Epropulsion E-Series Lithium Batteries

Epropulsion’s E-Series lithium batteries are the optimal power source for your Epropulsion Navy EVO Outboard or Pod Motor. They use the safest lithium chemistry (LifePo4) and are excellent value.

LiFePO4 batteries are effectively the only viable choice for electric drive systems on boats. At today’s pricing – and when you take into account the USABLE capacity and life expectancy in terms of charge cycles – they’re actually cheaper than lead acid batteries anyway!

We refer to USABLE capacity because most older technology batteries can only be discharged to about 50%, if you want them to last more than a few cycles. Lithium batteries are much more tolerant of much deeper discharging, so you can use much more of the nominal rated capacity each time you use them.

LiFePO4 batteries are also typically one third to one quarter of the weight, with a similar advantage in volume (space needed to fit them), compared to traditional lead acid batteries.

With the new (much) lower pricing for 2026, ePropulsion’s E-Series lithium batteries are notably good value (still not cheap!). If, that is, you are comparing like-with-like… LiFePO4 batteries are not all the same.

The high-end features of E-series batteries include:

• IP67 water resistant case, designed for marine use
• very high quality grade A cells
• very high quality BMS housed within the casing
• colour display built-in

You can buy cheaper batteries, or “DIY-build” even cheaper ones, but your insurer may not like it!

First of all – with apologies to those who know this already – we need to go back to basics! The only useful comparative measure of battery capacity is Watt hours Wh, or kilowatt Hours kWh (1kWh being 1000Wh). Voltage or Amp Hours on their own do not tell you the whole story. You can calculate Watt hours by multiplying Voltage V and Amp hours Ah, for example:

• a 12V 100Ah battery has a total capacity of 1200Wh, whereas
• a 48V 100Ah battery has a total capacity of 4800Wh, or
• a 48V 25Ah battery has a total capacity of 1200Wh (same as the 100Ah 12V battery)

That is not the end of the story though, as some types of batteries can use more of their capacity than others. As a general rule of thumb:

• you can use about 40-50% of the capacity of lead acid type batteries before you start seriously affecting their life time cycle limit (number of times they can be charged/discharged)
• you can use about 90% of the capacity of lithium batteries with very little detriment to their life, and even 95% is not a disaster (one discharge to 95% has a massive effect on lead acid batteries)
• if you restrict your discharge to 80% on LiFePO4 batteries the number of cycles is all-but infinite for leisure users (3000 cycles for E-series)

So that’s where the term “usable capacity” appears from, for example:

• a 12V 100Ah lead acid battery has a usable capacity of about 550Wh (based on 45%)
• a 12V 100Ah lithium battery has a usable capacity of about 1100Wh (based on 90%)
• a 48V 100Ah lithium battery has a usable capacity of about 4300Wh

All three could reasonably be described as “100Ah batteries” but are completely different in what you can get out of them!

The latest (2026) Epropulsion E-Series batteries have capacities as follows:

• E60 3072Wh total (at 90% that’s 2800Wh usable, or about the same usable capacity as nearly 5 100Ah 12V lead acid batteries)
• E100 5120Wh total (4600Wh usable, over 8x 100Ah 12V lead acid)
• E163 8345Wh total (7500Wh usable, or about 13x 100Ah 12V lead acid)

As you can imagine one E163 battery weighs a lot less than 13 lead acids (76kg vs ~270kg), and takes up a lot less space!