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Maplin 12V Modified Sinewave 300W Inverter

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Quoting product code: N66JU


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About this product


  • 300W continuous output to power a range of household appliances
  • Modified sinewave output to power chargers, heaters and air conditioners
  • 240VAC mains socket to power a product without additional converters

Product overview

• 300W continuous output
• Modified sinewave output to power chargers, heaters amd air conditioners
• 240VAC mains socket to power a product without additional converters
• 12VDC input power that can be achieved through either the car accessory socket or with the included alligator clips.
• Weighs only 720g, its compact design (120 x 73 x 73mm) prevents it getting in your way in the car
• 2.1A USB socket included to charge an additional device such as a Smartphone or Tablet
• Shutdown protection against power overload

Connect your home appliances to a car, truck or solar panel
This 12V 300W inverter is a converter that connects to a sealed lead acid (SLA) battery that is usually connected to a car, a truck or a solar panel. The inverter can connect to the battery either through a car accessory plug or by clipping directly to the battery. A mains powered device can then be plugged directly into the inverter’s AC socket.

Energy efficient and safe to use
This 12V 300W inverter can connect to the car battery through either the car accessory socket or directly using the included alligator clips while being positioned out of the way with its compact design. The 12V inverter can power a device up to 300W such as a laptop or a phone charger or a portable games console. It is highly efficient, converting 90% of its energy into output power. It is fitted with a 2.1A USB socket to charge a wide range of items such as a Smartphone, MP3 player or Tablet while still keeping the mains socket available to power an additional item such as a battery charger. The inverter includes shutdown protection to power down the inverter if the battery power drops below a certain level.

Power your charger, laptop or printer
This 12V 300W inverter and can power devices such as laptops, printers and chargers, although some items may pick up interference from the inverter. A solution for this is to upgrade to a pure sinewave inverter. A pure sinewave inverter is used to power sensitive electronic devices such as power motors, power tools, clocks or microwaves.


Rated 4 out of 5 by from Just finished wiring this into my motorhome. It is to run the laptop, and charge phones, camera etc etc. Love having mains and USB charging. Running this lot, it runs gently warm, fan doesn't need to run; which is nice. Wanting to know the hit on my leisure battery consumption, I checked the "off" current - too small to measure and the "zero load" current - as per spec. One serious con though, why oh why does this one not come with flanges to screw it down - I did know when I bought. Yesterday was spent bending up and painting two aluminium "U" straps to go over the unit to hold it down. 25mm strip ali from B&Q, anneal it, bend to fit and paint. Remove lid of the inverter to drill holes to tap for steady-screws, clear all swarf and reassemble. All that for want of flanges. Nice compact unit.
Date published: 2012-07-08
Rated 5 out of 5 by from Just bought this in store; good value at the sale price. I wanted an inverter to use from the car cigarette lighter for my laptop on long car journeys when the wife is driving. My previous 75W inverter got overloaded. This one has automatic cut off; is 150W through the cigarette lighter socket, and has leads to attach to the car battery if you need 300W. This is a bonus to run your laptop, etc., from a portable car battery, which I can use at field shows where there is no electricity or you have to pay for electricity. The USB socket is a bonus. Maplin's store staff are excellent with their advice. I might have gone for another 75W inverter if staff had not explained the wattage issue. In the sale, this 300W inverter was as cheap as a 150W one. With two sets of leads (and spare fuses included), it is quite versatile. Instructions say that it cannot be used with fluorescent lighting, which is not mentioned by another reviewer who criticises this. It is about 15cmx8cmx8cm and is very quiet, compared to car engine noise. Its fan is quieter than another car inverter I have used.
Date published: 2013-06-20
Rated 5 out of 5 by from Dependable. Bought this after a small amount of research on short notice before a supporting role in a long distance cycling event. We had this up and running off the internally mounted battery within minutes running a laptop and charging gps/phones/cameras all through a 3 socket extension lead. Made for a perfect little base station, with the only niggle being the USB socket not being powerful enough to charge today's power hungry smart phones. Highly recommended, we had this running 18-20 hours a day for 5 days straight and the fan only came on a couple of time (hot weather made it warm in the van on occasions). Our little trip would have been alot more difficult without this little beauty.
Date published: 2014-07-06
Rated 5 out of 5 by from The unit is well finished, came with a choice of battery connecting leads which I wasn't expecting and, though I haven't yet tested it to full advertised power output, it works well on lower output demand and i have no reason to suppose it won't do everything I had in mind when I ordered it. I'm very pleased with my purchase.
Date published: 2013-01-10
Rated 5 out of 5 by from Very pleased with the Invertor and delivery was next day. My dealings with Maplin have been excellent so far.
Date published: 2012-01-20
Rated 1 out of 5 by from Never got it to work I've had a 150w inverter from Maplins and it works well and has done for many years. However this 300w version is a different kettle of fish. It kept repeatedly blowing the fuse or pulling the battery voltage down so low it wouldn't power up. I tried various combinations of batteries on my solar system, but still nothing. Have now got a brand new 110Ah battery and all I get is the green LED light up, no mains power and after a few seconds I either get a continuous tone or an intermittent from the unit.
Date published: 2014-04-17
Rated 3 out of 5 by from This inverter is not suitable for Ipod 7th generation. It just will not work, mainly because there are no reference voltages applied to the signal leads, they are just left open circuit. Having looked at the circuit board it is not even easy to modify.
Date published: 2013-04-27
Rated 3 out of 5 by from low voltage protection kicks in every time i start the car This inverter works fine. I use it to power my mobility scooter charger in the back of the car. The cigarette socket switches off when ignition is off, but when i switch the ignition back on and start the car the low battery alarm keeps going. I have to unplug the inverter and plug it back in each time i start the car. Annoying
Date published: 2016-04-17
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Sinewave Type:

Modified Sinewave

Operating Specifications

Output Power:


Peak Output Power:


Input Voltage:


Input Current:


Output Voltage:


Output Frequency:


Dimensions & Weight













USB Output:


Product Specifications

Low Battery Protection:


Hi there, I have a 240v 300w panel heater in my campervan. Will this inverter be suitable to run the heater when we are not on EHU and relying on our leisure batteries ? Thanks

Asked by: Carpy
Unfortunately, this would not be suitable to run your heater.
Answered by: Billy
Date published: 2017-11-21

Hi does this inverter have cooling fan?

Asked by: Customer
Yes this does.
Answered by: darren cordon
Date published: 2017-10-04

Could I use one of these to connect to my liesure battery to use a household lamp??

Asked by: Shany79
as long as the wattage draw of the lamp you are connecting is less than 300w it should be fine.
Answered by: Les
Date published: 2017-09-27

Will the inverter run a 20" portable tv 25watts

Asked by: Cabby
Yes, this would be suitable.
Answered by: James
Date published: 2017-09-26

Will this inverter run a table top fridge 75w in my camper when I am on the move?

Asked by: kenif
We would not recommend modified sine wave inverters for use with items with motorised components, such as peltier cooling systems or compressors. You would need a pure sine wave inverter for that purpose, however the 300W would be more than enough for the 75W device.
Answered by: Gareth
Date published: 2017-09-25

Does this have a 240v lead to charge the internal battery /

Asked by: Jim1
unfortunately not no .
Answered by: darren cordon
Date published: 2017-09-22

Will this run the Lg Xboom 9730 Hifi speakers? I believe it is 180w required input, however before i do anything id rather feel safe asking you guys?

Asked by: James123
The item will be able to power loads of up to 300w.
Answered by: Dominic
Date published: 2017-09-16

Why does it keep beeping 4 times when turning it on for 1st time

Asked by: Aldred
It could be a flat battery or overloaded?
Answered by: Dominic
Date published: 2017-09-11
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