Echo Charger

[PHitchcox]

Without stepping on anyone's toes, readers should use caution; some of the above advice is solid; some is a little squishy (best diplomatic term I could come up with).

For what it's worth, after many years of using the standard A-B switch (thankfully no brothers-in-law to fry the alternator) but the occasional forgetfulness and resulting dead battery, I installed an ACR and couldn't be happier. I understand the advantages of most of the approaches, but have taken the view that it is not what works when everything goes as planned that matters, but what works when something goes awry. For me, the ACR (or their variations) has made a world of difference, keeping my starter battery fully charged but independent of the house bank. Your mileage, age, memory and personal preference may vary.

 

[Stu Jackson]

Always having your engine ready to go

Informative and lively thread!
I would like to add one thought not mentioned in this thread of charging and switching. ...it may not be prudent to switch your starting battery off. Many times you may need to quickly start the motor to get out of situation. No time to leave the helm and go down below to switch the starting battery on to start the engine.

Shell,

If you investigate the wiring diagrams and the discussion above, you will see that in either case of the "preferred" systems I mentioned and that MS discussed, at NO TIME was the engine not able to start. This is because in my reply #27, in Item 2, scenario (a) Separate Switching: the reserve bank is ALWAYS connected to the starter; and in (b) Still Using the 1-2-B Switch: the house bank is ALWAYS connected, so the engine is ALWAYS ready to go. If you use (b), leave it on the house bank position all the time unless you kill your house bank and need the backup bank (which is why we keep calling it that). Don't switch to the reserve bank to start your engine (except for a periodic check run to assure it's working fine).

The points we keep trying to make to people about this subject are:

1. Stop calling it a "start" bank; call it an emergency, reserve and/or backup bank, and USE it that way. The house bank is perfectly capable of starting your engine.

2. Wire it either of the two ways described and linked to real life wiring diagrams (unless you have a Beneteau!).

3. Get you alternator output OFF the 1-2-B switch -- since the output then always has a load, you can even turn the switch off if you want with no fear of fried diodes. Your brother-in-law will never kill your alternator ever again!

4. Work hard to trace your wiring and understand how, first, it may be wired either from the factory (usually horrible) or the PO; and, second, make whatever changes you deem acceptable to YOU and how YOU want to run your boat and draw a wiring diagram of THAT, so both you and the next owner can understand it.

The importance of a reliable electrical system cannot be understated. After years of neglect, due to questionable factory installations (alternator output to 1-2-B switches, for instance) and the growth of electrically hungry boat systems (autopilots, chart plotters, GPS, radios, computers, electrical appliances like microwaves, coffee makers, etc.), we ALL depend more and more on our electrical systems' integrity.

It becomes, now, a SAFETY issue, rather than mere convenience.

Because of that, it behooves us all to spend a little more time learning this stuff, and putting the days of "Electrical?? I just don't understand that stuff; I thought you just turned the key and off ya go" behind us.

With these forums, the sharing nature of many of us to help you understand, and the incredible amount of information that's out there, and a little "quality time" "under the hood" it's not really that hard ONCE YOU DRAW A WIRING DIAGRAM.

Many of us started out with smaller boats, with simpler systems. When we got our Big Boat with its more complicated systems, the first thing I bought was Calder's Boatowner's Manual. I studied it, and didn't get it all right away, it took some time. But I personally traced and drew the wiring on my boat. I found out how wrong the POs wiring diagram was, and where it was incorrect. I learned how it was supposed to work, and over the course of the past ten years have discussed this here and on our C34 Message Board. I've learned a lot from many others who have chimed in, and have developed the "preferred" systems (again, Beneteaus notwithstanding ) from websites, equipment manuals, The West Marine Advisors, Ample Power, and others. I didn't make this stuff up, but MS and Bill Roosa and Don and many others have contributed to my, and I hope, your understanding by simplifying as much as we could and sharing our knowledge with you all.

I once had a friend who, when my engine started right away, said: "Wow, that's great, how do you manage to do that? Mine doesn't always start!" That's when I realized the time I spent learning this stuff was well worth every moment. We boat safe, we boat smart and we can relax much more knowing how it works, why it works and troubleshoot any glitches which, because it's a boat, will invariably occur.

Fair Winds, and Happy Electrons,

Stu

 

[John Nantz]

Some more comments...

Yup, four golf-carts in the original battery location, that's 440 AH with normal golf-carts or 490 AH with the 245 AH models. Okay, here goes.

1. The battery boxes I used are from a company over near Vancouver. I've got the name and address but it's not handy at the moment. You may see some around as they are milk-white plastic and about 1/4" thick material. All the sides are flat (yea!) so there is no wasted space. They make several models of battery boxes but the ones I got are designed for two golf-carts in one box. The lid has a couple notches for the battery cables but it is easy to cut another notch if your cable locations don't match up. I believe the box itself doesn't have any notches to relocating the cables doesn't compromise closure. There is also room under the box for the tie-down strap should you need to put it there.

Back to box size. The box height is a couple inches or so higher than the battery but I had to cut some off to get it to fit under the bunk, but not so much that the lid touches the battery terminal. Which brings up another point. There are four basic battery terminal types - the one I went with is a more-or-less plain "stub" which is flat on one or two sides, with a bolt through a hole. This is the lowest of the battery terminal types and is commonly available so when it comes to replacement time there isn't a problem.

I had to adjust the compartment somewhat to get the horizontal space required and build a new "floor" board (replaces the old one) to go under the new boxes which took a bit of trial and error. There is extra space for a container of baking soda (so one doesn't have to raid the galley), hydrometer with container, and a jug of distilled water, all in one place. The overhead light is handy so one can see what you're doing and don't have to add water by brail. I've got a picture of the setup but, alas, also not readily available at the moment. This was a long project to get it neat, sanitary, and not looking like a hack-job.

I know what you mean about the lazarette. That's where I store my mountain bike indoors and out of sight! One of the only boats under 60 feet that I know of where you can do this. Still have room for the storm jib, spinnaker, storm anchor with 375ft of 5/8" rode, dingy oars, fenders, and other stuff.

2. Maintenance-free battery: What I was thinking was the kind that are black, look like lead-acid, but have caps that can't be removed. If they're AGMs then obviously that changes the game plan. Maybe.... - I'm thinking here so that may be dangerous - if the start/emergency/reserve/back-up battery isn't really, what you would call, "used" much, then it shouldn't need much charging, and, ergo, shouldn't gas much and need water. If it is in a cool place, like under the aft end of the bunk (I'll get to that in a moment), then it shouldn't need much water. My Group 27 very seldom needs water and then only a small amount. It is a lot cooler back there.

3. Aft storage space: The space I'm talking about is UNDER the aft berth cushion, not to be confused with the space aft of the berth with the removable "door". At least on our boat there is a factory installed panel under the aft berth aft cushion. Clarification Note: The original cushions came in two halves, a forward half and an aft half, but a previous owner may have changed that. The removable access panel provides access to the four strut bolts.

Hope this helps clarify things a bit.

 

[Ron20324]

"2. Maintenance-free battery: What I was thinking was the kind that are black, look like lead-acid, but have caps that can't be removed. If they're AGMs then obviously that changes the game plan. "

John, I have seen a couple magazine articles that point out that, really, a diesel starting battery does the same thing a car battery does- provide alot of initial starting juice. Accordingly, they say why not save the money and get a car battery? Good point if you have a "starting battery" in your boat. My car has one of those sealed batteries, and since it is up in the wheel well and the tire has to be taken off for access, I can assure you it has lasted 8 years without being touched. I only replaced it in February because I was going on a long road trip.

 

[mitiempo]

Re: Battery Wiring
I am currently rewiring a CS27 (all dc including lights, etc). At present I have a "start" type sealed lead/acid battery and a deep cycle battery (group 24?). The deep cycle will be replaced by two Trojan or similar 12 volt deep cycles in parallel. As long as the sealed battery is ok - it appears to be - I'll keep it. The shore power charger is a Statpower (now Xantrex) 10 amp 3 stage unit that works fine. Later I will upgrade it as it is a bit small. The Xantrex Truecharge2 looks good and probably the 40 amp version as I will live aboard and the batteries will not get all 40 as long as I am aboard using 12 volt lights and accessories. Currently I do not plan to have refrigeration, just lights, laptop, tv, and stereo, but I may change my mind later and add a Nova Cool unit or similar. I will probably add solar later. I am installing a Heart Incharge 3 stage alternator regulator. The start battery will be charged by an Echocharge I just purchased. All direct charging will go to house only. I have removed the 1-2-off switch and will not re-use. Instead I will use Blue Seas #9006 simple on/off switch for house and to use the house to start if necessary (2 separate switches).
My questions are these:
While I have three of these #9006 switches, do I need to be able to switch off the dedicated start battery? It will only be connected to the starter and Echocharge. Is the ignition switch ok as the only means to turn this battery off?

My engine is a Yanmar YSE8 with the stock alternator - not sure of size but pretty small. How big an alternator can it turn without choking? I have a Hitachi alternator of the same frame size believed to be 80 amp. Will this work?

I have been told that the accuracy of battery monitors gets worse as the batteries age. Is this true? My plan is to install a digital Blue Seas voltmeter at this time and I already have it. I would consider a battery monitor depending on the answers.

Looking forward to your replies.
Brian

 

[Stu Jackson]

Electrical System Basics 101

1. Is the ignition switch ok as the only means to turn this battery off?

2. I have been told that the accuracy of battery monitors gets worse as the batteries age. Is this true?

1. No. Having read the thread, dare I suggest looking at the wiring diagrams? The wiring from the ignition switch doesn't control battery 12 volts, like a 1-2-B switch or other heavier duty switches do..

2. Nonsense, they measure voltage and amp hours in and out, that's all. You need to check the electrolyte with a hydrometer.

You seem to have a good handle on the equipment.

 

[mitiempo]

I'm learning....

But in my wiring plan I am only going to wire the start battery to the starter - no other use ever. I realize that the ignition switch does not carry the start battery voltage and current, but it controls its use (the only use in my case), does it not? I have and will install a Blue Seas 9006 switch for the start battery, but I don't see a real need unless the ignition shorts out somehow. The batteries will be fused near their terminals.
As far as the Linklite or similar battery monitor, doesn't the remaining battery capacity (as they advertise they provide-a gas gauge to quote Xantrex) depend on the batteries' condition, ie age? Doesn't a digital voltmeter give a good indication of battery state of charge (11.7 to 12.7 volts of measured open circuit voltage)? While I agree that a hydrometer is the most accurate for individual cells state of charge, how much do I gain over the voltmeter by installing a battery monitor?
Brian

 

[mitiempo]

By the way, the information about battery monitors came from the store (Energy Alternatives) where I purchased my Echocharge. Their advice was to use the voltmeter which I told them I already had as opposed to buying a battery monitor. Their business is exclusively alternative power, no drinkholders in sight!

 

[Maine Sail]

A Dvm

By the way, the information about battery monitors came from the store (Energy Alternatives) where I purchased my Echocharge. Their advice was to use the voltmeter which I told them I already had as opposed to buying a battery monitor. Their business is exclusively alternative power, no drinkholders in sight!

If you are willing to let your batteries sit, with absolutely zero charge, either in or out, for a minimum of about 1-2 hours, 4+ hours is yet better, and over night is ideal to attain a true "resting voltage" then a volt meter will suffice.

Many people use a DVM incorrectly to test battery resting voltage. The voltage of the tested battery must be a true open circuit resting voltage and most folks never do this thus giving a bogus reading. Most boats have items connected directly to the banks like LPG sniffers, electronic bilge switches or stereo memory wires that need to be physically disconnected before taking a resting voltage and very few boaters are willing to go to this level.

A DVM will NOT tell you how many amps you have removed, nor put back in, and will not give a very close ball park on state of charge on the fly.

There are very few boaters who are willing to shut off the batteries, disconnect all charging sources and let them sit long enough to attain an accurate resiting voltage.

You've clearly spent good money thus far to do this right so why not add a battery monitor. The best value I see going these days is the Victron BMV-600 from Jamestown Distributors (Victron used to make the Xantrex XBM for Xantrex so they are not new to the scene)..

My personal opinion is that the battery meter should be the absolute first thing anyone buys as it can save you thousands on un-necessary bank, alternator or solar/wind upgrades. I have seen this time and time again when people don't have a good understanding of how a system actually operates until they own a battery meter. I have never known anyone whom I suggested buy a battery meter that regretted it. Most people are pissed I did not mention it to them before.

Before I bought my first battery meter in the 90's I though I had a good handle on my usage and thus the alternator I needed. What I found out was that I was actually using far less batt capacity than I thought, or had figured on my energy budget, and that I did not need a 90 amp alternator on that boat. It's too bad because I had already bought it, and the external regulator, and then found it to be a complete waste of money but only after I had installed the battery meter.

I could have saved $700.00 had I bought the battery meter first...

 

[Ron20324]

Proper wiring dictates no fuse in the cable to the starter. Maybe a 500 if you really must.

 

[Maine Sail]

Huh??

Proper wiring dictates no fuse in the cable to the starter. Maybe a 500 if you really must.

Huh??

If you fuse close to the battery as many US builders do you have essentially fused the starter cable. My starter cable is 3.5 feet long from the batt switch and the battery to switch is 16". My fuse is about 6" from the battery. That is a fused battery cable in any sense of the term....

I run an ANL fuse that is NOWHERE near 500 amps. On this boat it's 200 but on other boats I have used a 250 and have never blown one in ten+ years of using the same exact fuses and fuse blocks on small sailboat AUX engines but you need to know your starters capacity.

Even on the huge Cummins diesel on my power boat I only used a 300 ANL and never once blew the fuse...

Our 2005 Catalina even came from the factory with a 250 amp ANL on the house bank and I added a second on the start /reserve...

Advising not fusing the cable between the starter and the switch is one thing but to have no fuse in the entire starting circuit, as in, close to the batteries, would be a tad foolish IMHO.. Chafe happens..

 

[Ron20324]

That some people have gotten away with something (like state registration sticker placement) for years doesn't make it right- or wrong. My new boat does not have a fuse to what is labeled as the "engine battery". The other batteries do have 400 "mega fuses" as the manual calls them. For those whole like to thump the bible that is Nigel Calder's Boatowner's Mechanical and Electrical Manual, check page 315 for two diagrams that do not show a fuse. Fire issue aside, I think in a life or death situation when you need the engine, you don't want to be hindered by a blown fuse.

I didn't read all the text, but he states that starters can draw 300 amp initially, and 200 amps while cranking. If you are to believe that, then the Catalina may be just be getting buy if using just one battery to start (and I wonder if he has a battery designated as "start" or "engine"?). As the starter ages, maybe the amperage draw may increase. I'm sure over the years the standards have changed, and I do not have with me the present ABYC "standards", though "really they are more like guidlines". My 2006 boat's construction and the bible tells me "no fuse in the battery-to-starter circuit".

 

[Stu Jackson]

Managing banks with just voltage

is not 21st century technology.

Once I saw your post #45, mitiempo, I looked for this link immediately:

http://forums.catalina.sailboatowners.com/showthread.php?t=105340

 

[mitiempo]

Thanks for your replies
After reading the linked post, I certainly am not planning a spreadsheet like Bill Roosa! There is a lot of information out there and you have to disseminate it to find the "real truth" I guess. Blue Seas in the manual for their digital voltmeter says "There is disagreement about the length of time the battery is required to rest before a usable open circuit voltage is obtained. However, the user will observe that in the first 10 to 20 minutes of rest the voltage will settle to a figure close to its completely rested open circuit voltage, which is generally considered to be obtained at 24 hours. With experience the user will learn the time required for reliable readings on any particular system." I now realize that a good monitor will give me more useful "instantaneous" data and I will not have to turn off propane solenoids, lights, etc to get an accurate reading. What is the real usable difference between the Victron and the other monitors like the Xantrex (Link 20, Linklite)? Still confused about fuses. If I install a battery switch (simple on/off) for the start battery and the starter is the only device it is hooked up to (except the Echocharge output) is a fuse recommended?
And I think my last question was lost in the shuffle. How large an alternator can my Yanmar yse8 turn without problems - I think the current one is 25 amps and I currently have a 80 amp - will this work?
Thanks for all your replies. My experience as far as the electrical planning is more theory than practice at this stage.
Brian

 

[Stu Jackson]

Reply to Brian's Questions (Echo Charger & Electrical System)

Thanks for your replies
After reading the linked post, I certainly am not planning a spreadsheet like Bill Roosa!

Brian, you don't have to. The purpose of posting that is that Bill is more than willing to let you share it. You don't have to reinvent the wheel. Two other sources for similar information are:

http://www.westmarine.com/Images/wa/Elecbugt.pdf

http://c34.org/bbs/index.php/topic,3976.0.html

Also, Calder's Boatowner's Manual has a good one, as do many other books and references on line, Google "energy budget" or "boat energy budget"

There is a lot of information out there and you have to disseminate it to find the "real truth" I guess. Blue Seas in the manual for their digital voltmeter says "There is disagreement about the length of time the battery is required to rest before a usable open circuit voltage is obtained. However, the user will observe that in the first 10 to 20 minutes of rest the voltage will settle to a figure close to its completely rested open circuit voltage, which is generally considered to be obtained at 24 hours. With experience the user will learn the time required for reliable readings on any particular system." I now realize that a good monitor will give me more useful "instantaneous" data and I will not have to turn off propane solenoids, lights, etc to get an accurate reading. What is the real usable difference between the Victron and the other monitors like the Xantrex (Link 20, Linklite)?

Yes, you're right, an energy monitor beats voltage, hands down! That's why I gave you the link to the Simple Battery Management thread. Voltage as the only measurement, regardless of how much "rest" time, is, basically a nonsensical way to care for batteries given the cost effective technology in battery monitors available today. BOTH MS and I put that off to last, and we BOTH recommend it should be among the FIRST. How much more basic and straightforward can we be???

Like anything else in life, there are choices of purchasing monitors. Your boat, your choice, they all pretty much work well. Magnum is a newer vendor with a good reputation. Do some comparative shopping and make a choice, for the same reason we won't force you to choose which of the two "preferred" electrical system designs and their small variations (see below), it's impertinent of us to tell you what to buy.:naughty:

Still confused about fuses. If I install a battery switch (simple on/off) for the start battery and the starter is the only device it is hooked up to (except the Echocharge output) is a fuse recommended?

The purpose of fuses is to protect the batteries. Put a fuse close to the batteries, and read this, which discusses systems with a slight twist on the first of my two "preferred" system wiring diagrams, but primarily for battery fusing: http://c34ia.org/wiki/index.php?title=Catalina_34_Electrical_System_Upgrade
Since Jim wrote this article a few years ago, he revised it to put the echo charge wiring right at the banks, not the switch(es).

And I think my last question was lost in the shuffle. How large an alternator can my Yanmar yse8 turn without problems - I think the current one is 25 amps and I currently have a 80 amp - will this work? Thanks for all your replies. My experience as far as the electrical planning is more theory than practice at this stage.
Brian

Will this work? Sure, but... Here's why the "but" is included: like ANY charging source, you have to do the math on recharge times. The smaller the charging source, the longer it takes, however you also have to figure in battery acceptance. See this, previously linked for you: http://c34.org/bbs/index.php/topic,4787.0.html

Between a realistic energy budget and your proper understanding of battery acceptance with its diminishing law of returns when charging, and, most importantly, HOW YOU choose to use your boat, i.e., marina hopping or anchoring out, you have choices to make. You're on the road to understanding all of this quite well, and are asking all the right questions.

 

[mitiempo]

Thank you for your response. You say that this will work (80 amp alternator on my 8 hp Yanmar. How much power does an alternator use? Am I better off to buy a 55 amp alternator? I understand battery acceptance and have read the link as well. But I think I understand that I would be better off with a larger rather than smaller alternator. As with the shore charger, if I am using accessories then not all output is going to the house batteries, currently planned to be about 260 amp hours ( 2 Trojan scs225 12 volt in parallel - 130 x2 =260 amp hours). 260 x 20% is 52 amps max acceptance during bulk charge. I also recognize that the amp rating of an alternator is an ideal and in real life it will put out less. My main question is how big an alternator can my little 8hp yanmar turn without sacrificing too much motive power?
Thanks
Brian

 

[Ron20324]

I just had lunch with one guy- an ocean sailor- who lives aboard his 40-foot C&C, and another guy with a Pacific Seacraft 36. Both knowledgeable people. They had split opinions on fuse/no fuse, so there you go- it's a matter of opinion. I don't know who the guy is who writes the C34 atricles, but I do know Calder is well-respected on things nautical. As I said in another thread, just because someone writes an article, it does not make them an authority- it only makes them an author. If someone has the current ABYC standards that they can quote, please present them. As I said, they are not the law on boat construction- more like guidelines, really. The U.S. Coast Guard is the law on SOME boat construction requirements. The fuses are there to protect the wiring, is the general consensus I hear. I can quote the page of my owners manual and the way the 2006 made-in USA boat comes from the factory as factual evidence there is no "requirement". So, to me, that over-rides beliefs, opinions, or here-say as may be posted on the starter-to-battery fuse question. Let those who know not what they do consult the experts- and not EVERYONE one this forum who has a differing opinion that they offer as fact.

 

[Stu Jackson]

Alternator Sizing on a Small Yanmar

Thank you for your response. You say that this will work (80 amp alternator on my 8 hp Yanmar. How much power does an alternator use? Am I better off to buy a 55 amp alternator? I understand battery acceptance and have read the link as well. But I think I understand that I would be better off with a larger rather than smaller alternator. As with the shore charger, if I am using accessories then not all output is going to the house batteries, currently planned to be about 260 amp hours ( 2 Trojan scs225 12 volt in parallel - 130 x2 =260 amp hours). 260 x 20% is 52 amps max acceptance during bulk charge. I also recognize that the amp rating of an alternator is an ideal and in real life it will put out less. My main question is how big an alternator can my little 8hp yanmar turn without sacrificing too much motive power?
Thanks
Brian

Sorry I didn't answer that question specifically, because I am not familiar with the Yanmar engine designations and sizes. Your small engine will sacrifice HP with an alternator running. I suggest others are more appropriate to answer that specific question.

That said, that small a diesel simply can't support a larger alternator. Our 100A Blue Circle pulls about 2 HP out of our 21 HP M25 engine, IIRC. "Too much" is a subjective issue, and the "acceptance" link to the C34 'site discussed the draws from a night on the hook in detail regarding the last 20% of battery charging.

You wrote earlier: " I think the current one is 25 amps and I currently have a 80 amp - will this work?"

It appears that you have a 25 A installed and an 80 A in box ready to be put in. Is that right? You could try this: http://c34.org/bbs/index.php/topic,4669.0.html

MS and I have differing points of view on external regulators. He's had three bad experiences with Balmars, mine works just fine. He points out that internal regulation works just as well for him on his boat as external, and has been for the PO since the boat was extensively cruised. I have no reason to disagree.

What kind of regulation do you have on your 25A and for your new proposed 80A?

This is yet another reason for installing a battery monitor to read your house bank's amp hour status. I recommend you install the entire new electrical system with your existing alternator and see how it performs, while you get more input on the size of an alternator that can realistically be supported by your engine with your well described planned house bank.

If it's internal on your 25A you could see tapering charging, which would require more shorepower charges than would a larger externally regulated, albeit perhaps not power-supported, alternator, even with the battery management feature that is available with some, not all, external regulators.

 

[mitiempo]

Re: Alternator Sizing on a Small Yanmar

Thanks for your quick reply. I have an am planning to install a Heart Incharge 3 stage alternator controller. Your advice to wait and see is well taken as far as leaving the alternator alone until later.
Brian

 

[Maine Sail]

I just had lunch with one guy- an ocean sailor- who lives aboard his 40-foot C&C, and another guy with a Pacific Seacraft 36. Both knowledgeable people. They had split opinions on fuse/no fuse, so there you go- it's a matter of opinion. I don't know who the guy is who writes the C34 atricles, but I do know Calder is well-respected on things nautical. As I said in another thread, just because someone writes an article, it does not make them an authority- it only makes them an author. If someone has the current ABYC standards that they can quote, please present them. As I said, they are not the law on boat construction- more like guidelines, really. The U.S. Coast Guard is the law on SOME boat construction requirements. The fuses are there to protect the wiring, is the general consensus I hear. I can quote the page of my owners manual and the way the 2006 made-in USA boat comes from the factory as factual evidence there is no "requirement". So, to me, that over-rides beliefs, opinions, or here-say as may be posted on the starter-to-battery fuse question. Let those who know not what they do consult the experts- and not EVERYONE one this forum who has a differing opinion that they offer as fact.

While you are technically correct, and yes I do have E-11, that cranking batteries do not require fuses, house banks do and this is part of the CFR and is federal law for builders.

Many US builders do choose to fuse cranking batteries as a matter of safety. As I said above I think suggesting that folks not fuse them is a tad risky but to each his own and that was my only point.

I have had cranking battery fuses on every boat I have owned and never blown one and never had one anywhere near 500 amps. Suggesting a 500 amp fuse as a blanket statement can be short sided becuase any overurrent device should not exceed 150% of the cables rating and this is referenced in the CFR as well.

In the event that I get knocked down and the battery breaks free, while doubtful, and the wire pulls out of a lug or breaks off the starter post I am protected from having a live wire in my boat flailing about.

Many folks, including myself start on the house bank which is, by law, mandated to be fused at the build level. My starter has never drawn more than about 165 amps and I have measured it in order to size my fuse. My only point was that fusing both banks is a safe and prudent measure provided that you size the fuse correctly.

FEDERAL LAW
183.460 - Overcurrent Protection: Special Applications

(a) Each ungrounded output conductor from a storage battery must have a manually reset, trip-free circuit breaker or fuse, unless the supply conductor is in the main power feed circuit from the battery to an engine cranking motor. The circuit breaker or fuse must be within 72 inches of the battery measured along the conductor, unless, for boats built prior to August 1, 1985, the circuit has a switch that disconnects the battery.



P.S. I have stated many, many, many times in writing on this forum not to take my words only and to do your own research beyond what you read here.As most knowI tend to err on the side of caution, which often seems like over kill for some, but I have been in some pretty scary situations and look at things with a "what can happen" not a "what might not happen" attitude. I try my best to always preset evidence along with my view points.