Running aircon from 16A supply. More advice?

[John100156]

If your boat incorporates a pumped piped chilled water distribution system to fan coil units in each berth (and not a DX ducted air cooling system) you should be able to couple-in a smaller capacity chiller unit solely for use at night, which can be isolated during the day - rejected heat (condenser) coupled into the existing pumped seawater circuit. I have designed numerous commercial systems using multiple chillers in the past so if you still need help let me have your existing schematic and I will indicate how it could be done.

For instance, guestimating a reasonable night time cooling load of say 200W/m2 which should suffice, no idea what the area of your berths are so say three cabins at 10m2 each would equate to a cooling load say 6kW or (20,472 Btu's) assuming a COP of say 2.5 this would equate to a 2.4kW electrical load drawing say 10.5 amps at 230v. This could be piped as a series return depending on your schematic without affecting the hydraulics of your existing CHW circuit.

 

[DougH]

...provided no one touches the pins of one plug whilst the other is still connected.

PW

It's 2 x SOCKETS connected to one plug.

As Mapism says, whats wrong with that?

 

[PilotWolf]

It's 2 x SOCKETS connected to one plug.

As Mapism says, whats wrong with that?

The sockets are on the pontoon therefore require 2 plugs on the leads to plug in to those sockets (before becoming one to 'attach' the shore power cable too). Unless you isolate the pontoon sockets or can unplug both at the same time one of those plugs will be live until the other is unplugged.

Been there done it and got the t-shirt as my normal command draws around 15 - 20 amps with just the essential systems running, as stated few marinas have lots of 32 amp sockets. As a commercial vessel we can't justify the risk so have to use the generator instead.

W.

 

[jfm]

It's 2 x SOCKETS connected to one plug.

DougH, it isn't. It's the exact opposite: the LBOK is 2x plugs connected to one socket in Y formation. Fine if you are careful but you wouldn't want a guest using it in the rain. When one of the plugs is inserted to the shorepower socket on the dock the exposed pins on the other plug become live. They don't sell 'em in the shops!

 

[Hurricane]

Like DougH - I didnt see it like that.
I have a Y piece like he says. I use for connecting my A/C and general services to a single socket. And thats fine - just have to watch the load but it's all protected in the shore circuit breaker.

But the other way round.
Thats ?loody dangerous.
This is our services pile

Note that the red connector is 3 phase but I'm plugged into 2 of the 32a single phase (blue) outlets.
I happen to know that these two connectors are on separate phases.
This means if you connect the Y piece you are talking about to each of the outlets above. you will be connecting a wire across two phases = big bang.

 

[MapisM]

This means if you connect the Y piece you are talking about to each of the outlets above. you will be connecting a wire across two phases = big bang.

Nah, this has also been previously discussed. A breaker would break, that's all.
The only REAL risk is to touch a live pin on one plug while the other one is already connected.

My previous joke on using the tongue as a tester was not to deny the existence of such risk, but just to point out that it's simply one of many boating-related things for which it's advisable to engage brain before acting...

 

[MapisM]

When one of the plugs is inserted to the shorepower socket on the dock the exposed pins on the other plug become live.

Actually, in most dock sockets you must also turn a switch on after inserting the plug, therefore if you insert the plugs first, and turn the switches on afterwards, there's no exposure.
I don't disagree anyway, someone could still disconnect one of the plugs without turning the switch off first.
And do that in the rain barefoot, for good measure...

 

[Deleted User YDKXO]

Thanks to all for advice and lively (sic) debate on LBOK device. I am not convinced that a 2 into 1 system like that is going to work in all marinas. It might be OK in your home marina where you can experiment with sockets and phases but then my home marina isn't the issue since I have a 32A supply there anyway. Since my basic requirement was to be able to run aircon in the cabins overnight from a 16A supply, I had Karl go back to the boat and take measurements of current draw with just cabin airhandlers switched on and it seems that once temp has reached a stable state, current draw doesn't exceed 10A. On this basis I have gone back to solution no1, the Multiplus inverter, for a number of reasons. First it would seem with a current draw of 10A, the batteries are not going to be drained and even if the current draw exceeds this figure for a while, the battery drain is going to be slow. Second, I'm getting an inverter which I can use for other 220V purposes on the boat. Third, the Multiplus can be fitted in the same position as the existing charger and I won't lose any precious lazarette space and fourth, it's an off the shelf solution which I can have operational for the next time I visit the boat in early July. I did consider solution no3, the additional chiller unit, and this was my preferred solution but taking account of delivery time and the difficulty of getting anything complicated done in Croatia, the likelihood was that I wouldn't have got this done in time for our main holiday period in August. I will probably get this done over next winter when the boat will be in a yard I can trust and time isn't an issue

 

[BartW]

the Multiplus can be fitted in the same position as the existing charger and I won't lose any precious lazarette space

actually I left my original battery charger in place, to keep the engine battery's topped up all the time.
Before I had the Victron, I had to choose with a switch, wich batt. bank the charger was charging,
When away from the boat for longer periods, (fe in winter time), its good to keep both banks topped up.
Moreover, now I have a spare charger permanently installed.

 

[DougH]

DougH, it isn't. It's the exact opposite: the LBOK is 2x plugs connected to one socket in Y formation. Fine if you are careful but you wouldn't want a guest using it in the rain. When one of the plugs is inserted to the shorepower socket on the dock the exposed pins on the other plug become live. They don't sell 'em in the shops!

Yes I agree John, but most boats that have 2 supply cables installed by the boat builder, supply seperate parts of the boat and are not interconnected so that this problem does not occur.

Of course if you try to double up by using 2 shore supply cables to ONE connection on the boat that is dangerous and is why I am installing the Energy Solutions ES Dockpower equipment next week.

All of my electrical systems are on 1 phase and wired to accept 60 amps but only 1 32amp shore supply is installed.

By adding a second 32amp shore supply in conjunction with the Dock Power unit it is problem solved.

With the Dock Power unit I have protection with the 2 shore side plugs being inserted across 2 phases and also if only 1 shore plug is inserted the other one does not receive a 'back feed' and is not live until connected into the shore supply.

At £4250.00 the equipment is not cheap but at least it is a proven system

 

[Deleted User YDKXO]

actually I left my original battery charger in place, to keep the engine battery's topped up all the time.
Before I had the Victron, I had to choose with a switch, wich batt. bank the charger was charging,
When away from the boat for longer periods, (fe in winter time), its good to keep both banks topped up.
Moreover, now I have a spare charger permanently installed.

Yup, I was thinking about that myself. It certainly wouldn't do any harm to have a spare charger ready to go if the Multiplus fails for any reason

 

[John100156]

...guestimating a reasonable night time cooling load of say 200W/m2 which should suffice, no idea what the area of your berths are so say three cabins at 10m2 each would equate to a cooling load say 6kW or (20,472 Btu's) assuming a COP of say 2.5 this would equate to a 2.4kW electrical load drawing say 10.5 amps at 230v.....

Well, it looks like my guestimate at 10.5 amps was not that far out given 10 amps measured!

With a two plug arrangement there should not be a cross connection of two phases.All circuits would be on their own phase albeit the same one if only fed via single phase pole. No one would be daft enough to rely on a circuit breaker to protect one of two disconnected plugs with potentially exposed live pins would they! It would be utter madness, unless you fancy a spell in cabin-sized accommodation at the expense of the Government of the Republic of Croatia.......!

Mind you, I have a Y-Piece lead made up on my F43 (not used in home berth), it has two Marinco plugs(?) at the service tower end - these are actually sockets as the pins are exposed in the sockets fitted to the boat...

 

[Deleted User YDKXO]

Well, it looks like my guestimate at 10.5 amps was not that far out given 10 amps measured!

Spot on, John

 

[BartW]

here's the drawing of my setup,
added the chargers, (low voltage DC side only)

will be similar in other Italian boats I suppose,
the backup switches (1) and (2) can be usefull, when a charger doesn't work anymore,

I had a blown 12V charger once,
and the mastervolt going in error with too low battery's.

should have my guy's drawing this in autocad,
but don't dare to asc, too bussy with real work right now,
sorry for that

 

[MapisM]

Bart, what's the purpose of backup switch (1), exactly?
Looks to me as a bad way of using one of the engine batteries...

 

[BartW]

Bart, what's the purpose of backup switch (1), exactly?
Looks to me as a bad way of using one of the engine batteries...

last winter I had a broken 12V charger,
and 12V battery's dead (alarm system is connected to 12V)

switching "On" the backup switch(1)
I could start the generator
and switch (1) off again
and recharge the 12V battery's


in reality,
each 24V bank is 2 x 6 x 12V battery's
the 12V bank is only 2 x 12V battery's

 

[MapisM]

switching "On" the backup switch(1)
I could start the generator
and switch (1) off again

Ok, as a temporary/emergency switch, it makes sense.
I was fearing that if used for some time (e.g. to run the stereo, or whatever), it could cause an unbalanced discharge of one of the batteries in the 24v bank.

PS: on second thought, do your engines really require so much power for startup?
The same number of batteries for engines and services sounds unusual (assuming they are the same - but maybe not?).
I've got just TWO 12V-110Ah batteries for engines, and EIGHT of the same as domestic.

 

[vas]

Ok, as a temporary/emergency switch, it makes sense.
I was fearing that if used for some time (e.g. to run the stereo, or whatever), it could cause an unbalanced discharge of one of the batteries in the 24v bank.

PS: on second thought, do your engines really require so much power for startup?
The same number of batteries for engines and services sounds unusual (assuming they are the same - but maybe not?).
I've got just TWO 12V-110Ah batteries for engines, and EIGHT of the same as domestic.

+1

I'd have thought that 2X12V 100+Ah should be ok for starting up, the rest for service (I've only got 2X2X12V for service...)

MM I'm also installing a switched bridge like that to charge the 12V 55Ah genny starter battery when it dies (has done once already...)
But as you say, ONLY to start the genny, then turn off.

 

[BartW]

PS: on second thought, do your engines really require so much power for startup?
The same number of batteries for engines and services sounds unusual (assuming they are the same - but maybe not?).
I've got just TWO 12V-110Ah batteries for engines, and EIGHT of the same as domestic.

they are all the same, 105Ah (Delphi) deep cycle battery's
appart from the engine starters,
there are a lot more consumers on this bank, such as;
-auto pilot
-flaps
-Instruments
-navigation lights
-wipers
-stern winch
-anker winch
-passerelle
-tender crane
-bow thruster

perhaps that might be a reason ?
never thought about this,
don't know how it is in similar sized or other Italian boats, appart from yours.

 

[vas]

odd, up to 45ft that I've seen a few, all have just the 2 engines on one back all the rest on the other.

I'd like to hear what jfm has to say on that as I'm afraid such a setup is a bit iffy in case of a current leak from one of the loads connected in this bank.
Maybe Canados wasn't happy to have ALL that in one el panel?
Still I'd keep them split in two panels BUT add a third bank of 2X12V just for the engines...
Of course one just argues that if both banks are empty, just fire up one genny, load them a bit and start the engines.

V.