Key takeaways
- Motor current × hours = Ah for the session; add 20–30% reserve.
- The 24V 100Ah and 200Ah packs are rated 100A continuous.
- 24V packs are 1S4P: parallel only, never series.
- Use a marine fuse, tinned lugs and equal cable lengths.
1. Start with the motor current
Check the motor’s maximum current, not just thrust in pounds. A 24V motor drawing 40A for four hours uses about 160Ah; a 55A motor for five hours uses about 275Ah. These are session estimates, not full-depth ratings.
| Motor current | 2 h | 4 h | 6 h |
|---|---|---|---|
| 30A | 60Ah | 120Ah | 180Ah |
| 40A | 80Ah | 160Ah | 240Ah |
| 50A | 100Ah | 200Ah | 300Ah |
2. 24V 100Ah or 200Ah?
Both are rated 100A continuous. A 24V 100Ah gives 2,560Wh nominal (about 2.0kWh usable at 80% DOD); the 200Ah gives 5,120Wh (about 4.1kWh). For a 40A motor, that is roughly 2 hours vs 4 hours at 80% DOD.
The motor may draw well under 100A, but a jammed prop or a bow thruster can exceed it. Check the surge and duty cycle before using the pack for anything beyond the trolling motor.
3. Wiring and fusing
- Fuse the positive close to the battery; size for the motor’s max current and cable length.
- Use tinned marine lugs and heat-shrink; check for corrosion each season.
- Keep cable runs short and equal if you parallel two packs.
- Secure the battery against rolling and vibration; IP65 is spray-resistant, not submersible.
4. Charging on the water
Use a 24V LiFePO4 charger or a DC-DC from the main engine. Do not connect the trolling battery directly to a smart alternator. Charge after each trip; do not leave it at 0%.
Common questions
Can I use one 24V 200Ah for a 24V trolling motor?
Yes for a motor that draws well under 100A continuous. Check the motor’s max current and session length; for sustained high current, parallel a second pack (1S4P max).
Can I series two 24V packs for 48V?
No. The 24V models are parallel-only (1S4P). For 48V, use four 12V models in series or a native 48V product.