Charging System Blues: my energy generation improvement plan

My energy generation improvement plan was to install a Sterling Power Pro Alt C alternator-to-battery charger, a 50 watt Renogy monocrystalline solar panel and created my own pole-top mount

Baby steps along the road to energy nirvana

It all started with the fridge. No, to be honest it started with the first couple of nights we spent aboard our project Norlin 34, Ostara, which at the time had a single 90Ah house battery. A late night up, with the stereo playing, the anchor light on, and a couple of lights on down below was all it took to have the voltmeter showing a pitiful 12.2 volts the following morning. That’s 50 percent discharged.

That season, I added a dedicated 65Ah engine cranking battery and a second 90Ah lead/acid deep cycle battery to double the house bank to 180Ah. I also swapped out the most-used interior lights from halogen to LED. That improved things, but with only a 40 amp alternator on our little Yanmar 2GM, it still took hours of motoring to bring the batteries up to full charge after a night on the hook.

After that I added a chartplotter at the helm and then a drop-in Isotherm refrigerator. There’s no point in having a fridge if you don’t use it, and its 2.5 amp draw—equal, when you think about it, to a pair of halogen lights—meant I was only comfortably using it when I knew we had a lot of motoring ahead, or when we were in a slip connected to shore power—a rare event indeed. Clearly something needed to be done.

Phase One of my energy generation improvement plan was to install a Sterling Power Pro Alt C alternator-to-battery charger, which it was promised, would bring my batteries up to charge nearly 5 times as fast as the existing regulator. It does this by converting the alternator’s output to imitate the action of a mains 4-stage battery charger—optimizing each charging stage to bring the battery up to full charge quickly. I chose the Pro Alt C over a smart regulator chiefly because it was much easier to install. It has two outputs, one to each battery bank, and prioritizes charge according to which bank is lowest.

It sounded too good to be true, but has proved flawless in operation. Even a half hour of motoring after a night on the hook brings the house bank back up to full charge. But still, wouldn’t it be great not to have break the stillness of an anchorage with the clanking of a diesel engine in the morning and evening?

Stage Two was the installation of a solar panel. I bought a 50 watt Renogy monocrystalline panel via eBay for $99, shipping included—bargain! The problem was where to install a 29in x 26in panel on a small 34-footer. Eventually I decided to mount it atop a pole bolted to the stern railing, where it would be out from underfoot and also mostly clear of the shadow of the rig and sailplan.

I wanted to be able to tilt and swivel the panel to face the sun, but dedicated pole-top mounts were excruciatingly expensive—a stainless steel pole and swivel mount was close to $1,000. So I bought a 6ft length of Schedule 40 aluminum pipe and a length of 6in x 1/4in aluminum from for $35, paid $57 for a swiveling Magma grill mount that fitted inside a rod holder of the same internal dimensions as my Schedule 40 pipe, bought some 304 stainless steel pipe brackets and rail clamps from, and made my own pole mount for around $100.

The panel is connected to the battery via a $75 Genasun MPPT controller that makes the most of the available sun. I can tilt the panel in two directions easily, and turn the grill mount so that the panel faces the sun. If really strong winds are forecast, I can just unplug the MC4 connectors, lift the panel off the pole and stow it below.

As soon as I connected the controller to the house battery, the battery monitor registered a 3.6 amp charge, which is what I had hoped for. In full daylight, with the fridge on and the stereo playing, the panel is still inputting an amp more than we are using. As I am an inveterate fiddler and tweaker, I’ll have no problem making sure the panel is oriented toward the sun for maximum charge.

This is still a new system—I finished the installation last weekend—so I’ll have more to say after we’ve spent a full night aboard with the fridge on. I’m looking forward to seeing how long the panel takes to bring the batteries back to full charge.



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