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The battery that charged the battery that charged the battery

Or how to save half a billion dollars & the environment in one go

Thoughts on saving power

This morning, there was a power cut where I live in India, which is an accepted part of life here. However it’s mainly the poorer Indians who are affected, as those who can afford it usually have a battery or inverter at home to store up energy while the power is up. This seamlessly kicks in during power cuts so we won’t even know about a power cut, unless we try to use high power equipment like ACs, which won’t run on battery power.

Solar panel charges battery/inverter which charges the battery power pack which charges my phone and bluetooth headset in low power mode

Defeating the purpose of power cuts

What’s ironic is that if usage of inverters during power cuts becomes universal in India, it could theoretically lead to more power being consumed overall. That’s because inverters increase electricity consumption during power uptimes when they are used to store energy in inverters, and there's additional energy losses during charging and discharging of batteries.

This would defeat the objective of load shedding. The only reason it still happens is because commercial establishments get shut down during power cuts as they need higher power than inverters can supply, and not all industries can afford to invest in expensive diesel generators.

The battery that sparked a thought

Coming back, my bluetooth headset had run out of juice. Since its battery is tiny, I have to charge it in low power mode, and I can’t use the usual phone chargers lying around the house. Incidentally, I learned that the hard way when my first bluetooth headset died after just a year. The service mechanic informed me it was designed to be only charged with a low power USB port, which is what you normally have on your laptops and PCs. Fortunately, my power bank has a feature by which a double press on its on/off button causes it to charge in lower mode (a slow blinking light indicates low power charging).

So that’s how I connected my power bank to charge my headset, only to notice it too was drained. It was as I connected the power bank to the wall socket that I realised that my solar panels were charging my inverter, while it was charging the power bank, which in turn was charging my bluetooth headset.

I found the whole idea pretty intriguing.

Energy loss and batteries go hand in hand

Logically, it’s more efficient to run something directly from the mains, than through a battery as there is always some energy loss in charging a battery. Think about it. Don’t phone chargers usually feel warm? Some energy is being wasted as heat while charging a device’s battery. So when one battery is charging a second which in turn is charging a third, it’s incredibly inefficient.

Of course, the power usage of batteries on my phone, power bank and bluetooth headset are negligible. So it’s not like it’s going to make any perceptible difference in my electricity bill or anywhere else.

Except possibly, inside my head.

Is it just me? Or should the world rethink how it uses batteries? Considering the billions of portables devices in use worldwide, the savings in energy on all those tiny batteries might just add up to a lot.

I was curious so I decided to do the math.

Putting a dollar value to energy loss

According to statista.com, there are about 5 billion mobile phones in the world. Most phone users have additional portable battery powered devices. Like I have a MacBook, an iPad, a power bank, and random bluetooth devices… never mind! For simplicity’s sake, let’s assume each phone owner has one portable device, which means there are 10 billion portable devices/batteries in existence.

According to this 2013 Forbes article, it costs around $0.25 to power a phone for a year, and $10/year for a phone-tablet-laptop combination. Phone screens have got larger since 2013, and may need a bit more power. This Indian site makes it like 5 units per year, which would be ₹35 (or around 50 cents). To keep it simple, let’s stick with $0.5/year as the average phone’s electricity consumption cost.

Is the energy loss while charging a battery significant? To quote the above site:

Mobile phone chargers as well as many other battery chargers have transformers that convert AC (Alternating Current) to DC (Direct Current). Transformers not only convert electricity but they also consume it. They have 50–90% efficiencies in using electricity (source: EPRI). In fact they consume electricity even when cell phone is not connected to the charger and the switch is on.

Can we put a dollar value to this energy loss? Let’s take the loss while charging as 20%. That means 20% of the yearly 50 cents spent on electricity to charge my mobile phone is actually being wasted in battery inefficiency, like in the charger getting heated up. In other words, a mobile phone wastes 10 cents a year in battery charging inefficiency.

As all my portable devices are usually within reach of an wall outlet during use, I should be able to run on mains at least half the time I use them. Now let’s imagine a new generation of portable devices allows me to use the mains. This means I can reduce energy losses via battery charging during half the time I use the device. So instead of wasting 10 cents every year, a phone that can bypass the battery will waste only half that amount, or 5 cents a year.

So if there are ten billion portable devices, configuring each of these devices to work by bypassing the battery will save us 10 billion x 5 cents, or $500 million.

That’s a mind boggling half a billion dollars a year saved for Planet Earth.

Is it practical or not?

Can all future portable electronic devices have built-in parallel circuits to run directly on the mains? This is not impractical as it sounds. My old 17" MacBook Pro’s battery failed sometime ago. I didn’t bother to replace the battery, and now use the MacBook exclusively on the mains.

Of course, there are other factors like the cost of rewiring future devices to bypass the battery. This will bulk up portable devices, which is against the current trend but may be an acceptable trade for the win for our environment. Besides, to bypass batteries, all future homes will have to be built with wall USB outlets as standard fittings at all power outlets. There’s a positive side too as batteries (and devices) will last longer when the battery is used less.

The same applies to those home inverters. If the Indian government wants to really reduce power consumption at homes, it should figure out how to supply homes with enough power to keep fans and lights running (while being insufficient for high power equipments like pumps, irons, mixies, grinders, ACs, etc). This way, people won’t be tempted to invest in inverters. That’s a lot less dead batteries to pollute our long suffering planet.

The above are just thought starters, and probably as full of holes as a piece of cheese. However I’m sure specialists can come out with far more effective ideas. But for it to work, someone in big business needs to take the lead.

Any takers?



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