Battery

The DF148 battery is manufactured by the Spanish company Amopack.  It has a recommended charge voltage of 58.8 volts and a maximum charge current of 12.5A.  It provides a very sophisticated diagnostic capability that's available to the end user via LEDs.  Cells are manufactured by Samsung and should be good for 500 charge cycles at 25° C. 

The following battery information was updated in January 2024.  Three batteries are presently available.  In all cases, energy capacity is rated at 58.8 volts.  Note that rating battery capacity hot off the charger yields the most favorable capacity values and is not representative of real-world conditions.

The standard 3.2 battery has a capacity of 1882 Wh and is priced at $2,850.  This is the battery that comes with the bike.  There are 112 cells in this battery, so it's configured 14S8P.

The big 4.0 battery has a capacity of 2352 Wh and is priced at $3,395.  There are also 112 cells in this battery, so again 14S8P.

The lightweight 3.0 battery has a capacity of 1764 Wh.  It weighs 5 pounds less than the other two battery types and is priced at $3,395.  There are 84 high-performance cells, so a 14S6P configuration makes sense.

The battery's operating voltage range of 40 to 58.8 volts.  Below 50 volts, power output will decrease and performance will suffer.  At 40 volts, the battery will shut itself off to protect the cells.  Thus, discharge is allowed down to 2.85V / cell (which seems pretty low to me)

For the standard 3.2 battery, the maximum continuous discharge current is 80A.  Assuming 50 volts * 80A = 4kW = 5.3 horsepower.

Permissible “over-discharge” is as follows:

165A for 60 seconds, so 8.25 kW = 11 horsepower.

200A for 35 seconds, so 10 kW = 13.4 horsepower.

400A for 1.2 seconds (I doubt the controller is going to allow that).

Short-circuit detection and shutdown occur at a current of more than 500A for 400 microseconds.

Battery Alarms

The table below is adapted from Amopack's manual.  If you are familiar with the binary number system, it's easy to see that the alarm code is a 5-bit value with its least significant bit being represented by the 100% SoC LED.

This display is a huge benefit compared with EM's battery which tells the rider nothing.  However, I suspect this may be necessary partly because the Dragonfly's battery will be under greater stress than the EM's battery.  Only time will tell. 

We can also infer that modern solid-state devices (MOSFETs) are used in place of the charge and discharge relays employed by the EM battery.  MOSFETs are lighter than relays and have the potential to be more reliable (assuming they have been sized by engineers and not accountants). 

Battery Temporary Shutdown Procedure

The battery manufacturer calls this procedure “temporization” (which essentially means to introduce a delay into a process).

This procedure is necessary any time the battery is connected to the controller to avoid a large surge current and consequent arcing at the battery lead.

To temporarily shut down the battery, hold the battery “Test” button for at least six seconds and then release it. 

After a few seconds, the LEDs will start flashing in a particular sequence.  During the following minute, you may reconnect the power leads before the battery turns itself back on.

Presumably, when the battery restarts it does so initially in a current-limiting mode to facilitate a gentle pre-charge of the controller's capacitors.

Also note that if the battery voltage is less than 50.4V during the shutdown, the battery will go into sleep mode and will not restart automatically.  This would be ideal for storage.