# 12vdc and power inverters - any ideas?



## jd_boss_hogg (Aug 26, 2009)

Hi All - hoping someone can help me, after making a rash purchase.

I've just bought a Linsar TV/DVD combo on ebay. I bought it because it was 12v dc - so i thought it would come with a 12v accessory plug (cigar lighter), but it doesn;t. It comes with a 220/110v transformer that transforms down to 12v dc. Boo !

I spoke with linsar support - they said i can;t just connect directly to 12v dc, because if the voltage drops on the van battery, then it draws higher current, which could damage the set. So, they said to be safe, everything has to go through the transformer. They suggested connecting it upto an inverter.

So, just done that. The power supply that i used is one that was pre-fitted on the van, with a car-type 10a fuse. It blew after 5 mins.

So, my questions would be:-

Should i replce the fuse with 15a?

The TV is just 50w, the inverter 200w. Should that be blowing fuses?

Does the inverter take my 12v upto 220v, just for the transformer to drop it back down to 12v? How stupid is that?

is there any other gizmo that i can buy , so that i can use my TV next week when i'm on holiday (apart from when i'm on hook up)

Any feedback, GREATLY appreciated !


----------



## Pudsey_Bear (Sep 25, 2008)

I use a 300w inverter, which will run my TV with on board DVD, and it runs the PVR at the same time, so not sure why the fuse blew, and yes you can get a piece to kit to run it on 12V, but don't get a cheap one, if poss take it to the shop and ask if you can try it to see if it's suitable, Maplins do one


----------



## clive1821 (Mar 27, 2010)

I'll have a punt here.... a 200watt inverter could well take 20amps and just make sure how its wired to the leasure battery... and if the cable is correct then 20amp blade fuse is recomented... there are ways to deal with your tv and the power unit to directley to the 12 volt supply but only do if you are into electrics if not just leave alown and use the inverter... the inverter will indeed take your 12volt DC up the mains voltage.... if you are using a switch mode power supply unit on your tv to convert the mains to 12volt to your tv... I would recomend useing a pure sine wave inverter... as many units are not pure and a switch mode power supply will not like it and will fail.... hope that helps


----------



## Hsimpson (Apr 9, 2008)

Yep, Maplins would be the place to go. 

An inverter is usually used when you have a standard 3 pin plug that you want to change into a *** lighter plug for 12v - the size of the inverter should not matter as long as its wattage is higher than that of the TV. The first inverter I bought kept blowing fuses and when I sent it back to the manufacturer it was diagnosed as being a faulty one - this could be happening to yours too

There are 2 types of inverter, the cheaper long wave inverter and the more expensive pure sign wave inverter - I'm powering a 30inch TV off a pure sign wave as without it the TV makes a distortion noise, whereas I'm powering a 22 inch tv/dvd using the cheaper long wave inverter (£29.99 from maplins).

I would try a different inverter before I changed the TV - why not take the actual TV along to maplins and try their inverter instore?


----------



## JeanLuc (Jan 13, 2007)

I am surprised the inverter is not working; I could understand if it gave out warning signal as voltage drop along the wires from the battery can be a problem. A 200 W inverter needs fairly heavy cable to ensure voltage drop is minimised. However, I am surprised at the fuse blowing. A 50W load on 12V will draw about 5 amps through an inverter. Have you checked the input power requirement of the power pacK? It may be more than 50W. Your 10A fuse will blow if the load on the inverter is around 100W.

As mentioned, a modified sine wave inverter can cause trouble with some power packs and flat screen TVs. A pure sine wave version should work fine, but they are quite a lot more expensive. I fitted a 150W pure sine wave inverter three years ago, and it was about £85 then.

You might consider one of these if you cannot sort out the inverter:
<< Voltage regulator >>

Philip


----------



## jd_boss_hogg (Aug 26, 2009)

The inverter is, i'm guessing, a cheap rubush thing from China/Ebay. It got VERY hot. (cost me £15)

Powerpack input to the TV is 100-240, 1.2a. And the export is 12vDC, 4.2a. The TV says it's 50w.

Philips suggestions for a DC regulator look good, but i'm guessing that i'm better off spending £50 on a good inverter that will run many things, than a DC regulator that i will have to wire for the TV alone ?

I'm slightly pissed that this thing was advertised as 12v DC, suitable for caravans and boats... when any old TV would have worked fine...


----------



## JeanLuc (Jan 13, 2007)

If you want to play it safe and get a pure sine wave inverter, don't assume they are cheap. Here is a link to a Sterling 200w supplied by Snelly, one of this forum's trade members. Sterling is a good make but as you will see, it costs almost £150.

<<200 watt Sterling PS Inverter>>

Philip


----------



## clive1821 (Mar 27, 2010)

Yes and thats very cheep!!! if I recal my 1KW unit was around £450.00... still it mean it and would run at 1KW all day if the batteries would last!!! but if you are considering conecting any electrical item that uses a switch mode power supply then only use a pure sine wave inverter.... be cheeper in the long run..... in my view.. nice weekend for us happy campers....


----------



## Pudsey_Bear (Sep 25, 2008)

The inverter we had at first was a Silverline and cost about £18, we had no problems, a pure sine wave would of course be best, but I'd try a cheaper one first.


----------



## macone48 (Mar 14, 2006)

jd_boss_hogg said:


> Hi All - hoping someone can help me, after making a rash purchase.
> 
> I've just bought a Linsar TV/DVD combo on ebay. I bought it because it was 12v dc - so i thought it would come with a 12v accessory plug (cigar lighter), but it doesn;t. It comes with a 220/110v transformer that transforms down to 12v dc. Boo !
> 
> ...


Back the OP's question.

I have a Matsui Tv with similar set-up (Mains to 12v). I cut the input 12v cable and connected it via a 10 amp fuse direct to the Leisure 12v supply. It's been like that for 18+ months, no problems.

Your choice to follow what I did, as i cannot see what "problem" can occur with "my" leisure supply side which would "damage-the-set"???

Save you going down an expensive invertor set-up!! (Incidently I have a 2Kw Invertor & 300 Amp Hr supply, but still took the 12v route !!).

HTH

Trev


----------

