Choosing Car Inverters

Many of us spend a lot of time on the road – in our cars and most of us would like a little convenience along the way – the convenience provided by AC mains operated gadgets and equipments. We have quite a number of power hungry gadgets – Laptops, Mobile phones, Digital camera chargers, hair dryers and power tools to name a few.

“There are three kinds of people in this world:

The ones that make things happen,

The ones that watch things happen,

and the ones who look around and say what happened? “

 

This article is intended for those who make things happen – in style.

 

Before we start we must find out what is our requirement. Everything else is based on this critical decision. If you intend to use your laptop for extended periods and also cater to a few small appliances – you could manage to do this with a 300 W car inverter. The cost difference between a 75 W/100 W power inverter and a 150 W Power inverter is not much. A small 75 W inverter sells for about US $30 while a 150 W inverter retails for about US $40. A 300 W inverter sells for about $60 at the time of writing this blog.

 

The following table shows typical power requirements for most appliances we use at home – powered from the AC Mains.

Appliance

Power requirement

Laptop

45 – 90 W

Mobile Phone chargers

15 – 25 W

Digital Camera chargers

10 – 25 W

Hair Dryer – Cold /Hot

30 W / 300 W

Compact Fluorescent Bulb 20 W

30 W

15 inch CRT TV /Monitor

120 W

15 inch LCD TV/ Monitor

45 – 60 W

Table Fan with about 8 inch blade

60 W

Electric Drill

150 – 300 W

Electric Saw

1200 – 1800 W

Microwave Oven 17 L capacity

1200 W

Some appliances may need more or less than what has been mentioned in the table above. Refer to the manufacturer’s manual or read the small letters near the power cord.

 

Many types of equipment which use motors require a larger starting current than when they are running normally. That is why the inverters have dual rating – normal or continuous and Surge or peak power ratings. A typical 150 W inverter may have a continuous rating of 150 W with a peak or surge rating of 200 – 250 W.

 

Even here – the term continuous is only relative. Don’t expect the inverter to run for days on – located in the remote corner of the car unless you have a well designed product.

 

Anything above 150 W of usage requires forced air cooling to keep the electronics inside the inverter cool. The outer shell of the inverter often serves as the Heat sink. So placement of the Inverter is critical for its safety as well as yours. It is like the Cigarette warning – “don’t smoke from the bed – for the ashes falling may be your own!”. Don’t keep the inverter on top of anything which will melt or burn.

Choosing a Car Inverter

Safety Factor:

If your requirement is 100 W, add at least 20 % safety margin to this and get a 120 W inverter. Inverters of 300 W and above will need direct connection to the batteries. You will need heavy duty large core cables to connect them to the batteries. If you are planning to use them regularly, use rubber grommets wherever you require. Always add a correctly rated Fuse in between the inverter and the batteries. Inverters use power transistors which can short out when failed. Automotive batteries can supply hundreds of Amperes of current and you will see disastrous fireworks in your car if you don’t use fuses.

The cables must be adequately rated for the inverter. A 150 W modified sine wave inverter takes about 20 Amperes from your 12 V car battery assuming 80 % efficiency and adjusting for other losses. If your cable is not adequate to carry this current continuously, it will cause over heating and the inverter will malfunction as it sees low voltage at its end. You will need 24/48 V deep discharge batteries to run high powered inverters. Even with a 48 V bank of batteries, a 1500 W inverter will require about 33 Amperes. You will have to position the Inverter in close proximity to the batteries. Remember that non sealed lead acid batteries release hydrogen gas (explosive in nature) when they are active.

 

Types of Inverters: There are two categories – Pure Sine wave Inverters and Modified Sine Wave Inverters. Pure sine wave inverters deliver almost mains kind of supply – but they are inherently inefficient. They tend to be bulkier and heavier than the modified sine wave types and expend lot of heat. For most electronic appliances, modified sine wave is adequate. Some motors will buzz when run from these modified sine wave inverters and it is no reason for distress.

 

If you use high powered inverters, don’t drain your car battery. Automotive batteries are not designed for deep discharge cycles. You should not discharge them to less than 50 % of their capacity if you want any decent life out of them. You will have to use stand alone Deep cycle lead acid batteries for loads of anything more than 500 W. Run the engine for 15 minutes or more for every hour of usage – for lesser power inverters.

 

If you consider the points mentioned above, there is no reason why you can’t enjoy the services of your domestic appliances away from home.

 

New Browsers Comparison

Browser War ? Some speculate that with the release of new browsers ( or new versions) the dominance of Microsoft with its Internet Explorer will be chipped away. It is unlikely to happen anytime soon.

We have tested the new browsers and this is what we gather:

Memory Foot Print:

Safari: 44 MB
FF : 37 MB
IE 8 : 18 MB
Google Chrome: 26 MB

Versions:

Safari Version : 3.1.2
IE 8 version Beta 2
Google Chrome Version: 0.2.149.27

Internet Explorer 8 Beta:
Many new features added – InPrivate Browsing, Web Slices (snippets of a page viewable from the favorites bar), SmartScreen Filter (checks about the status of the site from Microsoft server), Caret browsing (you can select text and move around within a page using standard navigation keys) and automatic crash recovery. This version appears stable and renders the recent CSS and DOM with decent backward compatibility.

IE8 Browser Features

IE 8 Developer Tool

Smart Screen in IE8

Safari browser uses the WebKit Open Source Application Framework rendering engine. Incidentally Google’s Chrome also uses the same WebKit which inherently has a security vulnerability  -  it allows execution of Java code without warning. Safari is robust and comes packed with plenty of useful features we are used to with FF addons. You can use any of the supplied options or create your own User Agent when you browse. You can use Web Inspector to inspect components of a page or even check out the latency period involved between the server and your browser. The simple interface at the beginning – later on developing into a complex system of menu to accomplish complex task endears Safari to any user.

Safari has “Private Browsing” – a mode where the history, cookies and cache are wiped clean after each session. Although it has come under flak for encouraging surreptitious  escapades into porno territories, it still has its genuine more mundane uses – like booking a surprise Gift for your partner.

Safari Browser

Talking of this private browsing, IE8, Safari and Chrome all have this controversial feature built in.

Google Chrome Browser

Google Chrome beta has some “cool” features – It opens with a thumbnail of the recently visited pages and the status bar when you browse becomes invisible until you hover over a link. It uses a completely rewritten JavaScript rendering engine under the name of V8 which is claimed to offer significant increase in client code execution. Besides, Chrome also offers one significant feature – it is multithreaded which uses individual processes for each tab. What is more you get to see the Task Manager which shows the processes of Chrome where you can select an individual process and end the process like you do with Windows Task Manager. Another hidden feature is when you run other browsers – the same Chrome Task manager lets you see what the memory usage of each browser is under the link – “Stats for the Nerds”. On the flip side, Chrome connects to Google servers to know the status of the site you are visiting. This might throw up concerns of the Big Brother watching you.

Chrome Browser Features

Task Manager in Google Chrome

As of now, personally I like Safari for its rich set of Developer Friendly features, Google Chrome for its innovation and IE8 for its stability ( Yes this version of IE is stable).

Digital Camera Maintenance

Caring for the expensive digital cameras and Camcorders is easy enough if you have a steady hand and armed with the right knowledge and the right tools.

 

1. Keep Your Digital Camera Clean:

“ A Stitch in time saves nine” – “ An ounce of precaution is worth a pound of cure ” If you observe the basic precaution of keeping your digital camera clean on the inside and outside, you will have less problem in their maintenance. Invest in proper camera bag and at the minimum a blower brush. Never wipe the lens with your fingers or any cloth. The lens will have a chemical coating to protect against surface reflections. It is this coating which enhances the image contrast by reducing the reflections from the surface of the lens element. This protective coating is susceptible to grime and the natural oil in your fingers.

Use the blower brush with new bristles to clean the dust away from the lens. If you have a digital SLR camera, you could start with a Skylight filter to protect the expensive the lens. If your lens has picked up enough dust, you could clean it with a proprietary camera lens cleaning liquid with a micro fiber cloth. This cloth has extremely fine fibers closely woven so that it cleans well without leaving any trace.

 

Clean the body with a clean dry cloth. For stubborn grime, clean the outer parts of the camera with isopropyl alcohol dipped cloth. It is a good idea to clean the electrical contacts (if any) with a paper card. Do not use any organic solvents to clean the body or lens.

 

For general routine cleaning the sensors of the digital SLR, you would need the following:

a. A pair of rock steady hands

b. Fresh batteries or fully charged batteries

c. Set your camera to manual and B mode.

d. Set the camera on a foam pad on the desk illuminated with a bright lamp

e. Sensor Cleaning kit ( if your camera really is in such a bad shape)

f. magnifying Glass (if you are not a spring chicken)

In case the camera times out and closes the shutter, you might end up damaging the mirror or the shutter or in the worst case all the above in addition to the sensor. If you are not sure, you will be better off to attend to this professionally.

 

Blow the dust with a blower brush aiming the jet of air in such a way that the dust is blown off the innards. Check the sensor with a magnifying glass for any trace of dust. With a fine bristled brush from the kit, wipe away the dust if any. Reassemble.

Digital Camera Maintenance - pitfalls

The Photo illustration adjacent here probably shows all the elements that can hurt a digital camera – sand, dust, fur and the electrostatic charge from stroking a cat.

2. Storing Digital Camera: Always store your camera gear in an air tight cover with silica gel bags. There are indicator types of silica gel bags which change color when fully doused with moisture. They can be kept in a warm oven to dispel the moisture and they can be ready. But the fact remains that they are cheap and can be discarded. Remove the batteries when not in use for more than a week. Store the camera in a separate air tight cover and the rest of the accessories in another cover. Your camera bag should include padded bottom to protect the camera from occasional knocks. Don’t count on the padded interior to protect the gear from a fall. Charge the rechargeable batteries every couple of months. All nickel cadmium batteries have a “memory effect” which will tend to reduce the available capacity. Metal Hydride batteries and Lithium ion batteries have no such memory effect.

 

3. Memory Card Maintenance:

These days memory cards come in high capacities – a few Giga bytes at very reasonable rates. Still it pays to be careful with them as a sudden failure can lead to complete loss of precious images you have shot. Always carry extra memory cards. Avoid wiping a few images every time. It is far better to wipe a batch after downloading to your hard drive. Avoid handling the contact surface. When connected to the computer, use standard PC precautions waiting for the signal like “safely remove hardware” before you remove the card.

 

Shoot a visiting card or a self addressed label as the first shot in the memory card. In case the camera is misplaced, the finder may return the camera.

You will have noticed that if your hard drive is almost filled to its capacity, it slows down the performance of your computer. Same way leave some space in the memory card – another reason to carry additional memory cards.

 

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