Hunter 49 / 50 shore power transformer

[artboas]

Ok, first of all, I'm just not sure how many owners have this transformer mounted in their boats.
It is only used on 50 Amp 220 volt input models, and became optional at some point, whereas it was standard in the beginning.
Firstly, it was a wonderful decision for Hunter to design the larger boats at 220 volt.
Many benefits, including keeping wire sizes smaller, single (albiet larger) power inlet, ground isolation from shore, etc.

So, for you folks out there who have the transformer, there are many other things you probably don't know:

The boat can be run from a since 30 amp 120 volt cord, in case you get in a marina that doesn't have 50A outlets. Now, your current is cut in half, but it's enough to run your charger, one airco, and hw tank

Next, many marinas are 208 service, on the 50A. Which means you will only be getting about 100V per line in your panel. The airco units will run with much less fan output, and your microwave will have terrible performance
You can re-configure the transformer to give you 240 volts, or 120 per phase. Perfect!

Now,,during the summer, I am moving around to different spots, and I'm constantly wanting to adjust my line voltage. Normally,, this takes about an hour of messing with the transformer, and it isn't fun.
I've just figured out a way to do it in < 5 minutes. Now, I could have bought a very fancy 50 A multipole switch, but this is hundreds of dollars. Plus, there is a VERY GOOD reason to never, ever, ever, ever do this.
When my boat is laid up in the hard for the winter, all I have is a single 120 volt extension cord service.
So, I use a (custom made) 15A straight blade to 50A pigtail adapter, and plug in my boat.
But, I must reconfigure the boat for 120 service, which means I'm basically doubling my shore power.
I put a HUGE label at the chart table that says 120 VOLTS!!! THINK!!!!

Because if I launch my boat & plug it into 50A 208, I'm feeding 400 volts into my panel, and this will be a bad day.

So, is anyone out there interested in this changeover stuff????

 

[jviss]

I think you should save up for the switch.
Too bad there's no automatic switching solution for this.

 

[DayDreamer41]

"But, I must reconfigure the boat for 120 service, which means I'm basically doubling my shore power."
15A at 120 V in, is 15 amps at 120 V the transformer will not double the amps available? in fact depending on the transformers efficiency it would be less than 15 amps available.

 

[artboas]

I think you should save up for the switch.
Too bad there's no automatic switching solution for this.

Ok
There is no way you want the switch. (Believe me, the money wasn't the issue)
You do not want to make it as easy as rotating a switch to change the voltage ratios.
If I accidentally have it in "120 mode", and plug into a 220, service, I smoke all my airco controllers, washing machine, etc, etc.
I need to have an "idiot tag " at the chart table,, and a very purposevelle procedure to switch over.
Now, I have developed one which goes from more than 1 hour to approx 5 minutes, which doesn't allow me to make a massive mistake.

 

[artboas]

Respectfully, you are wrong.
The "boat" (think of the boat's systens) need 220v.
If you plug into a 220v 50A available) dock outlet, then you have 50 Amps available at that voltage.
If you plugs into a lower voltage service, and use a step-up transformer, you lose half the available current.

Think of it in terms of ohms law & watts.
Power (P) = I (current) x (V) Voltage

The power at a dock outlet is constant. If you step it up the voltage, you lose current capacity.

 

[artboas]

I had an automatic way to switch from 120 to 220. Thought very carefully about putting it in, and weighted the plusses & minuses.
To do a simple 120-220 conversion was 1 jumper link, and about 10 minutes.
But, it was the most dangerous of all conversions. By that, I mean adjusting from 208 to 240 was a huge job by comparison.
I did not switch from 120 to 220 very often; only when cruising, or laying up for the winter.
So, it wasn't worth the risk of having the automatic switch (it used 2 relays) crash for any reason

 

[artboas]

I addressed this. I said you only had capability for a few things such as charger, microwave, 1 airco. The fact was you had basic service versus zilch

 

[tkwhalen]

I have the same set up in my boat that you have and I find it is all way over my simple minded 12V or home 110 head. I plug into 30 amp service at Marina's with out 50 amp plugs and 110 service (when on the hard). I understand I can't run every thing but generally find the things I need battery charger and hot water run fine. I don't make any adjustments to the transformer nor did I realize any were needed and fro that matter not sure any are needed if I am happy with what I have been doing ..... All that said I now feel ok changing the subject ...

I have a potential Issue and artboas you seem to have a deep understanding of the electrical systems on board our boats so see if you can give me some ideas about this problem.

Twice this season (three months apart) I arrived at my boat and found that the new this season start battery was dead. Both times I found shore power was not charging it ( shore power was charging the house battery and as an FYI I plug into 50 amps at my dock) and when I jumped the engine off of the house batteries the alternator did not start charging the start battery ( the alternator did start charging the house batteries). Opening up the battery switch panel at the end of the dinette settee I found both times that the parallel breaker was popped out. Pushing it back in did not start charging of the start battery on shore power or the alternator. However if after resetting the parallel breaker and starting the generator (had to jump it both times) it charged the house and the start battery. When I shut down the generator everything was back to normal with shore power and the alternator both properly charging the house and the start batteries. My assumption is that there is an automated switch somewhere that controls the charging source that has issues which causes it to blow the parallel breaker and cut off charging to my start battery enough time goes by and the battery is dead. That switch only resets and starts when the generator kicks it in the teeth. My solution for now is to keep the panel voltage meter display permanently on the start battery so I can constantly monitor it's status...... So bad switch? loose circuit? my guess is way in the weeds? multiple unrelated problems? If you are now thinking oh you simpleton you that just means explain your conclusions with 3rd grade science ...

Any help or ideas would be appreciated

 

[artboas]

Ok
Give me a bit of time to mull this over. I'll figure it out.
Can we get back to 1 think?
You have a 50 amp power inlet.
You typically plug into 230 v.
How is it you are running the boat off 120v?
Do you have a separate power inlet on the stern?

 

[tkwhalen]

No separate inlet I have 2 short pig tales. One is a 50 amp female plug one end and a 30 amp male on the other and when I am on the hard I add a second pigtail to the first which is 30 amp female on one end and a 110 male plug on the other.

 

[artboas]

Oh,,,,,,
I'm sorta thinking your boat is not wired as 220 volt, but 50 amp 125 volt.
Can you comment on this?
I think I know the answer to your other problem, but need to sort this out first

 

[artboas]

Hmmm.
Just went back to the Hunter schematics, and it appears that boats are wired as 220 with or without transformer.
When you are normally connected at the dock, are you running a big 50 amp cable with no pigtail adapters from a shore 50 amp feed to your stern 50 amp?
Is the 50 amp service at your dock 50 amp 120 volt?
I sorta suspect it is, and somebody has wired your transformer to be always 120v input.
We really should figure this out, cause if that's how it's done then it's not correct.
Are you original owner?

 

[jviss]

I'm basically doubling my shore power.

The power at a dock outlet is constant.

Respectfully, you are the one who was wrong, when you said you were doubling your power.
These two statements of yours contradict each other. The latter is correct.

 

[artboas]

Respectfully, you are the one who was wrong, when you said you were doubling your power.
These two statements of yours contradict each other. The latter is correct.

Good catch
The first statement should have said "I'm halving my shore capacity"
It's hard to proof read your own tech stuff sometimes.

 

[jviss]

I'm curious about this. What kind of receptacle do you have on the boat? Is it a 50A 125/250 receptacle?
What bothers me, is that there are standards for the voltages and connections on shore power boat connectors, and if you're changing the transformer wiring, at some point you are violating the standard, I think. Is that so?

 

[jviss]

You can re-configure the transformer to give you 240 volts, or 120 per phase.

240V service is still only one phase. 120 is derived from a neutral, which is a center tap on the service transformer. In a residential electrical service, his is the wire that is grounded, and connected to the neutral (white) wire. Going across two blacks in the service entrance cabinet gives the 240V, but still only on phase.

 

[artboas]

No separate inlet I have 2 short pig tales. One is a 50 amp female plug one end and a 30 amp male on the other and when I am on the hard I add a second pigtail to the first which is 30 amp female on one end and a 110 male plug on the other.

Ok
I know what's going on with your shore power. Basically it isn't wired right.
Allow me to explain, and I would ask you to refer to the Hunter tech docs where they show the transformer wiring connections.
Some basics
The typical 50 amp shore connector is a 125 /250 listed receptacle which has 3 blades and the ground is connected via a metal shell around the connector body.
The shore receptacle has 4 connections:
Line 1
Line 2
Neutral
Ground.
Between L1 & L2 is (approx ) 230 volts, with 50 amp capacity on each leg.
Now, unlike normal 30 amp 120v service, the L1 & L2, are not 180 degrees out of phase. They are 120 degrees out of phase.
If you take a meter and read the voltage Between the L2 (or L2) and the white neutral, you will read 120 volts.
But, (depending on whether you have 230 or 208 3 phase service) you won't read double the voltage between L1 & L2.
In my case in Toronto, we have 208v service.
If you measure between L1 & Neutral, you have 120 volts.
But, beetween L1 & L2 its only 208v.
Now, the way that the boat is wired is to take maximum advantage of both phases of the shore power, ie 50 Amps per leg.
So, on the shore power cord coming into the boat, it only uses the Black & Red wires, feeding the primary of the transformer. The shore neutral is not used.
But, the transformer has a secondary side center tap, which derives exactly half the primary voltage. This is now your Neutral.
So, on the secondary side of the transformer you have 3 connections :
L1
L2
Neutral

Across L1 &L2 is either 220v (or 208) ,
And from the L1 (or L2) to Neutral is either 120v or 102v (approx)

In this configuration, you are getting maximum current from the shore receptacle, ie 50amps down 2 legs 120 degrees out of phase with each other.

Now, there is a middle tap on the input of the transformer, which is exactly halfway between the two outside legs.
But of transformer theory here.
Transformers are devices which couple input to output with no direct electrical connection. They do this by the magic of electro- magnetism.
If you wrap a wire around a nail 100 times, and power it, you make a small electro-magnet.
If you connect a meter to the same coil, and wave a permanent magnet around the nail, you will see a voltage induced into the coil.
What a transformer does is use a common ferrous frame to wind electrically isolated coils of wire on.
You connect voltage to one coil, (the primary), and the other coil (the secondary) has a voltage induced into it by the common magnetic coupling
Phew!!
Now, here is where transformers get handy.
Assuming a perfect world with 100% efficiencies , zero losses, if you had the same number of wire coils on the primary and secondary, if you fed 10 volts into the primary, you'd read 10 volts on the secondary.
Now, one small thing...
Transformers only work on AC, not DC. Let's just leave it at that.
But let's say you wrapped twice the number of coils on the primary as the secondary.
You'd have 1/2 the voltage on the secondary, making this what's called a "step-down transformer"
But, because energy cannot be created or destroyed (assuming 100% efficiency) you'd have twice the current at half the voltage.
So, in summary,
A step up transformer increases the voltage, but reduces the current.
A step down transformer reduces voltage & increases current.

On the Hunter transformer, it gives you the option of using it as a 1:1 transformer , by connecting L1 & L2 to the primary, and using the centre tap on the secondary to get the neutral voltage at the halfway winding point.
You now are using the full current that the shore is providing.
But, if you connect L1 on one of the primary legs, and the shore neutral at the centre tap (halfway point) on the primary, you are only using half of the primary windings.
So, you will have a 1:2 ratio of primary to secondary windings, making this a step-up transformer.
And, on the secondary, you will have (approx) 220v between the output L1 & L2, and half of that between either of the L1 &L2 with respect to neutral.
BUT....
You only have half the current.
So, you are only using half of the available shore power current which could induce voltage drops in your onboard voltage.
You wont blow the breakers, because they are 50 Amps.
Think of this as a sort of "brown out"
So,the purpose of the primary centre tap on your transformer is to use it only when you don't have 220 50A at the dock pedestal.
I hope this has cleared up one or 2 things.

Now, on your other item, I think is a fairly simple situation that the Blue Seas combiner on your battery panel is defective.

I can work out a trouble shooting routine to deduce this

Regards

Arthur

 

[artboas]

240V service is still only one phase. 120 is derived from a neutral, which is a center tap on the service transformer. In a residential electrical service, his is the wire that is grounded, and connected to the neutral (white) wire. Going across two blacks in the service entrance cabinet gives the 240V, but still only on phase.

Not the way it's wired at the marinas.
They use 3 phase wiring with legs either star or delta. There is a good reason for this. It saves on wiring, and balances the loads.
What they do is run all 3 phases to each power pedestal. But, they only use 2 of the 3.
The next pedestal, they use the next 2 of 3. And so on
By "leapfrogging" the connections, they save wiring, and balance the main power system better.
In a home residence, I fully agree that it is 220v single phase.

 

[artboas]

I'm curious about this. What kind of receptacle do you have on the boat? Is it a 50A 125/250 receptacle?
What bothers me, is that there are standards for the voltages and connections on shore power boat connectors, and if you're changing the transformer wiring, at some point you are violating the standard, I think. Is that so?

Very good question.
The inlet receptacle is 125 /250
So, you can wire it up as L1 & L2 (120 out of phase) with neutral,
If you choose to simply wire 120v across L1 & L2, then you are using it as a single phase inlet.
I had a crazy mis-wiring incident on my boat, which I didn't catch until I owned it for almost 4 years.
The ground is connected to the metal shell, and only has capacity for #8 wire.
Now, Hunter only uses the shore L1& L2, and does not use the neutral.
But,,,, they had 6/3 marine cable going from the power inlet to the 50 Amp DP breaker. (By ABYC must be within 6 feet of inlet)
Well, they stripped about 6" of outer jacket off the cable, which left some fairly short inflexible leads.
Now, if you recall, (as I just mentioned) the receptacle case ground screw is #8 maximum, and is further away from where the wires enter the back of the connector shell.
So, (you guessed it,,,) they put the green ground wire into the unused neutral position, and there was no shore ground on the inlet receptacle metal casing.
Oops!!!
I caught it just by a fluke. (No pun intended with ref to my meter.)
The way that the marine transformers work is that shore ground is connected to a shield between primary to secondary.
The transformer case is actually ship's ground.
So, with the mistake they made, you would need one or 2 things to go bad before you'd end up getting shocked. Just glad I found it!!

 

[artboas]

Ok
Some more things to solve your mystery
The generator starter motor is connected to the engine start battery. It uses the same connection to charge this battery once the generator is running, by using the 12v generator (small alternator) on the FP.
So, it makes perfectly good sense that the engine start battery is charging with the FP running.
Now, on the back of your battery switch panel is a blue seas battery combiner.
Here is how they work:
It is basically a solid state relay (BAM), connected between house & start.
Normally it is open circuit.
If either terminal senses (approx) 13v, it assumes that either of any of these:
The Yanmar alternator is running
The battery charger is on
The FP charging output is running
At that point it closes the relay, (turning on the BAMs)
So, it combines the banks.
There is a switch on the engine control panel which says "battery parallel", or something like that. It manually turns on the combiner.
It is not a 100% sure fire test that the combiner is working, but it will tell you if the BAMs are turning on.

Now, on your battery panel, there is a small led which says "Battery parallel" or something like that.
So, we're going to test if the Blue seas unit is sorta working
Turn off your battery charger.
You need to get your house battery load lower than 13v
What you could do is tut on your inverter, and use your microwave to make a bag of popcorn.
This has 2 very distinct advantages:
The load on the house batteries (80 Amps for 2 minutes) will definitely take the charge down
Secondly, you need something to munch on while you're having a brew.
So, after the popcorn is done, look at the "parallel" led on the battery panel, and it should be out.
Now, turn on your battery charger.
Watch your house battery voltage. When it gets up to approx 12.8, (or higher), does the led turn on?
If yes, we know the sensing is working.
Then turn your Battery monitor switch from house to start. Do they read the same?
If not, then the relay is not working.
So, this is a beginning trouble shooting
Let me know
Enjoy the