Epoch Batteries, elegant drop-in LiFePO4

Ben Stein

Ben Stein

Publisher of Panbo.com, passionate marine electronics enthusiast, 100-ton USCG master.

32 Responses

  1. Dave Jones says:

    Epoch currently has the 100 Ahr for $449!

    • Allen says:

      Smokin deal

    • Ben Stein Ben Stein says:

      Thanks for pointing this out. As Dave points out, Epoch has added a new, 100-amp-hour, 12-volt battery that’s currently available for $449. This battery looks like it has the same electrical specs as the unit I reviewed but appears not to be IP67 rated. Additionally, the more basic case doesn’t include the mounting feet of the IP67 batteries. But, at $149 cheaper, this could very well be a great battery for many applications.

      -Ben S.

  2. Allen says:

    Amazing. I just put a 36 volt unit in my Golf cart and its been great. I have 6 on order for my Trawler now.

  3. Rod collins says:

    So glad you are bringing attention to Epoch. These are by far the best built, best value drop-in batteries being made. No short-cuts!!
    -Rod Collins

  4. Tom Whitehead says:

    Hi Ben – Nice review – What is the charge rate on this BMS? Tom

  5. Ben Ellison Ben Ellison says:

    Ben, does the Epoch CANbus implementation use some sort of data protocol that could be displayed on a boat fairly easily?

    • Ben Stein Ben Stein says:

      That’s a great question. So far, I haven’t found any information on their CANBus integration. I’ve asked Epoch themselves and they are investigating. My hunch is the CANBus capabilities were built into the BMS and they haven’t figured out how to use them yet. I suspect I’m not the only person after this information, so I’m hoping they will get something published on it soon.

      -Ben S.

  6. paul Borchardt says:

    The $499 option would be great for the boat, but it appears to lack the Bluetooth option. It’s IP65 and mounting options match my existing FLA batteries.

    • Ben Stein Ben Stein says:


      Good catch, I hadn’t seen that difference. That’s an interesting feature to have removed. The battery does still have a CANBus port. So, if more can be learned about the CANBus communication options, you may be able to get the information you need via that route.

      -Ben S.

  7. Tom Whitehead says:

    Also, can the CAN bus talk to an alternator regulator like the Wakespeed in order to turn off the alt in case of and HVC or LVC event? Most of the so called “drop in” batteries don’t and this can cause problems later on.

  8. Grant Jenkins says:

    Ben, great write-up and excellent photos. The performance numbers alone are impressive – when combined with the build quality and price point, Epoch seems to be in a league of it’s own.
    I’m starting to appreciate the the price premium of LiFePO4 batteries is not just a market-based number justified by their performance – there’s really a lot of complex design and manufacturing involved in creating this powerhouse. Really nicely done, Epoch.

    • Ben Stein Ben Stein says:


      LiFePO4 batteries are fascinating to me. Initially, I wasn’t sure they were that big of a game changer. But, the more time I spend working with them, the more I’m convinced I was wrong. They’re a pain to install because of all the broader considerations of charging voltage, load-dumps, charge acceptance, and more. But, once installed, they’re just vastly superior to what we’ve been using.

      As I came to better understand lead-acid’s behavior, I became more frustrated by the fundamentally fragile and fussy nature of the batteries. The more I understand about LiFePO4, the more I appreciate the characteristics of the batteries.

      I’ve got a pretty good contrast going right now. I’ve just wrapped up testing on Epoch’s batteries, and now I’m moving right into testing a Li Time battery. At $3/amp-hour, it’s about as cheap of a battery as you will find. I’ve just done the tear-down and while it’s not anywhere as elegantly made as the Epoch, it’s still a fine battery. Plus, run-down tests show this battery too is over-achieving it’s rating. At $3/ah, you’re talking about $3.75 per usable amp hour, assuming 80-percent depth-of-discharge.

      In March of 2021 I did some analysis on the cost of LiFePO4 versus the cost of lead acid (https://panbo.com/lithium-battery-math-better-than-you-may-think/). At the time, I could find a 100ah deep cycle lead-acid battery for $100 while a 100ah LiFePO4 battery was $900. Today, a 100ah flooded-lead-acid battery is roughly $125 and a the cheapest 100ah LiFePO4 battery is $300. That lead acid battery might make it to 300-500 cycles if you’re exceptionally kind to it. Every bit of testing I’m seeing says that LiFePO4 battery will make it to 2,000 cycles and may make it to as many as 5,000 cycles.

      As you can see, I’m really bullish on the technology. My testing gives me far greater confidence in the safety of LiFePO4 than I’ve ever had in FLA. Yes, BMSes can decide that now is a good time for a shutdown event or they can fail, but I believe that can be easily mitigated with system designs that employ multiple batteries. I’ve logged about 30,000 miles in my RV with LiFePO4 and now have quite a few deployed. So far, not one has given me a bit of trouble.

      -Ben S.

      • Grant Jenkins says:

        Thanks Ben. I’m definitely leaning more in the LiFePO4 direction, since pricing continues to become more competitive, and the technology matures. I would say that the biggest selling points for me is the almost 100% improvement over FLA in DOD capability, which reduces the size/weight consideration by a half as well, combined with no (watering) maintenance. And the .5C charge acceptance rate, compared to .15 – .2C rate for FLA, can make a big difference in real world cruising scenarios.
        The total life cycles, on the other hand, seem almost meaningless – so much so that I often wonder why folks give them so much attention. If I live to be 100, and keep the same boat the whole time, I’d still never fully cycle my house batteries more than perhaps 400 times (10 times a season). So the cycle limit is never really a factor. I suppose if you live aboard with no shorepower or generator, then cycles become an almost a daily occurrence. But that would seem to be a very small minority of marine installations.
        The FLA battery is going to need replaced after 6-7 years, no matter how well it’s maintained. If the LiFePO4 can outlast that in terms of years, not so much cycles, that’s of real value.

        • Ben Stein Ben Stein says:

          I haven’t owned a set of LiFePO4 batteries for 6-7 years yet. But, extrapolation of what I’m seeing combined with reports from trusted sources makes me believe you’re likely to be pleased by the calendar longevity of the batteries.

          In regards to your thoughts about cycle life… I hear you and agree that most boaters won’t fully cycle their batteries very often. So, depending on your use case, you may or may not see value in cycle counts. I tended to cycle my batteries something between 50 and 100 times a year. Those cycles varied from 30% DoD to at least 50% DoD depending on the situation. On the Have Another Day, once I moved to LiFePO4, I loved that I could cycle to greater than 50% DoD without feeling like I was murdering something. I guess that meant part of the return for LiFePO4 was non-financial. It was peace of mind that I wasn’t abusing the batteries and hence setting myself up for a replacement.

          -Ben S.

      • Ray says:

        We just finished a two week electrical upgrade on our cat that includes installing 900ah of Kilovault batteries. I know it’s cliche to say lithium on a cruising boat is a game changer but we are simply blown away at what this system does.

        I only wish we made the change years ago.

      • Hans Johnson says:

        Last year, we upgraded our Sagres (an Ericson 27) to LiFePO4, and it’s been an absolute game changer. We now have 460Ah of usable house power (compared to 90Ah with our old FLAs), a 2kVA Victron inverter/charger, and all the other bells and whistles. Yeah, it wasn’t cheap, but we now never need to worry about electrical power any more as we explore the coast of British Columbia. The entire electrical system is integrated so the battery, inverter/charger, alternator, and solar controls all communicate and work appropriately with the battery. The battery is in full control of all charging. Because the system is fully integrated, load dumps aren’t a major concern. If the battery decides it does not want any more power (due to balance issues, or being full, or out of temperature spec) it just sets the battery current limit to 0A, and the charging sources move to just powering house loads.

        For a BMS, we went with a REC ABMS, which is a contactor based BMS. If it does crap out on us in the wilderness, I can override it fairly easily. My main contactor is a BlueSea 7700 series solenoid, which can be manually overridden. If that happens, all the charging sources go into a limp mode, which will protect the battery.

        We can also monitor it all remotely through Victron’s VRM system, so even when the boat is tied up at the dock, I can check on her every few days to make sure things are good. If something goes wrong, the VRM system automatically emails both myself and my co-owner, letting us know the problem, and gives us the time to get out to the boat.

  9. Allen says:

    Funny…i just did a review of th3 36 volt version. There is also another area that shows historical data that will work great to monitor charging over time and allow you to look back over the previous days or weeks. https://youtu.be/fLEwJadwuTc

  10. What type of charger can be used with these batteries? Do I need to junk my FLA/ Gel / AGM inverter charger and install all new LiFePo capable charger? What about my dead simple Alternator with no special smarts that wants to run at 13.6V at all times? Can it be used with these batteries or do I need to retrofit that as well?

    I have to admit that after looking at your IR images of the batteries, the idea that my batteries are going to be running at say 120F under more realistic conditions has me pretty nervous. When running for several hours on a cruise with the engine room hitting 90F or better in summer conditions, what does that mean for battery life with continuously elevated temps? Extended battery life is critical to pay back calculations when making a decision like this. Is there any information on whether these batteries will exceed the 5-6 year lifespan of my FLA by a factor of say 2X to payback the initial investment?

    Lastly, in my previous life I designed electronics for Safety of Life reliability (called Level A for Avionics). All of our electronics required the simplest possible implementation at the lowest possible power dissipation levels, with the least possible parts count to achieve a required level of reliability and safety. Analysis of system failure modes was also critical and implied the simplest system block diagram is the safest and most reliable. I know this is not an aircraft but it’s also not a car – you can’t stop and get out if batteries fail in some unsafe manner. The massive number of BMS components running at elevated temperatures is a huge source of potential failure modes and implies reduced operating hours before failure. All FETs, capacitors, chips etc are rated for expected lifetime that is reduced as a function of increasing junction or ambient temperature (junction is the internal device 3 terminal connections of Gate Drain and Source in the case of FETs). So if these batteries operate at elevated temperatures most of their lives, I wonder if I can really expect 10-12 years of service life and in the back of my mind I worry about catastrophic failures.

    • Ben Stein Ben Stein says:


      There’s not a simple answer to the ability to re-use an existing charger. If the charger can be programmed for in-range voltages through bulk, absorption, and float it may be usable. But to be usable, you also need to be able to disable temperature compensation, otherwise, you risk too high of voltage in colder conditions. A simple alternator can be usable with LiFeP04 batteries, but you need to look at the rating of the alternator and whether it’s likely to be destroyed by the higher charge acceptance of LiFePO4 batteries.

      The best advice given about a conversion to LiFePO4 is that you need to look at it as a system upgrade, not just a battery upgrade. All portions of the charge system will need to be, at a minimum, verified.

      There’s lots of information about longevity of LiFePO4 batteries. Most estimates are around 10x the cycle life of lead-acid batteries. Additionally, 10 years seems to be a very safe lifespan for the batteries. Rod Collins of MarineHowto.com often references his own 13+ year old DIY battery that continues to test at rated capacity after 2,200 cycles. That’s pretty compelling, though anecdotal, evidence of battery longevity.

      Please understand that I didn’t put in the really boring images of the battery sitting at almost exactly environmental temperatures. It required a huge load to a single battery to get the temperatures moving at all. If the same load had been applied to a multi-battery bank, I don’t think there would have been much temperature rise at all.

      -Ben S.

  11. Timo Giling says:

    Why is “Li-Ion” molded on the casing when they are clearly not? This is not just a marketing thing. For firefighters it is probably quite relevant what type of Lithium batteries they are dealing with. Even so for future boat owners.

  12. moose says:

    we have been working recently with Roypow here in australia “epoch seems US only and why not go straight to the source” the batteries “whilst slightly heavier than other lithium offerings” seems rather good! a factory represenitive was out here recently and was very keen to hear how far they are progressing with 48volt as well.
    there looks to be a few other battery monitoring systems coming soon. and 200AH 12v/24v batteries on the way.
    but so far so good πŸ˜€

  13. Allen Jones says:

    Ben…question: when you induced some of the faults, did the monitor give an audible signal and flash?

  14. JP says:

    There are no manufacturers of Lithium cells of that sort made in the USA or else apart from China. This may explain the affordable price in US dollars.
    Your sales price is unique and I hope you sell many of them to catch-up on the cost of certification. In fact is there any international certification to UL and UN standards.
    Lab test standards are necessary to guarantee safety and good business practice. Selling a price may be attractive but selling a safe product should be essential.
    As you should know, Lithium batteries are subject to be unsafe once they come close to end of life. Safety is an important issue and you should also be able to supply instructions for recycling.

    • Ben Ellison Ben Ellison says:

      I thoroughly agree that all batteries should be recyclable if not repairable. But the technology is getting there and most of the LiFePO4 batteries we’re using on boats look like they’ll last quite a long time. As for LiFePO4 batteries being “unsafe once they come close to end of life,” I don’t see evidence of that. Please explain.

  15. Joseph Pica says:

    Ben, Great report!
    Nice well built battery. While no longer owning my boat Carolyn Ann it’s custom etc. LFPO4 bank system is still good after 11 years as of last report.
    I still wait for drop in’s to incorporate an alert audibly and or light as well as a slight delay function prior to invoking an LVC or HVC cut-off of the bank. Ours was both audible and warning light at the helm and had a 2 minute delay. We had agm group 31s for start batteries these also acted as a buffer 12volt supply if bank shutdown from LVC or HVC. Good if underway and needing Navigation operational. We ignored the charging difference between the two chemistries which was biased to the LFP04 chemistry. The agms didn’t seem to mind and lasted 8 years.

    • Ben Ellison Ben Ellison says:

      So, Joseph, did you typically operate with your AGM and LiFePO4 banks in parallel? I understand that some think that a big no-no, but I’ve been researching an interesting German company that has designed LiFePO4 batteries to do that, resulting in what seem like several nice features: https://www.bos-ag.com/

  16. Jeffrey Torsrud says:

    Would like to see a listing of FAULT or ERROR Codes that these batteries Generate off the BMS!

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