This just seems like a no-brainer. We all know that everything with “marine” stamped on it means it cost 4-5 times as much as it ought to. Sometimes this is justified – bronze or high-quality stainless hardware is pricy, and things that are made to last use high-dollar components. Other times, though, those high prices are just an attempt to soak boat owners for more money. I think that’s the case with volt meters for boats. Earlier, I posted about my analog volt meter made by Blue Sea that costs $45. It is has been on the boat as long as I’ve owned it – installed perhaps by a previous owner. It was definitely better than nothing, but that doesn’t mean it was a quality piece of gear. I’m learning now just how inaccurate it is, as I use my digital multimeter in its place.
I glued up a small bracket from scrap teak and .25″ plywood to hold the multimeter in place. I mounted it today by drilling two small holes in the plywood back, counter sinking the holes for flathead screws, and screwing it into the bulkhead. Here’s a photo of the bracket again:
After cutting off the probes, I installed new ring connectors on the leads and attached the positive lead to the middle pole of the battery switch, and the negative lead to the negative bus bar. I’ve attached hook-and-loop fabric to either side of the unit to hold it securely in the bracket. Now I can test each battery’s state of charge and get an accurate figure.
The state of charge at any given time is subject to interpretation. The meter can give you a rough idea of current usage, and let you know when the voltage is getting very low. It can give you a more accurate picture of the state of charge in a battery after the battery has been unused for 24 hours. The multimeter can also give you an idea of the rate of charge acceptance for your batteries. This information is useful in determining the health and status of your battery bank. And, the information is a lot more accurate with a digital meter than your typical consumer-grade analog meter – I discovered through this project that the old analog meter was reading several tenths higher than was true.
The meter cost me about $10, and I’ve just ordered another from Amazon for under $10. I would have ordered just a new set of leads and continued to use the meter as a tool also, but the with shipping costs, it made sense just to order a new meter for – literally – a dollar or two more.