Aircraft Overview
| Aircraft | Beechcraft Baron |
| Also Known As | Baron 55 / 58 / G58 |
| Type | Twin-Engine Piston |
| Engine | 2× Continental IO-550-C (300 hp each) — Baron 58/G58 |
| Electrical System | 28V DC (G58 and later 58s) / 14V DC (early Model 55, some 56TC) |
GPU Requirements
The Beechcraft Baron is the most popular piston twin in general aviation, with over 6,600 built since 1961. The current production G58 features Garmin G1000 NXi avionics and a fully redundant electrical system — two independent buses, each powered by its own 100-amp alternator and 13 amp-hour battery. The buses operate independently during normal flight and tie together automatically when external power is applied. Starting loads are modest: each Continental IO-550-C draws approximately 400–500A peak for 2–3 seconds. The real GPU consideration is continuous draw during extended preflight — the G1000 NXi panel with dual 10-inch displays, dual GPS receivers, and Mode S transponder can draw 40–60A. Without a GPU, this drains the ship batteries during long preflight programming sessions, database updates, or IFR flight planning at the ramp.
| Specification | Requirement |
|---|---|
| Starting Voltage | 28V DC (G58, post-1978 Model 58) / 14V DC (verify on early 55/56 models) |
| Peak Amps Required | 400–500A per engine start (800–1,000A total for sequential starts) |
| Continuous Draw | 40–60A (G1000 NXi equipped) / 25–35A (steam gauge) |
| Battery Chemistry | Lead-acid or lithium — both adequate for piston starting loads |
| Recommended Unit Weight | Under 20 lbs |
| Electrical System | Dual independent buses, dual 100A alternators, dual 13 Ah batteries (G58) |
Our Recommendation
Primary pick: Red Box RB25A or Start Pac Mini 1000
The Baron G58’s 28V dual-bus system with two 100-amp alternators and two 13 amp-hour batteries means starting loads are well within a compact 1,000A GPU’s range. The RB25A at 11 lbs handles both IO-550 engines sequentially with margin. For the minority of older 14V Barons still flying, verify voltage before purchasing.
Alternative: Gill 7638-44 lead-acid cart or Concorde RG-380E/25
Cold Weather & Special Operations
For piston twins, oil viscosity matters more than GPU capacity in cold weather. Pre-heat both engines with a Tanis or Reiff system before attempting a cold start. A standard GPU combined with proper pre-heating handles winter starts in the Baron without difficulty. The IO-550’s fuel injection makes it somewhat more sensitive to cold than carbureted engines — flooding is the more common issue, not insufficient cranking power.
Related Guides
For a broader comparison of GPU manufacturers, see our Best Aircraft GPU 2026 review. For battery chemistry decisions, our Lead Acid vs Lithium analysis breaks down total cost of ownership. The GPU Sizing Guide covers voltage, amperage, and duty cycle calculations for any aircraft.
Product Categories
- Battery Start Units — portable starting power
- Continuous Power Supplies — sustained avionics power
- Combination GPU — start + continuous in one unit
- Frequency Converters — 400Hz AC power
- Aircraft Tugs — ground movement equipment
Frequently Asked Questions
Is the Beechcraft Baron 14V or 28V?
It depends on the model. The Baron G58 and all post-1978 Baron 58 models use a 28V DC system. Some older Model 55 and early Baron 56TC aircraft used 14V systems. Always check the electrical system placard on the instrument panel or reference Section 7 of the POH before purchasing a GPU.
Can I start both Baron engines with one GPU charge?
Yes, easily. Each IO-550-C draws only 400–500A peak for a few seconds. Any GPU rated above 800A handles sequential starts without recharging. Most Baron operators use GPUs primarily for avionics power during preflight, not for starting assistance.
What GPU do Baron flight schools use?
Flight schools operating G58 Barons typically use the Red Box RB25A or equivalent compact 28V lithium units. The priority is portability and fast turnaround between students, not raw starting power. Schools with mixed fleets including older 14V Barons need dual-voltage or voltage-specific units.
Does the Baron G58 need a GPU?
Not strictly — the dual battery system provides ample starting power. However, a GPU protects battery longevity during extended G1000 NXi programming sessions, IFR flight planning, and avionics database updates. It also provides a safety margin for cold-weather starts and ensures reliable performance with aging batteries.
Editorial Policy
Red Box Power is editorially independent. We may earn commissions from links on this page, but this never influences our rankings or recommendations. All GPU assessments are based on published specifications and verified operator feedback.