Back on July 22 I posted an article and link, which you can still access here: http://www.followthescience.org/.

The title was More Ethanol Horrors. In that entry I provided the link above that I really wish more people would check out because this whole ethanol thing is really starting to annoy me and a whole lot of other folks representing many industry sectors including environmental, food, motor vehicle, power equipment and our own NMMA (National Marine Manufacturers Association) to name a few. Why do I bring this up again? Our good friends at the EPA (let me spell that out: Environmental Protection Agency) are scheduled to protect us by the end of September, a mere 4.5 weeks from now. They're going to protect us by making a decision on whether or not to propose an increase of from 10% to 15% for ethanol in our gasoline.

I have a better suggestion. If the EPA really wants to protect us, they should ban the use of ethanol fuels as they are currently produced. I haven't heard of, seen or read anything in the last several years that tells me this movement is  in any way actually protecting the environment. The only thing as near as I can tell, that's being protected with this movement are a few big time corn farmers that produce the raw material for making the ethanol. Science can do way better than this and use other plants to produce ethanol if they must. Why not use the corn to feed some of the starving millions around the globe? That'll keep farmer John busy.

Please people, we're running out of time here. Read the link above and then call or write your congress person and tell them you really want this whole idea squashed. Its not helping us, and the EPA to date has shown no real grasp of the science and economics involved in this matter. I'm afraid they'll just sign off on the 15% requirement. There's a whole lot more than how well your boat engine runs at stake here.

Somehow I'm not too surprised at one of the newsbites that came in earlier today. It seems that the results of a survey conducted recently by the Alliance for Safe Navigation has discovered that most of us are terrible at keeping our charts up to date. The survey found that 64% of the respondents are not concerned enough about their navigational aids to make needed updates.

Further the survey disclosed that 79% of boaters fail to track US Coast Guard updates as found in regionally avaliable Notice to Mariners documents.

As I think of some of the areas I've cruised here in the US, today's revelations are  particularly scary to me.

 I'm thinking about the Outer Banks here. Lots of moving sandbars and super shallow water. The Florida Keys? Same thing. Were I live in New England we don't have as many sandbars, but we have some really big rocks, and by the way they don't move much if somebody hits them with their boat. The rock usually wins that encounter. I just came back from a cruise in the San Juan Islands in Washington state. More big rocks.

The bottom line here is that one of the fears I talked about in a recent interview Soundings Magazine did with me seems to be totally supported by this survey. The fear I expressed was that too many boaters today rely way too much on their electronics to tell them everything. But remember folks this stuff is only as good as the latest update for the electronic charts. Even then, things go on in between updates that you need to be aware of. Aids to navigation move, fishing gear gets relocated, sandbars shift location... all nice to know items. How can you find out? Its easy, simply go to the USCG Navigation web site and download the latest Notice to Mariners before you head out on your next trip. The web address: http://www.navcen.uscg.gov/ Do it now, before you have to make friends with your local SeaTow or Boat US salvage operator.... 

Yesterday in part 2 of this series on electrical overload issues you could see that fuses that are continually stressed to near or even above their nominal trip specification will actually begin to generate a significant amount of heat. In the video below, you can see just how much heat we were able to generate in our test set-up over the course of just 10 minutes at a high load. It was enough to surpass the thermal rating for the wire we were using....

The issue here is excessive heat being generated. Keep in mind that the fuse will not blow under these circumstances, but enough heat can be generated to cause damage to the fuse holder. so, several things come in to play here.

First, use of high quality fuse holders is a must. They are not all made of the same material, so some are definately better than others, and unfortunately you really can't tell much just by looking at them. I'm obviously a bit biased, but do know for sure that my friends at Blue Sea check for these sorts of issues. I'm reasonably certain that the folks at BEP and others probably do as well, but understand that testing may actually have to go beyond some of the traditional tests for thermal rise as prescribed by UL and SAE, to name several engineering Standards entities that help to define test criteria for such things.

OK, so fuses and their holders can get really hot, maybe hot enough to actually melt a fuse holder if undersized wiring is used or the fuse is being run near it's maximum capacity on a continuous basis.

Next, let's talk about the issue I alluded to in part 1 of this series.

Today, we as boaters are being offered some really high tech batteries. Companies like Mastervolt, Odyssey and others are really pushing the envelope with battery technology. This is of course a good thing, but opens the door to some new potential problems that frankly haven't been seriously considered by most people in the industry. As I mentioned in part 1 of this series the ABYC has historically based its AIC rating (read part 1) on the CCA rating for the battery or batteries connected to the circuit. The question is, is that still a valid approach today? Is that good enough? Well both Wayne Kelsoe and I know for sure that the available short-circuit current at a battery's posts is much higher than the CCA rating for the battery, but we really weren't sure by how much exactly. So in the video below, we subjected a Maxi-fuse to some super abuse and unleashed four golf-cart sized batteries on it to see what would happen. While we were doing that, we were monitoring the current flow. Of course we wanted to see what would happen to the fuse and its holder as well. Keep in mind that the fuse has a 1000 Amp AIC rating, so if exposed to more than that, all bets are off as to what's going to happen.  

In the video below, our measured peak amperage ended up being approcimately 10,000 amps. Let's see what happens:

Well, in this case the fuse did its job. It effectively opened the circuit shutting off power and saving the day. But, not without a little damage to the fuse holder as shown in the photos below. Personally I would not re-use this fuse holder. Others might, but I personally don't think its worth the risk, as some of the plastic has clearly been carbonized during this event. Carbon in a moist environment is actually a good conductor of electricity. I don't want a fuse holder on my boat that could actually contribute to a low level current leak (which will only get worse over time).

So, at this point, all I can say is stay tuned. We are looking at some new fuse types that may be quite viable to deal with this extremely high short circuit current issue and we are considering asking the BCI (Battery Council International) to expand its labeling requirements so that end users can have better information. We still have a way to go here, but if anything at this point I'm sure that some of the earlier assumptions that "there really is no problem" are wrong. Stay tuned.

Tuesday I told you I'd explain the reasoning behind the fuse holder having a melt down and the fuse not being affected at all. The fuse shown in that photo (see below) had been subjected to a DC load (in amperes) at or near its nominal trip rating for an extended period of time. A real world example of this would be the DC supply fuse for something like an inverter installation with continuously running AC appliances. The fuse in that situation may get hot enough to cause a melt down of the fuse holder and maybe even some of the wire insulation near the termination points at the fuse holder. Wayne Kelsoe and I were curious about how long this might take so one of the experiments we conducted in his lab was to hook up a variable load machine to a typical ANL fuse assembly and track the temperature rise over time. In our test we were never able to actually melt the fuse holder (high quality material selection on the part of the manufacturer) but we do know for sure that not all fuse holders are cut from the same cloth, as evidenced by the photo in yesterday's post and many others in our collection.

The question becomes how do you avoid this type of situation? The best solution is not to load fuses continuously at anywhere near their nominal trip point. Additionally, make sure the wire gauge you select is if anything oversized in high current draw situations. Larger wire will do a better job of conducting the heat away from the termination points at the fuse holder. In the video below, Wayne Kelsoe, chief technology officer for Blue Sea Systems in Bellingham, Washington provides a short explanation of what we are doing and what we expect to happen:

For several years now I and some of my colleagues have been raising questions about how we have traditionally prescribed applications for fuses and circuit breakers used on boats. The reasoning behind our questions is based on observations we’ve made in real field applications on real boats. To give you a visual to help you follow along here, the photograph below illustrates what can happen to a fuse holder on a boat under certain conditions. Now the uninitiated might ask: How come the fuse didn’t blow? It’s a great question and one that I’ll answer over the next several installments to Ed’s Boat Tips.

That is not the only question however. The next question is whether or not a fuse or circuit breaker will function in the event of a serious short circuit at or near your boat's battery bank.

 First, you need to understand one of the basic, but extremely obscure ratings that all fuses and circuit breakers have, known as the AIC or ampere interrupting capacity rating.

 Many folks wrongly think that if they install a 10 amp fuse in an electrical circuit the fuse will blow at a circuit load of anything greater than 10 amps. Well, that’s not actually the case. Most fuses and circuit breakers will actually trip out at somewhere between 125-200% of their nominal rating depending on their specific design. The AIC rating really has nothing to do with this fact.

AIC in simple terms describes how much amperage a fuse or circuit breaker can be exposed to without either turning into a solid ball of metal in the case of fuses, or welding the internal contacts together in the case of circuit breakers. This is obviously important because in the event of an electrical short circuit, we want to open the circuit and shut off the power flow ASAP!

For decades, the ABYC electrical standard has recommended AIC ratings for fuses and circuit breakers in DC applications based on a battery or battery bank’s CCA or cold cranking amp rating; the larger the CCA rating the higher the AIC rating, up to a maximum of 5000 amps.  But, some of us in the industry have begun to really question this thinking because we are seeing increasingly larger battery banks in use, particularly on cruising boats both power and sail. Further, we are seeing more and more new battery technology being employed; AGM and lithium technologies are beginning to become mainstream in more sophisticated applications. We need to start thinking in terms of short circuit potential vs. CCA rating. This problem and the question gets further complicated by the fact that the battery vendors often don’t even provide a CCA rating on any labeling on their batteries and you sure can’t tell much by simply looking at the battery. Suffice to say that my colleagues and I know for sure that the short circuit amperage potential at a modern battery far exceeds the CCA rating in any event. The question becomes by how much? Well, it will certainly depend on the specific battery and its age and general condition for sure, but the value will in virtually every case be significantly higher than the battery’s CCA rating.

So during this week I’ll share with you some of the findings in a recent series of experiments myself and Wayne Kelsoe at Blue Sea Systems in Bellingham, Washington conducted in his lab. By the way, if you want to find out the CCA rating of fuses and circuit breakers you might be using, the Blue Sea web site is a great resource as they are all listed. Check it out at: www.bluesea.com