Our NiCD Force Conversion
Extending our Force's Range with Advanced Batteries
Page 3, "Advance to the rear!"
|JUMP TO PAGE 1||JUMP TO PAGE 2||JUMP TO PAGE 4||JUMP TO PAGE 5|
It was now April 25, 2002, and it was time to get started on the back end of the car. I jacked up the rear end about a foot and placed it on jack stands. The entire car was now up in the air, making work underneath a lot easier.
The first order of business was to get the corrugated plastic fairing that Solectria had installed under the rear battery box removed. This would allow me to gain access to the bottom of the rear battery box, which was installed in the trunk area. This fairing is attached to the bottom of the car with two bolts and an aluminum strip on the forward end, and there are four nylock nuts and washers on each side. Interestingly, the nylocks Solectria used weren't stainless and were rusty. This surprised me because they tend to use stainless hardware in most areas, and this is a tough area for metal, being exposed to road salt and stuff. Oh, well, I made a note to pick up stainless nuts and washers to replace the normal steel hardware. This photo shows the two leading-edge attachment bolts and the hold-down strap:
On May 2, I was able to get back to work on the vehicle. Before I could start loading batteries into the rear battery box, I had to work up the battery hold-down system. For this, I decided to use a 5/16" threaded rod on each side of the two back rows of batteries that would hold down a 1x1" square aluminum tube across the top of the battery modules. This threaded rod would be attached to the bottom of the battery box with a stainless acorn nut and lockwasher. I had placed a row of battery modules into the box, shoved them all together and centered them, and there was just barely enough room for a 5/16" rod on each side. Whew!
The front row of batteries sits in a narrower section of the battery box, located between the rear suspension arms. There was no space for threaded rods to fit on the sides of the battery modules, so I'd have to mount them on the flat top of the box somehow. I wasn't sure how to do this, because while I had access to the top of the box in the trunk, the bottom of the box wasn't visible from under the car -- This part is over a critical structural area (the rear suspension) and the car was left intact underneath. I was going to need a way to attach the threaded rods in blind holes. Hmmm. I'd have to think about that...
Undaunted by this fact, I went ahead and installed the four hold-down threaded rods for the back two rows of batteries. This was a pretty simple procedure, though I needed to grind down the washers that would sit inside the battery box so that the nuts on top would snug right up against the sides of the box well. It was that tight in there. The photos below show the hold-down rods for the back two rows inside the battery box on the driver's side and the acorn nuts underneath the car on the passenger side:
On May 3, it was time to get some holes in the car so that I could run the main cooling system hoses from the rear battery box down under the car, where the cooling system pump and radiator would be located. On the Solectria vehicle, this was mounted where the gas tank was originally, and I couldn't think of a better area. The main cooling hoses provided in my Solectria "kit" were a 5/8" ID, 7/8" OD polyurethane type, very flexible and tough. I decided to drill 1-inch holes for these. This would allow me to wrap them in a rubber material as a grommet that would protect them from rubbing against the metal of the chassis and battery box.
For this job, I knew I was going to be messing around where the back seat was located, so I just removed it to get it out of my way (and out of harm's way!)
First order of business was to locate and drill the holes under the car. I had noted their location on the NiCd Force at Solectria in my notebook. On that car, they were located about 9" apart, on either side of the gas tank mounting bracket. Looking at the layout and measuring carefully, I drilled the holes. They came out perfectly, right at the front edge of the battery box well. In the photo below, you can see the pink foam attached to the battery box inside.
Next, I located and drilled holes in the battery box leading edge flange, making sure they'd lie inside the battery box cover. Also 9" apart, these holes lined up perfectly with their lower counterparts. I carefully de-burred the holes after drilling.
On May 4, I cleaned up the inside of the battery box and reinstalled the thin foam pad that sits under the batteries, then carefully lowered the battery modules into place. Placement is critical, because there are two battery configurations in this box and the water filling system nipples have to be properly aligned.
It was a great feeling to get these modules off my garage floor and into the vehicle!
May 6: The front battery box as supplied by Solectria had no side panels on the lower portion, which holds 7 modules. This is similar to the construction of the original Force lead-acid front battery box, which had plastic panels installed in these areas with black RTV adhesive. I took the same approach and installed plastic panels cut from the huge plastic battery box cover vacuforms that Solectria had supplied.
In the photo on the left, you can see the open area at the end of the battery box (brown primer showing) and the black panel sitting above it. The photo on the right shows the panel installed, with a thin strip of wood providing tension to hold the panel in place while the RTV adhesive cures.
While waiting for the front box to dry, I moved to the rear battery box and installed the watering circuit connecting hoses. These are set up in groups of 8 (Saft allows groups of up to ten batteries maximum in a cooling circuit). The hoses themselves are two types, a straight one that connects two batteries whose long sides rest together, and a "squiggly" one that connects batteries which share short sides. The "squiggle" routes the hose around the electrical terminals and cooling system hose nipples.
May 8: I started installing batteries in the front battery box. The box supplied by Solectria had notches cut in the upper box lip that would allow the battery modules to drop in, but my guess is that for the NiCd vehicles they built, they had installed the main drive motor differently, because in my car the electrical junction box on the motor sticks out over the notched area, preventing a battery from being lowered there. I used my trusty Sawzall to extend the notch toward the passenger side, where a battery could be lowered properly. You can see this notch in the photos above which show the front battery box sides being installed.
May 10: I got started on the front battery pack wiring and plumbing, both watering and cooling. Since I wasn't able to take photos of the NiCd Force at Solectria, I was kind of winging this. The Saft guidelines for cooling circuits on the battery modules indicate that you shouldn't hook more than three cooling compartments in series, and that you need to keep the two sides of each battery module's cooling compartments separate. I followed these guidelines carefully. The upper three batteries in the front box are connected together for cooling in two circuits, and the lower seven batteries are hooked into a series of 3, 2 and 2 battery modules for six additional cooling circuits. The watering circuit for the front box works out perfectly (remember, 10 battery modules in series maximum for watering), so I just started at the passenger side in the upper tier of batteries and when I got to the driver's side, I brought the cooling plumbing down with a 3/8" hose to the driver's side lower battery, then worked across to the passenger side. I was very careful to use 3/8" elbows in the drop to the lower tier of batteries rather than try to bend the hose and cause a kink that would restrict water flow.
Wiring the front batteries together was pretty straightforward -- Solectria had included a number of short #4 interconnect cables with lugs in their kit, so as I plumbed, I also connected the batteries' terminals, negative to positive. The connection from the upper tier to the lower tier required a slightly longer cable, and there was one in the kit that worked fine for this. I made sure to follow Saft's specification for the terminal bolt torque, using a torque wrench. You don't want to use gorilla strength and ruin one of those expensive batteries...
As I was connecting all this wiring and plumbing, as I got to the last two batteries on the passenger side, I realized that the #2 battery cable running from the positive battery terminal in the front to the negative terminal of the first battery in the rear wasn't going to be long enough to reach the new battery configuration. Noting that Solectria had used #2 boat battery cable, I got on West Marine's website and ordered some #2 cable, #4 cable (used for battery interconnects) and #2 and #4 lugs with 5/16" holes. That was due by May 15. With the last two batteries waiting for this cable extension (because of the flange on the top of the battery box, you had to make the last connection on the passenger-side battery then slide it into place, then drop the battery next to it into the box) I stopped for the day.
May 13: Got started on the rear battery pack cooling system plumbing and electrical interconnects. I used the six remaining short #4 interconnect cables I had sitting around from the lead-acid pack on the forward batteries and connected the little U-shaped cooling system hoses to the batteries front-to-rear. This arrangement maintains the three cooling compartments per circuit guideline, with the two rear batteries on each side having only two cooling compartments per circuit.
With this work complete, and another two days until the West Marine order was supposed to arrive, I called it a day.
NiCad Conversion, Part 4
Back to main EV page
This page last edited August 06, 2002