pull the sock leggings up over the underwear legs so that the cable and battery pack will be accessible.  Now I'm ready for a warm adventure!

What sets these heated socks apart from some other products is the micro wire assembly: very small but strong and flexible wires run throughout the red foot portion, small enough that I cannot feel them at all, despite the thinness of the Lycra material.  Once I've got the socks fitted as described above, I hardly notice that they're not regular wool or polyester socks.  Sometimes I can feel the cable where it runs across my foot and up the ankle, but a quick removal of my boot and repositioning of the cable fixes that for the rest of the day.  And importantly for alpine ski boots, the battery pack sits high enough on my calf to clear the boot tops with room to spare.

A note about sock thickness and placement:  The Gerbings are somewhere between a thin and a thick hiking sock so I usually slip on another thin sock over them.  For alpine ski boots, I've found that just the Gerbings are sufficient because of the way my ski boots are sized.  However, I'll always wear these heated socks directly against my skin, since that's the best way to get maximum benefit from the heat; I can always find a good combination with second-layer socks to fit whatever footwear I'm going outside in.


All right, now I'm on the trail and ready to keep those feet toasty!  The battery has four levels, labeled from lowest to highest as 25, 50, 75, and 100 percent of maximum power.  Most of the time I choose 25 or 50 percent, but if I'm cold at the start, or it's an especially cold day outside, I'll choose 100 to start.  I can feel the heat within two minutes, and will often turn down the setting after five or ten minutes of activity after the blood gets going.  Although I have not measured the heat output to verify Gerbing's specs, I can say that the highest setting is definitely warm - not hot, but I know it's there.  Most of the time I just need to keep my feet from getting cold, and don't need them to feel hot, so I choose the lowest setting that keeps them from going numb.  Starting out cold means it'll be hard to get the feet warm and even with the advantage of heated socks I'll use up far more of the batteries than if I had started out warm.

Battery at 100%Since the battery packs are strapped onto the outside of the legs, it's easy to see and adjust the output using the power button, which is big enough for my fat fingers (but not big enough to use with thick gloves, unfortunately).  The photo at left shows the green light at the 100 percent level (in operation, the battery would be inside the holder and under the transparent cover, secured by the strap at the top).  The button has a nice responsive click, and the percentage indicators light up green in succession:  first click from off is 100 percent, and so on back down to off.  In bright sunlight the green level light can be hard or impossible to see, so I'll either cup it with my other hand, or turn away from the sun to make it more readable.  There is no beep or other sound when the button is pressed.

Battery Performance

Gerbing states that the 2.2 Ah power cells will deliver heat for two hours at 100 percent, three hours on 75 percent, five hours on 50 percent and up to eight hours on 25 percent.  While I've not myself monitored their performance as closely, for me the batteries are good for one or two all-day winter outings, depending on how high I needed to set the heat, giving a total battery time of about 6-8 hours before they need to be recharged.  Most of that time is spent at either the 25 percent level or off, with only occasional time at higher levels for a quick warm-up.   I'm not sure how very cold temperatures affect these lithium batteries' performance, but I haven't noticed any significant drop in heating ability with very low temperatures (below 0 F (-18 C)).  When the batteries do start to lose power they won't switch to the higher levels via the button, indicating time to recharge when convenient.

Battery Maintenance

Gerbing recommends starting an activity with the batteries fully charged, but if I know I've not used them much on a previous outing, and it's been only a week or two between since then, then I'll use them without recharging first.  The battery charge may also be checked when not connected to the socks: after unplugging the cable from the battery, push and hold the power button to show the percentage of charge left on the battery.Battery charger

The 120V wall charger has a double-ended attachment and will charge both batteries at once.  As they are charging, the green lights will successively light up from bottom to top; this also indicates the batteries' charge level.  If the lights stop at 50 percent, then it's only half-charged.  I find that it takes as much as 6 hours to fully charge one of these batteries from a fully-discharged state, about half that time for half-charged.  Having both batteries charging at the same time does not affect rate of recharge.  An indicator light on the charger, one for each battery, glows red when charging, green when done.

Gerbing also recommends that these batteries not be left discharged for lengthy periods (exact time not specified), but that at least 25 percent of charge be maintained to preserve life and performance.  So after my winter activities are done, or if I expect a long break between uses, I'll fully charge them for the shelf.  I'll check them again about every 2-3 months during the warm season and recharge when necessary.

I have no information on life expectancy of the batteries or how many recharges they'll take, but when they need to be replaced they are available directly from Gerbing and other retailers.  However, to date there has been no noticeable degradation in my batteries' performance or charge time.

Sock Maintenance

I wash my socks once or twice during the winter use period, by hand, in gentle soap, being very careful not to roughly handle the red foot section containing the micro wire system.  I squeeze out the excess water and hang them to dry in the sun.  Even if not washed, hanging the socks (or any clothing, for that matter) outside in the sun helps to freshen them up, and the UV radiation (especially at the high altitude where I live) will eliminate some microbes from the fabric.  (But note that UV can degrade synthetic materials as well.)  Even so, I don't notice that the socks smell very much after use.  Also, as mentioned above, I keep my toenails trimmed to avoid tearing the heated foot section and the fragile upper leg area.

Final Thoughts    

These Gerbing heated socks have allowed me to participate in cold-weather activities like snowshoeing and skiing that would be hard for me without the extra heat for my feet.  The socks do seem to wick some moisture, but I can't substantiate Gerbing's claim that they also insulate; in any case, I let my second pair of socks, plus the boots, provide the necessary insulation.  Although their cost seems high, with careful use I expect these socks to last for many more years of use.

  • fast heating time
  • entire foot is heated
  • comfortable fit of sock around the foot
  • comfortable fit and light weight of battery pack, which is easily adjusted to leg
  • long-lasting battery charge
  • upper leg fabric is very fragile, can rip easily if not careful
  • lower foot fabric is less fragile, but still care must be taken while slipping on and off
  • battery power button too small to use with heavier gloves or mittens

Reviewed By
Bob Dorenfeld
Central Colorado Mountains

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Reviews > Clothing > Socks > Gerbing 7v Sock Liner > Owner Review by Bob Dorenfeld

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