Lithium Trolling Motor Batteries
Few years ago, lithium batteries were considered as something exotic, futuristic, but with the improvements in technology, lithium batteries more and more present in our everyday lives. Lithium trolling motor batteries initially cost several times more than the AGM SLA batteries of the same capacity, but they can save significant amount of weight and can outlast AGM batteries 5-10 times.
These are the reasons why lithium batteries are becoming more and more popular as lightweight but long lasting deep cycle trolling motor batteries.
Trolling Motors - Features and Specifications
Electric trolling motors are used when quiet, simple and efficient propulsion is required. Main power sources are onboard batteries that supply required current at rated voltage. Most smaller electric trolling motors operate at 12 volts, but other voltages are used as well:
- 12 V are used for a thrust up to a 60-65 pounds,
- 24 V are used for a thrust up to a 100 pounds,
- 36 V are used for motors that provide more than 100 pounds of thrust.
By increasing the operating voltage, maximum currents are kept under 50-60 Amps, which is very important for keeping the cables not too thick.
Following table lists the most popular electric trolling motors:
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During operation, electric trolling motors are not constantly pushed at the maximum - they must have certain power reserve in order to be able to push the boat in the emergencies.
But, just like electric trolling motors, trolling motor batteries must be dimensioned to include certain power reserve, in order to be able to power accompanying motors in emergencies as well.
So, when calculating required battery capacity, it is recommended to always use maximum motor current - and even then add some reserve, just in case.
Little bit of math: If you have Newport Vessels 62lb Thrust NV-Series electric trolling motor with maximum current of 58 Amps at 12 volts and you want to have autonomy of at least two hours, your battery must have 2h capacity of ~120 Ah.
Since the capacity of the batteries is value measured when the battery is being discharged with constant current for 20h, actual 2h capacity is lesser than 20h capacity, especially for AGM SLA batteries.
- 20h capacity of 104 Ah,
- 2h capacity of 'only' 62 Ah.
Note: these values are measured at 77°F (25°C), for the new, fully charged battery being discharged down to 10.5 volts (1.75 volts per cell).
In order to be able to power Newport Vessels 62lb Thrust NV-Series for two hours at full throttle, one must connect two UPG UB121000 batteries in parallel for effective 122 Ah capacity when the batteries are discharged for 2 hours!
Of course, this also doubles the weight of the battery pack from 64 pounds (29 kg) to 128 pounds (58 kg) - and that is rather heavy just to carry around :)
And that is where lithium trolling motor batteries come to play!
For more about this topic, feel free to check out Electric Trolling Motors for Small Boats, Pontoons, Kayaks and Canoes article.
Rechargeable Lithium Batteries - IMR, INR, IFR, and ICR Lithium Batteries
There are numerous potential lithium ion battery chemistries, but most common are sometimes 'hidden' via abbreviations like IMR, INR, IFR, or ICR. These abbreviations describe actual battery chemistry:
- IMR lithium ion batteries feature LiMn204 (Lithium Manganese Oxide) chemistry. Their nominal voltage is 3.6 - 3.7 V per cell, with the maximum recommended charging voltage of 4.2 V per cell. IMR batteries commonly have smaller capacity, but are capable of delivering large currents and are often used in the starting lithium ion batteries.
- INR lithium ion batteries feature LiNiMnCoO2 (Lithium Manganese Nickel) chemistry. These batteries are very similar to IMR batteries, since they can provide plenty of currents, with slightly lower capacity. INR lithium ion batteries are commonly used in starting and power tools batteries.
- IFR lithium ion batteries feature LiFePO4 (Lithium Iron Phosphate) chemistry. Their nominal voltage is 3.2 - 3.3 V per cell, with the maximum recommended charging voltage of 3.5 - 3.6 V. They can't provide extra large currents, but are much safer than other lithium ion batteries and are commonly used as 'drop-in' replacements with some sort of Battery Management System (BMS) in place.
- ICR lithium ion batteries feature LiCoO2 (Lithium Cobalt Oxide) chemistry. Their nominal voltage is 3.6 - 3.7 V per cell, with the maximum recommended charging voltage of 4.2 V. They commonly have higher capacities, but maximum allowed currents are often limited to just few C. ICR lithium ion batteries are used for low-current, deep cycle applications.
Note: there are other lithium battery chemistries on the market too, like: Lithium Nickel Cobalt Oxide (LiNiCoO2), Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO2), etc. These hybrid technologies often feature improved charging/discharging features with improved safety, but the cost of such batteries is still too high for everyday use.
Commonly, lithium electric trolling motor batteries are 'IFR lithium ion batteries', featuring LiFePO4 (Lithium Iron Phosphate) chemistry. They are the safest for use and with proper BMS they can safely replace AGM SLA batteries in most applications - trolling motor batteries included.
Advantages of Lithium Trolling Motor Batteries
The main disadvantage of the lithium trolling motor batteries is their initial price, which is easily 3-4 times the price of the equivalent AGM SLA battery of the same capacity.
But, lithium trolling motor batteries advantages include:
- larger number of charging/discharging cycles. While deep cycle AGM batteries can withstand 400-500 cycles (at most) when being discharged down to 80% DoD (Depth of Discharge) or 20% of SoC (State of Charge), many lithium ion LiFePO4 batteries with the proper BMS can withstand at least 2000 charging/discharging cycles commonly down to 100% of DoD (when BMS cuts off the battery), with some high-end models easily tolerating 5000 cycles down to 80% and even 100% DoD.
- output voltage of lithium batteries is much more stable during operation, although this depends on the built-in BSM and rest of electronics.
- lithium batteries are 2.5-3 times, sometimes even more lighter than their AGM equivalents, saving plenty of weight.
- lithium batteries feature very low self discharge values and can be stored for months (6-12 months) with the minimal loss of charge.
- lesser drop of capacity when being discharged with slightly higher currents.
Other issues of the rechargeable lithium batteries are:
- safety concerns: most lithium trolling motor batteries are Lithium Iron Phosphate batteries which are relatively safe to use. When combined with BMS, they are safe to use since BMS systems monitor condition of the individual battery cells and the whole battery pack and act accordingly.
- connecting in parallel: lithium trolling batteries can be connected in parallel only if their BMS are intended for such use.
- lithium battery charging: lithium trolling batteries can be charged with intelligent AGM battery chargers or onboard alternators if their BMS systems are built for such charging - practically all 'drop-in' replacement batteries do feature such BMS systems, but it is recommended to check prior ordering.
Examples of Lithium Trolling Motor Batteries
The following table lists some of the most popular lithium trolling motor batteries:
|Model||Battery Type||Group Size||Cell Type||Capacity (Ah)||CCA||MCA||RC||Weight (lbs/kg)|
|AIMS Power LFP12V100A||Deep Cycle||31||LiFePO4||100||-||-||-||30.2 lbs; 13.7 kg|
|Battle Born 100Ah 12V LiFePO4 Battery||Deep Cycle||31||LiFePO4||100||-||-||-||29 lbs; 13.2 kg|
|Bioenno Power BLF-12100WS||Deep Cycle||31||LiFePO4||100||-||-||-||28.1 lbs; 12.8 kg|
|Eastup 1250750||Dual Purpose||-||LiFePO4||50||750||930||-||15.43 lbs; ~7.0 kg|
|ExpertPower EP12100||Deep Cycle||31||LiFePO4||100||-||-||240||29.7 lbs; 13.5 kg|
|ExpertPower EP12200||Deep Cycle||4D (6D)||LiFePO4||200||-||-||480||48.3 lbs; 21.9 kg|
|GreenLiFE GL50-50AH||Deep Cycle||21||LiFePO4||50||-||-||120 min||15 lbs; 6.8 kg|
|GreenLiFE GL80-80AH||Deep Cycle||27||LiFePO4||80||-||-||190 min||28 lbs; 12.8 kg|
|GreenLiFE GL100-100AH||Deep Cycle||31||LiFePO4||100||-||-||240 min||31 lbs; 14 kg|
|GreenLiFE GL260-260AH||Deep Cycle||8D||LiFePO4||260||-||-||620 min||80 lbs; 36.24 kg|
|Miady LFP100AH||Deep Cycle||31||LiFePO4||100||-||-||-||28.9 lbs; 13.1 kg|
|Mighty Max ML100-12Li||Deep Cycle||30H||LiFePO4||100||-||-||-||29.54 lbs; 13.4 kg|
|Renogy RNG-BATT-LFP12-50||Deep Cycle||-||LiFePO4||50||-||-||-||14.77 lbs; 6.7 kg|
|Renogy RNG-BATT-LFP12-100||Deep Cycle||-||LiFePO4||100||-||-||-||28.1 lbs; 12.73 kg|
|Renogy RBT100LFP12S-G1||Deep Cycle||-||LiFePO4||100||-||-||-||26 lbs; 11.8 kg|
|Renogy RNG-BATT-LFP12-170||Deep Cycle||-||LiFePO4||170||-||-||-||46.3 lbs; 20.97 kg|
|RUIXU RX-LFP-4S-100B||Deep Cycle||-||LiFePO4||100||-||-||-||33.1 lbs; 15 kg|
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As one can see, these batteries are much lighter than AGM SLA batteries.
Also, capacity drop is not as nearly as capacity drop in AGM SLA batteries, and when not discharged with strong currents, there is practically no capacity drop.
For example, GreenLiFE GL260-260AH features:
- 260 Ah 20h capacity (13 Amps for 20 h),
- 260 Ah 13h capacity (20 Amps for 13 hours),
- 260 Ah 5h 12 min capacity (50 Amps for 5h and 12 minutes).
So, no capacity loss for currents up to 50 Amps - that means that this 80 lbs battery is able to power 50 Amps load for slightly more than 5 hours. Equivalent AGM battery (or battery pack) would weigh at least 170 or even more pounds, not to mention maximum number of charging/discharging cycles.
AIMS LFP12V100A Lithium Battery 12V 100Ah LiFePO4
AIMS LFP12V100A is deep cycle lithium ion battery based on the LiFePO4 chemistry. Its nominal voltage is 12.8 volts and nominal capacity is 100 Ah (at 0.5C and 77°F).
Minimum rated capacity is 95 Ah, measured as 0.5C and 77°F.
Recommended charging voltage is 14.4 - 14.6 volts, with 14.6 volts being maximum allowed charging voltage.
AIMS LFP12V100A maximum continuous drain current is 100 Amps, with 200 Amps being allowed for 10 seconds.
When the battery is charged and discharged at 1C discharge rate at 77°F, according to the manufacturer, the battery is able to withstand more than 4000 cycles down to 80% DoD (Depth of Discharge).
When the battery is stored at 50% DoD, it features monthly self-discharge rate of less than 3%.
Builtin Battery Management System (BMS) shuts off the battery when charge voltages spikes to 15.6 volts (+/- 0.2 volts), or when the discharge voltage drops below 8 volts (+/- 0.5 volts).
AIMS LFP12V100A physical dimensions are (L x W x H) 13 x 6.63 x 9 inches and it weighs 30.2 pounds - AIMS LFP12V100A belongs to the BCI Group 31.
AIMS LFP12V100A comes with 10 year limited warranty.
For more reviews and recommendations, feel free to check AIMS LFP12V100A Lithium Battery 12V 100Ah LiFePO4 Amazon link (link opens in the new window).
Battle Born 100 Ah 12 Volt LiFePO4 Deep Cycle Battery
Due to the LiFePO4 technology and protective electronics, battery also feature high number (3000-5000) of charge-discharge cycles, high/low voltage protection, short-circuit protection, temperature protection, automatic cell balancing and can be even charged with battery chargers designed for lead acid batteries.
20 hour capacity is 100 Ah (5 Amps for 20 hours), maximum allowed continuous current is 100 Amps, while maximum surge current for 30 seconds is 200 Amps.
Also, manufacturer states that even higher surge currents are allowed for half a second (0.5 s) surges, but actual amperes are not stated.
This battery weighs only 29 lbs (13.2 kg), but it also costs more than similar 100Ah 12V SLA AGM batteries.
Battle Born 100 Ah lithium batteries are excellent deep cycle batteries for applications like trolling motor batteries, lightweight kayak/small boat fishfinder batteries, RV house batteries, golf cart batteries, marine deep cycle batteries, and similar. As starting batteries, forget them, no need to ruin such batteries even if they are protected by electronics.
For more information about this battery, check our Battle Born 100 Ah 12 Volt LiFePO4 Deep Cycle Battery article and/or Battle Born 100Ah 12V LiFePO4 Battery Amazon link (link opens in the new window).
Eastup 1250750 Lithium Iron Phosphate (LiFePo4) Automotive Replacement Battery
Eastup 1250750 is designed to withstand some 2000 cycles, which is excellent for a battery primarily intended for staring applications.
Onboard BMS turns off battery when the output voltage drops to 10.5 volts, but it allows the user to turn the battery On in order to start the vehicle/boat, after which the battery may be recharged with the vehicle's/boat's alternator.
Eastup 1250750 weighs only 15.5 pounds (~6.9 kg), with physical dimensions of (L x W x H) 10.1 x 6.9 x 7.5 inches (257 x 175 x 190 mm).
As lithium trolling motor battery, Eastup 1250750 is excellent kayak trolling motor battery due to the lightweight design and compact dimensions. As a trolling battery for larger boats, it can be used, but its capacity is 'only' 50 Ah - it can withstand the drain currents of such trolling motors, but trolling time is relatively short.
Eastup 1250750 comes with 10-year limited warranty.
For more information about this battery, feel free to check Eastup 1250750 Amazon link (link opens in the new window).
GreenLiFE Battery GL50-50AH 12V Lithium Ion Battery
GreenLiFE GL50-50AH is designed as deep cycle battery with constant discharge current of 50 Amps (for 1 hour). Also, it can be discharged with 25 Amps for two hours, practically featuring Reserve Capacity value of 120 minutes.
GreenLiFE GL50-50AH battery is excellent kayak trolling motor battery, but it can be used for larger boats as well, or for any off-the-grid application requiring lightweight and reliable source of electric power.
Its nominal voltage is 13.4 volts and charging voltage arund 14.4 and 14.6 volts, with the self-discharge rate of less than 3% per month.
GreenLiFE GL50-50AH features built in BMS system that monitor the parameters of the battery and shuts it off if required - over-voltage threshold is 15.8 volts, low voltage disconnect is at 10.5 volts, etc.
For more reviews and recommendations, feel free to check GreenLiFE Battery GL50-50AH Lithium Ion Battery Amazon link (link opens in the new window).
Mighty Max ML100-12LI
Mighty Max ML100-12LI is BCI group 30H battery, but it is much lighter than similar AGM batteries - more than 2x lighter.
Mighty Max ML100-12LI comes with the Battery Management system (BMS) which provides high and low voltage protection, high-current protection, high-temperature protection, short circuit protection, and over charge protection.
Nonetheless, it is not typical drop-in replacement battery, since it is recommended to charge it via lithium battery charger.
Mighty Max ML100-12LI maximum continuous current is 100 Amps, with maximum surge current of 200 Amps for 15 seconds. Battery is designed to withstand at least 2500 charging/discharging cycles.
For more information about this battery, feel free to check Mighty Max ML100-12Li Amazon link (link opens in the new window).
Long Story Short: Lithium trolling batteries are not part of Science Fiction any more. They do cost more, initially, but in the long run, they save money and if the batteries must be carried regularly, they also save plenty of effort :)
Also, these batteries are commonly used in off-the-grid applications, as RV house batteries, solar batteries, golf cart batteries, various electric vehicles etc.
Before ordering new trolling motor battery, consider lithium batteries as well, just be sure that they feature good BMS systems that in combination with battery features (dimensions, capacity, maximum current), fit your needs and requirements.
Don't forget - safety first!