So What Makes You Think Your Compressor is Bad?
- Category: Refrigeration
Most marine refrigeration, and all Frigoboat systems, use the Danfoss BD 35 and BD 50 compressors which are incredibly reliable machines and very robust. It takes a lot of abuse to "kill" one (they don't simply die from natural causes), so if you suspect that your compressor is faulty, it's important to know how these compressors work, how they can be damaged, and what symptoms to look for.
The Danfoss BD 35 and BD 50 compressors are identical except that the BD 50 has a little more cubic capacity and therefore a slightly higher Btu rating. The compressor and motor are hermetically sealed inside a steel canister and supported on vibration-absorbing springs. There is no shaft seal that could leak refrigerant.
COMPRESSOR – The compressor is a single-cylinder device with a crankshaft that when rotated pushes a piston in and out of a cylinder, compressing the gas. A simple valve plate allows gas to be drawn in on the down-stroke, and the gas to be compressed and then released on the up-stroke. The compressor assembly is mounted above the motor, and the vertical crankshaft is a continuation of the motor shaft.
MOTOR - The compressor crankshaft is rotated by means of a poly-phase inductively coupled motor that has no brushes to fail or wear out. There are three sets of windings arranged around the stator, and the ends of these windings terminate on a three-pin connector that provides for the electrical connection through the compressor shell. The rotor is built around the shaft that connects directly to the compressor crankshaft.
ELECTRONIC COMPRESSOR CONTROLLER – Also known as a "module", this is a vital part of the compressor, and the motor cannot run without it. The controller is mounted on the compressor on a special bracket, and secured with a screw. It is electrically connected to the motor via a three-wire plug that is pushed on to the three-pin connector on the compressor shell. The compressor controller basically takes the 12v or 24v DC input and energizes each of the three windings in turn, causing the motor shaft to rotate. Varying the speed at which the windings are energized varies the speed of rotation of the shaft.
So what could possibly go wrong?
What's so Special about this Battery?
- Category: Battery
What's so special about this pesky Firefly Oasis battery that I'm tripping over everywhere I go?
The word seems to be out about the Firefly Oasis battery. So much so, in fact, that we seem incapable of keeping them in stock, and the manufacturer is so swamped that they can’t produce enough of them!
What is it about this battery that has stirred up so much interest? Maybe it has the same sort of allure that the Ford Model T did back in the day. With a choice of just one size, it can be ordered in any color as long as it’s a rather fetching green and blue, something that wouldn’t look out of place on the mantelpiece at Christmas.
Or maybe some folk are keeping them as pets, showing them off to fellow boaters in between feeding them freshly charged volts and cleaning up their discharge. No, there must be more to it ….
It’s a Group 31 AGM battery - Nothing ground-breaking there. It’s a VRLA (Valve Regulated Lead Acid), AGM (Absorbed Glass Mat), PSOC (Partial State Of Charge) battery, for all you AL’s (acronym lovers) out there. It’s a nominal 12 volt battery containing lead and acid and is no lightweight, weighing in at 75 pounds. It has comparable capacity to other Group 31 batteries and has similar charging requirements. No super-acidic acid; no extra heavy lead; no kryptonite or unobtainium. Pretty boring so far, so what’s the big deal?
10 Myth Busters - Solar Panels on Boats
- Category: Solar
I've just come across yet another sailing magazine article giving inaccurate and misleading information on solar power for boats. (Why don't they bother to do some research and ask the real experts?) So here is a list of ten myths and busts in an effort to set the record straight.
MYTH 1 - Glass solar panels with aluminum frames are the most efficient
BUST - No, no, no! The type of cell determines how efficient a solar panel is, not how it is constructed. Coastal offers three types of panels all made with the highest available efficiency SunPower® cells:
1) aluminum-framed glass panels,
2) razor -thin walk-on panels, and
3) flexible panels for installation in canvas areas like biminis.
All three types enjoy the same high efficiency because they all use the same cells with 22.5% efficiency. Glass panels are more common and less expensive, but not necessarily more efficient.
MYTH 2 - You can't walk on solar panels.
Air Cooled or Water Cooled?
- Category: Refrigeration
Which marine refrigeration system is better when cruising in warm waters: air cooled, pumped-water cooled, or Keel Cooled?
A well designed and fabricated air cooled refrigeration system, like the Frigoboat Capri 50, should be able to maintain refrigerator and freezer temperatures in the tropics if the application, installation, and operation are all within the manufacturers' guidelines.
But in tropical/Caribbean conditions, air cooling will be 25% to 35% less efficient than water cooling. As a result, the overall power consumption of an air cooled system will be considerably higher than for a pumped-water cooled system, and very much higher than for a Keel Cooled system.
Many serious cruisers these days install hybrid Air-plus-Keel Cooled systems, where the air cooling is only used when the boat is hauled for any reason. For a new installation, this could be a Frigoboat Capri 50 installed together with a Keel Cooler, with a switch installed in the fan circuit of the Capri 50. Existing Frigoboat Keel Cooled systems can be easily converted to an Air-plus-Keel Cooled system by installing an Air Add-On condenser. This is accomplished with the use of just basic tools, and without any adjustment to the refrigerant charge.
If your boat is aluminum, then due to corrosion considerations that prohibit the installation of a Keel Cooler, you would be best served by installing a pump-water cooled system like the Frigoboat W50. That, together with the Air Add-On air-only condenser for use when hauled out, will provide the same efficiency as a Keel Cooled system, although the added current draw from the water pump will negate some of the power savings normally experienced over an air cooled system.