What size invertor do I need?

[Artstu]

I have ended up with a 230 volt TV for my Campervan, rated power consumption is 45 watts, so I'm looking at a 150 watt pure sine wave inverter. For short periods of use with a 110ah battery with support from a 60 watt solar panel.

Now the real question is will this be enough for my ebike charger with a rated input of 110-240v ~ 1.4A max which could equate to a max of over 300 watts.
My netbook charger quotes similar figures too, do they really consumne more power than the LCD 19" TV?

Any help appreciated please

 

[eddieo]

I fitted a 5-600? watt Maplin one in my camper last year..from memory about £25. It needs to be fused and use thick cable from battery. You may well only need a small one, but if you get a plug in make sure your vehicle socket is up to it

its the initial draw of current that can be a problem so you always need a bigger one........

 

[Fecn]

I have ended up with a 230 volt TV for my Campervan, rated power consumption is 45 watts, so I'm looking at a 150 watt pure sine wave inverter. For short periods of use with a 110ah battery with support from a 60 watt solar panel.

Now the real question is will this be enough for my ebike charger with a rated input of 110-240v ~ 1.4A max which could equate to a max of over 300 watts.
My netbook charger quotes similar figures too, do they really consumne more power than the LCD 19" TV?

Any help appreciated please

The 1.4A rating is the surge current which happens for a few milliseconds when the charger is first plugged into the mains. Your inverter will be more than capable of dealing with that surge (they all are). Depending on what model of bike you have, the charger most likely takes somewhere between 65 and 140 watts of power. For working out the power it realy uses, look at what the charger outputs and add 20% (e.g. 2A @ 36V = 72watts... +20% fiddle factor for the charger's inefficiency = 86.4 watts taken from the mains)

I suspect that your TV is an LCD panel rather than a cathode ray tube, and if that's the case then a Pure-sine inverter isn't really necessary. Both the TV and the charger will turn the mains into rectified DC, so you can save the expense of pure-sine and get a cheapy 'modified-sine' model instead.

 

[Artstu]

Thanks Fecn that's perfect

My charger output is 29.4v at 2A so 70.5 watts with the 20%.

I have now read several times that Laptop transformers don't like modified sine-wave invertors and pure sine wave is needed, hence the reason I'm looking at pure-sine wave.

I'm looking to get one of these I think Waeco MSP162 12v 150w Sinewave Inverter | ROADKING.co.uk

 

[Fecn]

Power supplies will be slightly noiser when running on Modified-sine, but it shouldn't really make any difference to the laptop at all. My laptop has been happily running from modified sine inverters for many years.

Within every laptop power supply, the absolute first thing that happens when the mains comes in is that it is rectified to DC and then stored on a big capacitor at around 360VDC. Apart from the bridge rectifier and one capacitor (which really don't care whether it's sine or not), the rest of the laptop supply will be blissfuly unaware of what kind of electricity it's running on. It's the reason that so many of the supplies are 'worldwide' now and run on anything from 110VAC@60Hz to 250VAC@50Hz... They'd also do 110VDC if you fed it to them.

Regardless of the laptop supply... Pure-sine is most definitely better, and Waeco gear is superb... I have a Waeco CoolFreeze in my van - It's brilliant.... I've just haven't felt the need to spring for a pure-sine inverter yet (I do have a fair few modified sine ones though... 75W Ring Inverter, 150W generic one... 300W ring inverter, 500W home-built inverter and a 2KW Ring inverter)...

 

[Artstu]

Thanks again, I had thought the Waeco looked like a quality product.

Just one more question if you don't mind, Would the next model up (350W) consumne more power than the 150W one whilst powering something requiring around 50 watts ?

 

[onmebike]

I monitored my charger, 42volt 1.8ah approx 91watt.
Maplins are currently doing a 750watt for £40.00 here Black & Decker 750W DC 12V to AC 230V Invertor with USB Charging Socket : In-Car Power Invertors : Maplin
or loads more choice here,

inverter : Maplin Electronics

 

[Fecn]

Thanks again, I had thought the Waeco looked like a quality product.

Just one more question if you don't mind, Would the next model up (350W) consumne more power than the 150W one whilst powering something requiring around 50 watts ?

As inverters get biger and bigger, they use more and more power when idle. My 75W inverter burns 1W when it's doing nothing. My 2KW inverter burns 10W when it's doing nothing. Theoretically, they can both reach a maximum efficiency of about 85%, but the max-efficiency point is always near the max-output point. If you're leaving the inverter on all the time, get the 150W version.

My personal experience with inverters is that it's all or nothing. a 150W inverter will do TVs, Laptops, Chargers etc... and once you get above ~1.5KW, then you can do microwave ovens, toasters, hair dryers etc. I can't think of a single electronic device I own which would want ~300-500W of power.

 

[Artstu]

Thanks it looks like a 150w one then.

 

[onmebike]

Thanks it looks like a 150w one then.

Okay provided you won't need to connect several things at the same time. I wouldn't be to concerned about idle consumption it's not that high and you'd be well advised not to leave charging batteries unattended anyway.