12volt distribution and new 'leccy heads

[NickTrevethan]

Hi there,
This is probably a question for Halcyon but anyone else have an idea?
I am looking to fit an electric head to the forward heads compartment my Sealine 365.
It draws 20 amps so I reckon I need a 16mm conductor at the least from the battery switch to a breaker. I had hoped to use the existing cable run, but looking at the back of the 12 volt panel, rather than the one big cable coming in from the battery to a single block then distributed to the panel all I see are 4 much smaller cable carrying the +ve to the various panel supplies.
How were these things originally wired? I can’t see a really heavy duty cable running through the engine bay forward so I suspect several smaller cables were run.
Would it make sense to run a single 25mm (AWG 5?) cable from the battery switch to an insulated buss bar/stud and then cut and connect the four cables to the panel from the buss bar.
I guess I’d need to beef up the ground too.
Other solutions? I thought about a battery in the forepeak. But have no idea how to wire into the charging circuit. I guess I’d buy a mains charger, but would also need to run a supply from the alternator, which would also have to be a decent size given it’s probably 10-12 metres in total.

 

[superheat6k]

If it were me I would do as suggested with a 125amp fuse as well. Less connections less voltage drop. Bluesea do some really good busbars and blade fuse holders. I have just rewired the distribution on OB with these but using miniature MCBs instead of blade fuses.

If you want details of what to use and where t get the bits PM me.

 

[Aurai]

Hello

Getting to the end of your note, there are forward placed battery solutions, as for windlass and bow thruster, that use a product called an Echo Charge, and only requires "thin cables", to sense back to a House Battery Bank and keep the forward battery charged.

Then you only have short runs of "thick" cable from your forward battery to your heads.

AWG 2-4 come closest to your needs without a fwd battery and your negative should be the same gauge as your positive.

If you go the fwd battery route, the list will include a circuit breaker, battery fuse and the cable.

Cheers

 

[halcyon]

Hi there,
This is probably a question for Halcyon but anyone else have an idea?
I am looking to fit an electric head to the forward heads compartment my Sealine 365.
It draws 20 amps so I reckon I need a 16mm conductor at the least from the battery switch to a breaker. I had hoped to use the existing cable run, but looking at the back of the 12 volt panel, rather than the one big cable coming in from the battery to a single block then distributed to the panel all I see are 4 much smaller cable carrying the +ve to the various panel supplies.
How were these things originally wired? I can’t see a really heavy duty cable running through the engine bay forward so I suspect several smaller cables were run.
Would it make sense to run a single 25mm (AWG 5?) cable from the battery switch to an insulated buss bar/stud and then cut and connect the four cables to the panel from the buss bar.
I guess I’d need to beef up the ground too.
Other solutions? I thought about a battery in the forepeak. But have no idea how to wire into the charging circuit. I guess I’d buy a mains charger, but would also need to run a supply from the alternator, which would also have to be a decent size given it’s probably 10-12 metres in total.

Hi, which panel have you got ? the AC & DC over the entertainment centre, or single combined panel on aft bulkhead.

The first one should have a 5 or 10 sq mm positive feed to the M5 bolt on the back of the DC panel, the feed comes from the centre aux terminal on the VSR.

Later ones pick up power from the shunt bar-driver module.

Either way you should have a large feed cable as the 365 panel could be pulling 65 amp load.

Brian

 

[Cookee]

Hello

Getting to the end of your note, there are forward placed battery solutions, as for windlass and bow thruster, that use a product called an Echo Charge, and only requires "thin cables", to sense back to a House Battery Bank and keep the forward battery charged.

Then you only have short runs of "thick" cable from your forward battery to your heads.

AWG 2-4 come closest to your needs without a fwd battery and your negative should be the same gauge as your positive.

If you go the fwd battery route, the list will include a circuit breaker, battery fuse and the cable.

Cheers

What he said!

 

[NickTrevethan]

Thanks Halcyon its the one over the TV cabinet.

Hi Aural, I am going with the forward battery and the echo charger. I have one on order but it will take weeks

In the meantime I wonder if something like this could cope?

http://www.halfords.com/webapp/wcs/..._productId_858677_langId_-1_categoryId_255206

I was thinking of getting one anyway for the compressor, although as a power pack might be a bit weedy.

 

[Cookee]

If you're going to Halfords go with a split charge relay or get a proper marine VSR (Voltage sensitive relay) from someone like Merlin http://www.merlinequipment.com/markets/group.asp?groupid=18

 

[NickTrevethan]

Thanks Cookee,

I have a xantrex echo charger on order, but will be a few weeks. It seems likea very sensible device that redistributes power from the house bank to the secondary, providing the house bank is charged/charging.

My secondary bank will comprise a 110 amp leisure battery, box, switch and fuse under the forepeak and again, waiting for bits.

In the meantime I wanted to know whether that little all in one doohickey would be ok to run the heads until I get all the bits I need for the permanent circuit.

If you're going to Halfords go with a split charge relay or get a proper marine VSR (Voltage sensitive relay) from someone like Merlin http://www.merlinequipment.com/markets/group.asp?groupid=18

 

[Cookee]

Thanks Cookee,

I have a xantrex echo charger on order, but will be a few weeks.

In the meantime I wanted to know whether that little all in one doohickey would be ok to run the heads until I get all the bits I need for the permanent circuit.

Why the long wait? There are a number of other options available ex stock - having said that the power pack would probably do for now and it would be a useful item to have on board.