Here is what I learned
Your charging system must be in good shape as these batteries are , like all other types sensitive to over and under charging. Mine was not. On the 907 with dual headlights I was barely able to get 12 volts at idle and 13.5 at around 4k.
I could not ride the bike with the headlight on for more than a hour without discharging the battery to a point the ignition would fail. Without the headlights it could be ridden all day. On the 906 with the same dual headlights things worked better but the stator constantly overheated. Sometimes the charge light would come on for no apparent reason, most times it would come on at idle and then slowly go out as the bike was ridden. One day the stator just gave up altogether suddenly, took about an hour to discharge the battery to a point the ignition no longer worked. To be fair all batteries need about the same charge rate ,lead acid,gel, glassmat or lithium.
1) If you are using the smallest battery possible for your bike to save weight (for example for race use a 4 cell in a 600cc bike, or an 8-cell in a 1000cc bike) you may find in 50 degree weather and below it may be sluggish initially. But with each attempt to start the battery actually warms itself from the amp discharge and gets back its full strength. If you often ride in weather below the 50s we recommend going up one or two sizes on the battery, this will give you more cranking amps to get power even if its very cold.
2) You can ruin the battery if you let it drain to below 10.5v volts!!! This is true of ANY battery, lead/acid or lithium. Draining a battery to this level will damage the battery cells. This is not a concern if you remember to turn off your ignition, or turn off any accessories that are not ignition switched and monitor your battery is you plan on not riding frequently. You should also make sure your vehicle does not have an “parasitic drain” or “short circuit”. A “parasitic drain” is something like an accessory that is pulling energy from the battery even though the ignition is “off” this can drain your battery below 10.5v and ruin it … Sometimes a short can also be the cause of a drain on the battery though all accessories are “off”. For the best battery life you should monitor your battery and if you do not ride for a time make sure you disconnect the battery.
3)Also, important is that OVER CHARGING above 14.6 v can damage Lead or Lithium batteries. For this reason older bikes should make sure their eletrical system and specifically the Voltage Regulator is operating correctly or you will find youself damaging your batteries if your bikes charging systems voltage to the battery is going above 15v.
4)DO NOT ABUSE the battery…. These batteries express extremely high amperage and can get over heated if you keep cranking a bike repeatedly over 7 seconds multiple times in a row. Though they are made to start your bike with fantastic results they can become over heated if you keep trying to crank a bike that just isn’t starting.
I have since replaced the stator/regulator and improved the wiring on the 907. It now without the headlights maintains 13.5 volts at idle and 14.3 at anything over idle. With the dual headlights on it maintains 13.7 volts at anything but idle. At idle it holds 12.5 volts with the headlights on. I now plan to try Lithium again. You just can't beat the starting power of a Lithium battery. The 907 jumps to life faster than you can push and release the starter button
but when I get my act together and finish off my 851 I will definitely look into the lighter alternative 
