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Ivanholder
Ivanholder

Posted: Fri Mar 06, 2009 3:37pm

Post Subject: Inverter or batteries

What is the best way to use battery power to run 12v tv and sattelite on my boat.I have 2 cabin batteries and 1 engine battery.?

Tony-B
Tony-B

Posted: Fri Mar 06, 2009 6:20pm

Post Subject: Inverter or batteries

Dear Ivan. You say its a 12v TV & satellite so where does the inverter come into it? The pair of cabin batteries are probably in parallel to give 12 volts (24 volts is still unusual on narrowboats)so Just plug them the 12v outlets. If either are not true 12v for vehicles/boats appliances (e.g. is supplied 12v via a power supply that plugs into the mains) then to be on the safe side supply both through a voltage stabiliser to prevent voltage spikes damaging the equipment. If you mean something else please come back with a bit more detail. Thanks Tony Brooks

Ivanholder
Ivanholder

Posted: Fri Mar 13, 2009 1:36pm

Post Subject: Inverter or batteries

Dear Tony, Thankyou for your prompt reply. I have been trying to reply but have had problems. The question I meant to ask,which is the best way to use 12v batteries,(2 cabin and 1 starter)to power a 12v tv and 12v satellite together,via the batteries or via an inverter.Sorry I was not clearer 1st time round. Ivan Holder

Tony-B
Tony-B

Posted: Fri Mar 13, 2009 4:05pm

Post Subject: Inverter or batteries

Dear Ivan, I am still not much clearer because an inverter produces 240v AC (mains) and if you feed that into a 12v DC appliance it will destroy the appliance so the only way to power 12v DC equipment is from the battery bank. However we come back to needing to know if these "12v" appliances are 12v as in designed for vehicle/boat use or just happen to be fed from a 12v power supply that is plugged into a mains outlet such as is commonly used for portable "mains" TVs nowadays. I will come back to this. If the TV & satellite receiver are true 12v appliances then supply them from 12v obtained from the two domestic batteries as used for the other electrical equipment on your boat. You may have to run suitably sized cables from your "fuse box" to a socket of your choosing close to where you want to watch TV, but I would have thought most boats would be equipped with this as standard nowadays. If you do have to wire a new socket my website tells you how to find the correct size of cable (it depends upon current drawn and length of run) and choose a socket and plug combination that can not be reverse connected. In past days one of the old small 3 pin, 5 amp mains sockets were often used but nowadays with so many boats with mains circuits it may be safer to use cigarette lighter sockets and plugs. The two domestic batteries should already be connected together positive to positive and negative to negative to provide the rest of the 12v electrical equipment with 12v and twice the capacity (amp hours) of a single battery. Ignore the engine battery. Now back to the type of supply the TV & satellite box are designed for. If either are designed for a mains supply via a transformer in the mains plug then connecting it to the boats electrical system may (not will) result in damage caused by the voltage surges typical of such systems. In this case, just to be on the safe side, either run them from an inverter or via a special 12v power supply that smooths out the voltage surges - Maplin sells them for laptops and so do people like Roadpro. However if you go down the inverter route anything other than a pure sine wave inverter may cause noise and picture interference (again note "may", not "will") so I would tend to go for a 12v supply stabiliser option. If this is not what you want please try to explain a bit more. If you prefer to do it privately email Tony@TB-training.co.uk

Ivanholder
Ivanholder

Posted: Fri Mar 13, 2009 5:20pm

Post Subject: Inverter or batteries

Dear Tony,Both the tv and satelitte will run off either 12v or 240v - In the boatyard I can run them off 240v but when travelling off 12v batteries or through inverter onto 240 volts. Which is the best way to use the batteries? Ivan

Tony-B
Tony-B

Posted: Fri Mar 13, 2009 5:46pm

Post Subject: Inverter or batteries

Dear Ivan, an inverter is not 100% efficient and we usually assume they are only 80% efficient so if you run the items from an inverter you will be using perhaps 20% more battery capacity than you would if you ran them from 12 volts, so all else being equal, run them from 12v to save the batteries. However I still come back to the need to be sure they are designed to cope with the voltage surges you get on vehicle and boat electrical systems. Just because the inlet socket is marked 12 dc it does not mean it is designed for vehicle or marine use, you have top go back to the instructions, who supplied it and if it came with a mains 12v adaptor. Tony Brooks

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