At Optera Gear we love Cold Case phone cases. We resell them and help Cold Case with its distribution channels.

This summer Andrea Tanner from Wet Dreams River Supply in Grand Junction, Colorado (one of Cold Case’s resellers) reported getting 10 days of battery life on her phone when using a Cold Case on a Desolation Gray river trip in May 2023.  We are very confident getting at least three days out of a phone battery when using a Cold Case but 10 days was pretty amazing.

So, we decided to do a bit more of a formal test of battery life when using a Cold Case on our next river trip.  We learned a couple of cool things.

About the Trip - San Juan River

We launched August 16, 2023, on our favorite section of river - the San Juan from Sand Island to Mexican Hat, Utah.  An August trip on the San Juan is a great real-world test of Cold Case’s thermo- insulation properties given that it gets really damn hot in August.  

Our trip lasted three days and two nights.  For Bluff, Utah (the nearest town to the river put in), the actual temps for our trip were (per USGS):

• August 16, 2023 - High: 101.6F, Low: 73.4F
• August 17, 2023- High: 100.5F, Low: 77.7F
• August 18, 2023 - High: 95.5F, Low: n/a

We clipped our Cold Case with a 4-year-old Apple iPhone XS inside to our captain’s bag in full view of the sun for the entire trip. During the trip, we did use the phone for photos, one video, and a couple of GPS position checks.  The phone was set to airplane mode and left on. The Cold Case and phone stayed on the raft for the entire trip (day and night) - 54 hours in total. 

Battery Life

We launched at 9:35 am on August 16 with a full charge on our iPhone.  We checked the battery level of the phone at about 10 am every day and at the take-out on August 18.  The results are as follows (see Appendix for actual phone charge level data):

Over the approximately 54 hours we were on the river our iPhone only used 34% of our battery.  This data suggests that we used about 15% of our battery life per day over our trip.

If we extend this data trend, the data suggests 6.66 days of battery life out of a single charge when using a Cold Case - given consistent temperatures and app usage patterns.

So, could our friend Andrea who reported getting 10 days out of a single charge be valid?

Our iPhone reports that our iPhone's Maximum Charge Capacity is only 83%.  Using the same math above, if our phone was new and did not have degraded battery capacity, we would get approximately 1.1 days more of battery life or 7.8 days in total. Pretty darn close to 10 days.

More importantly, our trip was substantially hotter than Andrea’s. Andrea reported average high temps of about 85F while on our August San Juan trip, we consistently saw temps over 100F.  Higher temps degrade battery performance and capacity.

We can totally see getting 10 days out of phone battery when using a Cold Case - depending on temps, settings, and app usage.

Magnet Closure

On this same trip, we brought a BadFish Badfisher stand-up paddle board and thought a stand-up board would be the best way to test the IPx8 magnet closure on the Cold Case. 

So, we strapped a Cold Case to the bow with a phone in it for the entire 27-mile float.  One thing to know about the San Juan River is that it is insanely muddy. The San Juan would be a great way test out how waterproof the Cold Case magnetic seal was.

We are happy to report that we never noticed any water or mud enter any of the Cold Cases or get our phones wet.   This includes running three Class 2 rapids on the standup board.  Picture above is the top of 8-foot Rapid.

Note - we did not use any aids to test for water entry except basic observation when we removed the phones from the Cold Case.

Our Thoughts

Over many trips using Cold Case, we have become very comfortable doing three days and two nights out without taking a means to recharge our battery when we use a Cold Case. We have generally found that without a Cold Case, our phone would only last about 24 hours on a single charge.

The data above suggests that we could push our rule of thumb - 3 days, 2 nights - up a bit.  This information is helping us get comfortable with a trip limit on a single charge of 5 days, 4 nights when using a Cold Case with daytime temps around 100F with light application usage.  We could push past five days but that might be going too far if you need to use your phone a lot in an emergency.

Please note, we did not use our phone much on the San Juan trip.  We took some pics and got a few GPS fixes to make sure we were at the right camps.  We did not watch videos or play games on our phone.  You can see our low application usage patterns in the Appendix data. How you use applications will dramatically change your battery consumption and is something you need to consider.

Before you decide on how long you can go without taking a means to recharge your phone, please give thought to the weather, how much you will be using your apps, and the state of your phone.  Everyone needs to make situationally appropriate decisions for themselves. Hopefully, the information above can help guide those decisions.

Notes on Testing and Data

We did not plan this exercise or execute it as a scientific test.  Rather we thought it would be meaningful to capture some observational data and share it. We understand and are not claiming that the information presented above is scientifically or statistically accurate.  Rather we are reporting a single set of real-world data from a real-life use case for Cold Case.  We used basic math and made basic conclusions. We understand that a control point would make this information more meaningful, and we don’t present one.  Please use this information in combination with your own personal experience to make informed decisions.

 Appendix - Supporting Data

Image 1 shows the screenshots from the Battery Information Screens from Settings on our iPhone.  These screenshots show the time of the measurement, battery level at the time of the screenshot, battery level over time, and activity (application usage) over time. 

Image 2 shows the Maximum Capacity rating of the battery of the iPhone used to capture the data above.

Image 3 shows the iPhone version and iOS level of the phone used to capture the above data.