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.
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.
The Victron SmartShunt. Click to see it on Amazon.
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.
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.
Uh oh....
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?
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?
The shunt (and a few other things) installed.
Next up: The Lithium Dream
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