Which Battery Is Best For A Trolling Motor?
Lithium-ion (LiFePO4) batteries are optimal for trolling motors due to their high energy density, lightweight design, and deep-cycle capabilities. With capacities ranging from 50Ah to 100Ah, they provide extended runtime at 12V, 24V, or 36V systems. LiFePO4 batteries maintain stable voltage under load, unlike lead-acid alternatives, ensuring consistent thrust. Pro Tip: Pair a 100Ah LiFePO4 with a 55 lb-thrust motor for 8–10 hours of runtime at medium speed.
What defines a trolling motor battery?
A trolling motor battery must deliver sustained deep-cycle performance and resist voltage sag. LiFePO4 batteries excel with 2,000+ cycles at 80% depth-of-discharge (DoD), whereas lead-acid degrades after 300 cycles. Key specs: 12V–36V configurations, 50–200Ah capacity, and IP67 waterproofing. Pro Tip: Always oversize capacity by 20% to account for current spikes during abrupt throttle changes.
Deep-cycle batteries prioritize longevity over cranking amps, making them ideal for trolling motors that run for hours. For example, a 36V 100Ah LiFePO4 pack powers a 112 lb-thrust motor for ~6 hours at full throttle. Practically speaking, voltage stability matters—lead-acid drops from 12.6V to 11V under load, reducing efficiency by 30%. Lithium maintains 12.8V–13.2V, ensuring consistent RPM. But what if you mix battery chemistries? It’s risky—lead-acid and lithium have different charging profiles, causing imbalance. Always use identical cells in series.
| Battery Type | Cycle Life | Weight (lbs) |
|---|---|---|
| LiFePO4 | 2,000+ | 28 |
| Lead-Acid | 300–500 | 60 |
Lithium vs. Lead-Acid: Which performs better?
Lithium batteries outperform lead-acid in energy density and efficiency. A 100Ah LiFePO4 provides 1280Wh vs. lead-acid’s 600Wh (usable). Lithium weighs 70% less, critical for boat balance. Pro Tip: Lithium’s 95% efficiency reduces charging time to 2–3 hours vs. 8+ hours for lead-acid.
Beyond runtime, lithium handles deeper discharges without damage. Lead-acid degrades if discharged below 50%, while lithium tolerates 80% DoD. Imagine a 24V system: lithium delivers 20% more thrust hours due to flat discharge curves. However, lithium’s upfront cost is 2–3x higher. But what’s the long-term savings? Over 5 years, lithium’s cycle life cuts replacement costs by 60%. Warning: Never install lithium in unventilated compartments—though safer than lead-acid, thermal runaway risks exist if BMS fails.
How do voltage and thrust correlate?
Higher voltage systems (24V/36V) enable greater thrust and efficiency. A 36V motor draws 1/3 the current of a 12V system for equivalent power, reducing wire heating. Pro Tip: Match battery voltage to motor specs—overvoltage triggers controller faults.
A 36V 80Ah battery supports 80 lb-thrust motors for 4–5 hours at 50% throttle. Voltage directly impacts torque—36V motors spin 3x faster than 12V, propelling heavier boats effortlessly. For example, a 24V 100Ah LiFePO4 runs a 45 lb-thrust motor for 10+ hours in calm waters. Transitioning from 12V to 24V? You’ll need two 12V batteries in series. But what if one cell fails? The BMS in lithium packs isolates faults, preventing total shutdowns.
Why prioritize deep-cycle batteries?
Deep-cycle batteries withstand repeated 80%–100% discharges, unlike starter batteries designed for short bursts. LiFePO4’s 2000+ cycles make it ideal for daily trolling. Pro Tip: Avoid AGM batteries in cold climates—their capacity drops 40% below 0°C vs. lithium’s 15%.
Deep-cycle designs use thicker plates to endure prolonged energy extraction. For instance, a 12V 100Ah lithium battery can discharge 80Ah (80%) daily for 10 years, while AGM degrades after 1.5 years. When it comes to charging, lithium accepts 1C rates (100A for 100Ah), refilling in 1 hour vs. AGM’s 10–12 hours. But what happens if you deeply discharge lead-acid weekly? Plate sulfation destroys capacity within months. Always monitor DoD with a battery meter.
| Feature | LiFePO4 | AGM |
|---|---|---|
| Cycle Life | 2,000 | 500 |
| Weight (100Ah) | 28 lbs | 60 lbs |
Fasta Power Expert Insight
FAQs
~15 hours at medium speed (50% throttle). Reduce runtime by 40% in strong currents.
Can I mix old and new batteries in a trolling motor?
No—mismatched capacities cause overcharging/undercharging. Replace all cells simultaneously.
Are car batteries suitable for trolling motors?
No—starter batteries lack deep-cycle endurance. Use only marine-grade deep-cycle models.
Do lithium batteries work in saltwater?
Yes, if rated IP67 or higher. Rinse terminals after exposure to prevent corrosion.
Is lithium worth the cost for occasional use?
For <1x/month trips, AGM suffices. Lithium pays off with 2x weekly usage.