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)
- 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. (*1)
- 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 power requirements
- Same weigh charged or empty(carry them out!)
- Regular trips can make disposable batteries expensive
- Alkaline batteries perform better in warmer temperatures
Carry extra NiMH / Alkaline batteries cells (AA/AAA) for each device, as well as a charged set in the device.
- Batteries are compatible with all devices, so can be switched from low priority devices to high if required.
- With a portable charger,(*2) batteries from less priority devices can also be used to top up USB devices. (*3)
- Cheapest method,
- Limited to the batteries you are carrying (in and out)
- Disposable alkaline start getting expensive if you do a lot of hiking.
2.) Power Bank
Power banks are essentially pre charged sealed battery packs used for recharging USB devices. Most include an LED for back up lighting also.
- Simply and light weight.
- Low to Moderate Set up cost.
- Depending the power bank may contain 1.5 – 3 full charges of a device like a phone.(*3)
- Recharged via Computer USB, Solar panel or mains charger.
- Limited recharges available (can charged NiMH via portable charger but best saved for USB only devices)
- Only able to charge USB compatible devices
3.) Solar Charging
For longer multi day hikes a good quality solar panel with included portable battery charger
This dramatically increases the charging options;
- Charge batteries via the portable charger from the Solar Panel or other USB source like a computer.
- Charge a USB device direct from the open sky (not advised but possible.(*4))
- Use any compatible batteries ( NiMH, Lithium or Alkaline’s) in the portable charger to charge USB device.
- Modern good quality hiking solar panels only require UV light to charge, perfect for New Zealand’s high UV conditions.(*5)
- Unlimited charging in UV conditions
- 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.
- You need all of your outdoor electronics to use compatible batteries or USB charging.
- Greater Set up cost
When using NiMH Batteries there are a few things you can do to ensure a good reliable service life of your batteries and power banks;
- Label all your NiMH Batteries with at least a purchase date, to assist in tracking it’s service life.
- Power Banks and NiMH Batteries need regular charging when not in use to keep their performance. Make sure to get a NiMH charger that includes a discharging cycle.(*6)
- When you buy new NiMH batteries, before you use them its best to charge and discharge NiMH batteries in the charger for 5 cycles to get the best out of them
- Carry all charged batteries in Battery Containers, which prevent accidental discharge, mixing charged and discharged cells.
My Battery Profile
Day hikes I usually carry;
- Hand held GPS: 2 AA NiMH + 2-4 spare AA NiMH spare
- Smart phone: USB charge + Power bank spare (1.5 charges)
- Head lamp: 4 x AAA Alkaline’s + 4 AAA Alkaline’s spare.(while really long lasting your stuffed if they run out)
Overnight / Multi day hikes I usually carry;
- Hand held GPS: 2 AA NiMH
- Head Lamp: 4 x AAA Alkaline’s + 4 AAA Alkaline’s spare
- Goal Zero Nomad 7 Solar Panel(*7) and Guide 10 Plus – Portable Charger(*8) + 4 x AA NiMH (remain charging – substituting with dead batteries as required.)
- Smart phone: (charged as required from portable charger)
- Hiking UV water steriliser: (4 x AA from charger as required)
My current favourite NiMH battery available in New Zealand is the AA Panasonic Eneloop Pro (2550 mAh 1.2 V)
- 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) 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. Battery life also depends if the device is being actively used all day, or just on stand by.
(*2) The portable charger is the “storage side” of my Goal Zero solar charging kit, it can be used independently of the panel, using batteries to charge other usb devices, or to charge batteries from a USB source.
(*3) So long as you remember USB charging cable for your devices, other wise its frustratingly useless..
(*4) 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.
(*5) i have seen charging occurring under overcast sky, through plastic kayak deck, and even in light rain.
(*6) even better if you can find a unit that charges different size batteries at the same time..
(*7)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.)
(*8) 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.