House Battery Isolation

[hattitude]

go to newmarpower.com they have a product called start gaurd. works great and will solve your problem.

I agree, they also have a NAV PAC for $200 dollars that I hooked my radio & GPS up to. It has an internal battery that protects the units during start up and will run them for awhile if the 12V goes away...

 

[Pete]

I have a StartGuard installed and it will solve the problem. Having been inside it to change the internal small AGM battery after about 6 years, I examined the guts. How it works is you connect it to your start pushbutton, when you push the button, a relay transfers the electronics to to the internal battery, and when you let up on the push button it transfer the electronics back to the engine battery and recharges the internal battery off your alternator. If you do something with diodes and a battery on your own, keep in mind the forward voltage drop of the diode that will prevent your added battery from getting up to full charge. I suspect that is why StartGuard used a relay instead of a diode.

Pete

 

[Trojan]

Your not going to see any voltage drop by using diodes. $200 bucks versus $4. bucks. I guess the diodes are to simple. What happened to the Kiss system. You could always add an SCR with a little IC and a hand full of resistors and caps to control it. Better yet, I think you should let the marina do the work and hook something up. I'm sure they can over complicate it and do it for at least $2,000.bucks. You guys sure like to over complicate things and spend money.


BILL

 

[MikeP]

I gotta agree with Bill - the oem system, if functioning properly, won't cause the electronics to drop out. Automobiles don't have separate battery systems for the electronics and they don't lose data/whatever everytime you start them. Neither do these boats. Well, OK...I guess I should say that a totally oem 1980 53MY doesn't do it - so I'm assuming that Hatt paid the same attention in all their boats. None of my previous (non-Hatt) boats exhibited that behaviour either and they were all oem electrically.

You would be far better off to correct the problem and forget the additional complication. If I bought (and I probably wouldn't) a Hatt with the PO-added system as you describe, it would be one of the first things I'd rip out.

 

[TomT13]

Yes Mike and I guess our cars haven't advanced in electronic systems and components in the last 25 years? I know I don't have an open array on top of my hood a refrigerator, an electric head, wash down pumps in my car and I can only assume you don't in yours either. Just like computer technology changes minute to minute I can only assume changes in marine electronics have been made in the last 25 years since my boat was manufactured. Are our boat’s immune to technological changes and advancements in engineering? I can only applaud you for having a perfectly operating boat without any issues but not all boats are created equal. Isn’t that one of the reasons we refer to them as “her or she”? I had no idea this thread was going to cause so much animosity but I have to say it's been fun reading.

Tom

 

[MikeP]

There's no animosity intended - just opinions.

I apologise for any offense but I have the same sort of "new" electronics (computers/plotters/etc)that everyone else has and nothing ever resets or otherwise behaves badly. The DC/AC system is oem. My intent was to help someone avoid spending money when in my "opinion" it would be cheaper and more effective in the short and long term to approach it differently.

But it's just my opinion and just as I may prefer a black Porsche 911 and you may prefer a silver Porsche 911, whatever anyone wants to do with their boat is their business as is whose opinions they accept/reject.

As the old saying goes, "Opinions are like a$$h0ll$, everybody's got one!"

 

[Trojan]

Do you operate all your electronics and 12v systems at the same time? How many amps do they draw at idle. Any electronics made today take very little power compared to years ago. My 1973 does not cut out my electronics when I start my old 6-71s. Think about it. So every one that has a Hatteras looses there electronics when they start. Come on. Just find the trouble and fix it or work around it. There is enough intelligent people on this forum that you could fix anything and not just boats. We have the smartest and nicest people right here on our forum, enjoy. Sorry guys if I offend some of you, I get tired of typing on deaf eyes. Mike is correct and I don't even like a Porsche. Were all here to save a buck or you would not be here.
BILL

 

[Genesis]

I gave serious considering to converting Gigabite's battery system when I owned her.

If we anchored out frequently, I absolutely would have done it. My preferred configuration is two separate AGM banks for the engines (one for each); two Group 31 AGMs will easily roll over those GM diesels (believe it or not - I've tried it.) They have the amps to do it.

Then you use the rest of the space for a house bank full of 6V golf car batteries. Link the whole thing together with combiners so that each engine preferrentially charges its start bank, then the excess goes to house. The AC charger goes to house, and the combiners will top off the engine starts when that's full. The genset gets its own small (e.g. motorcycle size) AGM battery and a combiner there as well to the house.

This means that when running each engine preferrentially charges its start bank, then shares its extra charging capacity with all of the other banks.

With this setup you are totally protected against being stranded provided that ONE engine will start, as that charge source will eventually restore all of the other banks in the system without drama. You're also protected against one bank killing anything else as the combiners will open when they see a net discharge condition.

This would have been fairly easy to do because on my boat the engine disconnect switches can run directly to the starters, leaving the big V+ bus in the main DC cabinets for house use. The ANL-fuse terminals were trivially separable to isolate the single necessary backfeed (the alternator from the engine). This change would not have required much other than the primary battery cables to the main DC panels from the battery trays.

I did not do it because we very rarely anchored out, and my batteries were in reasonable conditions. Tossing expensive 8Ds out seemed rather silly to me.

 

[Pascal]

as much as i agree that HAtt designed great electrical systems and that we are often better off not re inventing the wheel, things have changed over the past 20 or 30 years as we all (builders and owners) have gained experience.

I think most "serious" boats these days come with dedicated house banks and there are good reasons for this. let's face it, on a large boats, there is plenty of space and load carrying capabilities to add a dedicated house bank, taylored to your needs : if you spend a lot of time anchored, make a larger bank.. if you run the genny all the time, keep it small.

i don't see what the downside is.

and again, i'm not the kind of guy who falls for every new gadget out there!

 

[Trojan]

You guys are right. I to would change my system in a heart beat if I though I could, would improve it. New does not mean better. But too many times the first thing that is said is, it is to old change it out. My first thoughs are what has gone wrong? Can I fix it inexpensively. If not, what will it cost to replace and how much of an item must I replace. I never wholesale replace anything unless it cannot be repaired or its out dated. I never suggest replacement first before I suggest repair. If something was working and today it is not, something changed. Find out what created the change. I have 90 % all new electronics on my boat. But I'm not changing my entire 12volt system because I have new electronics. You changed yours for a good reason. If I hung on the hook like you guys. I to would change to something like yours. But to spend large sums of money to change a system because of something simple is ridiculous. Most all voltage losses in older boats, excluding the battery is from bad connections, including corroded wires. The diode I suggested earlier was only a patch ,an easy fix or cover up for the real problem. OK, I'm done. I think.


BILL

 

[luckydave215]

There is another reason to add additional battery banks not touched on here, and that's redundancy. On the west coast, ports are hundreds of miles apart. If one cell in one of your battery banks fails, that bank is usually kaput.
If the next port is 20 miles away, no big deal. If it's 36 hours away, it's dark, the weathers slammin' rough, your nav stuff turned black............
I know my system sounds like overkill to the east coast purists, but you don't boat here.
Until you've seen what the "Pacific" can deal out, and how far it is from place to place, you won't understand my urge for redundant systems. Hell, my boat has TWO autopilots.

 

[Pete]

I read the following response with interest:

"Your not going to see any voltage drop by using diodes. $200 bucks versus $4. bucks. I guess the diodes are to simple. What happened to the Kiss system. You could always add an SCR with a little IC and a hand full of resistors and caps to control it. Better yet, I think you should let the marina do the work and hook something up. I'm sure they can over complicate it and do it for at least $2,000.bucks. You guys sure like to over complicate things and spend money."

Definitely want to keep this friendly, but given this site is such a good source of accurate information, this discussion needs a few facts to set the record correct.

The fundamental fact being discussed is "do diodes have a forward voltage drop that will cause a battery down stream from the diode to be less than fully charged"? All diodes have a forward voltage drop; fact. What you buy for $4 will be a low end silicon junction diode with a forward voltage drop of up to .7 volts. Better quality silicon diode can get down to .5 volts. The electrical spec for this value if "Vf". A brief primer on this subject can be found at http://www.kpsec.freeuk.com/components/diode.htm. And incase anyone is thinking that a parallel setup may improve the situation, it does not change anything except a doubling of the amp capacity, similar to parallelling two batteries.

Given this voltage drop, your charger float voltage of about 13.2 volts will provide 12.5 volts to the downstream battery. We all know that a battery held at 12.5 volts is far from fully charged.

Bottom line is maybe the folks spending more than $4 do know what they are doing, just maybe.

Pete

 

[Trojan]

If you have the diodes you don't need the battery down stream. It allows you to draw voltage from ether source with minimal loss .7 volt and yes it will double the amps, but that's not the issue here. You need to go back and read why the diodes are being used. Its not a charging circuit and that .7 volt won't mean a tinkers damn even in a charging circuit. If you give the general public to much information and they do not have a background in electronics you are just going to confuse them more than they are. What are they going to do with your facts? Its good information, but I don't think most of the guys can put it to use. We have some folks here that have never used a VOM meter. I'm here to help. I hope. Not to confuse. You can buy good inexpensive rectifier diodes cheap. You just need to shop a little. Unless they ask for more info I don't supply it. Sorry Pete no harm intended.



BILL

 

[luckydave215]

that .7 volt won't mean a tinkers damn even in a charging circuit.

Yes it will.
.7 volt drop in a low voltage charging circuit is huge, the difference between half a charge and a full charge.

 

[Pete]

Bill, sound like things are really heating up on this subject. So I will close out my side of the exchange with three points.

First, your statement that there is no forward voltage drop on a diode is incorrect. Fact

Second, your statement that a .7 volt drop on a charging circuit is insignificant is wrong, especially on a 12 volt boat like you and I own. Fact

Third, I for one do not consider this forum anything close to "Owning a Hatteras for Dummies" (I made up the title). The folks on here seem to be both smart and searching for more and more accurate knowledge, as I am. So I will always pass out correct information, and error on the side of technical detail for those who are interested.

I'm done

Pete

 

[Trojan]

What ever Pete. No one said you were wrong. First I didn't say that there was not a volt drop across a diode. You obviously did not read the whole thread. We are dealing with a voltage drop of a significant value that when he starts one of his motors. All his electronics will reset to zero. By adding a diode to each one of his house banks and feeding each one of his house banks to his electronics. The voltage drop to his electronics will not be any greater than .7 volts from what ever his house banks are charged to. The voltage drop across the diode was not the issue. I said that there was not enough of a voltage drop through the diode that you would see it. This is true. This is not a charging circuit. It is an operational supply voltage. .7 volt is still not a large sum in any 12 volt charging circuit. Most chargers are not even capable of regulating that close unless it is one of the new type. The quality of people and the intelligence of the people on this forum is not in question. We have some of the smartest and nicest people here. But the fact is not all of them are electricians or mechanics or engineers. And there are a hell of a lot of them that are smarter than me. This is not a school, we are a forum. Everyone can contribute. But if greater detail is needed, it is available. These post are long enough without everyone going into any great detail or over complicating something when its not needed at the time. I've been 40 years in electrical and mechanical engineering and I know what kind of problems you can get into when you give someone too much information when they don't understand. If I ruffeled any feathers so be it. I'm here to try to help someone with something I do know something about and try to save a someone a few bucks along the way. I don't comment unless I know what I'm talking about and I certainly don't need to impress anyone at my age.


BILL

 

[Boatsb]

OK you guys need to get away from the tech talk and discuss politics and religeon.

 

[Beckytek]

Bill, for what it's worth I thought your fix was great, simple, easy, and cheap.
I appreciate your advice and hope you continue giving it. Ron

 

[Trojan]

Thanks Ron. Boatsb, now your trying to get Me in more trouble. I don't know a darn thing about Politics. Ya-all have a good day. Were getting another 1 1/2-2 inches of snow tonight. But by Friday it is supposed to be 40 degrees. Yahoo and only 6 Saturdays or 44 days till launch.



BILL