12V DC To 240 AC Inverter Question

G

GAJ52

Well-Known Member
Joined
23 Jul 2013
Messages
206
Visit site
Hi

I have a Ring 300w Inverter fitted to my boat, assume wired by a previous owner, to power a small flat screen TV only. I have 4 fully charged (between 12.8 and 13v) 110Ah batteries supplying the DC electrical system.

The TV consumes about 43w according to the label on the back and draws about 3.8 amps on the lead to the inverter, but the voltage across the pos and neg lead to the inverter is only about 10.6 volts and there is no drop in the battery voltage. The result is the inverter constantly makes a buzzing sound and the TV turned on and off, as I think the inverter auto shuts off at about 10.5 volts.

Now this 300w inverter and my battery supply should handle this TV easily, but its not. Before I go out and buy a new inverter, can anyone think what may be wrong - is it normal to get such a big voltage drop across the inverter input leads.

Glen
 
Bad connection between the inverter leads and your batteries.

What is the voltage across the battery bank with the tv on and with the tv off?
 
I take it it is wired in, not via a cigar type plug/socket?

My 150w inverter, when I used it, sulked when connected to the saloon 'cigar' outlets. The wiring was not up to the load, though fine for phone chargers etc.

Croc clipped to the battery posts it works fine (though a bit of a lash-up).

For other installers, keep the 12v as short as possible and feed the ships mains sockets via your blue inlet as 220v (at this load) doesn't mind skinny cables. You need to be able to turn off the inverter easily after watching that film in bed to save drain even idling its consuming a little.

Make sure you CAN'T connect shore power and inverter at the same time

Now with a 10" tablet for nav/net/entertainment and led saloon lights the inverter gets little use

N
 
With the TV on or off the battery bank remains at 12.8 to 13 volts doesn't move.

My wife would like to watch DVD's so we are thinking of buying a Blu Ray player as well, but we don't need 240v for anything else while away from our berth.
 
GAJ52 said:
Hi

I have a Ring 300w Inverter fitted to my boat, assume wired by a previous owner, to power a small flat screen TV only. I have 4 fully charged (between 12.8 and 13v) 110Ah batteries supplying the DC electrical system.

The TV consumes about 43w according to the label on the back and draws about 3.8 amps on the lead to the inverter, but the voltage across the pos and neg lead to the inverter is only about 10.6 volts and there is no drop in the battery voltage. The result is the inverter constantly makes a buzzing sound and the TV turned on and off, as I think the inverter auto shuts off at about 10.5 volts.

Now this 300w inverter and my battery supply should handle this TV easily, but its not. Before I go out and buy a new inverter, can anyone think what may be wrong - is it normal to get such a big voltage drop across the inverter input leads.

Glen
Click to expand...

Or ditch the inverter and don't bother with the blu ray and buy one of these (or similar) instead, unless you specifically want blu ray rather than DVD

http://www.amazon.co.uk/CELLO-C1611...keywords=cello+portable+tv#productDescription
 
nigelmercier said:
The only way I would be happy to do this is via a big switch. Don't be tempted to use a double-ended mains lead (although I do this at home during power cuts).
Click to expand...

I agree- my 13A house plug to blue female on a short pigtail can only plug into the blue mains inlet after the shore power has been removed so fairly fool (or me ) proof.

N
 
+1 for the faulty leads. But Glen, you don't say what type of inverter it is, not sine wave I would guess. I have a trapazoidal wave 350W one. It's OK for charging my laptop, if the laptop is switched off. When it's on, the mouse pointer goes a bit mad. Too much noise on the AC output I guess.
 
Last edited:
prv said:
+1 - I contemplated fitting an inverter as part of this winter's electrical refit, but then couldn't think of a single thing I'd want to power from it.

Pete
Click to expand...

hairdrier, microwave, kettle and toaster are used most on mine. 2.5 kW sinewave inverter. It does a great job, chinese cheapy from ebay.
 
Elessar said:
hairdrier, microwave, kettle and toaster are used most on mine.
Click to expand...

I don't own a hairdrier (and the ladies on board haven't expressed any urge to bring one either). Don't have room for a microwave. Grill makes good toast, quicker than an electric toaster. An electric kettle might be convenient, but it seems like a scandalous waste of electricity versus using the gas one, and it's yet another thing to stow.

Pete
 
Played around with it some more today and the cooling fan comes on after about 5 secs, so I'm hoping its just a duff Ring Inverter. That's when the voltage drops and the thing starts playing up.
 
prv said:
I don't own a hairdrier (and the ladies on board haven't expressed any urge to bring one either). Don't have room for a microwave. Grill makes good toast, quicker than an electric toaster. An electric kettle might be convenient, but it seems like a scandalous waste of electricity versus using the gas one, and it's yet another thing to stow.

Pete
Click to expand...

I dont gave gas on board........
And the microwave is an oven too. Zero space effectively.
 
nigelmercier said:
Sounds like it. Here is a nice replacement: http://amzn.to/SIOh9W
Click to expand...

Ring version is similar but has a second set of wiring for direct connection to battery. i.e. Plug for up to 180W & croc. clips for 300W.

They should really mention that output via cig. socket should be limited to 120-180W (~10-15A). Someone is not going to be happy when trying to pull 25A via a 12V socket. :D

It is cheaper than the Ring equivalent.
 
Last edited:
Mistroma said:
Ring version is similar but has a second set of wiring for direct connection to battery... It is cheaper than the Ring equivalent.
Click to expand...
Those Ring labels are quite expensive :)

Mine only had a cigar plug, I removed it and wired it via a fuse and a switch (I removed the switch from the unit and extended the low current wires, they switch a relay on the input).
 
Last edited:
General advice: Put your inverter as close to your batteries as you can, low voltage side = 20 times the current of mains side (assuming 240v and not 110, and 12V batteries of course). Use you r big wires there. Your TV has negligible draw, but a 300W Inverter is 25A at 100% efficiency, which it won't be, so wire for 30A. 30A is easiest done with 4mm cable, to leave a comfortable bit of slack. With only 12v on the input side, you can't afford much of a drop there.
Auto changeover switches highly recommended. Avoid double ended plugs like the plague.
Careful, with mains on your boat comes ever larger inverters. Hairdryers etc need kilowatts, all of a sudden you are 300A draw from your batteries, now that's a serious bit of cable on the LV side.
 
You must log in or register to reply here.

Share this page

Top