Technology: This is what you need to know about Lithium-ion batteries
All dirt bike manufacturers nowadays use Lithium-ion batteries to start the engine. Only Suzuki uses a system that does not require a battery: it is called a kick starter. Ken Roczen is the only one who has to (successfully) punch it to bring his machine to life. But we need to talk about the battery in your dirt bike.
If you have a recent motorcycle, there is a good chance that it contains a lithium-ion battery. That is good news because the technology has many advantages over a traditional lead/acid battery. It has three times the starting power, is only 1/3 of the weight of a conventional battery and has a longer lifespan. You can also mount this type of battery in any position, in many cases even upside down.
What is CCA?
Each battery has a number on it that represents the cold cranking current. It is expressed in CCA which stands for Cold Cranking Amps and indicates the amperage at -18 degrees Celsius for a 30 second cranking. The loaded voltage must remain above 9,6 Volts during the test. So the higher this number, the more starting current is available. So this is the most important number on a battery.
How does a Lithium-ion battery work?
The positively charged lithium ions move through the battery to the cathode, while the negatively charged electrons move through a circuit outside the battery from the anode to the cathode. This external electron flow supplies the power to the starter motor. When charging the battery, the process is reversed. Electrons are forced by an external voltage to the graphite electrode, where they will force positive lithium ions in the electrolyte to be reduced, and therefore the positive lithium ions travel back from the lithium-cobalt oxide electrode to the graphite.
What is in a Lithium-ion battery?
There are four (in the case of a 12 Volt battery) Lithium-ion cells of 3,2 Volt in the form of rectangular plates glued together or in some cases round elongated battery cells similar to the shape of an AA battery. It also contains a printed circuit board to manage the charging current, the so-called BMS, which stands for Battery Management System. This system ensures that each cell receives the correct amount of charging current and that there is no overvoltage.
In many cases, the BMS also contains a UVP, the so-called Under Voltage Protection. The UVP ensures that a Lithium-ion battery switches itself off to prevent it from discharging too deeply. That is one of the few downsides of this technology: A Lithium-ion battery cannot withstand a complete discharge. A good trickle charger therefore has a so-called wake-up function to………. a deeply discharged battery. uh ……. to wake up.
If the battery is left in safety mode for too long as instructed by the UVP, it may break. Then replacement is the only option. Another minus: This type of battery discharges up to 4 times faster than a lead/acid battery when additional accessories such as a tracker are installed. And this battery doesn't like it cold. Starting in extreme cold is more difficult than with a conventional battery. Lithium-ion batteries heat up quickly.
Leaving the lights on briefly (max. 30 seconds) on a street bike is good for the battery. There are no lights on a dirt bike, so you briefly press the starter button several times at intervals to create heat in the cells of your battery. Some (more expensive) batteries have one or more LEDs built in that allow you to display the charge status at the touch of a button.
How to maintain?
If you drive the motorcycle a lot, this type of battery does not require maintenance. However, you must be attentive when the engine is standing still for a long period of time. It is then a good idea to occasionally charge the battery with the correct charger. Do not use a conventional charger for lead/acid batteries because these do not do the cells of a Lithium-ion battery any good. A charging current above 14,4 Volts is detrimental (due to the desulfation program of a conventional charger).
So preferably use a trickle charger for Lithium-ion batteries. The devices are equipped with the correct maintenance programs and can "wake up" a very discharged battery via the aforementioned UVP. We use a Ctek CT5 Powersport trickle charger in our workshop. This is suitable for any type of battery such as lead/acid, AGM, Gel and Lithium-ion.
Tekst: Danny Hermans
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