Battery Power - SCCo ARES/RACES

All ARES/RACES stations need to have battery power. External power may not always be available, and may have interruptions. Most stations need enough battery capacity to last for a 12-hour shift. Exceptions:

The handheld radio in a 2-hour go kit, used while returning home to get the full kit, needs 3 hours.
Stations in a served agency facility with backup power need 1 hour of battery capacity, to run while the building generator is being started up or refueled.

The most common battery types in ARES/RACES operations are sealed lead acid with absorbent glass mat (“AGM”) and lithium iron phosphate (“LiFePO₄“). (Battery packs for some handheld radios use other battery types, not discussed here.) AGM batteries are the old standard for station batteries. They’re cheap, mature, and plentiful (every car has one, and every auto parts store carries them). However, LiFePO₄ batteries have largely taken over: they are smaller and lighter, hold a charge longer, and have a more advantageous voltage discharge profile.

For basic field operations with a mobile radio, an LiFePO₄ battery should have at least 20 Ah capacity in order to last the expected 12 hours. Because of its steeper voltage discharge profile, an AGM battery should have at least 26 Ah capacity. (See the linked paper for how this was determined.) Net control and packet operators transmit more, so they will need larger batteries.

It can be difficult to tell how much charge is left in an LiFePO₄ battery. An inline power meter can help keep track of how much of the battery’s capacity has been used.

* Manufacturer, product, and vendor names and images on this page are given as examples and are not endorsed by SCCo ARES/RACES.