A colleague sent over some photos yesterday of a small fire that had occured at one of the electrical connections on a ELCI breaker device he had sold to a customer. The photo below shows the aftermath of the small fire and the melted plastic around the terminal.

The terminal above got really hot!

This whole thing all centers around something I've said here many times before: "The primary by-product of excessive electrical resistance is HEAT". In this case enough heat to start a fortunately small fire. So what caused the excessive heat here? Simple. Check out the next photo, it tells the whole story:

The "stacked" crimp connectors were loose, creating excessive elecrical resistance.

The idea here is that whenever you need to affix more than one terminal on a single screw or stud (limit 4 max according to ABYC) you need to fan the terminals out so that they are NOT stacked as shown. The stacking will always tricks the installer because the screw or nut will feel tight but in reality isn't and it will leave a gap as you can clearly see between the two terminals. This in effect reduces the electrical surface contact area for the connection and depending upon how much amperage you are trying to push through, will generate heat. The moral here? Fan don't stack multiple terminals on a single screw or stud.

OK, so this year I'm starting something new, the Eds Boat Tips Boater Innovation Award. You see every now and then I run into something that demonstrates some very creative effort on the part of a boater to solve a problem. So this year's EBT Innovation Award goes to Dan in Nova Scotia. For what you ask? Check this little beauty out:

So, now you're probably asking, what is it?  Well, its an electric outboard engine...conversion. What started out as a burned out Yamaha 40 hp outboard engine is now an electric drive for Dan's homemade pontoon boat that he keeps on a lake in Nova Scotia, Canada. Dan took what was essentially an electric lawn mower motor and had a local machine shop fabricate a coupler and welded mount to affix the motor to the drive shaft on the outboard. For the electrical  controls, a golf cart controller box has been added. The whole thing runs at 48 volts DC and Dan is supplying it from some AGM deep-cycle batteries. Totally quiet power that pushes his pontoon around the lake at 6-9 knots.

So, what are the problems? Well cooling for the motor is the only real issue at this point. Initially getting the right prop pitch was a problem, but that's been resolved. The motor, which is designed to be air cooled is getting warmer than Dan would like when he runs the set-up with the stock motor cover on. Running the drive as shown with the cover off is no problem and the electric motor cools nicely. So, what's he going to do about this little design issue? More innovation. He removed the standard impeller water pump from the mid-section of the motor and has installed a bilge pump motor in its place. The white hose you see at the lower end of the drive motor is routed up through the old engine exhaust cavity and is ultimately going to be connected to a coil of copper pipe that will be wrapped around the motor housing. It in turn will self-drain back down through the drive leg into the lake. Sounds like a plan to me. About the only question I have on that is the duty cycle for the bilge pump motor...... Not sure its rated for continuous duty. Anyhow, nicely done Dan, and congratulations on your award. Look out Torqeedo!

 Wire Sizer screen is simple to work with. Just drag a finger up or down on the iPad touch screen to change the parameters in each field.

 I found myself searching my way through the Apple iTunes store over the long Thanksgiving weekend and tripped over a really useful application for us boat wiring junkies. Simply titled Wire Sizer, this ap is a joy to use! Although only useful for DC wiring applications it does a great job. It has an initial set-up for measurement units and is basically a matter of entering the system operating voltage (up to 50 vdc), amount of amperage the circuit will be drawing, whether or not the wire run is going through an engine room space or not and what level of voltage drop you want to achieve. By simply scrolling through the on screen scales to set the specific values as shown in the video here: http://youtu.be/8QDeLeCjNwI you'll be able to get the right wire gauge to use every time. Nice.

One of our readers, Rick, sent in an interesting query regarding last week's post on The Appetite for Amps Goes Down.

To quote Rick: "Good article Ed. One thing I'd like to know about these units too is the start-up current they draw. I'm likely to be using a Honda EU2000i portable generator and would like to size the AC accordingly. I do believe there are "soft start" gadgets to get these types of loads up and running without tripping the breaker on the genny".

Well to Rick's question there are several points I'd like to make that might help him out here. First and foremost, Rick you need to understand that I'm not a fan of using the portable gasoline fueled generators you mention on boats. Not because I have anything against Honda. I drive one..... They make fine products. But these generators, even though I've seen them being hawked at boat shows are not really intended for use as on board sources of AC power. They're great as emergency power sources and to function as a back-up or temporary source of power at a job site or for a tailgate party at a football game or even to power up the flat screen TV while camping. But, they use a gasoline fueled engine that no matter how clean burning emits dangerous carbon monoxide gas. These generators are meant to be used in well ventilated areas ONLY! Temporarily mounting one of these generators on a boat can create a serious potential safety hazard. Further, due to their grounding system design, they may or may not be compliant with ABYC standards that require a neutral to ground link at the source of AC power. I'm not certain on the particular model Rick mentions, and couldn't find a wiring diagram to tell me one way or the other. Historically these units were problematic in this area.

As for the power available for start-up, for sure there are soft start devices available, the Charles Industries unit shown above is one example. The unit shown is really designed for much heavier loads than Rick is contemplating here, but for sure these units are available.

I'm not certain what the start-up amperage draw for the specific Dometic compressors I mentioned in The Appetite for Amps Goes Down is, but based on a quick survey of Dometic products at one website I checked, it looks like their typical start-up draw for AC compressors is approximately 5 X the running current, which is not atypical.  I do know that most of the inverters I have dealt with over the years can easily handle twice their continuous rating for start up concerns. Key point, for a very short time duration! It does not look like that is the case with this Honda generator. I checked the spec sheet for it and it is rated a 2000 watts (16.7 Amps@ 120 VAC) maximum and 1600 Watts or 13.3 Amps continuous. So, really light duty in the grand scheme of things, and Rick based on that, I'd say don't try it with this particular generator.

The bottom line on all of this is really rather simple and to Rick's question, when calculating loads you really do have to take into account peak start-up current when trying to determine the appropriate rating for any power source.  

 Cruisair units like this actually use less power today than ten years ago, in effect they are greener units, not just because of the new refrigerants used, but also because they use less electricity

 For some years now I've written that it seems like the average boat owner's appetite for amps is insatiable. I'm referring to all of the electrical and electronic toys and gadgets that we seemingly can't live without. But, after thinking about it for a bit, I began to question myself on this very premise. Sure the gadget count keeps growing, but what about the actual power usage?

I spend a part of every fall inspecting boats as a part of the Cruising World Boat of The Year judging team. This year one of the big themes from the sales folks was the use of LED lighting on board and the huge difference it makes in terms of electrical power usage. It true, LED's use milliamps vs. multiple amps to shine a light. This all got me to thinking about other commonly used appliances on board, and what their power usage looked like. So, I made a little bet with the folks at Dometic about their air-conditioning systems. Simple enough, but noone in their display booth at IBEX could answer me immediately. My bet was that their air-conditioning units used less electrical power today than a similar unit of ten years ago. They weren't sure but agreed to check for me and get back to me. This is significant because things like air conditioners and refrigeration systems in general are notorious users of big power.

Even things like electronic equipment use less power today. I haven't yet done an apples for apples comparison, but I do know for example, that an HD digital radar unit uses far less power than a conventional unit. LCD display screens consume far less power than their cathode ray tube counterparts from yesteryear.

Dometic (the makers of Cruisair products) supplied me with some numbers for their modern vs. old tech airconditioning systems and although the numbers may seem small in terms of actual amperage, the percentage of gain is notable.

Examples: 10,000 BTU unit @ 115 volts= 8 amps   (old style unit)  New tech unit: 5.6 amps  or a 35% average improvement. A 16,000 BTU unit for years gone by, 11.4 amps.  A new unit, 8.8 amps or a 27% gain.

So, all of this has got me thinking about a really comprehensive article where I take a new 40 ft. boat let's say, and equip it for today's market and do a total load analysis for both AC and DC systems. Then compare it to a 12 year old boat with the same equipment and see what the comparative appetite for amps actually is. I'll bet we're going to see a significant difference. sound like a good winter project. Got to get ready now to deal with yet another huge east coast storm coming at me overnight.