Thursday, November 10, 2016

We're Lovin' LEAF

Lovin' Life with LEAF salvage, that is.  The two collision-salvage battery packs arrived this week, as did the prototype Wolftronix LEAF Pack Sniffer.  This amazing little device turns on the BMS and reports back the pack voltage, average cell V, # of bars of remaining capacity, identifies the high and low voltage cells, and then scrolls through all the individual cell voltages.  One of the packs was sitting at 396V with four bars of capacity, the other at 383V and 10 bars of capacity.  Voltage as a state of charge indicator is mainly valid at the upper and lower end, and these packs were built two years apart.  I think they will balance out nicely, as individual cells voltages were tight after months of sleep, with only 6 thousandths of a volt difference between the highest and lowest cell.  Most were within 3 thou..  Here's a video of the sniffer in action!
Leaf Pack Sniffin'

The packs arrived on a rollback wrecker, so without a forklift we very carefully set the back edge of the pallets on the ground and then drove out from under them!


It may seem scary to sic a student with an air chisel on a highly charged battery pack, but research revealed the safety of this technique, as the sealed surface to be separated is outside of a one-inch protective lip of steel (and by another air gap and metal module covers on the inside) meaning one would have to overshoot the target by quite a distance and cut through multiple layers of steel after the target of a single layer of sealant! The air chisel made short, but very noisy work of this job, much to the students' delight!  The students quickly learned to distinguish by both sound and feel whether the chisel was hitting sealant or steel!

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