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12v Cable size?


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Just now, foleyhancox said:

Hope someone can advise. What size cable would we need to wire a 12v/25w tv directly from a 12v Battery? 

What distance?  The actual cable run, not as the crow flies.

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10 minutes ago, foleyhancox said:

Sorry forgot that bit  ?It would need to be 60ft in length. 

Taking 2.2 amps.

 

4mm2 would be the minimum and would give you about 0.4v voltdrop, 6mm2 would be better but would still give you 0.25v  voltdrop over a 20m length

8.5mm2 would give you 0.2v voltdrop.

 

The choice is yours but bigger is better and will avoid problems.

Edited by Alan de Enfield
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7 minutes ago, foleyhancox said:

Sorry forgot that bit  ?It would need to be 60ft in length. 

4mm2 would be fine (2.6% loss). 6mm2 would be better (1.75%) loss, but not really necessary.

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Thank you will have a look for a 6 to 8.5mm to be on the safe side. By any chance would you know if we would beed a regulator or could we just use a fuse? 

8 minutes ago, WotEver said:

4mm2 would be fine (2.6% loss). 6mm2 would be better (1.75%) loss, but not really necessary

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9 minutes ago, foleyhancox said:

Thank you will have a look for a 6 to 8.5mm to be on the safe side. By any chance would you know if we would beed a regulator or could we just use a fuse? 

A voltage regulator is a very different thing to a fuse.

 

You may find that your TV doesn't like being connected to a battery directly - if you have the engine running (or solar panels) putting out 14.7 volts TV's have been know to release the 'magic-smoke' and refuse to work ever again.

Ideally you would use a stabilised voltage supply 12v - 12v

 

Edit to add - (this is not a recommendation) something like this :

 

https://www.ebay.co.uk/itm/DC-DC-5-32V-to-12V3A-Automatic-Voltage-Stabilizer-Power-Converter-Regulator-SO7/353125289144?hash=item5237e84cb8:g:flQAAOSwhvVe~Cn8

Edited by Alan de Enfield
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3 minutes ago, Alan de Enfield said:

Ideally you would use a stabilised voltage supply 12v - 12v

Agreed, unless the TV is specifically designed for use in vehicles/on boats. Obvious;y this doesn't affect the cable size, and the regulator would be at the TV end of the cable.

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5 minutes ago, Alan de Enfield said:

A voltage regulator is a very different thing to a fuse.

 

You may find that your TV doesn't like being connected to a battery directly - if you have the engine running (or solar panels) putting out 14.7 volts TV's have been know to release the 'magic-smoke' and refuse to work ever again.

Ideally you would use a stabilised voltage supply 12v - 12v

We were advised to go straight from the main boat batteries to a regulator, then heavy duty Cable from that to a 12v plug. Ready for the tv to be plugged in. The tv would not be used when the engine is on however the batteries are connected to solar panels. Does this sound about right? 

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17 minutes ago, Alan de Enfield said:

A voltage regulator is a very different thing to a fuse.

 

You may find that your TV doesn't like being connected to a battery directly - if you have the engine running (or solar panels) putting out 14.7 volts TV's have been know to release the 'magic-smoke' and refuse to work ever again.

Ideally you would use a stabilised voltage supply 12v - 12v

 

Edit to add - (this is not a recommendation) something like this :

 

https://www.ebay.co.uk/itm/DC-DC-5-32V-to-12V3A-Automatic-Voltage-Stabilizer-Power-Converter-Regulator-SO7/353125289144?hash=item5237e84cb8:g:flQAAOSwhvVe~Cn8

 

9 minutes ago, Jen-in-Wellies said:

And a fuse, or breaker would still be needed.

Thank you to you all! Now I know what exactly we need can order and get it sorted. Thank you again for your advice It’s very much appreciated!!! Thank you ? 

Edited by foleyhancox
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8 minutes ago, foleyhancox said:

We were advised to go straight from the main boat batteries to a regulator, then heavy duty Cable from that to a 12v plug. Ready for the tv to be plugged in. The tv would not be used when the engine is on however the batteries are connected to solar panels. Does this sound about right? 

 

That is an BSS fail. Any but  a very few circuits shoudl be connected to the switched side of the battery isolating switch. I have no idea who advised you but as long as we are talking 12V DC throughout its a load of bull. The same sized cables as discussed above can be sued for the whole circuit. If one was being really silly  we could suggest a heavier cable between isolator, fuse and regulator because of the few mA it uses to work itself.

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14 minutes ago, foleyhancox said:

We were advised to go straight from the main boat batteries to a regulator, then heavy duty Cable from that to a 12v plug. Ready for the tv to be plugged in. The tv would not be used when the engine is on however the batteries are connected to solar panels. Does this sound about right? 

No.  Put the regulator at the TV end.

Plus of course it needs to be fused.

At the battery end.

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4 minutes ago, Tony Brooks said:

 

That is an BSS fail. Any but  a very few circuits shoudl be connected to the switched side of the battery isolating switch. I have no idea who advised you but as long as we are talking 12V DC throughout its a load of bull. The same sized cables as discussed above can be sued for the whole circuit. If one was being really silly  we could suggest a heavier cable between isolator, fuse and regulator because of the few mA it uses to work itself.

Will look to doing it either from the Boats main fuse box (with advice) or separate batteries/solar panel rather than Connect to the main batteries and solar panel. 

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9 minutes ago, WotEver said:

No.  Put the regulator at the TV end.

Plus of course it needs to be fused.

At the battery end.

May try this using a spare battery and a solar panel. Keep it separate from the main bank of batteries. Could be less hassle. 

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Just now, foleyhancox said:

Will look to doing it either from the Boats main fuse box (with advice) or separate batteries/solar panel rather than Connect to the main batteries and solar panel. 

Can you be more specific about what you mean? It sounds as if you may be considering a separate TV battery and that is poor practice because to minimise the regular depth of discharge and thus maximise battery life (given adequate charging) one large bank is better than several smaller ones.

 

Solar charging is one for the circuits allowed to bypass the isolator switch so if you picked the feed up from there is or should be a BSS fail.

 

I would pick the feed up from a main fuse box.

 

 

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3 minutes ago, foleyhancox said:

May try this using a spare battery and a solar panel. Keep it separate from the main bank of batteries. Could be less hassle. 

No, that’s a poor idea as Tony B has explained. 

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Our other thought was to put two batteries in the front separate locker of the boat not linked to anything else electrical in the boat. Use a solar panel to charge them when we are out.  We was then going to use a solar regulator to put a cable from to a socket for the 12v Tv. When in our mooring we can plug into the 240. 12v is so confusing lol. 

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7 minutes ago, foleyhancox said:

Our other thought was to put two batteries in the front separate locker of the boat not linked to anything else electrical in the boat. Use a solar panel to charge them when we are out.  We was then going to use a solar regulator to put a cable from to a socket for the 12v Tv. When in our mooring we can plug into the 240. 12v is so confusing lol. 

12v is quite simple when you follow the proper conventions, start messing about and making your own rules up with 230v and you end up dead..

 

There is only one way to do it and that is the correct, (safe), way, it has been explained how to do that, if you do it or don't do it is up to you but do not be surprised when you get your safety certificate refused or the cables start to melt.

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8 minutes ago, foleyhancox said:

Our other thought was to put two batteries in the front separate locker of the boat not linked to anything else electrical in the boat. Use a solar panel to charge them when we are out.  We was then going to use a solar regulator to put a cable from to a socket for the 12v Tv. When in our mooring we can plug into the 240. 12v is so confusing lol. 

Its only confusing because you are trying to do it unconventionally. Just come from your DC distribution board to where the TV is situated, put your voltage regulator there and then a short flex to the TV. It gets complicated when you start adding more batteries and their charging circuits and controls

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12 minutes ago, foleyhancox said:

Our other thought was to put two batteries in the front separate locker of the boat not linked to anything else electrical in the boat...

Why are you making this so complicated?

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9 minutes ago, foleyhancox said:

Our other thought was to put two batteries in the front separate locker of the boat not linked to anything else electrical in the boat. Use a solar panel to charge them when we are out.  We was then going to use a solar regulator to put a cable from to a socket for the 12v Tv. When in our mooring we can plug into the 240. 12v is so confusing lol. 

 

As a solar panel will provide an output of all bu zero in the depths of winter I doubt that idea is a starter. you would do far better to connect solar and solar controller to charge your main bank and feed the TV circuit from the fuse box.

 

12V is only confusing if you don't do your research. Try studying the electrical notes on my website. http://Tb-training.co.uk.

 

You may have a spare fuse holder you can use or you may have to connect to the positive bus bar and adds an inline fuse. Then its up to you to decide where the regulator goes.  Positive cable: Positive bus bar > fuse > regulator > TV socket. The return negative: TV socket > Negative bus bar in the fuse box.

 

Post photo of the guts of your fuse box ans we nay be able to advise further.

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3 minutes ago, ditchcrawler said:

Its only confusing because you are trying to do it unconventionally. Just come from your DC distribution board to where the TV is situated, put your voltage regulator there and then a short flex to the TV. It gets complicated when you start adding more batteries and their charging circuits and controls

And more expensive ?. Will look at going from the main fuse board. Thank you for your advice. Will look at getting the right size cable and other accessories  And get it done. Thanks again. 

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2 minutes ago, Tony Brooks said:

 

As a solar panel will provide an output of all bu zero in the depths of winter I doubt that idea is a starter. you would do far better to connect solar and solar controller to charge your main bank and feed the TV circuit from the fuse box.

 

12V is only confusing if you don't do your research. Try studying the electrical notes on my website. http://Tb-training.co.uk.

 

You may have a spare fuse holder you can use or you may have to connect to the positive bus bar and adds an inline fuse. Then its up to you to decide where the regulator goes.  Positive cable: Positive bus bar > fuse > regulator > TV socket. The return negative: TV socket > Negative bus bar in the fuse box.

 

Post photo of the guts of your fuse box ans we nay be able to advise further.

Exactly what we need!!! Thank you!! Will message you photos Tomorrow if you don’t mind. Thank you!!!


My husband has started reading your page already!!! It’s just what we need !!!

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4 minutes ago, foleyhancox said:

Exactly what we need!!! Thank you!! Will message you photos Tomorrow if you don’t mind. Thank you!!!


My husband has started reading your page already!!! It’s just what we need !!!

Just keep in mind that they were course notes and they would have been amplified and discussed on the course. They are about 20 years old so do not have the latest equipment. For instance i would now fit a Voltage Sensitive Relay (VSR)  instead of a split charge relay.

 

Also study Wotever's Battery Charging primer

Found pinned at the top of this sub forum.

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