FastBikeGear
21st June 2012, 10:47
All you need to know about feeding and caring for your lithium batery
Most lithium automotive batteries on the market today are Lithium Ion batteries that use Iron Phosphate LiFePO4 e (LiFePO4) as the cathode material. In the past manny motorcycles were fitted with either lead acid batteries in recent years most lead acid batteries used in motorcycles were the maintenance free gel cell type.
Disclosure: FastBikeGear sells the Dutch made Ultrabatt Lithium motorcycle batteries. These are the same brand of batteries used by several Formula One teams for their KERs systems. I have a background in electronics (New Zealand Certificate of Engineering) and have designed several electronic accessories for motorcycles. I spent some time researching lithium batteries for motorcycles and assessed many suppliers battery technologies before we chose a brand to distribute in New Zealand. Initially this was a frustrating exercise, because while there are many advantages to Lithium batteries there are several potential and serious issues with Lithium batteries, luckily all of which can be addressed.
Lithium batteries are becoming the first choice for replacement motorcycle batteries and offer many advantages including :
- Extremely light weight! For example a typical 16 amp/hour battery weighs 5kg. A typical replacement Lithium battery weighs an amazing 0.728 kgs (complete with the built in Battery Management System).
- Very high cranking amperage. The UltraLite 400 mentioned above has a rating of 240 CCA. (By comparison the Cold Cranking Amps of a typical 14 amp/hour battery fitted to bike a Ducati 1198 is typically just 175 CCA.)
- Ability to hold a charge for extended periods of inactivity. They have a very low self-discharge. A lithium battery could sit on a shelf uncharged for a year and still be able to start the motorcycle.
- Very small size a typical 240CCA battery has a size of just 114 x 62 x81mm (LXWXH). This means the battery can be packaged in alternative locations on your bike where a normal lead acid battery would not fit.
- Very fast charging times typicall a discharge battery can be fully recharged in 1-2 hours compared to minutes! By comparison a discharged lead acid battery will take over 12 hours to charge to full capacity.
- Economics. Good Lithium batteries with built in BMS systems typically cost twice as much as good quality lead acid batteries they have predicted life spans of 5-10 years. If charged regularly with a BMS (Battery Management System system) If not the lifespan can actually be less than a lead acid battery.
As mentioned before there are several potential and serious issues with Lithium batteries,
- Potentially premature failure due to , unbalanced cell charging.
- Bricking (becoming so flat that it cannot be recharged)
- Thermal runaway, rapid and excessive temperature build up (if the individual cells voltage are not evenly balanced while being charged on the bike) ...with sometimes catastrophic results.
Thankfully the technology exists to eliminate these issues.
Why do lithium batteries need cell balancing during the charging process? With all types of batteries the faster each cell charges the hotter it gets. Charging cells to quickly greatly reduces the lifetime of any type of battery.
As each cell in a lead acid battery charges, the internal resistance of the cell increases. If one cell begins to charge faster than the others, it's higher resistance slows down it's charge rate in comparison to the other cells. Hence cells in lead acid batteries automatically limit their charge rate and balance with each other as they charge.
As the cells in a Lithium battery charge the opposite occurs, as each cell in a Lithium charges, the internal resistance of the cell decreases. If one cell begins to charge faster than the others, it's lower resistance further speeds up it's charge rate in comparison to the other cells which further decreases it resitance and further increases it's charging rate. Hence cells in Lithium batteries do not automatically balance with each other as they charge.
As the cells charge → they heat up → their resistance decreases → which further speeds up their charge rate → which means they further heat up
This thermal runaway cycle can quickly cause catastrophic and dramatic temperature induced failure. This is why lithium batteries without in-built BMS cell balancing are not legal for road use in some countries and why some radio controlled car clubs insist that Lithium batteries used to power the cars are charged in explosive prove containers at club meetings.
Most Lithium battery manufacturers recommend that if their Lithium battery does not have a built in BMS circuitry that you also purchase an external BMS charger when you purchase their Lithium batteries and that you use this to regularly charge your Lithium battery from 230V wall outlet. This plan works well if your using it on a race bike use in a total loss system to save weight (No alternator or regulator on the bike) and just recharge your bike between races with the external BMS system.
A built-in BMS systems eliminates the need for an external BMS system and can provide full protection while the battery is being used on the bike and being charged by the bikes standard charging system.
On-board BMS systems provide:
1. Cell balancing and over voltage protection: You can charge the battery safely with the bikes alternator and you will never need to balance the cells with an external BMS system.
2. Complete discharge protection: You never have to worry about the battery bricking (getting so flat that it is impossible to re charge it.)
3. Short protection: Over current protection.
With an inbuilt BMS system you are assured of much higher safety while actually riding the bike and charging from the bikes alternator, not just when you are charging it at home with a 230V with an external battery BMS charger.
Q. Why can't Lithium batteries be charged by a standard automotive workshop trickle charger?
A. As the cells in a lead acid battery charge the internal resistance of each cell increases, the current decreases and the voltage across the cells slowly rises over many hours. Lead acid batteries like to be charged slowly with a constant low current while the charging voltage is steadily increased. Automotive workshop trickle chargers and smart chargers are specifically designed to suit these charging characteristics.
As the cells in a Lithium battery charge the opposite occurs, Instead of the internal resistance of each cell increasing it decreases. By contrast to Lead acid battteries, Lithium batteries like to be charged quickly with a constant voltage and a moderately high current.
Q Can you charge a Lithium battery while riding with a standard motorcycle charging system
A: It depends: The best way to charge your Lithium battery is with your motorcycle charging system. Modern motorcycles charging system employ a constant voltage regulator that can supply a moderately high current, which as noted above is the perfect charging regime for a Lithium battery. However as we will see further on if you intend to charge your Lithium battery on your bike it is important that your battery has a built in BMS system so that you do not encounter potentially hazardous situations with thermal runaway.
Before installing a Lithium battery on your bike you should also ensure (using a voltmeter across your battery terminals with your bike running at about 3000 rpm) that your motorcycle’s regulating system is functioning correctly and its voltage output is regulated to no more than 14.7 volts.
What else do you need to know about caring for your Lithium battery?
Not a lot actually but the following should be useful and perhaps even interesting information.
Cold Cranking Amps: CCA is a measure of a batteries ability to turn your starter motor over quickly. You should select a replacement battery that has the same or more CCA as your existing battery. The CCA rating is the most important criteria for selecting a battery that will meet your requirements.
Amp Hours: Is a measure of the storage capacity of a battery or how much charge it can hold. It is of little importance unless you operate the electrics of your bike while the engine is not running and charging the battery on your bike. If your motorcycle has a higher current draw when the bike is not being ridden due to being fitted with an immobilizer system, clock, electronic dash, or other accessories that continue to consume your batteries capacity when the key is turned off then you may need to select a battery with a higher amp hour storage capacity.
Self-Discharge rate: The self-discharge rate is a measure of how quickly your battery loses capacity when it is sitting on a shelf or plugged into a motorcycle that is not drawing any current when the ignition is switched off. Ultrabatt batteries have an extremely low discharge rate of just 3% of their capacity every month. A normal lead acid battery will have a much higher self-discharge rate even when new and a lead acid battery that is half way through its service life will typically have a monthly self-discharge rate of higher that 15%-40%.
Charge time: Lithium batteries (especially those with built in Battery Management Systems) have extremely fast charge times. Typically within 5 minutes of starting your motorcycle your battery will have fully recovered the capacity that was used in starting your bike. A discharged Lithium motorcycle battery can typically be charged with the external 3 amp charger in just 1-2 hours. By comparison a discharged lead acid battery will take over 12 hours to charge to full capacity.
Cost comparison Lead Acid Vs Ultrabatt : A typical good quality motorcycle lead acid battery will cost approximately two and half times less than a good quality Lithium battery such as an Ultrabatt with a built in BMS system. Typically a lead acid battery in a motorcycle will only provide between 2 & 4 years of good service. Many riders replace their batteries every 3 years. In addition due to the high self-discharge rates of lead acid batteries and the periodic use of motorcycles most experienced motorcycle owners usually purchase a smart charger to maintain and condition their lead acid batteries. Good quality smart chargers such as the CTEK units (which FastBikeGear also sells) typically cost as much as the purchase price of the battery. However a Lithium battery with a built-in BMS provides a potentially very long service life (more than 5 years).
Many owners will discover a lithium battery will work out to be the cheapest option to own while they enjoy the benefits of extremely light weight, very low self-self discharge in between rides and fast starting.
Winter Storage: To store your battery off-season measure the voltage to make sure it is fully charged, 13.2 volts or greater - recharge if necessary. Disconnect the negative battery cable to prevent any parasitic current drain by you motorcycle - or store the battery separately from motorcycle. It is a good idea to occasionally measure the voltage of your battery while in storage. If you wish to charge you battery while in storage we recommend taking your bike for a short run or use a purpose built Lithium battery charger (Like the Ultrabatt 300). Do not use a lead acid battery trickle charger.
Most lithium automotive batteries on the market today are Lithium Ion batteries that use Iron Phosphate LiFePO4 e (LiFePO4) as the cathode material. In the past manny motorcycles were fitted with either lead acid batteries in recent years most lead acid batteries used in motorcycles were the maintenance free gel cell type.
Disclosure: FastBikeGear sells the Dutch made Ultrabatt Lithium motorcycle batteries. These are the same brand of batteries used by several Formula One teams for their KERs systems. I have a background in electronics (New Zealand Certificate of Engineering) and have designed several electronic accessories for motorcycles. I spent some time researching lithium batteries for motorcycles and assessed many suppliers battery technologies before we chose a brand to distribute in New Zealand. Initially this was a frustrating exercise, because while there are many advantages to Lithium batteries there are several potential and serious issues with Lithium batteries, luckily all of which can be addressed.
Lithium batteries are becoming the first choice for replacement motorcycle batteries and offer many advantages including :
- Extremely light weight! For example a typical 16 amp/hour battery weighs 5kg. A typical replacement Lithium battery weighs an amazing 0.728 kgs (complete with the built in Battery Management System).
- Very high cranking amperage. The UltraLite 400 mentioned above has a rating of 240 CCA. (By comparison the Cold Cranking Amps of a typical 14 amp/hour battery fitted to bike a Ducati 1198 is typically just 175 CCA.)
- Ability to hold a charge for extended periods of inactivity. They have a very low self-discharge. A lithium battery could sit on a shelf uncharged for a year and still be able to start the motorcycle.
- Very small size a typical 240CCA battery has a size of just 114 x 62 x81mm (LXWXH). This means the battery can be packaged in alternative locations on your bike where a normal lead acid battery would not fit.
- Very fast charging times typicall a discharge battery can be fully recharged in 1-2 hours compared to minutes! By comparison a discharged lead acid battery will take over 12 hours to charge to full capacity.
- Economics. Good Lithium batteries with built in BMS systems typically cost twice as much as good quality lead acid batteries they have predicted life spans of 5-10 years. If charged regularly with a BMS (Battery Management System system) If not the lifespan can actually be less than a lead acid battery.
As mentioned before there are several potential and serious issues with Lithium batteries,
- Potentially premature failure due to , unbalanced cell charging.
- Bricking (becoming so flat that it cannot be recharged)
- Thermal runaway, rapid and excessive temperature build up (if the individual cells voltage are not evenly balanced while being charged on the bike) ...with sometimes catastrophic results.
Thankfully the technology exists to eliminate these issues.
Why do lithium batteries need cell balancing during the charging process? With all types of batteries the faster each cell charges the hotter it gets. Charging cells to quickly greatly reduces the lifetime of any type of battery.
As each cell in a lead acid battery charges, the internal resistance of the cell increases. If one cell begins to charge faster than the others, it's higher resistance slows down it's charge rate in comparison to the other cells. Hence cells in lead acid batteries automatically limit their charge rate and balance with each other as they charge.
As the cells in a Lithium battery charge the opposite occurs, as each cell in a Lithium charges, the internal resistance of the cell decreases. If one cell begins to charge faster than the others, it's lower resistance further speeds up it's charge rate in comparison to the other cells which further decreases it resitance and further increases it's charging rate. Hence cells in Lithium batteries do not automatically balance with each other as they charge.
As the cells charge → they heat up → their resistance decreases → which further speeds up their charge rate → which means they further heat up
This thermal runaway cycle can quickly cause catastrophic and dramatic temperature induced failure. This is why lithium batteries without in-built BMS cell balancing are not legal for road use in some countries and why some radio controlled car clubs insist that Lithium batteries used to power the cars are charged in explosive prove containers at club meetings.
Most Lithium battery manufacturers recommend that if their Lithium battery does not have a built in BMS circuitry that you also purchase an external BMS charger when you purchase their Lithium batteries and that you use this to regularly charge your Lithium battery from 230V wall outlet. This plan works well if your using it on a race bike use in a total loss system to save weight (No alternator or regulator on the bike) and just recharge your bike between races with the external BMS system.
A built-in BMS systems eliminates the need for an external BMS system and can provide full protection while the battery is being used on the bike and being charged by the bikes standard charging system.
On-board BMS systems provide:
1. Cell balancing and over voltage protection: You can charge the battery safely with the bikes alternator and you will never need to balance the cells with an external BMS system.
2. Complete discharge protection: You never have to worry about the battery bricking (getting so flat that it is impossible to re charge it.)
3. Short protection: Over current protection.
With an inbuilt BMS system you are assured of much higher safety while actually riding the bike and charging from the bikes alternator, not just when you are charging it at home with a 230V with an external battery BMS charger.
Q. Why can't Lithium batteries be charged by a standard automotive workshop trickle charger?
A. As the cells in a lead acid battery charge the internal resistance of each cell increases, the current decreases and the voltage across the cells slowly rises over many hours. Lead acid batteries like to be charged slowly with a constant low current while the charging voltage is steadily increased. Automotive workshop trickle chargers and smart chargers are specifically designed to suit these charging characteristics.
As the cells in a Lithium battery charge the opposite occurs, Instead of the internal resistance of each cell increasing it decreases. By contrast to Lead acid battteries, Lithium batteries like to be charged quickly with a constant voltage and a moderately high current.
Q Can you charge a Lithium battery while riding with a standard motorcycle charging system
A: It depends: The best way to charge your Lithium battery is with your motorcycle charging system. Modern motorcycles charging system employ a constant voltage regulator that can supply a moderately high current, which as noted above is the perfect charging regime for a Lithium battery. However as we will see further on if you intend to charge your Lithium battery on your bike it is important that your battery has a built in BMS system so that you do not encounter potentially hazardous situations with thermal runaway.
Before installing a Lithium battery on your bike you should also ensure (using a voltmeter across your battery terminals with your bike running at about 3000 rpm) that your motorcycle’s regulating system is functioning correctly and its voltage output is regulated to no more than 14.7 volts.
What else do you need to know about caring for your Lithium battery?
Not a lot actually but the following should be useful and perhaps even interesting information.
Cold Cranking Amps: CCA is a measure of a batteries ability to turn your starter motor over quickly. You should select a replacement battery that has the same or more CCA as your existing battery. The CCA rating is the most important criteria for selecting a battery that will meet your requirements.
Amp Hours: Is a measure of the storage capacity of a battery or how much charge it can hold. It is of little importance unless you operate the electrics of your bike while the engine is not running and charging the battery on your bike. If your motorcycle has a higher current draw when the bike is not being ridden due to being fitted with an immobilizer system, clock, electronic dash, or other accessories that continue to consume your batteries capacity when the key is turned off then you may need to select a battery with a higher amp hour storage capacity.
Self-Discharge rate: The self-discharge rate is a measure of how quickly your battery loses capacity when it is sitting on a shelf or plugged into a motorcycle that is not drawing any current when the ignition is switched off. Ultrabatt batteries have an extremely low discharge rate of just 3% of their capacity every month. A normal lead acid battery will have a much higher self-discharge rate even when new and a lead acid battery that is half way through its service life will typically have a monthly self-discharge rate of higher that 15%-40%.
Charge time: Lithium batteries (especially those with built in Battery Management Systems) have extremely fast charge times. Typically within 5 minutes of starting your motorcycle your battery will have fully recovered the capacity that was used in starting your bike. A discharged Lithium motorcycle battery can typically be charged with the external 3 amp charger in just 1-2 hours. By comparison a discharged lead acid battery will take over 12 hours to charge to full capacity.
Cost comparison Lead Acid Vs Ultrabatt : A typical good quality motorcycle lead acid battery will cost approximately two and half times less than a good quality Lithium battery such as an Ultrabatt with a built in BMS system. Typically a lead acid battery in a motorcycle will only provide between 2 & 4 years of good service. Many riders replace their batteries every 3 years. In addition due to the high self-discharge rates of lead acid batteries and the periodic use of motorcycles most experienced motorcycle owners usually purchase a smart charger to maintain and condition their lead acid batteries. Good quality smart chargers such as the CTEK units (which FastBikeGear also sells) typically cost as much as the purchase price of the battery. However a Lithium battery with a built-in BMS provides a potentially very long service life (more than 5 years).
Many owners will discover a lithium battery will work out to be the cheapest option to own while they enjoy the benefits of extremely light weight, very low self-self discharge in between rides and fast starting.
Winter Storage: To store your battery off-season measure the voltage to make sure it is fully charged, 13.2 volts or greater - recharge if necessary. Disconnect the negative battery cable to prevent any parasitic current drain by you motorcycle - or store the battery separately from motorcycle. It is a good idea to occasionally measure the voltage of your battery while in storage. If you wish to charge you battery while in storage we recommend taking your bike for a short run or use a purpose built Lithium battery charger (Like the Ultrabatt 300). Do not use a lead acid battery trickle charger.