Novel lithium ion battery protection circuit design for better working life reduce toxic waste
Lithium ion batteries issues
How toxic are lithium batteries? Can lithium batteries be recycled? Can we prevent failed li-ion batteries being dumped into landfill dumping sites? Can we re-examine the lithium battery charger?
Failed lithium batteries are thrown into landfill dumping sites
Many countries do not have a procedure or process to recycle failed or damaged li-ion batteries. Even in Malaysia these batteries are thrown into the rubbish bin for disposal into landfills.
Lithium batteries can be very toxic if they corrode or are damaged. When that happens the lithium chemicals leak into the ground and are consumed by bacteria, plants and animals which in turned are consumed by animals. If these landfill dumping sites are converted into agricultural land, we will consume the food grown on these lands. Isn't there a lithium ion battery recycling process to stop disposing these batteries into landfills?
There are several potential ways to reduce lithium battery waste. Good manufacturing practices ensure a longer shelf life of the batteries. These good manufacturing practices include good welding of the parts so that they do not leak. Furthermore, extremely thin sheet metal casings will allow for corrosion and damage that can reduce their working life. Most importantly we need to increase their shelf life and working life.
Accusations by lithium battery sellers
I have heard of many accusations by sellers of portable equipment when we complain that the batteries do not last long. Many batteries just last a few months and then have to be replaced and this was my personal exprience too. Many of them only last less than 2 years. I suspect that the short life of these batteries is so that manufactures can increase sales of replacement batteries without any care or concern for facial injuries and toxic waste generated.
They claim that the lithium batteries are damaged by improper usage. Their claims are :-
We were charging the battery while using them
We overcharged the batteries
We charge the batteries overnight.
These are excuses to cover up poor & cheap product designs and block refunds and other financial claims.
Is it possible for lithium ion batteries to last 10 years?
Is it possible for batteries to last 10 years? Currenlty lithium batterries have a very short working life of under two years and in some cases only a few months. If we could make them last longer then we would have less battery failures and less failed batteries being dumped into out landfills.
What do we do when we run out of lithium ore? This is another reason we need to ensure that lithium batteries have very much longer working life, preferably a 10 year life span.
Analysis of a Huawei portable modem
My interest in lithium ion batteries began when I noticed that the batteries in my Huawei portable modem WIFI router had swollen. They, the modem and battery, were only 1 year and 2 months old when I noticed the problem. Now I suspect that the Huawei battery must have begun to fail much earlier. It could have begun to fail a few months after I purchased them.
I took it back to the shop and the seller accused me of handling the batteries wrongly and was not going to replace the battery. He claimed that the batteries were damaged because of improper usage that I have mentioned above. Was this guy crazy? How can you overcharge the battery when it could only be charged by a USB supply?
That was when I decided to find a solution to improve the working life of the lithium batteries which meant that I had to address these three issues:-
the overcharging of the batteries and charging over long durations or overnight.
the stopping of the usage of the battery when the USB supply was plugged in.
only allowing either the USB supply or battery supply to be used when the modem was in use.
What I found out applies to a host of other products from modern digital cameras to smartphones to other portable equipment.
Improved working life of li-ion batteries
I examined how the batteries were connected to the modem circuit and how the USB power supply was used. Then I came out with a circuit design to correct the power supply circuit and how to switch between the USB supply and the battery supply.
What I noticed about the modem circuit
When I was testing out the circuit, I noticed that the modem would not work if the battery was not detected. I noticed that the battery was swollen which meant that it could explode at any time. The battery casing was flimsy thin and could be pressed in to deform it. After more testing I found out that the modem would work with a 3.8V supply from my Nikon battery charger. This meant that the battery was not being charged but the modem was powered up.
On the left are two diodes. They drop the USB 5 volt supply down to 3.8 volts so that they can operate the modem circuit.
On the extreme right top there is the option of using a trickle charger or a battery charger circuit that has built in short circuit protection and detects when the battery is fully charged and stops charging. These chargers can be bought from China by the thousands or you could use a charging chip. The trickle charger is basically a resistor that limits the current to the battery and will slow down considerably or cease charging when the battery voltage is maximized. Using a charging chip would be the better solution and no one can claim that the battery was overcharged or charged for too long.
In the center of the circuit is a transistor circuit that activates when the 5 vols from the USB supply is available. It open circuits the relay so that the battery voltage does not power the modem circuit. This will prevent the battery from being charged and simultaneously being discharged. As a result, no one can claim that the battery was being charged and used at the same time. The relay is a NC, normally connected, relay. A cheaper but more inefficient solution would be to replace the transistor circuit with a resistor. That resistor would need to match the relay operation.
Of course, there will be a lot more design work to make this a chip that can be used in modems, cameras, phones to make the world a safer place and prolongs lithium battery life. The camera manufactures like Sony, Nikon, Canon, Fujifilm and others and smartphone manufacturers, like Google, Apple, Samsung, Huawei, Sony, Nokia, . . . etc and portable equipment manufacturers like modem manufactures could bring out a variant of this protection circuit so that consumers can still use their lithium batteries safely.
- Dr. Peter Achutha, 9th November 2020
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