With the every increasing popularity of outdoor devices dependant on batteries, hikers also need to consider how they will keep the device batteries charged.
This post covers the 2 Battery types and 3 methods I now use for keeping my device batteries charged while hiking.
When I buy outdoor electronics, I always make sure they use;
- The same size and type of battery as my other devices, OR
- Can be USB charged by this common battery type, OR
- If not compatible with the common, then they use an even number of batteries.
1.) Nickel Metal Hydride Batteries (NiMH)
I use the AA size NiMH(*1) as my common battery for use between my devices or for charging my smart phone battery.
- Rechargeable (at least 5 years if looked after) via mains or solar.
- NiMH batteries last longer in high drain devices.
- Perform best at lower temperatures. (*2)
- Discharge faster in hotter temperatures.
- Discharge about 1% per day when not in use.(always charge and check with a Battery Tester before you leave home.)
2. Disposable Alkaline Batteries
- The the lightest over all weight.
- Last longer in low drain devices.
- Low Set up cost.
- Perform better in warmer conditions.
- Longer unused shelf life.(loosing 3% per year @20 Degrees/C) so perfect for buying in bulk and storing between trips.
- Not suited to devices with high drain requirement
- Same weigh charged or empty- (carry them out!)
- Regular trips can make disposable batteries expensive
- Alkaline batteries perform better in warmer temperatures
When I am heading out for just a Day hike I usually take a total of 6 fully charged NiMH batteries, 2 in my hand-held GPS, and 4 spare in a battery box. On hot summer days the 4 spares can also be swapped in to my Steripen for the 5 minutes it takes to filly my water bladder again.
In addition to the NiMH, I also have the 4 AAA Alkaline’s in my headlamp (and an equal number of spares in the headlamp bag, as while they last a long time they always run out when its dark and your depending on it…!)
2.) Power Bank
On day hikes I always carry my smart phone on flight mode together with the charging cable and a fully charged Power Bank, which extends my phone battery by 2 charges for an unexpected delay or emergency..
- Simply and light weight.
- Low to Moderate Set up cost.
- Depending on the device you are charging – can hold a number of charges.
- Recharged via Computer USB, Solar panel or mains charger.
- Limited recharges available
- Only able to charge USB compatible devices
3.) Solar Charging
This dramatically increases the charging options;
- Charge 4 x common NiMH batteries via the Guide 10 charger connected to the Solar Panel.
- Charge a phone under and open sky direct from the solar panel or split charging between batteries and phone.(not advisable but possible. (*6)
- Use 4 x charged NiMH in the Guide 10 as a standalone power pack for overnight charging of a phone or USB device.
- Using 4 x AA or AAA batteries of any type (Alkaline, Lithium or NiMH) the Guide 10 can also be used as power pack to charge USB devices.
- The Guide 10 can charge 4 NiMH AA or AAA batteries from a USB power source.(ie: computer)
- Requires only UV light, (In NZ high UV conditions = 4 hrs under clear sky and 6-8 hrs walking in under clouds or in and out of tree cover) I have also seen the Goal zero continue charging in under overcast sky and light rain.)
- Unlimited and mobile charging supply
- Guide 10 can charge with each battery at different charge states, and has an accessory LED torch lamp.
- The system panel and charger also inside a clear dry bag sealed in the hold of my plastic sea kayak ( yellow)
- Generally greater weight than carrying batteries or a power bank
- You still have to carry at least common NiMH batteries to allow rotation between devices and charging. (4 under charge for UV filter and phone only, 6-8 with another device like a hand held GPS that will need 2 batteries a day)
- You need all of your outdoor electronics to use compatible batteries or USB charging.
- Greater Set up cost
- I label all my new NiMH Batteries with a date and unique number.(this proofs useful later for calculating a replacement date.)
- At a least get a NiMH home mains powered charger that also has a discharge cycle. Even better are the newer chargers with digital read out and the ability to charge different size batteries at the same time.
- Out of the packet its best to charge and discharge NiMH batteries in the charger for 5 cycles before use to get the best out of it.
- Power Banks and NiMH Batteries need regular charging when not in use to keep their performance.
- Carry all charged batteries in Battery Containers, which prevent accidental discharge, mixing charged and discharged cells.
- Goal Zero Solar
- Batteries: Discharging at High and Low Temperatures
- The Best Rechargeable Batteries and Chargers Of 2019
- Energiser: NiMH Handbook and Application Manual
- Energiser: Alkaline Handbook and Application Manual
- Proper care and feeding of NiMH batteries
(*1) Currently my favourite NiMH batteries are the Panasonic Eneloop,(slow discharge) which are good for around 2000 charges, although I see there are now Eneloop Pro batteries sold with a longer discharge life.
(*2) In the New Zealand summer NiMH batteries in my hand held GPS last on average 0.75 – to 1 day in the North and 1-2 days in the cooler south.
(*3) Always have an alternate light source with you, as head lamps always run out in the dark. (think phone and other power devices that have a LED light supply.)
(*4)The Goal Zero Nomad 7, has now been superseded in 2018 by a newer generation Nomad 7 Plus in New Zealand outdoor stores. The New Guide 10 charger is now designed to also charge smart devices.(my version required an accessory chip.)
(*5) When buying Goal Zero Gear, make sure that the Solar panel and Charger has the correct output power for your device. (The Nomad 7/ Guide 10 has and output of 1 amp, with the Nomad 7 Plus/ Venture 30 Power Bank being greater.
(*6) Smart phones interrogate a charging source to make sure the voltage is correct and stable. They will stop charging when detecting any variation such as created by walking under shade or a cloud over the sun.