Melissa’s brow furrowed. “What do you mean we don’t have the power?  We’ve been motoring all day long.  Surely the batteries are charged now!”

Sadly, Melissa’s brow spent much of September and October a-furrowed. Our 440 Amp Hours of Lifeline AGM batteries were aging and and could no longer deliver the juice they once did (Something I can relate to). Even with good sun on our solar panels and the Balmar 110 amp alternator running, the batteries would not accept as much power when new.

Our old Lifeline batteries. These were top of the line when we left the dock in 2017. Somehow it escaped my attention that they were almost seven years old

I should have foreseen this crisis.  When we were preparing the boat for this cruise, I was busily adding new instrumentation and communications equipment.  We now sport Garmin Radar and wind instruments, an electric toilet, an AIS class B transceiver, and Starlink internet in addition to a not inconsiderable number of power hungry devices already aboard.

Oh and a 2000 watt Victron inverter charger! Let’s not forget that. That inverter opens up a veritable Pandora’s box of amp sucking geegaws that seem to mysteriously find their way onto the boat. This isn’t a new phenomena.  A quiet battle has been raging on Galapagos about supply and demand since the beginning. Even as I type, Melissa is wondering out loud if we could install a washer/dryer combo in the V-Berth.  Check out some of our earlier posts on the subject Here and Here.

By the time we reached San Diego it was clear that we would need to replace the old batteries. My first instinct was to simply buy another set of Lifelines.  That would be the easiest route. But who wants to do things the easy way? Not us!

We had been hearing that regular cruisers were now installing Lithium batteries (technically Lithium Iron Phosphate, or LiFePO for short) onto boats with great success.  This particular chemistry is now widely available and has addressed many of the safety concerns of earlier Lithium battery types.

Thus emboldened to consider a serious upgrade to our power system, I began to research, perseverate, ponder and cogitate on the myriad choices available. There are so many great resources available on the subject and it is amazing how much effort folks put into creating great advice and content.  Links to some of the articles and channels that helped me are below.

After much hand wringing, I bought two 460 Amp Hour Epoch batteries. These things are an amazing value and have features I would never have considered possible in a battery. For example:

• 300A Max Continuous Discharge (500A 30s Discharge)
• 230A Max Continuous Charge (300A 10s Charge)
• Built in 500 Amp Class T fuse
• IP67 Rated, Dust and WATERPROOF
• HEATED – Internal heating for below 0C charging
• BLUETOOTH – iOS and Android Apps
• CANBUS Communication allows BMS to communicate directly with Victron OS
• Mountable ON/OFF Switch
• Mountable Battery gauge

Our two Epoch 460 AHr batteries. These are an 8D form factor. On the right hand side, you can see the power switch and a row of dip switches for setting up series/parallel configuration. The power switch is an especially useful safety feature.

Out of this impressive list of features the fact that I could integrate the Battery Management System (BMS) with the Victron equipment I had was intriguing. This means that the battery would tell the charger what it needs. Charging batteries correctly is the key to a long and useful life. Living with lead acid batteries on a boat it is difficult to give them the love that they need; don’t discharge below 50% capacity, do bring them up to full charge often, AGMs prefer one charge profile while traditional wet cell batteries  want to be charged differently.

Each battery came with a well made set of 1 meter battery cables. These made the installation that much easier.

Now, the battery can tell most of the charge sources (not all) what it needs.  The Victron Multiplus charger and both solar chargers are controlled by the Epoch BMS.  The Balmar alternator is not that intelligent and special considerations have been made to ensure that the alternator maintains both a safe charge profile and is itself protected from working too hard.

Any project of this magnitude requires more than just a pair of batteries.  I installed a Victron Cerbo GX to provide the communications interface between the various charge devices and the batteries but it does so much more.  The Cerbo offers a number of digital and analog inputs for displaying alarms, tank levels etc.  It also has a built in web server which provides visibility and control of all of the various Victron devices. And since the Cerbo is networked via our Starlink router, that visibility and control is available anywhere in the world.

One concern I have is the reliability of these fancy new batteries in extreme conditions.  For example, would a lightning strike destroy the BMS, rendering the whole battery useless? I don’t have a spare BMS but plan on acquiring one. This worry led me to maintain a set of traditional wet cell batteries for the engine and windlass.  They are three inexpensive (Interstate) Group 24 batteries that are used only for start and windlass duties but if the worst should happen, I can switch them over to provide power to the house and vital navigation electronics.  While it would be difficult and expensive to plan for every dark contingency, I feel this strategy provides some old school redundancy. Let’s hope I never need it.

This is the power distribution diagram for Galapagos. Note that a Victron DC-DC 30 amp charger is used to supply charging voltage to the Wet Cell batteries. Click on image for a larger view.

One potentially controversial decision I made was in how the I use the alternator to charge the LiFePo batteries.  Because the BMS can disconnect the batteries from a charge source for a variety of reasons, there is a risk that the alternator could be unceremoniously disconnected from the batteries.  Alternators do not like to be dumped. Who does? If this happens a large field voltage spike is generated which can destroy the rectifier diodes.  For this reason, provisions must be made to prevent such an occurrence or minimize its effects if it does happen.

Conventionally, the alternator would be charging a lead battery and the LiFePo bank would be charged via a DC-DC charger. That way there is always a battery to charge into.  But when I was sourcing my Victron charger, all I could get was a 30 amp charger (I think a 50 amp charger is now available). Since my alternator can comfortably deliver 75 amps to the LiFePo bank I would be missing out on all that juice, something I am loathe to do.

So I have reversed the process and charge the lead battery from the LiFePo bank using the DC-DC 30 amp charger.  To mitigate any risks of damage of a battery disconnect, I  have installed the Balmar APM-12 protection module to our alternator which will clamp field voltage spikes to prevent damage to the diodes and other electrical devices. I also have a manual field disconnect switch which I can use if the batteries are approaching 100% State of Charge. Additionally, I have de-rated the alternator using the Belt Saver feature on the regulator to keep the alternator running a lower operating temperature, about 80 degrees C at present.

The DC-DC charger and the Cerbo GX module.

If I acquire a second, larger DC-DC charger, I may reconfigure this setting. For now, I am comfortable with the risks.  The likelihood that both batteries would go offline at the same time seems fairly low.  Maybe I can buy another Epoch battery and then further minimize the risk.

So far, I have been ecstatic about how this new system is working.  I have taken the 920AHr house bank down to 13 percent SOC and charged it back to 50 percent in 4 hours. If I run the generator and the alternator and solar at the same time, I can put 150 amps into the house bank without worry. Well, I still worry, but less than I used to.  I love not having to to charge the bank up to 100% SOC. For a cruising sailboat that is a big deal.

We are presently anchored off of Isla San Geronimo, about a third of the way down the Pacific coast of the Baja Peninsula. Today we motored for about three hours until the wind got up and we sailed the rest of the day. The graphic below depicts our energy demands and production.  This is probably not totally accurate as it does not correctly account for the power generated when the alternator was running. Maybe I need a smart shunt.

One of the many nice features of the Cerbo GX is the ability to create a Victron Remote Monitor (VRM) account. With it you can not only control your Victron devices but gain insights into your energy production and usage.

This is a long post and most readers are likely bored silly. Hopefully it will help those of you that may be considering the switch to LiFePo batteries. Remember, this is just one data point by a guy on the internet. Do your research and make decisions based on your own circumstances.

Here are a few of my favorite resource as I began this journey.

Off Grid Garage :This guy is very knowledgeable and entertaining.  He is an Australian dirt dweller but well worth a visit.  Lots of youtube videos about LiFePo and various battery monitoring systems.

MV Intrique He has a couple of videos on the Epoch 460 AHr batteries and has done a good job of explaining some of advantages of these batteries.

Panbo An excellent review of the Epoch Battery with a tear down.  This site gave me great confidence in the build quality of these batteries.

Marine How To If you have done any research into batteries and charging, You have visited Rod Collins’ site.  He has done a lot for the DIY community.  Rod had a massive stroke two years back and is slowly recovering. If you find his articles useful, think about donating to his site.

Gui Mods The Cerbo GX is a Linux based platform so of course smart folks have hacked the interface and made it better.  I highly recommend the Gui Mods.  This video is a primer on what the mods do and how to install them onto your Cerbo.