Product Ideas
These are concepts I'm currently researching and evaluating. If you're interested in any of these projects or have feedback, I'd love to hear from you.
Table of Contents
A. Hybrid LFP Battery Power Supply
A power supply that combines a low-power switching or linear supply with an LFP (Lithium Iron Phosphate) battery for handling high-power transmission peaks. The key insight: most amateur radio operation involves more listening than transmitting.
During receive periods (low power draw), the supply charges the LFP battery at a modest rate. When transmitting (high power demand), the battery supplements the supply to deliver the required current. This allows for:
- A smaller, cheaper primary power supply
- Battery provides instantaneous high current without voltage drop
- Natural load leveling over the duty cycle
- Low noise operation
Design Challenges
The viability depends on calculating:
- Expected duty cycle: Typical listen/transmit ratio for various operating modes (SSB, CW, digital modes, etc.)
- Charge rate requirements: How fast the battery needs to recharge between transmissions
- Battery capacity: Minimum capacity to handle transmission bursts without excessive depth of discharge
- Charge efficiency: LFP cells are efficient but not 100% - losses need to be factored in
- Overall running cost: LFP batteres are not cheap and the charge/discharge efficiency is 95%.
Example Configuration
For a typical amateur radio setup:
- Transmit current: 20.5A
- Battery capacity: 50Ah LFP
- Battery depth of discharge (DoD): 80% -> 40Ah usable
- Charge current: 5A
- Duty cycle: 50% RX / 50% TX
Operating time:
- ~5 hours of continuous 50/50 duty cycle operation, if charger is enabled -> 40Ah / ((20.5A × 0.5) + (3A × 0.5) - 5A)
- ~3 hours of continuous 50/50 duty cycle operation, if charger is disabled -> 40Ah / ((20.5A × 0.5) + (3A × 0.5)) Recharge time:
- ~8 hours of transceiver off to return to 100% charge at 5A
- ~13 hours of transceiver in RX only to return to 100% charge with 2A of RX consumption
Costs
| Component | Capacity/Type | Cost (EUR) | Operating Time (50/50 RX/TX) |
|---|---|---|---|
| LFP Cells | 100Ah (4 EVE) | 140 | ~10 hours |
| LFP Cells | 50Ah (4 EVE) | 120 | ~5 hours |
| LFP Cells | 25Ah (4 CALB) | 60 | >2 hours |
| BMS | - | 5-20 | - |
| Case | - | 50-100 | - |
| Electronics | - | 40-70 | - |
Total estimated cost:
- 25Ah system: 155-250 EUR
- 50Ah system: 215-310 EUR
- 100Ah system: 235-330 EUR
EVE C40 40135 is also an option and potentially easier to embed in an enclosure
Potential Benefits
- Zero noise capability when the charge circuit is disabled
- Reduced power consumption during standby/receive
- Smaller, quieter power supply (no need to size for peak transmit current)
- Battery can provide backup power during brief mains interruptions
- Could be more cost-effective than a full 40A+ power supply (??)
Open Questions
- Linear or SMPS for the charging supply?
- Battery management and balancing requirements?
- Integration with existing transceivers?
B. Regenerative DC Electronic Load
Testing power supplies requires dummy loads that convert electrical energy into heat. For high-power testing (20-40A at 13.8V = 275-550W), this becomes wasteful and requires substantial cooling. A typical session could waste several kWh.
A regenerative DC electronic load that converts the DC test current back to AC and feeds it into the mains grid, recovering 95%+ of the energy that would otherwise be wasted as heat.
Key Features
Energy Recovery:
- Active rectification/inversion to feed energy back to grid
- Target efficiency: 95%+ (only 5% becomes heat vs. 100% in resistive loads)
- Significant cost savings over time for frequent testing
- Reduced cooling requirements
Functionality:
- Programmable constant current, constant voltage, constant power, and constant resistance modes
- Wide current range: 0-40A (to match power supply testing needs)
- Voltage range: 0-15V (covers 13.8V nominal with margin)
- Current regulation accuracy and stability
- Protection: over-voltage, over-current, over-temperature
User Interface:
- Digital display for voltage, current, power readings
- Adjustable setpoints via rotary encoder or digital controls
- Real-time power and energy measurements
- Data logging capabilities
Use Cases
- Power supply development and testing
- Quality control and burn-in testing
- Battery charger testing
- Educational tool for power electronics