Battery Info

As the Krys lithium battery is light weight, it is easy to replace without the need for lifting equipment and provides greater range per kilogram than heavier lead acid systems.

Benefits

• Fast charging time. LiFePO4 batteries have great recharge times, even over a lunch in a cafe – OK, a long lunch chatting with friends.
• Little to no maintenance. No memory effect, so no periodic discharge required. After 2000 to 7000 charges the battery capacity reduces and need renewing.
• The weight of the Krys rechargeable lithium ion battery pack is just one quarter of an equivalent nickel based battery pack. The lithium battery pack’s light weight enhances the bike’s load capacity, continuous riding range, maximum speed, and climbing capacity. And of course, your Krys bike is easier to wheel along or, for the Foldee model, carry in the shoulder bag provided.
• Low self-discharge, prolonged storage life. The self-discharge rate is less than half that of nickel-based batteries, after one year charged they retain up to 85% of charge. But, of course, your fun Krys bike will not be sitting around for long!
• Can be used in a wide temperature range from -4º F to 140º F, but really, who wants to be riding in those extremes!
• >2000 depth of discharge cycles to 80% - several years of operation if cared for well. This means if the battery is drained to 80% empty (20% full) then recharged soon afterwards it will have a long life.
• Each battery pack is protected by the strong Krys aluminium bike frame, with an impact-resistant internal casing that enhances durability and shock tolerance.
• Battery Management System (BMS) provides excellent power control and voltage stabilization to the motor. It automatically disconnects the power supply when the battery pack does not operate under safety conditions, including overheating if left standing in the Aussie sun too long, abuse by your kids dropping their Krys off a cliff, or a sudden drop in voltage.
• No Lead to lug around with your bike or to worry about disposing of carefully at the end of its very short useful life.  Krys has always been and always will be Lead Free.

Some Battery Background

Maintaining Krys Lithium battery packs

Ideally you should try to recharge your Foldee battery after every use. Unlike Nickel Cadmium batteries, Krys' LiFePO4 batteries are memory-free batteries and do not require a full discharge before recharging. Importantly, it is NOT good to leave your Krys battery drained for several days. Leaving your battery drained for more than a month can lead to damage requiring replacement. This damage is generally considered negligence and may not be covered under the warranty. 

Nickel-cadmium (NiCAD) – NOT used by Krys

This is a mature technology but has only moderate energy density and a high drop off rate when the charge runs low. Nickel-cadmium is used where long life, high discharge rate and extended temperature range is important. Main applications are in aviation starters for gas turbines, two-way radios, biomedical equipment and power tools. Nickel-cadmium contains toxic metals and needs care in recycling and disposal.

Nickel-metal-hydride (NiMH) - NOT used by Krys

NiMH has a higher energy density compared to nickel-cadmium at the expense of reduced cycle life. There are no toxic metals. Applications include mobile phones and laptop computers. NiMH is viewed as an evolutionary path to lithium-based systems which are lighter and have longer cycle lifetime.

Sealed Lead Acid (SLA) - NOT used by Krys

SLA was invented in 1859 and are the oldest type of recharge battery. They are most economical for larger power applications where weight is of little concern. Lead-acid is the preferred choice for hospital equipment, wheelchairs, emergency lighting and UPS systems. Lead acid is inexpensive however they have a very short life in e-bike applications since they were not designed for high discharge rates. They are NOT environmentally friendly, being highly toxic and very heavy to pull around once they die.

Normal Lead Acid packs are only good for about 100 full charges, though some can be designed for more at additional cost. Lead acid batteries normally get charged up in a car as the car is running.  Special lead acid batteries called 'deep cycle' can tolerate more draining of the battery, but their life is relatively limited compared to most Lithium models.  Use SLA if you are on a tight budget and want to desperately have leg muscles like Arnold Scharzenegger!

Lithium-ion manganese (LiMn₂O₄) - used by Krys in some bikes.

LiMh were once known as the safest and fastest growing battery system for electric vehicle applications; offers high-energy density and low weight these are now being overtaken by Lithium Iron Phosphate (see below). Protection circuits are needed to limit the voltage and current supplied.

Applications include some notebook computers, cell phones, cars and ebikes. High current versions are available for power tools and medical devices. Easy to recycle and reuse. Some types are untested and have the potential for fires. Lithium-ion manganese batteries typically can be fully charged and fully discharged 500 to 1000 times.

Lithium Iron Phosphate (LiFePO₄ or LFP) as used by Krys in high performance bikes.

A modern but highly developed technology, LFP batteries were invented in 1996 and are used by General Motors Chevrolet Volt, Daimler, Cessna and BAE Systems. LFP is an intrinsically safer cathode material than LiCoO₂ and LiiMh and has a higher calendar life than other common Lithium Ion types.

If left unattended these batteries hold their charge well, however, we assure you you will not want to leave your Krys bike laying around for long! These batteries are used in electric cars by Aptera and in the One Laptop Per Child (OLPC) project. LFP batteries are gaining popularity now in the world of hobby-grade radio control, due to the benefits over the popular LiPo and LiMh batteries. They can be recharged much faster and for more cycles, are not prone to catching fire or exploding while recharging. They are also more robust than the LiPo type. Segway Personal Transporters advanced from a 10 mile range to a 24 mile range with LFP technology.

Perhaps the most valuable aspect of Krys LFP batteries is that they have a 100% depth of discharge cycle life to 80% capacity of 2000 – 7000 cycles. This means you can discharge to just 20% full then recharge the batteries to 100%, depending on the build quality, up to 2000 to 7000 times and they will still retain 80% of their original capacity. In practical terms for a Krys rider, on above average use, say commuting to and from work 5 days a week and then some fun times at weekends with your family and friends, charging the batteries twice a day, 6 days a week, the batteries should last from 3 to 11 years!

That means you will be spending an enjoyable 12 hours a week nipping around on your Krys!

Capacitance Batteries/

Going by many names due to being an immature technology, big capacitors are being used on some electric vehicles.  These offer numerous benefits, including really fast charging in the region of seconds, high power storage ability and good power to weight ratio.  There are also some downsides, such as energy storage ratio is still high - the batteries are large in comparison to normal Lithium batteries and, with a high current drain capability, there is an increased chance of fire and electrical shock.  The latter issues are being overcome by technology and innovation right now.  As the technology become more wisespread and proven, Krys will evaluate this technology.  At present (2011) this technology has not yet been proven to an extent where Krys is happy selling it to customers.

36 volt vs. 24 volt

36 volt systems boast faster speeds, quicker acceleration, better hill climbing however take up more space and weight for the same range.  Some Krys models use 36volt to provide an extra bit of pull up hills. 36 volt systems pump more electricity through the motor and so require larger and heavier banks of batteries and heavier, higher power motors.

At present Australian regulations limit the power of the motors attached to commercially available street legal e-bikes and so 36 volt systems have little use in Australia at present. As the Australian regulations move into the 21st century and 36 volt technology shrinks in size and becomes more practical Krys will incorporate this into its designs.