Seeking Advice on Common Configurations

[S/V Elusive]

And *I* was just further commenting on the ground by Alan - It was good stuff and mostly germane to the topic

[Alan Wheeler]

To take the grounding question a step further. As good a bond as possible, is of ultimate importance. So yes, clean is essential. But it is also another reason why copper lugs are important to use. When I say copper, that is the parent metal, they can and should be tinned. When tightend down, the copper deforems to obtain as great a contact area to the base metal as possible. Excluding all air is essential. (I am talking microscopic air bubbles here.) So a thin smear of a copper based anti-sieze paste is good. This stops corrosion between the contact surface. A conductive paste is even better, but difficult for most to obtain, so don't worry about that. Use a flat washer under the locking nut to ensure the best surface contact. Then use two nuts to lock the joint. This is to ensure two things. Copper has little elasticity. So when it is squashed, it deforms to contours, which is great, but if the slightest amount of tension comes back off, it does not try to "spring" back against the locking nut. So a joint can come loose very easily and quickly. Using the locking nut ensures it will not come loose, and the second point is, the second backing nut protects more thread and gives a greater thread contact area, that allows another source of electrical connection. Remember, the thread is buried deep inside the cast block. Cast Iron is a poor conductor, so the more surface area of conduction, the better.
Then finaly spray a protective film over the connection to protect it from corrosion. I don't like paint being used. It can cause issues over time and is a pain to unthread the nuts. Even lanocote will work fine.

[hellosailor]

Jef, when I make a ground connection I want to see bare metal, and then a star washer which cuts into the metal as the but is tightened. That way I *know* I've got a good connection. I know, in theory lugs will flatten down and make a good metal to metal connection...and if it all looks flat I'd omit the star washer for high power connections.

I've also become religious about either using silicon grease (aka "vacuum grease" or "high temperature brake grease") on all connections, or using antiseize (heavy oil filled with nickel/copper dust) if there's no grease around. That ensures there will be no oxidation or corrosion in the connection.

Sean, it is sadly normal and unavoidable IF you connect two batteries in parallel when starting, the low one will pull down the high one. And that can be very fast. You never know when someone has run some wiring that sets up a loop current somewhere. In theory, when you turn the starting battery "ON" and the house bank is already "OFF" there will be no such problem. Then add in the house bank after you've started. If you don't have separate isolated charge SENSE leaads, to each bank, the regulator's sense lead could be shared in common and problematic.

Any chance that you have the schematic for the charging system, and it reflects any mods that have been done as well?<G>

[ssullivan]

Hey folks. Sorry for the slow response. We had a bit of a slog out the Long Island Sound to CT and then a haul out. Now it's a race to get the topsides waxed and other haul out items done before the film crew arrives next week for our local station. Good news...

Anyway, as soon as the pace of the work slows a little bit, I'll try out the experiments. I have had just enough juice to get the engine to catch each time, so I've been lucky.

In my gut, I don't like to see the house batteries and starting battery paralleled. I would like to see a dedicated starting battery. This is exactly what Hellosailor is talking about. I was going to try and shut everything else off (house bank) and try starting with only the starting battery on to see if that would isolate the starting battery.

I think I might have mis-lead in my initial post, saying that the starting battery was drained at the same level as the house. It was entirely probable that the house batteries (420AH) just ate up all of the starting battery's power when I had all batteries on during starting... thus showing me a low voltage reading on my voltmeter at the helm.

Reminds me of when you are on an airplane and they seem to use only a starting battery to start the engines.

Still, I'll try both experiments when they dunk us back in early next week.

[hellosailor]

Sean?
"Reminds me of when you are on an airplane and they seem to use only a starting battery to start the engines. " Speaking of airplanes, did you ever see the *original* movie "Flight of the Phoenix"? If so, you'll never complain about batteries and engine starting again.<G> Ain't so bad for an old B movie.
There are ways to get the numbers and do the math to find out how much current your house bank really can suck down from the starting battery...but that would count as mental abuse.<G> Easier to say "use the ammeter" or better still like the punch line of many old jokes "So, don't do that!"
If it is WLIW-21 doing the shoot...Give them a spare VHS tape before they start. (Coupe (3-1/2?) of years ago, they had the only helo that was brave enough to go up in REALLY lousy conditions to0 cover the start of the ALIR. And we waved as they buzzed us multiple times, hoping to see the footage of the boat in that wx sometime later. Nope, they only did a 1/2 hour special about "boating" afterwards. The tape of the start? No one knows. We caught their crew the next year and asked about archives and they said "Oh, we don't have enough money for that, we scrub our tapes and recycle them." Which is why I say, give them a spare tape.
Then again, in that wx, the crew might have just forgotten to load the camera.<G>

[DeepFrz]

Sean, pilots of airplanes don't turn on any electronic equipment before they start the engines. That is why they only need one battery. Although, many newer planes with glass cockpits generally have a smaller backup battery on a partial backup bus in order to keep the mimimum of electronics operational should they lose the main bus.

On a boat the 2 main reasons for house and start batteries are:
1. always have enough juice to start the engine
2. protect your electronics from the surge currents and spikes caused by the starter.

Cheers, happy filming

Phil

[Alan Wheeler]

Sean, That's exactly what I have set up on my boat. The two banks are totaly independant of one another, and are linked by the charge spliting diode only.
Hey another thing to check, how is your charger configured? Is it a seperate charge circuit to each bank?

[ssullivan]

Originally Posted by hellosailor

If it is WLIW-21 doing the shoot...Give them a spare VHS tape before they start. (Coupe (3-1/2?) of years ago, they had the only helo that was brave enough to go up in REALLY lousy conditions to0 cover the start of the ALIR. And we waved as they buzzed us multiple times, hoping to see the footage of the boat in that wx sometime later. Nope, they only did a 1/2 hour special about "boating" afterwards. The tape of the start? No one knows. We caught their crew the next year and asked about archives and they said "Oh, we don't have enough money for that, we scrub our tapes and recycle them." Which is why I say, give them a spare tape.
Then again, in that wx, the crew might have just forgotten to load the camera.<G>

The station coming out to film us is NY1. Not a bad local station.

[ssullivan]

Originally Posted by Alan Wheeler

Sean, That's exactly what I have set up on my boat. The two banks are totaly independant of one another, and are linked by the charge spliting diode only.
Hey another thing to check, how is your charger configured? Is it a seperate charge circuit to each bank?

Yes, that seems the right way to go, Wheels. Anyway, the chargers are indeed quite well separated. From other posts, you may know I have 3 chargers aboard. 2 Iota 90 amp chargers to charge the 420AH house bank and the old 50 amp charger to charge the starting bank. Those all work extremely well. I only have an issue when no chargers are running for a couple days, the house bank is low, and I have all battery switches in the "on" position while starting the engine.

As soon as they splash us back in, I'll try turning off the house while starting.

[Alan Wheeler]

Yeah I new about your chargers and seeing as it was done with three and not a single multi bank, I thought it was worth an ask.
Well, it is possible that your engine start bank is getting tired and needs replacing. Ooops, shall I go wash my mouth out now huh?!?

[ssullivan]

Originally Posted by Alan Wheeler

Yeah I new about your chargers and seeing as it was done with three and not a single multi bank, I thought it was worth an ask.
Well, it is possible that your engine start bank is getting tired and needs replacing. Ooops, shall I go wash my mouth out now huh?!?

Ha ha ha! Funny, Wheels. I've replaced every single other system on this boat, so why not??

Oh wait... no... I *did* replace the starting battery when I first took delivery. It was toast because the previous owner had a blown fuse on the charging side of things that was not allowing the juice to get to the battery. He just kept buying new starting batteries instead of fixing the problem.

We have a nickname for this guy aboard the boat... "Lazy Larry"

You wouldn't believe the shortcuts this guy took even with simple things. Instead of rebedding the long ports in the salon and galley, he just smeared slicone around them from the ouside, getting silicone fingerprints on the windows and surrounding deck. Didn't bother to even clean up the silicone on the deck.

He would re-varnish without masking.

He applied Cetol without masking on deck.

The list goes on and on and on like this...

[Pblais]

I have similar set up to Wheels,

I have two house batteries and a starting battery. The 1,2,all switch is for the two house batteries and the on / off starting switch is just what it says. I also have a thiord 1,2, all switch that is between them. This one really just is used in ALL to start the engine with the house bank so it's only used as All when I would start that way. It's a good feature as the starter baterry could go bad.

I also used an isolator so I can connect all the batteries to the alternator yet not let the house draw down the starter battery. Recently my fancy isolater went bad it cut in as it should but never cut out. The repalcement so now it is as it should be. It works best if the switches do what they say on them .

So if the engine is runninmg both are charging no matter what and if I turn off the engine the starter is not running lights. It only runs the windlass (when motoring of course) or starts the engine. Set up that way you can use a battery built for starting so it has more cranking amps though less amp hours.

[hellosailor]

Phil, I think you've got it reversed. "...airplanes don't turn on any electronic equipment before they start the engines. That is why they only need one battery. " Rather, they only have one battery because LEAD IS DAMN HEAVY.<G> You can't carry much of it on a small aircraft. On larger aircraft, there are indeed larger batteries, sometimes multiples. And on some combat aircraft, there is actually an aero-generator that can be extended to provide power for a mid-air restart instead. Boats could follow the same 1-stone policy, but then we'd have to trust electronics (or the pilot<G>) to use it right.

Sean-
"You wouldn't believe the shortcuts this guy took even with simple things." I KNOW THAT GUY! Big big feet, floppy shoes, big red fright wig, works as a freelance clown and answers to the name BOZO?!<G>
If the only separation between your batteries is a diode, diodes can fail. Happens in alternators all the time. A bad diode can also simply be weak, allowing current to flow when it shouldn't. So yes, even an isolation diode can be bad. Personally I'd rather use a West Marine Combiner. I trust it more because it uses a relay, and at least when those fail you can diagnoze them very simply, and often visibly. Besides the smoke test.<G>
Never underestimate the cleverness of Bozo.

[Pblais]

Personally I'd rather use a West Marine Combiner. I trust it more because it uses a relay, and at least when those fail you can diagnoze them very simply, and often visibly. Besides the smoke test.<G>

The experience of the guy that helped me replace the bad combiner I had is over the years the combiners fail more than the simple diode isolators. He was an instructor for the Army in aircraft electrical systems and now is retired and had done boat electrical work for 20 years.

Combiners do fail too. Mine was a Xantrex less than a year old. I now have a diode based isolator. They are dirt cheap - they work. I also have a manual switch to start the engine with all batteries should the starting battery die.

[hellosailor]

Paul, the diode, being solid state and no moving parts, etc., probably is more reliable. On the other hand, the combiner isn't very complicated, has an indicator light, and makes a "clack" every time it cuts in or out. And, doesn't require adjusting the regulator voltage to make it work right.
The Xantrex (Pathfinder?) is more complex than the West/Yandina. Did you ever find out what part of it failed?