Before choosing to buy a trolling motor battery, you must consider few of the things including the weight and size of your boat, strength of the motor, trolling time needed, and the budget.
Actual needed thrust depends on these factors;
Water and Wind Condition
No extra motor power is required for still water and no wind. Strong current and wind may help your boat move faster down the wind and currents. However, if you have to cruise up the wind and current, you need larger thrust and more power.
Most inflatable boats and kayaks are lower in water with comparatively modest space of boat which can play as the sail, needing a bit of extra power. But, few trimarans/catamarans and pontoon boats are very high, needing extra thrust and power in conditions that are windy.
Presence of sea weed, grass or similar vegetation
Vegetation on the surface increases the boat’s resistance to keep the necessary trolling pace. Vegetation may wrap across propeller shaft, increasing the load and switching off the circuit breaker.
Power vs. Thrust
Thrust is defined as the mass of the water flow per second multiplied by water velocity difference. To avoid complicated calculations, remember that trolling motor with higher thrust needs extra electric power.
To keep max currents at adequate levels (50 to 60 amperes), stronger trolling motors work at 24 or 36 V. For instance, a trolling motor with thrust of 60 to 70 Pounds works at 12 Volts, with 70 to 100 pounds at 24 V, and a motor with a thrust of hundred or some more pounds, typically work at 36 Volts.
The Best Trolling Motor Battery
The motor must withstand a typical deep discharge operation cyclic use. Regular starting/ cranking boat/car batteries shouldn’t be discharged below 50 percent capacity, or their operating time period can be noticeably reduced.
So, for the best trolling motor battery, select dual purpose or deep cycle marine battery. These batteries have limited cranking currents, yet that isn’t what these batteries are meant for. They can withstand usual deep discharges to 20 to 30 percent without any negative effects on the life.
Lead-Acid of Lithium Trolling Batteries?
Lithium rechargeable batteries primarily cost more. These type of batteries are extremely sensitive to charging/discharging conditions. However, most 12 Volt lithium rechargeable batteries come as a drop-in alternative for SLA batteries. They have protective electronics which monitors and protect the battery conditions.
Lithium batteries are 3 to 5 times expensive than the lead-acid, yet they usually can bear 5 to 10 times more charging/discharging cycles and are around 3 to 4 times lighter as compared to lead-acid batteries. Therefore, in longer run lithium type becomes cheaper.
When connected parallel (for larger capacity) or in series (for larger Volts.), lead-acid types are very tolerant. Pick the very same batteries from same manufacturer and same batch, because little difference between the batteries may cause a battery to be under larger load/stress, causing imbalances in battery pack and finally to the failure and financial losses.
For instance, for a trolling motor which draws 55 to 60 Ampere at max power and need 90 min. of operation at full throttle, go for a 150 to 160 Ah.
60 AmpereX1.5 hour=90 Ah
As we do not need to completely discharge lead-acid battery, you will discharge down to 20 percent:
Minimum capacity drops when a lead-acid battery is being discharged faster. When discharged within 1.5 hour period, the capacity of lead-acid battery drops to around 70 to 80 percent. For safe measures, assume that battery capacity goes down to 70 percent when drained at the rate of (112Ah/.07=160Ah and 112Ah/0.8=140 Ah)
Although for worst situation, this calculation is for real-life case!
If you do not want to connect them in parallel to achieve required capacity, the options for the best trolling motor battery are;
- VMAXTANKS MR197-200 (AGM, 200 Ah, 112 pounds)
- VMAXTANKS SLR155 (AGM, 155 Ah, 90 pounds)
On the other hand, if you do not mind connecting them in parallel, there is a vast variety. A pair of a deep cycle trolling batteries with 75 to 80 Ah can be sufficient.
For a motor that works at 12Volts, get pair of 2 smaller or 1 large.
For a motor that operates at 24 Volts, get 2 larger and connect them in series or get 4 smaller connected in series and parallel.
For a motor that operates at 26 Volts, get 3 larger and connect them in series or 6 smaller connected in series and parallel for required performances.
One seldom use electrical trolling motors at full throttle in real life. Mostly, power of the motor is reduced, and max power is utilized in emergencies only or when there is a need of changing location. When using trolling motors at full throttle mostly, may it’s underpowered and choosing a stronger motor or choosing one more that with stronger batteries can enhance your safety.