Power Bank for Phones, GPS, Camera, etc
Posted: Sat Jan 21, 2017 1:54 pm
I thought of this thread when I began discussing using GaiaGPS on a smartphone and the need for recharging. I also know that many people don't know some of the information contained here.
I carry a headlamp/flashlight, an InReach SE satellite GPS/Text Messenger, an iPhone 6S Plus, and sometimes another camera besides the one on my phone. I have used the InReach to send a text to friends to have a ranger come to assist me in a non-emergency situation where some help was needed. I also use the phone with Gaia GPS installed as a GPS. On long trips there may be a need to recharge things that are used.
Since the InReach & Phone are sealed systems, you can’t change batteries or carry extras. I looked into various systems for charging where I could use the same batteries that are in the headlamp and the electricity could be used wherever needed. Many people carry small lipstick-shaped & sized rechargers such as those sold by Anker. The system described below will give something that is ca. 0.3 oz lighter than an Anker (3.0 oz) but is more flexible in that the battery can be used in a headlamp if needed.
While I can give you a lighter, more flexible system there are some drawbacks.
Power Banks
First a word about power banks. Most of these are a bit misleading in their advertising. While I have a PhD in chemistry I am not an expert in electricity and I hope any mistake I made is small.
A charger is not nearly as efficient as many of the advertisements lead you to believe. For example, I have an iPhone 6s plus with a 2750 mAh battery. I believe you can buy small, lipstick-style rechargers with up to 3500 mAh. The thought would be this would recharge my phone with power left over. However, only ca. 1800 mAh of this 3500 can be transferred. You will need 1.5 batteries to fully recharge my fully depleted phone. Two reasons. The first reason is the batteries in Anker & other chargers of similar type (including mine) operate at 3.7 volts. When recharging a device, rather than a voltage of 3.7, you need a voltage of 5.0. All rechargers contain a converter to do this. In converting to 5.0 you take a hit of 26%. 3.7 divided by 5.0 gives 0.74. Multiply 3500 by 0.74 and you get 2590 mAh of available charge. This is theoretical as converters in chargers are not 100% efficient. There is always some loss. The second reason is that the available mAh cannot be transferred 100% due to electrical resistance. There is internal resistance in the battery holding the charge, the charger, resistance in the cable used to transfer, resistance in the circuitry of the phone, etc. I’ve tested several different charging systems including an Anker (which worked fine) and I almost always find that I’m transferring no more than slightly more than 50% of the mAh reading that is on the battery. I've lost the piece of paper but I seem to remember 53%.
The system that I’ve been investigating is based on rechargeable lithium-ion batteries. In particular, the battery size, 18650. It is 18650 batteries that are inside almost all portable chargers including the lipstick size rechargers. This appears to be about the best weight to electricity content ratio I’ve seen in my limited experience. One 18650 battery weighs slightly less than 1.7 oz. I have found that in the past year or so that at least 3 companies that specialize in flashlights have begun selling a charger that can also operate as a power bank. The model I’m testing is the Nitecore F1. Fenix ARE-X1 is probably the same. As far as I know, the Nitecore & Fenix will only work with lithium-ion batteries. Both cost the same at ca. $10. Batteries will cost $12-15 each.
This charger weighs 1.0 oz. Adding the battery weight gives a total of 2.7-2.8 oz for a power bank with one 18650 battery installed. The current state-of-the-art for 18650s is 3500 mAh & I only use the protected versions - as only they will work in flashlights/headlamps. I have to estimate how many times I will recharge the phone & InReach and maybe the camera if I happen to record video which will burn through the battery.
Now you just carry extra batteries if you have a longer trip/need. The batteries need to be protected from contact with metals and from letting one end of one battery come in contact with the end of another battery. (Think videos on the internet of people who had fire coming out of their pocket where they had their Vape for smoking. These use 18650 batteries.) A flimsy 3 x 4” ziplock bag (found in craft jewelry departments) will do the job. It will hold 3 18650s for a total weight of 5.0 oz. I haven’t used this bag in the field and you would want it somewhere in the pack where there is no wear & tear.
I tested this system with my phone multiple times last fall and it always worked; however, it’s not very good at getting to 100% recharge but it will get to 95% quite easily.
The batteries are heavy; with one 18650 weighing about the same as 4 AAA batteries which are used in most of the headlamps I see used in equipment lists. You have to really make decisions about usage on long trips without resupply as you can easily end up carrying a pound of batteries.
By the way, although alkaline batteries generally have higher mAh capacities than rechargeable batteries, websites dedicated to batteries state that you cannot directly compare capacities of alkaline batteries with rechargeable batteries. They all claim that in high-drain devices such as cameras, a nimh battery of lower capacity will run a camera longer than an alkaline battery.
The charger/power bank I have used to recharge my iPhone, the InReach SE, a Sony a6000 camera, and a Nikon Coolpix P900 camera. I use a single cable sold by PowerTraveler which has both a lightning connector for the iPhone & a micro USB for most other devices. The cable is ca 6” long and weighs 0.3 oz. It’s also expensive at $25.
I’m still evaluating headlamps that use 18650 batteries & have narrowed it down to a couple of this season. Please note that discussing headlamps requires a whole other thread as the information given on manufacturers websites is dramatically misleading - especially run times. Example, there is a manufactures standard for run time. This standard allows them to report the time it takes a headlamp to go from emitting full lumens to when it’s emitting 10%. For example, it may start at 100 lumens and only run that level for an hour or so but it has a run time of 40 hours before it gets down to 10 lumens.
Another negative besides weight is rechargeable lithium-ion batteries are not very efficient in cold weather.
I carry a headlamp/flashlight, an InReach SE satellite GPS/Text Messenger, an iPhone 6S Plus, and sometimes another camera besides the one on my phone. I have used the InReach to send a text to friends to have a ranger come to assist me in a non-emergency situation where some help was needed. I also use the phone with Gaia GPS installed as a GPS. On long trips there may be a need to recharge things that are used.
Since the InReach & Phone are sealed systems, you can’t change batteries or carry extras. I looked into various systems for charging where I could use the same batteries that are in the headlamp and the electricity could be used wherever needed. Many people carry small lipstick-shaped & sized rechargers such as those sold by Anker. The system described below will give something that is ca. 0.3 oz lighter than an Anker (3.0 oz) but is more flexible in that the battery can be used in a headlamp if needed.
While I can give you a lighter, more flexible system there are some drawbacks.
Power Banks
First a word about power banks. Most of these are a bit misleading in their advertising. While I have a PhD in chemistry I am not an expert in electricity and I hope any mistake I made is small.
A charger is not nearly as efficient as many of the advertisements lead you to believe. For example, I have an iPhone 6s plus with a 2750 mAh battery. I believe you can buy small, lipstick-style rechargers with up to 3500 mAh. The thought would be this would recharge my phone with power left over. However, only ca. 1800 mAh of this 3500 can be transferred. You will need 1.5 batteries to fully recharge my fully depleted phone. Two reasons. The first reason is the batteries in Anker & other chargers of similar type (including mine) operate at 3.7 volts. When recharging a device, rather than a voltage of 3.7, you need a voltage of 5.0. All rechargers contain a converter to do this. In converting to 5.0 you take a hit of 26%. 3.7 divided by 5.0 gives 0.74. Multiply 3500 by 0.74 and you get 2590 mAh of available charge. This is theoretical as converters in chargers are not 100% efficient. There is always some loss. The second reason is that the available mAh cannot be transferred 100% due to electrical resistance. There is internal resistance in the battery holding the charge, the charger, resistance in the cable used to transfer, resistance in the circuitry of the phone, etc. I’ve tested several different charging systems including an Anker (which worked fine) and I almost always find that I’m transferring no more than slightly more than 50% of the mAh reading that is on the battery. I've lost the piece of paper but I seem to remember 53%.
The system that I’ve been investigating is based on rechargeable lithium-ion batteries. In particular, the battery size, 18650. It is 18650 batteries that are inside almost all portable chargers including the lipstick size rechargers. This appears to be about the best weight to electricity content ratio I’ve seen in my limited experience. One 18650 battery weighs slightly less than 1.7 oz. I have found that in the past year or so that at least 3 companies that specialize in flashlights have begun selling a charger that can also operate as a power bank. The model I’m testing is the Nitecore F1. Fenix ARE-X1 is probably the same. As far as I know, the Nitecore & Fenix will only work with lithium-ion batteries. Both cost the same at ca. $10. Batteries will cost $12-15 each.
This charger weighs 1.0 oz. Adding the battery weight gives a total of 2.7-2.8 oz for a power bank with one 18650 battery installed. The current state-of-the-art for 18650s is 3500 mAh & I only use the protected versions - as only they will work in flashlights/headlamps. I have to estimate how many times I will recharge the phone & InReach and maybe the camera if I happen to record video which will burn through the battery.
Now you just carry extra batteries if you have a longer trip/need. The batteries need to be protected from contact with metals and from letting one end of one battery come in contact with the end of another battery. (Think videos on the internet of people who had fire coming out of their pocket where they had their Vape for smoking. These use 18650 batteries.) A flimsy 3 x 4” ziplock bag (found in craft jewelry departments) will do the job. It will hold 3 18650s for a total weight of 5.0 oz. I haven’t used this bag in the field and you would want it somewhere in the pack where there is no wear & tear.
I tested this system with my phone multiple times last fall and it always worked; however, it’s not very good at getting to 100% recharge but it will get to 95% quite easily.
The batteries are heavy; with one 18650 weighing about the same as 4 AAA batteries which are used in most of the headlamps I see used in equipment lists. You have to really make decisions about usage on long trips without resupply as you can easily end up carrying a pound of batteries.
By the way, although alkaline batteries generally have higher mAh capacities than rechargeable batteries, websites dedicated to batteries state that you cannot directly compare capacities of alkaline batteries with rechargeable batteries. They all claim that in high-drain devices such as cameras, a nimh battery of lower capacity will run a camera longer than an alkaline battery.
The charger/power bank I have used to recharge my iPhone, the InReach SE, a Sony a6000 camera, and a Nikon Coolpix P900 camera. I use a single cable sold by PowerTraveler which has both a lightning connector for the iPhone & a micro USB for most other devices. The cable is ca 6” long and weighs 0.3 oz. It’s also expensive at $25.
I’m still evaluating headlamps that use 18650 batteries & have narrowed it down to a couple of this season. Please note that discussing headlamps requires a whole other thread as the information given on manufacturers websites is dramatically misleading - especially run times. Example, there is a manufactures standard for run time. This standard allows them to report the time it takes a headlamp to go from emitting full lumens to when it’s emitting 10%. For example, it may start at 100 lumens and only run that level for an hour or so but it has a run time of 40 hours before it gets down to 10 lumens.
Another negative besides weight is rechargeable lithium-ion batteries are not very efficient in cold weather.