12v 10a Power Adaptor Supply - Advice Please!!

[Alex_374419316]

Hi, I was wondering if somebody would be able to provide any advice. I have recently bought a starter caravan that has got a 12v lighting system and a Cascade 2 water heating system that also runs off 12v. My question is would I need to purchase a leisure battery or could I use a 12v 10amp power supply unit that could be plugged into the mains electric sockets. Here is a link for the type of unit that I was thinking of http://shop.avicraft.co.uk/product_info.php?currency=GBP&products_id=8092

The Cascade heater only requires 250ma of current when heating the water and I am unsure what ampage the lights require (although I would have thought it would also be quite minimal)

I intend running the fridge off the mains so would only require the 12v power for lights and the water heater, and thought that this power supply would remove the need for a leisure battery and additional charger.

Has anyone else out there tried using such a unit or can offer any advice then I would be extremely grateful. Many Thanks Alex (Caravan Novice!!)

 

[swpostie]

Hi Alex,

I would get a leisure battery.

Do you not have a charger built in to the caravan?

Are you sure your water heater works off 12v? (mine doesn't - only 240v or gas)

What will you do when you have no hook-up?

In my opinion, your idea, whilst imaginative, seems to be a complicated way of achieving an unsatisfactory solution!

However, I am a relative newcomer too and there a probably far wiser people on here that can give you better advice!

 

[Alex_374419316]

Hi Alex,

I would get a leisure battery.

Do you not have a charger built in to the caravan?

Are you sure your water heater works off 12v? (mine doesn't - only 240v or gas)

What will you do when you have no hook-up?

In my opinion, your idea, whilst imaginative, seems to be a complicated way of achieving an unsatisfactory solution!

However, I am a relative newcomer too and there a probably far wiser people on here that can give you better advice!

Hi Rupert, Many Thanks for your input, the water heater definitely works off 12v (and gas combined) as my mains electrics consist of 2 x power sockets that are wired independantly of the 12v system. I only intend to visit sites that have electric hook up as there are plenty to choose from in our locality. The idea behind the power supply adaptor is to remove the need for a leisure battery & charger which would be plugged into the mains anyhow, so my thinking is that the single adaptor would simplify rather than complicate things. Thanks again, I welcome any further advice from any other readers. Cheers Alex.

 

[Chris_374413356]

Alex, I'm not familiar with your problem, but, normally the heater requires 240 volts for the electric elements they are either 660watts or 970 watts and would take maybe half an hour or more to heat the water, on gas it would take less time. I think you should be able to use the electric and gas at the same time for quicker water heating.

The 12volt DC supply I think will be for the supply to the pump and electronic control board.

You don't need a battery as the 12 volts will be supplied by the charger/power supply. The problem occurs when using gas for the heater and you lose the mains supply.... No pump or control supply!

 

[GrahamSouthBrum]

Whilst not needing a battery to supply your 12 volt system when using the charger, by putting a battery in the circuit it will smooth the the current from the charger, or so I have been informed to power computers and LCD TVs

 

[ProfJohnL]

Hello Alex,

In principal you do not need a 12V battery to do what you are suggesting. However as Chris has pointed out if you loose your 230V mains supply you lose your 12V supply as well. You might decide that is not a problem for you.

As for the Carver Cascade, The gas side does require about 250mA to run the 12v control circuit, again if the 12V system dies then Cascade also stops working. A note for Chris:- Not all Cascades have electric elements

In general most of the 12V lamps will each consume about 1 to 1.5A of current, and a submersible water pump may draw 3 to 4 Amps, but of course this intermittent. So you can do the sums as to the size of 12v power supply you may need to cover all the items you need at the same time.

The power unit you identify is a bit of an unknown. The specification does not tell if the output is regulated or smoothed, and so I would have to take the worst case view that it is has an un-smoothed and unregulated output. As Graham says, this is bad news for some electronics, as the peak output voltages from an un-smoothed nominal 12v power supply can be as high as 25V. Even a small 12V motorcycle battery placed in circuit would provide the necessary smoothing.

Alternatively, If the unit is smoothed and regulated then there should be no problem. There are other nominally 12V (Often 13.8V) power supplies that would be suitable - but do make sure the specification includes either smoothed or regulated outputs.

 

[Alex_374419316]

Hello Alex,

In principal you do not need a 12V battery to do what you are suggesting. However as Chris has pointed out if you loose your 230V mains supply you lose your 12V supply as well. You might decide that is not a problem for you.

As for the Carver Cascade, The gas side does require about 250mA to run the 12v control circuit, again if the 12V system dies then Cascade also stops working. A note for Chris:- Not all Cascades have electric elements

In general most of the 12V lamps will each consume about 1 to 1.5A of current, and a submersible water pump may draw 3 to 4 Amps, but of course this intermittent. So you can do the sums as to the size of 12v power supply you may need to cover all the items you need at the same time.

The power unit you identify is a bit of an unknown. The specification does not tell if the output is regulated or smoothed, and so I would have to take the worst case view that it is has an un-smoothed and unregulated output. As Graham says, this is bad news for some electronics, as the peak output voltages from an un-smoothed nominal 12v power supply can be as high as 25V. Even a small 12V motorcycle battery placed in circuit would provide the necessary smoothing.

Alternatively, If the unit is smoothed and regulated then there should be no problem. There are other nominally 12V (Often 13.8V) power supplies that would be suitable - but do make sure the specification includes either smoothed or regulated outputs.

Hi John, Many thanks for your information you have made many comments which I have found very useful. I have taken your advice about the power supply adaptor's output and have contacted the manufacturers to request more technical specification for the Ultrapower 12v 10amp power supply unit. I will update this topic once I receive the information. Cheers Alex.

 

[Alex_374419316]

Hi John, Many thanks for your information you have made many comments which I have found very useful. I have taken your advice about the power supply adaptor's output and have contacted the manufacturers to request more technical specification for the Ultrapower 12v 10amp power supply unit. I will update this topic once I receive the information. Cheers Alex.

 

[Alex_374419316]

Hi John,

I have received this response from the manufacturers of the 12v 10a power supply:

The output voltage is around 14 volts and it is regulated to some degree but voltage does drop at higher amp loads.

You don't say what the max current load in Amps is for your lights and pump etc. For continuous use without running power supply too hot I would suggest your maximum Amp load should be around 2/3rds of its current rating ie around 6 to 7 Amps.

As such do you think the 14v output will cause any damage to the water pump, heater or lights?

Once again, many thanks for your kind advice.

Cheers

Alex.

 

[ProfJohnL]

Hello Alex,

The response you have received "The output voltage is around 14 volts and it is regulated to some degree but voltage does drop at higher amp loads. " tells me the unit is not fully regulated, and no reference to smoothing. the "about 14 V" is rather too vague. and, the manufacturers suggestion that you should restrict your continuous current to only about 6 or7 A leaves me concerned that the product is not really designed for the job in hand.

I suspect it is not designed for continuous high current output, and consequently it will be in danger of over heating. It is probably designed to be used in free air, so placing it in a bedding locker or similar will cause it to heat up even more quickly.

I think you have two options.

Firstly I suspect that you would be safer and better off with properly designed caravan power supply. Sadly these will be more expensive, but you will at least have some comeback on the supplier if it fails under normal use. All the modern ones use 'switch mode' technology, which keeps weight and heat down, provides a highly regulated and smoothed output voltage, and are available in different power output capacities typically 7, 10,12 and as high as 16A. In your case I think a 10A supply should be adequate.

The second option does use a battery, Keep it small such as a 12V motor cycle or small car battery, and an 'intelegent ' charger e.g C-Tek 3600 which can b left connected to teh battery permanently. see:- http://www.intacaravans.co.uk/acatalog/Battery_Accessories.html

Your average hourly current demand will be quite low and provided the charger can exceed the average demand, it will fully charge the battery. The battery supplies all your 12V needs and can cope with the max demand from pump etc. Proper provision will have to be made to keep the battery securely fixed and ventilated to the outside.

Hope this helps.