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  • Writer's pictureProject Fig-Leaf

Problems with Prius

So In my last post I had just acquired the battery pack from a Gen 1 Toyota Prius. After gingerly testing the battery I discovered that the collective voltage of the pack was marginally higher than that of an AA battery. This thing was dead, I mean seriously dead. Not just dead, but either the person who sold it to me or the person who sold it to him had composed this whole battery from dead cells collected from other cars (none of the serial numbers on any of the cells matched). I’m pretty sure Damien did say at least a half dozen times to make sure the batteries you’re buying actually work before you buy them...

The pack did at least come with all of the high voltage junction box (HVJB) components which still worked.

All I needed now was enough cells to produce a lot of voltage. If only I had spent months collecting, testing and hoarding (Katie made me add that) lithium batteries from old laptops. After sorting through them by capacity and power output, I soon came up with a design for a 3.8kWh test battery using the experience gained from designing ebike batteries and balancing the whole pack using

The test battery is broken up into 4 modules of 18650 cells in a 12s10p configuration, making a total of 48 rows of 10x 18650 cells in series. The most restrictive C rating on the cells is 3, making the total output power a meagre 10.5kW. Not earth shattering, but it will get the wheels turning at least. Now all that is left to do is to add connectors between the cell modules and the HVJB, then rig them all up to the motor/inverter and we should be in a position to get the Leaf motor spinning for the first time.


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