Electronic devices require a form of power to operate, whether it be from a permanent source like AC Mains or from a portable source such as Batteries.

However, using normal disposable batteries to power portable devices is not very efficient as you will have to constantly have to replace them. Also, disposing of them adds to the ever growing waste which is not good for the environment.

This is why Rechargeable batteries are a better option. 

Two commonly used rechargeable batteries used in portable electronic devices are Lithium Ion (LiOn) and Nickel Cadmium (NiCad).

But, can you charge a Lithium ion battery with a NiCad charger? No, you cannot charge a Lithium Ion battery using a NiCad charger. However, you can use a Lithium Ion charger to charge a Nickel Cadmium battery.

This article shall take a deeper look at Lithium-Ion and Nickel-Cadmium batteries (as well as the process of how they are charged) and why you cannot charge a Lithium Ion battery using a NiCad charger. 

Deeper look at Lithium ion batteries and NiCad batteries

To understand the question at hand, it will first help to take a closer look at the batteries and the process of charging them (I will keep it brief). 

Rather than going through unwanted information about each battery, I will cover key characteristics that for each battery. 

Lithium ion batteries

Let’s start with Lithium-Ion batteries.

Most (if not all) batteries are given their name because of the type of chemical composition they are made of. In this case, the battery uses lithium ions.

During the discharge cycle, the lithium ions move from the negative terminal (cathode), through an electrolyte to the positive terminal (anode). 

Different types of Lithium Ion Batteries

Lithium Ion batteries come in a variety of shapes for different applications. 

  • Small cylindrical (single cell with, solid body, with no terminals) –
  • Large cylindrical (single cell,solid body, with threaded terminals)
  • Flat or pouch (soft, flat body)
  • Rigid plastic case (large threaded terminals) 

Other key characteristics of Lithium Ion batteries are their Nominal voltage and Current Capacity.

Nominal Voltage: This is the normal voltage that the battery operates at. Some batteries might indicate a higher voltage at full charge, however, this value will soon drop down to its nominal voltage after a predetermined amount of time. 

All the packages above come with a nominal voltage of 3.7 volts. However, cells can be connected in series to generate larger voltages.

For example, three lithium-ion cells can be connected in series to give a voltage of 11.1 volts, or four cells can be connected to give a voltage of 14.8 and so on. 

Current capacity: Is the amount of current that the battery is capable of storing. It is usually given in Amp-hours (Ah) or Milliamp-Hours (mAh)

Lithium-Ion batteries come in a range of current capacities ranging from as low as 40 mAh all the way to 2.6 Ah. 

In order to increase the current capacity further, batteries are connected in parallel. However, this is a bit more of a complicated process as the internal impedance of the batteries need to be the same. 

What is the process of charging  lithium ion batteries?

The Lithium-Ion is a special kind of battery compared to other batteries of different chemistries. This type of battery has strict requirements when it comes to charging.

The battery charger is a voltage limiting device with some differences to other chargers. 

The key differences include;

  • Higher voltage per cell
  • Tighter voltage tolerances
  • Absence of trickle or float charging

Trickle charging is when a battery charger is able to charge a fully charged battery at a rate equal to its self-discharge rate, which allows the battery to maintain its full charge level. 

A lithium-ion battery charger does not offer trickle charging because the battery cannot accept overcharge. The battery can become unstable if charged above its nominal voltage which could result in permanent damage.

Damage can come in the form of an explosion.

The charger comes with strict settings that adhere to the restrictions that come with charging this type of battery which  will include features such as an end-of-charge detection circuit  to monitor when the battery is fully charged. 

Different battery chargers for different lithium ion batteries

Lithium-Ion batteries are used for many different applications which include consumer electronics like smartphones, cordless power tools etc.

There are couple of scenarios when it comes to charging batteries;

  1. The battery is embedded in device with a inbuilt dedicated charging circuit 
  2. The battery is detachable and comes with a dedicated charging unit

The first scenario includes things like smartphones, portable speakers, smart watches, etc. They have batteries embedded in them with a dedicated in-built charging circuit which takes care of charging to make sure the lithium-ion batteries are not overcharged.

You can use most wall adapter chargers as long as they are the right voltage. 

The second scenario involves charging individual lithium-ion battery cells, or where the battery is detachable from the electronic device (like power tools).

In this scenario, they come with a dedicated charging unit where the battery is placed to be charged. 

What is the process of charging NiCad batteries?

Ni-Cad batteries are aptly named due to their chemical composition which includes nickel oxide hydroxide and metallic cadmium as electrodes. 

The abbreviation combines the two symbols of the chemical elements of Nickel (Ni) and Cadmium (Cd).

NiCad batteries have a nominal voltage of 1.2 volts/cell and have current capacities that range from 600mAh to 3300mAh.

Just like lithium ion batteries, batteries can be connected in series to increase its voltage, or connected in parallel to increase the current capacity. 

NiCad batteries can be trickle charged. 

Can you charge a lithium ion battery with a NiCad charger?

So, we come to the main question. 

Can you charge a lithium ion battery with a NiCad charger? No, you cannot charge a lithium ion battery with a NiCad charger. 

But, why not? 

The main reason that you cannot charge a lithium ion battery with a NiCad charger comes down to the process of charging each battery and how the charger works to charge them.

Lithium ion batteries are much more fragile when it comes to charging them. As we saw earlier, you cannot trickle charge this type of battery as it becomes unstable when pushed past the limits of its full charge voltage. 

Therefore, lithium ion chargers are built with a specific type of end-of-charge detection charging circuit which has the role of monitoring the battery’s voltage level and stopping charge when required. 

On the other hand, NiCad batteries can be trickle charged. This means their chargers will keep charging them at a steady uniform rate to maintain full charge. 

Most of the time, NiCad chargers do not include an end-of-detection charging circuit. They can just include a power resistor to limit the current at which the NiCad batteries are charged at. 

So, you can see where the problem lies if you try charging lithium ion batteries with a NiCad charger. The NiCad charger might not have an end-of-detection circuit to stop charging the lithium ion battery at the right voltage which can cause it to become unstable and possibly cause damage to it. 

What will happen if you try to charge a lithium ion battery with a NiCad charger?

As we just learnt, lithium ion batteries become unstable when they are charged past their nominal voltage. This is the main reason lithium chargers do not use trickle charging.

If you charge a lithium ion battery using a NiCad charger, the charger will not know when to stop charging the battery and therefore its nominal voltage will be exceeded.

Exceeding the battery’s voltage causes the cathode terminal to become an oxidizing agent which results in the production of carbon dioxide (CO2). 

The higher the voltage the greater the production of CO2 which then causes the pressure to rise leading to the membrane of the battery bursting and causing permanent damage.

Categories: Batteries