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Batteries for portable QRP

QRP batteries

I often get asked about what are the best batteries to use when QRP. The answer is 'it depends'. Key factors include the current consumption of your equipment, the number of hours you wish to operate, your budget and weight constraints.

If you're running really minimalist low current consumption homebrew CW gear in the 100 to 500 milliwatt range then non-rechargeable alkaline batteries are an affordable option. Above that and you'll prefer some sort of rechargeable battery. Options include NiMH, sealed lead acid, lithium ion, LiPo, LiFePO4 and more. You might choose to make up a back from smaller cells (eg 18650s) or purchase a single pack that can be directly connected to the transceiver.

There are a few traps and tricks you need to be aware of. For example some battery types have inconvenient voltages that require some sort of voltage dropper or regulator before they can be connected to your transceiver. If the voltage reduction is only small you could just use power diodes but if it is larger you are better off using a voltage regulator. Switch-mode types are more efficient but beware of RF noise issues that poorly filtered or shielded regulators can generate.

One way to get an indication of this is to weigh the battery; those that are lighter may be poorer quality knock-offs. Also note that charging requirements vary with special smart chargers often required. If you're out in the field and wish to operate for multiple days then a solar charging arrangement might be useful.

As for actual power requirements, there's variations such as receiver current consumption, transmitter efficiency and duty cycle, but very roughly for a QRP transceiver you can allow roughly 1 amp hour of battery capacity per 1 hour of operating time for casual operating. For a casual weekend afternoon operating session a battery capacity in the 4 to 8 amp hour range is should be adequate. Do a power budget with data like your equipment's power consumption and estimated transmitting and receiving time for a more exact idea. And in cold countries be aware that battery capacity can lower with temperature.

Internal or external? Some QRP rigs have space for internal batteries. That can work if you're very limited with space. Personally I prefer external batteries as internal batteries are often too low capacity for the operating time I want. My all-time favourite battery for QRP is a 12.8v LiFePO4. It's not the cheapest battery type you can buy but it is pleasantly light to carry for the capacity delivered.

The videos below show various batteries I've tried for portable QRP and demonstrate their use.

 

How long can an FT817/818 operate from 8 x AA NiMH batteries?

 

Trying some cheap 18650 batteries

 

Using a 1503000 LiFePO4 battery charger to power an FT817/818

 

My QRP 'go-bag' (what I usually take including mention of battery)

 

Items like these might be useful for your QRP power and charging needs

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