12 volt stabiliser - necessary?

Post by **beergut100** » 06 Mar 2007, 19:06

Hi

I'm fitting a TFT TV and Freeview box in my van and, while searching for the various bits and bobs I will need, I have come accross several sites insisting that a 12 volt stabiliser is necessary. I was planning on running both devices straight from my leisure battery; is this safe?, or will I have to fork out for a stabiliser - or maybe even two of them?

Post by **irish.david** » 06 Mar 2007, 20:51

Do both the TV and the freeview box run on 12v or are you going to be running them through an inverter? If you're using an inverter then you don't need any sort of stabiliser. Also if both are designed to run from a 12v battery then i'd be amazed if you needed any sort of stabiliser. Chances are that the 12v input will be stepped down to 5v inside both appliances anyway so a super smooth 12v input won't be needed.

Dave

Post by **Dan Wood** » 06 Mar 2007, 21:05

Best to put a voltmeter across your van's battery and rev the balls off it, just to check the regulator is working. You shouldn't go over 14 Volts.

I'd guess your 12V appliances would be OKish at 14V, but I'd not go much above that!

The trick is to use a long run of wiring and drop the extra 2 volts along the way.

You don't need to worry if you never have it connected with the engine running - it will be fine happily running down your leisure or main battery.

Oh, and I'd advise against cranking the engine with the telly on!

Post by **futurecut** » 06 Mar 2007, 22:01

I think some appliances require a smoother signals such as those put out by the more expensive pure sine wave(?) inverters. In reality though i find that mostly when you plug stuff in it tends to work anyway, maybe just behave a bit odd occasionally. I would not be worried. It'll either work or not work.

Post by **ringo** » 06 Mar 2007, 22:23

My 12v 15" lcd and dvd player (on cheap inverter) work fine off one battery....

Ringo

Post by **Other-Power** » 06 Mar 2007, 22:42

hey just my thinking,

Best to spend a little bit and get a voltage regulated 12volt to 12volt psu. You can use the PSU that came with them via an inverter but this will incure losses, further the use of a cheap inverter which will produce at best a very triangular signal will course the power factor of the mains psu to decrease( basicaly using more power then say pluged into a wall socket).

So to sumarise, run it of the van battery no worries, might blow the tft but its cheaper. By a voltage regulator 12volt to 12volt use that. finally buy a good pure sine wave inverter or even a cheap one and use the mains psu.

Hope this helps??

Jon

Post by **irish.david** » 06 Mar 2007, 23:41

I don't entirely agree with some comments made about inverters. A good rule of thumb with inverters is that as long as there's an AC to DC converter in the object you're plugging in they'll work fine. This is going to be a wall wart type thing like in laptops or actually built into the appliance itself. These converters are almost exclusively Switched Mode power supplies these days which will work fine with the square wave produced by cheap inverters without any real difference to the power factor. The main enemy of square wave inverters is things with motors or heating coils that run directly from the 240 VAC.

However using an inverter in this situation is a bit wasteful as converting 12 VDC to 240 VAC and back again will waste some of your batteries precious charge. If the TV and freeview box will take a 12v input then thats the way to go.

Should you use a 12v regulator? As i mentioned before, the chances are that the 12v input will be regulated down to 5v and probably 3.3v as well as those are the voltages that the electronics in the gear will be using. The backlight in the tft screen might use 12v but it will be fairly tolerant of small voltage changes. Basically without seeing the stuff i'm not going to tell you it will definitely be fine without a 12v reg but if it was my stuff i'd probably skip the reg.

If you do decide to fit one make sure you get one big enough. Add the power consumption of both items together and divide by 12. That numbers the current that'll be going through the reg.

Dave

Post by **Other-Power** » 07 Mar 2007, 07:41

Hi Dave,

Just thinking, surely a heating element is a purley resistive load and as such it dosnt matter what the wave is like as there is no phase shift and as such no power factor.

*** Waaaaap waaaap GEEK alert GEEK alert *** the rest of this mesage has been censored by 'geek talking version 3.1 build 2056'

Jon

Post by **irish.david** » 07 Mar 2007, 10:55

You're right in the fact that heaters do have a resistive element to them but almost all heaters are based on a ceramic element with wire wound round it and any sort of component with wire in a coil with have an fairly big inductive element to their nature. Thats why hairdryers will tend to blow fuses. They have both an electric motor and a heating element so the spike when they're switch on can be pretty huge.

In conclusion, i'm also a geek and don't use your hairdryer in your van.

Dave

Post by **beergut100** » 07 Mar 2007, 11:05

Thanks guys

I won't be using the appliances with the engine running, so I'm going to risk running the devices (they are both 12v) straight from the battery.

Post by **"WEAZLECHIN"** » 08 Mar 2007, 09:01

ive got a similar question .. i have a tv reciever for my laptop and want to take it camping instead of a 12v tv. will i be ok running it through an inverter and the power lead that came with the laptop 250v to 19v ?

Post by **shepster** » 08 Mar 2007, 09:21

I have a 12v 15" tv and a seperate 12v dvd player all running from the leisure battery with no regulator and they have worked fine for the last 3yrs, this includes when driving too.

Post by **Beach Bum** » 11 Mar 2007, 17:10

Hi, I have run a 15" flat screen LCD TV and din sized DVD for 2 years. I too, looked into this in great detail. I bought the right rated cable for the TV and had it hard wired with an inline fuse to the leisure battery. Did not need the voltage stabiliser that I thought I might need. Just one thing to remember (posted this on another thread a few days ago) when my TV is turned off, not on stand by, it still draws from the battery so I had an isolation switch fitted to stop my battery draining. I did have an inverter but binned it, to many problems, granted it was a cheap inverter.
hope this helps
Steve