Tag Archives: Electronics and Electrical

Ending the Life of an old Lithium Battery

Clean Republic's e-Bike Conversion

So, my Clean Republic Lithium-Cobalt-Manganese (Li-Po) e-Bike battery pack finally gave up and had no more little LED‘s after numerous attempts to re-charge it.  It had the reported logarithmic die-off during the past month where it went from 15 minutes of usable life with numerous on/off power cycling required (because of the automatic voltage regulator which cuts off current when reaching lower limits to save the battery), down to refusing to re-charge at all.  Not bad for 2 years and an estimated 600 recharge cycles.

Contents of the nylon battery carrier

After detaching the power switch leads and taping them for safety, the block of power wiggles out of it’s nylon bag and reveals this. The main box and controller are covered in layers of duct tape to keep them packaged and vibration-resistant (since they’re bouncing around on a bike all day).  We peel off all that duct tape, which includes extra layers on the aluminum box to insulate it from the controller.

Charging circuit and voltage cut-off.

Taking off 4 small phillips screws from the box enclosure reveals the charging circuit with the 2 wires that connect to the battery pack circuit board (which basically is series connecting the batteries together to form the 24VDC 8A unit).  The white jumpers are individual battery cell connections to each pack allowing monitoring of each cell’s voltage for the charger/supply circuit to disconnect if things get too low.  Also shown is the white temperature thermistor that also cuts off voltage if it gets too hot.

Li-po packaging is flat and semi-flexible for compactness.
Make sure the voltage per cell is below 1.0 VDC before disposal.

Taking off the other 4 screws from the other end reveals a look at the packed-in battery packages from the other end (there are 14 individual mylar packages)

Salt water immersion drains voltage and oxidizes lithium.

Finally per recommendations from other battery manufacturers, we soak the packs in salt water (1/2 cup per gallon to obtain conductive salinity) for about 2 weeks to drain the residual current and oxidize the lithium into neutral lithium oxide.

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Visit Clean Republic at www.cleanrepublic.com or www.electric-bike-kit.com