Pros of  Li-ion batteries:

         
• 70% less  weight - Notable increase in power/weight ratio
         

So you don't need to offend your mother-in-law anymore for not having  seconds of her ever so famous Sunday roast and your mates will not call you p*ssy  for having carrot juice instead of beer while watching MotoGP (OK, that was a  bit over the top, we know that you would never do that :-))

         
• Cheapest  way to save weight
         

Consider how much you would pay to shave a few kilos from your set-up by  replacing your exhaust with a titanium one, or fitting light weight wheels . By  fitting a Li-ion battery these weight savings can be achieved for a fraction of this cost. 

         
• Mountable  in any position and smaller in size
         

Makes it ideal for custom bike builders where the placement of the battery could be a headache. Let your  fantasy rumble and make a bike truly special.

         
• Better  cold cranking performance
         

Due to their design, Lead-acid batteries can use as little as 30% of  their capacity when starting your bike. Lithium-ion batteries consistently use nearly 100% of their  capacity, meaning a Li-ion battery can provide the same starting power from  just one third of the capacity of a comparable lead acid battery. Please check  the link at the end of my video, where you can see how effortlessly a JMT  Lithium-Ion battery designed for motorbikes can start a 2L Toyota  Camry...easy-peasy. No ordinary motorbike battery is capable of doing the same.

         
• 90% less  self discharge
         

Ideal for bikes which aren't in daily use or great for jet  skis, quads, track bike, dirt bikes, go-karts...etc

         
• Much  longer lifetime
         

Uniform charging of all cells  is ensured by a built-in processor (the "balancer"), minimising any  excessive wear on any one cell, prolonging battery life. Up to 2000 cycles compared to 200 - 300  cycles of an old fashioned battery.

         
• Better performance  at high temperatures
         

Perfect for track bikes or  street fighters where the weight is the most important factor.

         
• Can save  space or increase performance
         

The dimensions of lithium-ion batteries match the dimensions of the  original lead-acid batteries by use of spacers, contributing to weight savings. 
         
          The electrical connections of Li-ion batteries are identical to those of the  equivalent lead-acid battery, so the existing battery can be replaced within  minutes without the need for further modification. 

         
• Completely  maintenance free
         

Just fit and forget.

         
• Fast  charging is possible with a high charge current (Charging in as little as  90 minutes)
         

JMT lithium-ion batteries can be  recharged using standard motorcycle battery chargers. The normal charging current usually corresponds to the  battery capacity (e.g. 2.8 Ah capacity = 2.8 A charging current). On a quick charge, however, Li-ion batteries  can be charged on a current that is ten times the battery capacity  (e.g. 2.8 Ah capacity = 28 A charging current).

         
• More  eco-friendly
         

Due to longer life-time and no heavy metals nor acids it is much  more environmental friendly than an ordinary battery.

Cons:

It  should be noted that constant sub-zero temperatures can affect the performance  of the battery and it is not the best option if you would like to use it in the  winter in Alaska or Siberia, however if you don't plan to ride it in the snow,  it is just the perfect battery all year  around in the UK climate.