Battery Life and Cold Weather Riding

Batteries don't get along with cold temperatures. 

GPS units, lights, phones, backup batteries, cameras.  All of these electronics have trouble as the temperature plummets.  We've noticed that at about 20 degrees Fahrenheit is when battery life become noticeably shorter.  At about zero degrees batteries die impressively quick; we've had trouble keeping a 14 hour battery last for one hour.  In fact, batteries can die 10-times faster, or more, as the temperature nears zero.

Overall, low temperatures cause a three primary of battery issues:

  • Reduced use time.  Anywhere from a 50% to 90% reduction.
  • Unreliable battery life reading.  Battery life readings become unreliable as the temperature drops.  You may well not have a warning when your phone or Garmin dies.  And this leads to...
  • Random inexplicable shutoff.  We've had this happen a few times over the years.

The fundamental question we ask is, "How do I survive an 8-hour ride if my Garmin, light, or whatever electronics are going to die in an hour?"

We've learned some simple tricks that enable a long ride in zero degree weather.  Each electronic item gets different treatment:

GPS Unit

We have worked with three methods:

  1. Carry two GPS units.  This is our preferred method, by far.  Why two?  While one unit is navigating for you, and slowly freezing, the other unit is in your jersey pocket, staying warm.  When the navigating unit reaches it's cold battery tipping point, swap it out with the warm unit.  Let the frozen unit warm up in your jersey.  Repeat the swap-out at appropriate tipping point times.  The worst, or fastest, swap-out rotation pace that we've seen is about 30 minutes.  If you use this method, two fully charged Garmin 1000s will last about 22 hours in zero degree weather.  Of course, most people don't want to own a second GPS unit. In that case, we know of two options:  
  2. Share GPS units.  If you're riding with someone that also has a unit, share them and use the swap-out method described above.
  3. Start-stop.  If you are riding alone, depending on your route and goals, ride with the unit in your jersey whenever possible and remount it on the bars when needed.  This is cumbersome but it's a lot better than having to stop because your GPS dies.  This is a good exercise for memory improvement.  Another side benefit of this method it that you have one continuous file to upload at the end of your ride.

Lights -- Headlights and Taillights

We have two methods for managing cold weather lighting:

  1. Carry two or more lights.  Follow the protocol we recommend for GPS Units:  swap them back and forth from warm pocket to cold handlebar or helmet as the cold tipping point approaches.  this is one of the many advantages of small modular light systems.  We strongly recommend a four light systems for mixed terrain riding -- one helmet mounted and one bar mounted.  Regarding taillights, see our battery notes below.
  2. Use a generator light system.  We've not had problems with generator hubs in cold temperatures.  The primary challenge with a generator is that a provides limited lumens -- about half of what we ride on the trails.  However, half is infinitely better than zero lumens.

Mobile Phone

This is simple:  Keep the phone in a jersey pocket.  That's all.  We also strongly recommend keeping your phone in a waterproof zip-lock bag; you get humid in cold weather and phones don't like this.  As an aside, we've read that keeping your phone turned off will help prolong battery life; this is true if it's going to be sitting out in zero degree weather for hours, however, you'll be keeping it warm so having it turned off will not be relevant to cold weather usage.  On a related note, on its website, Apple suggests that in addition to shortened battery life, "low-temperature conditions might [...] cause the device to alter its behavior [...]"  Be aware.

Backup Batteries  

This is simple, keep the battery in a body contacting pocket.  If it's warm it'll be ready to use.  

An important word of preparation:  A battery will not take a charge when it's too cold.  To charge, you have to get charger and chargee near your body core heat.


This would seem easy:  Just keep the camera in your jersey pocket and it'll stay warm for when you need it.  The only cautionary comment about this is that the environment under your jacket is very humid and cameras do not like this humidity at all.  The simple solution is to keep your camera in a waterproof bag.  A typical zip-lock bag is not waterproof.

Don't put any of your electronics in a handlebar bag or saddle bag.  While this will slightly slow down the cold hand of death, it will not prevent your batteries from dying.  This may seem obvious but we've seen numerous people make this mistake.  Keep your electronics warm and dry.

Why do batteries die so quickly in cold weather?  The battery isn't actually draining faster; the chemical reaction that produces the electricity proceeds more slowly and that means less energy is produced.  The colder the temperature, the more difficult for the chemical reaction to occur.  This is helpful to understand because it explains why the battery isn't discharging faster -- it's actually discharging more slowly -- so that warming it up will allow the chemical reaction to function properly again.

As a precise detail, the battery is actually discharging slightly faster in very cold weather, but that acceleration is minimal.  We've not found any data regarding this but our personal experience suggests that the total charge lost in trying to generate the chemical reaction is somewhere between 5 and 15%.

Battery Operated Taillights

The type of battery has an influence on battery life.  For most electronics, this is irrelevant because the battery is as it comes; you have no choice.  However, for a AA or AAA battery operated taillight, you do have some options.  Fortunately, the choice is simple: 

Lithium Ion:  This is the right choice for cold weather riding.  Best performance is with lithium-Ion -- Li-Ion -- batteries.  Performance begins to drop at about 30 degrees but that's a lot better than any alternative. At about zero degrees is when you see severe drop in light time.  by the way, you may read that lithium ion batteries are not great in the cold; that's true relative to some other battery technologies but those are not available in AA or AAA batteries.  So, lithium ion it is.

Alkaline batteries employ a water-based electrolyte that performs poorly in subfreezing temperatures.  This can also lead alkaline batteries to leak or burst.

Rechargeable Nickel Metal Hydride -- NiMH -- batteries are not great either.  They have the same basic issue as alkaline batteries.

Ready to Ride!

That covers most of what we've learned from riding in the cold.  What are your tricks for keeping your electronics running during the cold season?