Amateur Radio and Leisure Batteries

Many thanks to Ricky M6DII for suggesting this short guide on powering your amateur radio equipment on a field event. Comments and additions welcome…

Portable Power

If you’re looking to do any radio work “in the field”, then you’ll need to thing about your radio, antennas and how you’re going to power your kit. In the field, without mains power, your choices are essentially batteries, or a generator. On this page, we’ll be looking at battery power.

What to look for

The traditional 12V Leisure Battery seems to be a popular choice, as they are fairly easy to come by. These are ‘deep-cycle’ batteries capable of being charged and discharged hundreds or thousands of times, and generally suited for occasional use. They’re often used by campers and carannavers.

Leisure Batteries

The capacity of leisure batteries is measured in Amp/Hours, and it’s a case of calculating current usage to define how long your battery will last.

If you check in your radio’s manual, there’s normally something in the specifications section to outline how thirsty your rig is. As an example, my Icom IC-718 states the following:

• Receive / Standby: 1.3A
• Receive / Max Audio: 2.0A
• Transmit / Max Power (100 watts): 20A

My choice of Leisure battery for amateur radio operation was a Numax XV24MF battery for just under £60 from a local battery shop.This is rated as an 86 amp/hour battery.

So, if I were to assume that in the course of an hour, I’d transmit at 50 watts for 20 minutes an hour and receive for 40 minutes an hour, I’d be drawing an average of 7 amps over an hour. An 86 amp/ hour battery would therefore give me a little over 12 hours. If you’re powering other kit, such as an ATU or a laptop charger, factor in the current when doing the maths.

Leisure batteries are similar to the size of car batteries, and pretty heavy.Look for a sealed lead acid battery, and handle with care.

Bear in mind that you will also need a mains charger to recharge the battery. These are in the £15 to £25 price range and also sold from battery suppliers.

For extended field trips, such as the Thames ARG Crowsheath field days, many of the operators made use of large solar panels to recharge their leisure batteries “in the field”, as access to mains charging was not an option.

Smaller Portable Power

Obviously, lugging around a car battery isn’t always practical, and if you’re planning a shorter period of operation, or low-power work, then making use of a SLAB (Sealed Lead Acid Battery) may be more suited to your portable kit.

These are about the size and weight of a small brick, and the common 12V ones are rated to around 7 amp/hours – ideal for a few hours of portable use at low-to-modest power.

See: Sealed Lead Acid Bateries at Maplin.

Don’t forget you’ll also need a mains charger to charge the battery, and a pair of spade connectors for the lead from the battery to your radio.

Battery care

Care has to be taken with batteries – risk include short circuits or damage to the casing resulting in leaks of corrosive battery acid.

Also, read the instructions on how to care for your battery, to get the best performance and life from your battery.

It’s worth considering a portable case for your battery, for easy carrying and storage. Some come with built-in battery meters to check the remaining charge on the battery.

This is only a brief guide, and for more on leisure batteries, see this guide: Camping & Caravanning Club: Leisure Batteries

Got any suggestions or battery advice? Please add a note below.