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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 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 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 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 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
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 5 out of 5 by from Needed an inverter for our boat to power a laptop We needed a way to charge a laptop (220v / 120W power "brick") on our boat, which has 12v batteries. This inverter does the trick. Were worried a bit about the "modified sinewave", but other than a very little hum from the laptop power supply, it works as intended.
Date published: 2017-06-19
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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










Cable Length:






USB Output:


Product Specifications

Low Battery Protection:


How noisy is the fan? Need one that's almost silent

Asked by: Peter
Unfortunately, we do not have an inverter with a silent fan.
Answered by: Billy
Date published: 2018-02-13

Is it safe to wire this to the car battery and leave it connected permanently via the crocodile clips provided?

Asked by: Matt0941
If you intend to connect permanently then you must proper battery terminals. Also make sure the inverter is powered off when you start the engine. Failure to do so can send a sure to the inverter and to any equipment connected to it.
Answered by: Les
Date published: 2018-01-16

Can i use it to jump start a vehicle?

Asked by: Amka
Unfortunately not, as this is not designed to do this.
Answered by: Brad
Date published: 2018-01-13

will these power of a 12v 22ah battery? one blew my other 12v 300w inverter not whether it was too big a battery or a faulty inverter.

Asked by: aaroon
It will work with any large 12 v battery. The Amp hour rating is just a measure of how much charge a battery holds for example 12 v 22 Ah battery will provide 12 volts at 1 amp for 22 hours. If the last inverter failed it would more likely be down to a faulty unit or overload of the max wattage by using a device that draws too much power.
Answered by: Les
Date published: 2018-01-12

Will this power a 12v 22ah battery?

Asked by: aaroon
This does not power any batteries, it is powered by a battery
Answered by: Les
Date published: 2018-01-11

Hi will this power 100 watt guitar amp? 

Asked by: Littlejo
Yes this should be fine.
Answered by: Billy
Date published: 2018-01-06

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
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