I make sure our batteries are topped up whenever we head out for an anchorage, and once anchored our solar panels are often able to keep up with our daily usage. We always seemed to have enough power.

Until we didn’t.

At first I was in denial. Then I checked everything four times. How could we possibly run out of power with such a large battery bank? The question was impossible to answer because I really didn’t know how much energy we were using.

​A battery monitor would do this so I studied up on what was available on the market. Sadly, the idea of wiring in a shunt and then finding a location for one more gauge seemed like a daunting task, especially considering the hundreds of dollars many of them cost.

Then I found, on one of my favorite Youtube channels DIY Solar Power with Will Prowse, a review of a new device for monitoring batteries. Victron was marketing a Smart Shunt with Bluetooth that would do everything I wanted. It uses a phone or tablet for a display, and is easy to install.

It turns out that a good battery monitor was exactly what I needed. Finally I was able to see not just the rate of use (Amps A), but the amount of use (Amp-hours Ah). I can’t express how fundamentally important this was for understanding the overall function and health of our boat’s electrical supply system. I could write an entire post about this (and later, maybe I will).

The Victron shunt provides a large amount of information both numerically and graphically, but the most valuable information was the net Ah consumption; how much power did we take out of the battery and how much of that did the charging system put back?

A real-life test happened on our first anchorage of the year. During three February days I carefully watched the system, looking at all the data and happily relating that to the largest and smallest loads. It became obvious on the first day that the batteries were not doing well. The amount of power we were using verses the voltage of the batteries didn’t match up. It took another day for me to wrap my head around what I was seeing. On the third morning we didn’t have enough power to run our hydronic heater.

That cold morning, when the heater refused to run due to low voltage, the shunt reported the batteries were only down by 60 Ah. But wait! Our three house batteries are rated for 126 Ah each or 378 Ah total. We should have had lots of power left, but we didn’t. Yup, time for new batteries.

One note. On return to the dock and charging for several days, the batteries indicated they were fully charged (accepting zero current) but the monitor showed they were still about 20 Ah short.

One additional note. In case you were wondering, I thankfully have an ACR installed to isolate the start battery so I can always start the engine, even with dead house batteries.
​Do you?

Im not one to anthropomorphize the equipment on our boat nor any other object. The sea isn’t a harsh mistress, the weather doesn’t hate me, and talking to my outboard won’t make it run any better.

With that said, I’m pretty sure the house batteries have deceived me. 

Our three house batteries provide the electrical power for Odyssey whenever we are anchored out. Together they can store a large amount of energy.

Before we go off the dock I make sure the batteries are fully charged. Then, away from the dock, I keep an eye on the voltage. If it gets too low it’s time to figure out how to recharge. During the summer it rarely gets too low because we have solar panels that help charge the batteries when we are out.

This has worked well for us until recently when I noticed the battery voltage was dropping faster then expected, and it was getting worse. In an effort to understand what was happening I installed a device that, when installed correctly, shows the net energy the battery has delivered. Compare that to the rated capacity of the battery and you should have a pretty good idea how much energy is left.

But what if the battery capacity isn’t what it should be? What if, due to age and abuse, the amount of charge the battery should hold has dropped? It would still charge up, but out on anchor it would act like a much smaller battery and you would run out of power quickly. 

That’s the situation we found ourselves in last week on our first cruise of the year.

On our second morning the heater low voltage alarm went off moments after we switched it on. The battery voltage had dropped below 10.5 volts! Looking at the shunt information, we had only used a small fraction of the battery capacity and yet we were out of power. Not good.

Time for new batteries. 

Over the next few weeks I’ll be replacing the old AGM batteries with LiFePO4 (lithium iron phosphate) batteries, building a system from the ground up. This will include new equipment, a wiring change, and assembling the battery bank from individual cells.

I hope to document our progress with the design, reviews of the new equipment. I hope you enjoy the process.

Manzanita Bay is officially our first real destination spot in the area, and what a wonderful find. Anchoring just outside the bay gave us an incredible view of the snow covered Olympic mountains. It’s also a well protected spot with excellent holding.

This was our first cruise of the year. That’s a little sad considering it’s already the middle of March, but we need three days of fair weather before considering to go out and the weather for the last four months has been some of the wettest and windiest on record in Puget Sound. Why three days? That gives us a minimum of one entire day on anchor to enjoy all that anchoring out has to offer.

Lucky for us, not only did we have glorious sunshine for the entire trip, but due to the next frontal system arriving later then forecasted, we stayed for a bonus day. (We did pay for that extra day by being chased back to port by high winds and big seas, a herald of the soon to arrive storm.)