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M1 High Power Hypersonic
TM
Lithium Ion cells
–
3.60 volts per cell
The 3.6 volt setting is a special setting for M1 High Power Hypersonic
TM
Lithium Ion cells manufactured by
A123 Systems. When selected, the Xtrema will switch from constant current to constant voltage at 3.6 volts
per cell as required by these cells. Also when this setting is selected the battery voltage calculation
displayed just before charging (during the
“
Are you Sure?
”
window) is based on the nominal 3.3 volts per
cell multiplied by the selected cell count. Lastly when 3.6 volts per cell is selected the
LO BAT V
error
message will be triggered when the battery is below 2.0 volts per cell.
Lithium Polymer Cells
–
3.65 to 4.2 volts per cell
The factory default setting is 4.20 v/c and this provides you with the maximum capacity of common Lithium
Polymer cells. You may change this down to 3.7 volts for what is called a
“
storage charge
”
when using
lithium polymer cells. This allows you to charge your batteries to approximately 50% full charge and is the
factory recommended method for storing LiPo batteries long term. NOTE; M1 cells do not require a storage
charge and may be stored at any voltage without loss of performance.
Example: For a 3 cell pack 4.20 volts/cell equates to 3 X 4.2V or 12.60 volts max.
or For a 3 cell pack 3.70 volts/cell equates to 3 X 3.7V or 11.10 volts max.
The reason for all the in between values is that some manufacturers of Lithium Ion or polymer cells may
suggest a more conservative charge voltage. Or you may want to charge the batteries more conservatively
to extend their life. You now have the option of charging at 4.15, 4.10, 4.05 or 4.00 volts per cell. The lower
in voltage you chose, the earlier the Xtrema will limit charging giving you slightly less capacity per charge.
The reason you may want to do this is to extend the cycle life of your batteries.
Choosing 4.15 volts/cell may only reduce the capacity of your charge by about 5 percent but it will extend
the useful life of your pack by many cycles.
Note:
If you have reduced the volts/cell value and you try to charge batteries previously
charged at a higher volts/cell, they will cause the Xtrema to display a
HI BAT V
error
message. Simply discharge the battery below the desired max voltage.
Safety Timer
This setup menu allows you to change the maximum amount of time to allow for charging. The purpose is
to abort the charge when a battery is not charged in the amount of time expected. This may occur if a
shorted or weak cell prevents the pack voltage from climbing up to the expected voltage.
The default time is set to 120 minutes and this should be sufficient for charging at a 1C rate. (Ex. Charging
your 1000 mah battery at 1000 ma. Etc.) If you chose to charge at a lower rate, then you may want to
adjust this timer for a longer time period. The timer is adjustable from 0 minutes to 990 minutes in 10
minute increments. )
TIP!
Zero 0 minutes effectively disables the charger and may be used in situations where
you may want to disarm the Xtrema from charging.
Choose the desired minutes by moving the up
or down
buttons and press the joystick to the
right
when the displayed value is what you desire. You may abort the change by hitting the joystick
left.
Temp Cutoff
This setup menu allows you to change the maximum temperature that will abort the charge cycle. This
feature is not designed to save your battery since overheating during charge is a sign of a damaged cell.
However this feature may prevent reaching battery temperatures resulting in thermal runaway that may
cause combustion. Hopefully this may prevent a Lithium battery fire.
Choose the desired temperature by moving the up
or down
buttons and press the joystick to the