Independent comparison of portable battery start units for aircraft. Lead-acid and lithium options from Red Box, Start Pac, StartStick, and Powervamp rated by peak amps, weight, and value.
What Are Battery Start Units?
A battery start unit is a self-contained, portable ground power unit that delivers the high-current pulse needed to crank an aircraft engine — no mains power, no diesel generator, no extension cord required. For operators at unattended airports, remote heliports, and bush strips, a portable battery GPU is the difference between flying and sitting. The technology has evolved dramatically in the last decade: lithium-ion chemistry has cut weight by 60 to 70 percent while increasing cycle life from hundreds to thousands of starts.
How They Work
Battery start units store electrical energy in either lead-acid (SLA/AGM) or lithium-ion (LiFePO4/Li-Ion) battery packs. When connected to the aircraft's external power receptacle and the start switch is engaged, the unit delivers a burst of high current — typically 500A to 3,000A+ at peak — for the 10 to 20 seconds needed to spin the engine's starter motor through the start sequence. The best units maintain output voltage above 24V (for 28V systems) throughout the start pulse, preventing the voltage sag that causes hung starts and hot starts in turbine engines.
Manufacturer Comparison
Choosing the Right Battery Start Unit
The choice between lead-acid and lithium comes down to three factors: weight, cycle life, and cost. Lead-acid battery GPUs cost 40 to 60 percent less upfront but weigh two to three times more and deliver 300 to 500 charge cycles before capacity drops below useful levels. Lithium units cost more initially but deliver 2,000 to 5,000 cycles, weigh dramatically less, and maintain more consistent voltage during high-current discharge — which matters for turbine starts where voltage sag causes hot starts.
For helicopter EMS and tour operators who start multiple times daily, lithium pays for itself within two years through longer service life and reduced weight on the helipad cart. For a flight school that keeps a GPU on the ramp as a backup for dead batteries, a lead-acid unit's lower cost makes sense — it won't be used often enough for cycle life to matter.
Sizing matters more than brand. A GPU that's marginally rated for your aircraft will deliver disappointing results in cold weather and degrade faster from being pushed to its limits on every start. Choose a unit rated for at least 120 percent of your aircraft's peak start current for reliable year-round performance.
For a step-by-step approach to selecting the right GPU for your aircraft, see our GPU Sizing Guide. For a comparison of lead-acid vs lithium technology, read Lead Acid vs Lithium GPUs.
Recommended For These Aircraft
- Cessna 172 / 182 Skylane
- Cirrus SR22
- Bell 206 JetRanger
- Airbus H125 (AS350 AStar)
- Beechcraft King Air
- Cessna Citation (CJ/M2/XLS/Sovereign)
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Frequently Asked Questions
How long do lithium battery GPUs last?
Quality lithium battery GPUs deliver 2,000 to 5,000 start cycles over a typical service life of 5 to 10 years. Lead-acid units last 300 to 500 cycles or 1 to 3 years, whichever comes first. Actual life depends on depth of discharge, temperature, and maintenance.
Can I fly with a battery GPU in the aircraft?
Some compact lithium units (under 100Wh) can be carried in the aircraft without restriction. Larger units may require specific approval or documentation. Check your country's aviation authority regulations for carrying lithium batteries aboard aircraft.
Do battery GPUs work in cold weather?
Yes, but performance decreases below 0°C. Lithium units lose 10 to 20 percent of capacity at -10°C, while lead-acid units lose 30 to 40 percent. Keep the GPU warm (above 10°C) before use for best results. Some units have built-in heaters for cold-weather operation.