Trickle charging: The facts

Trickle charging is one of the most common methods of charging batteries and is often used in 12V chargers for cars. Whilst it is slow, trickle cell chargers are a reliable system and are particularly good for nickel cadmium and nickel metal hydride batteries. This article look at how this system works and compare it to other methods of charging such as float charging.

Why trickle charging works

Over time, all rechargeable cells lose charge over time due to the cells' self-discharge. This phenomenon occurs due to internal chemical reactions within the battery. This occurs even when the battery is not physically connected to a circuit. Speed The speed of self-discharge varies from battery to battery and is dependent on the exact type of cell chemistry. Lithium-based cell technology has a discharge rate of around 2% a month, whereas nickel-based cells, such as NiMHs and NiCads have a self-discharge rate of up to 30% a month. Long process Trickle charging works by charging the battery at a similar rate to the
self-discharge rate of the battery. The disadvantages of trickle charging are that this process can take a long time, typically as long as eight hours.
Lack of intelligent circuitry
Additionally, trickle chargers, specifically, many solar battery power chargers do not have any intelligent circuitry which prevents the batteries from over charging. They simply continue to push current through the batteries until it is switched off.

Alternatives

The fact that trickle chargers will continue to charge batteries indefinitely is a problem for many people. If a user forgets that the batteries are charging, then this can result in reduced battery life or more serious problems, such as leakages, overheating or even fires.
Timer-based cell recharger As a result, a variety of chargers and conditioners are available to avoid these problems. At the simplest level, it is possible to buy a timer-based cell recharger which will switch off after a finite period of time. Whilst this alleviates the problems of overcharging, it can lead to undercharging, depending on the state of the cells.
Charger using a microprocessor The best option is to look for an intelligent charger which uses a microprocessor to detect when the batteries are fully charged. Doing so will mean that your cells will always be charged to their full capacity and you will have piece of mind that you will not experience any problems. Inductive phone charges
Recently, inductive phone charges have become very popular with users of mobile devices, such as iPads, mobile phones and MP3 players. These devices use electromagnetic induction to charge the batteries in these devices. As a result, no charging wires are needed and the user experiences a much tidier environment.