Installation of 26 Panasonic 60Ahr batteries in USE S10

The range on the truck was down to 30 miles, and I knew the pack was close to dead.  Buying $5000 of Hawker PC1200's to replace my old set didn't appeal.  The opportunity to purchase a pallet of Panasonic 60Ahr batteries from the GM EV1 project came around and I jumped.  Calculations showed that the "new" Panasonic 60Ahr batteries were just a bit too wide to fit laterally in the box.  This was the only real issue, as provisions would have to be made to either extend the current box or build a new one.  It was close enough that I had to wait to physically test it out before making a decision to do 26 batteries or 52.

Removal of the old batteries was taken care of in short order.  It was a bit difficult to remove the batteries located under the cab, the final solution was to use a piece of wood to pry them out slowly.  Battery boxes were cleaned out and readied for the new batteries. All interior plastic panels were left in place.  Decision at this point was confirmed to do 26 batteries.

Here’s how it started… Be careful with those little copper interconnects!

The new batteries are set in two layers, the bottom (which extends under the cab) consisting of 8 per side (1 total) and 4 per side (8 total) on the top.  Batteries were spaced using a piece of 3" wide wood in the center, and a 1" wood spacer on both outsides.  There is 1" of wood between the ends of each battery.  Additionally, there is a rope in place to allow the under-cab batteries to be pulled out later.  This has already been found to be quite useful.  A total of 24 batteries were fitted to the existing box.  There is plenty of airspace between them, shouldn't have any localized heating problems.

Notice the many plastic pieces separating the different portions of the strings. Don’t want any short circuits!

This left two batteries out, requiring the fabrication of a small rear battery box behind the axle.  This small box is made up of 3/4" square tube, welded to a box section with restrictor bars on all sides and the bottom.  This framework was faced with .063" Aluminum sheet, riveted to the box sections.   HDPE and Lexan panels were used inside the box to ensure that there was no possibility of a ground fault.  a 1.25" plastic conduit is used to bring the 1/0 AWG cables into and out of the rear box.  The only caveat is that the spare tire will not fit in the stock location any longer.  As I don't carry a spare, this isn't a problem.

Clampers were fitted to all batteries before installation.  The heat sinks are "live" to one post of the battery, and so require physical isolation in the unlikely event that one got loose and swung around. This was accomplished via 3/32" HDPE sheet between adjacent rows.

The clampers are custom designed and built, partially based upon Victor's circuit- he has proven his design and so I moved over a few of his components.  Of course his design is for LiIon, mine is for Lead Acid, so there are some differences!  Clamper design and fabrication is discussed here.

Connections to the dual contactors remain very similar, instead of two individual string connections of course there is now only one. The main switch is on the most negative portion of the pack lead.

About this time I also changed the leads from the main shunt to the Emeter- before this was a pair of wires, not twisted nor shielded. Of course the meter would never read right, there was always a 6-9A offset.  The new twisted pair, shielded cable is perfect, when the truck is a rest it shows 0A discharge.

Driving.  So far, so good!  The vehicle is ~500lbs lighter, and as a result it handles better, accelerates faster, and has more cargo capacity.  The 60Ahr batteries will not have as much range as the 80Ahr dual strings of Hawkers did when they were new, but the vehicle has enough range to cover my daily driving cycle.  Extrapolated range is ~60 miles at this point.  Once the batteries are more exercised, I'll try getting some real range numbers.

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