Oct 14, 2020  •  4 min

Why You Should Choose Lithium iron Phosphate Batteries

Five years ago, you wouldn’t have found many LFP (lithium iron phosphate) batteries on Amazon or at marine stores, but they are becoming more common these days. The LFP battery is getting popular, and for good reason! At ePropulsion we recommend the use of our E-Series LFP batteries for your electric outboard, not a bulky inefficient lead-acid battery pack and we will tell you why below with comparisons, details, and advantages.

Below we will compare two battery configurations: ePropulsion E175 battery vs West Marine AGM 12V / 92 Ah.

You may wonder why we are comparing them at different labeled capacities, the LFP battery is 175 Ah, and the lead-acid battery is 276 Ah. It’s a huge capacity gap, but in reality, they deliver the same runtime of 90 Min at full throttle for the Navy 6.0 product. The lead-acid battery has a lower usable capacity, normally around 50% at 1C discharge, while an LFP battery has almost 98%. This means the lead-acid battery requires a larger labeled capacity to deliver the same amount of runtime. It’s a common mistake that buyers make when comparing the cost between the lead-acid battery and the LFP battery at the same capacity. Yes, the labeled capacity is the same or very close, but the usable capacity is what really makes the difference in performance. To learn more about the reasoning behind this and the math, visit this ePropulsion blog.

The LFP battery provides less cost, less weight, and a longer life.

Less Cost from Longer Life Cycles

The upfront costs are very similar. The purchase cost of ePropulsion E175 battery is $3,999, and twelve West Marine AGM 12V / 92 Ah costs $3,720. Don’t forget that battery protection boxes and electric wires (if required) put on an additional cost to the lead-acid battery. This makes for an almost identical upfront investment, with the added knowledge that you will be getting longer life cycles from the LFP system and lowering your long term investment.

What the LFP battery saves is the eventual replacement cost of a lead-acid system. LFP batteries have an incredibly long life. After 3,000 cycles at 80% depth of discharge, ePropulsion’s E175 remains at over 80% capacity. If you use it every day and it works continuously for over 8 years you will still have more than 80% capacity available, so it’s highly feasible to reach over 10 years of operational life, even in commercial use. Comparatively, the lead-acid battery has a short life span. For the same usage you will likely have to replace all of them every two to three years. Let’s put this scenario at three years for a full replacement, you will replace your lead-acid battery pack twice in 9 years. At the $3,720 cost of 12 West Marine AGM 12V / 92 Ah batteries, you will spend $11,160 for 9 years of operation compared to the original cost of $3,999 with the E175 LFP system.

Less Weight

An E175 battery is 191.8 lbs / 87 kg versus 12 West Marine AGM 12V / 92 Ah batteries are 756 lbs / 343 kg.

Our LFP battery has a larger energy density and a larger usable capacity than the lead-acid battery, allowing for more space and less weight in your boat.

The chart below shows the cost and weight savings based on our Navy 6.0 outboard, the LFP battery costs 64% less than the lead-acid over the span of 9 years, and it weighs much less. In addition, it’s very hard to get accurate run time information from a lead-acid battery bank. Our LFP battery is a smart system that keeps you informed of operating status, including runtime left. This makes the LFP battery a great choice for an ePropulsion outboard.

ePropulsion E-Series LFP Battery

The E-Series LFP Battery is primarily designed to lower the overall cost of electric boating. However, we realize it’s the expensive lithium battery stopping commercial clients from getting into electric boating. The No.1 selling point of ePropulsion E-Series Battery is a unit price as low as $0.50 per Wh. As the original ePropulsion battery, the E-Series Battery works best when paired with an ePropulsion outboard. Using 3rd-party batteries will result in a data discrepancy regarding remaining capacity. Based on the above data we recommend pairing your ePropulsion motor with original ePropulsion battery systems to ensure you are receiving a premier customer experience based on significant lifetime cost savings, more space on your vessel, less weight, and increased performance.

Yet another advantage for choosing the E-Series LFP battery is the flexibility to build up capacity. The E-Series battery starts from 2 kWh, so you can build 2 kWh, 4 kWh, 6 kWh and more to fit your needs.

The E-Series is available in three models, E40, E80, and E175. All are rated IP67 water-resistant.

For more information on ePropulsion and our products, please get in touch with your local dealer, we are also available via our official Facebook page.

Richard Bailey
September 13, 2021

How many linked E175 batteries would it take to power a 32 ft. pontoon boat carrying up to 30 passengers, with two 40 hp electric outboards. Average speed about 8 knots (with several start/stops per trip); maximum daily run time about 4-5 hours.

September 18, 2021

The math is very simple. The E175 battery has an 8960Wh capacity. so we only need to know how much power is needed in total to satisfy the speed and duration.
In this case. 5(hrs) times the power needed (from the 40HP electric outboards) and divide 8960.

Tom Rawson
August 30, 2022

Does anyone know if its possible to get a DC converter in order to bring down the volts from the Epropulsion’s external 51v battery down to a 12v battery so that I could power my front 12v troller motor?

October 20, 2022

Hi Tom, it is workable to convert the 51V to 12V, you can contact the nearest dealer for further informations:, thanks!

Politis ntinos
November 23, 2021

Hi i am an owner E80 battery. I would like to tell me how can I resgarge with solar panel on a boat. Thenk you

November 24, 2021

Hi there,
The ePropulsion only solar panel was designed for the Spirit batteries, it is only compatible with the Spirit 1.0 battery and Spirit Plus battery.
To charge the ePropulsion E-Series Battery with 3rd party solar panels, users need to set the solar charger float voltage to 57.6V. Meanwhile, the solar charger’s maximum discharge current needs to be less than 40A for the E80 battery. Otherwise, the E-Series Battery would not be charged.
Please also consult the technical person from the solar panel company to make sure it’s okay 🙂

alan charters
June 6, 2022

Hi chandler, same question but for a E 175 battery – would a Gensasun MTPPS Booster work – using a 12 / 24 volts panel with a booster – i am struggling to find a solution to charging my e175 battery on my 26 foot sailing boat ?

June 16, 2022

Hello Alan, you can contact the local dealer for further informations:, thanks!

Scott VanKirk
June 19, 2022

What is the operating and max current for these batteries?

August 9, 2022

Hi Scott, the maximum charging current for E40, E80 and E185 are 20, 40 and 80A, the max continuous discharging current for them are 40, 80 and 150A, thanks!
August 20, 2022

I have a Spirit 1 + and would like to use an e40 or e80 battery in addition to the battery that came with the motor. Do the e40 or e80 batteries need to be in a dry location ? The motor is in a motor well on my sailboat that does get wet.

October 20, 2022

Hi John. it is recommended to put the battery in a dry place, you can contact the nearest dealer for further informations:, thanks!

Jon Cain
October 2, 2022

Hi! Is it possible to configure your batteries as a house battery bank? For example, 4 E175 batteries in parallel for a 48V, 36 KWh bank.

October 18, 2022

Hi Jon, it is possible to use our batteries that way, you can contact the nearest dealer for further informations:, thanks!

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