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Narrowboat Remote Battery Monitor

Feb 2, 2024 - 2 minute read

If you live on a boat then batteries are probably something on your mind quite a lot, along with emptying the loo and having enough water in your tank.

It’s really important to know the state of your batteries so you can decided when to charge them. A surprising number of boats don’t have a simple voltmeter fitted. Ours didn’t when we got her. Sticking your voltmeter probes into vacant 12v socket works perfectly well for quick checks. A cheap and cheerful ‘lighter socket” meter can be left plugged in all the time.

There are more sophisticated solutions. For instance, we have a SmartGauge. That gives accurate voltage readings for both our leisure and starter batteries, and a solid estimate of the state of charge of the leisure bank. There are many others but by-and-large you have to be aboard to read them.

What if you want to know what’s going on when you’re away for a while? Or get a bit more data so you can see trends? That’s what motivated me to build something a bit more sophisticated.

I briefly toyed with the idea of just pointing a webcam at a voltmeter. It’s a workable solution, but not much good if you want to see trends, or get alarms.

I already had a basic home automation setup using Home Assistant so that seemed a logical place to start. I also had a drawer full of electronics oddments (Raspberry Pis , Arduino, and so on)

I’ll go into more detail in later posts but my overall setup is:

Coming soon…