Our NiCD Force Conversion
Extending our Force's Range with Advanced Batteries
Page 5, "Endgame"
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It was now Memorial day weekend, and we had a guest, so I wasn't able to get as much done as I would have liked. I had been hoping to get the car fully functional by the time our guest showed up, but that was not to be.
My notes for that weekend are sketchy, because I was rapidly entering the final stages of the project and didn't take a lot of time to write down when I did what. What follows is a list of things that got done that weekend in approximately the order they happened...
Installed the Brusa charger, LED box, charger filter, cooling interface and temperature sensors (front and rear packs). This was pretty straightforward, as the Solectria-supplied components had all the proper connectors on them. I had to whip up a connector to connect the cooling control box to the fan/pump assembly, because Radio Shack doesn't carry the connector that Solectria used. Once the temperature sensors were mounted onto the battery lugs, I re-torqued all the battery connections to Saft's specifications.
Installed the amp-hour counter, the little Brusa interface that allows the charge to monitor the amp-hours used/replaced, and connected it to the LED box.
Installed the new DC-DC converter I got from Solectria. The new unit is able to handle the higher voltage that can be present when the NiCD batteries are charged. The only problem here is that the original unit had a nice little bracket mounted to it that allowed it to be bolted to the inside of the engine compartment, but the new one didn't. It didn't even have holes for mounting one. I removed the bracket from the original unit and, when I had figured out how the new unit could be mounted with it, created an aluminum strap that wraps around three sides of the converter and screws to the original bracket, making a "ring" of sorts. Since I didn't want to have to drill into the new DC-DC converter's case, this strap was attached to the converter by black RTV silicone adhesive. It was nice and snug without the adhesive, but the adhesive guarantees that it won't go anywhere. I then bolted it to the car and connected its wiring harnesses.
I double-checked everything electric and verified that everything was set, and reconnected the "Service Disconnect" connector. Instantly, there was a loud buzzer sound -- The parking brake was off and that was the warning signal! I knew the DC-DC converter was working properly. I went in and applied the parking brake, tried the windshield wipers and lights -- Yes! They worked! I had figured that I might get some response from the DC-DC converter because I was reading about 135-140 volts from the battery pack. I quickly turned everything off to not drain the power completely yet. I wanted to test the cooling system.
The cooling system pump and fan are designed to turn on at 30 degrees C (about 86 degrees F). This can happen anytime, even if the car is off. I decided to test this now, so I grabbed my heat gun and started warming up the rear cooling system temperature sensor. After 30 seconds or so, the pump and fan kicked on! Good -- I turned off the heat gun and waited for the sensor to cool and turn off the system. It did. I repeated the process with the front cooling sensor -- It worked perfectly, as well. Nice.
I rigged the battery watering fill and drain hoses in the front and rear battery boxes. These would be used as soon as charging was complete, so I wanted them ready to go.
May 27: Memorial day. I got up early in the morning to start smoking some baby back ribs on the barbeque, and when I did, I got the car ready for the initialization charge cycle. I had been told by some other Saft battery users that I needed to drain the battery pack completely before running the initialization charge, or I risked overheating the batteries. I attached a couple 100-watt bulbs to the pack and waited for the voltage to drop. When it dropped to around 24 volts (1 volt per module) I removed the batteries and plugged in the car. Nothing happened. The charger didn't start up! Uh-oh.
I unplugged the car and plugged it in again. Nothing. Time to ask for help -- I sent out an email to the Saft mailing list and explained what was going on. It turns out that the Saft NiCD charger is parasitic -- It needs some voltage from the pack so it can "boot up", even if it's plugged in! Not a particularly good design feature, in my opinion. I didn't know this before, and I was pretty annoyed that I had drained the pack down so far that charging looked impossible!
I went back down to the car and as I walked up to it, I noticed that one of the lights on the LED box was on. The pack voltage must have rebounded while I was writing the email! A later email to Brusa indicates that the charger needs around 50V to boot up. I plugged the car in again and the charger started right up! The initialization charge was underway.
15 hours later, the charger shut off and I waited for the "Water Batteries" light to come on. According to the Saft manual, this happens 30 minutes after the charge is complete. Right on schedule, the light came on and I watered the batteries with distilled water, waiting for the excess to run out the drain tubes. At this point, the car was fully charged, but I had a few last items to wrap up.
May 28: Our guest had left, so I dug in on the final tasks for the conversion:
I installed battery box packing to make sure the batteries weren't going to shift while driving. The front pack was in its box so tightly that it was impossible to get any packing in there, but the rear pack had some extra space. I used some of the old packing from my lead-acid battery pack and slid it alongside the battery modules to hold them snugly.
I did some final hose wrangling in the front battery box and installed its cover.
I fabricated a new set of motor controller mounting brackets from aluminum stock and re-hung the motor controller from the crossbar. It's now installed vertically, where before it had been mounted horizontally. This is necessary because of the different battery box layout.
I reinstalled the fuel-fired heater unit. I didn't put the fuel tank in because it was now too large to fit. I'll have to pick up another, smaller one later.
I changed the gearbox oil. The car was at 12,300 miles, and was due for the gearbox oil change. No time like the present.
I reinstalled the front and rear airflow cowls under the car.
I closed up the cooling system, removing the 5-gallon reservoir bucket and installing an expansion tank. Not that the fluid is going to expand or contract that much, but I thought I'd better be thorough. The trick here was to cut the hose at the right point and close the cooling system without introducing a big air bubble. It went OK, though if I can find a nice little tank at some point that will function like my reservoir bucket, removing air from the system, I'll add it.
The car was now drivable, though I didn't bother installing the rear battery box cover yet. That could wait, as it wasn't critical. With the car still up on jack stands, I turned it on and carefully pressed the accelerator. The drive wheels turned, though with a sort of grinding sound. After a year of sitting in the garage, the brake surfaces were pretty rusty. I figured we'd work that off on the first drive.
I lowered the car and opened the garage door for the first time in ages. Powering up the car, I drove it out onto the driveway and my wife and I gave it a good washing -- A year of dust accumulation made the car look pretty sad!
The initial test drive
After washing the car, we decided that we'd take it for a real shakedown cruise, down to Minor's Garden Center in Milwaukee. This about 23 miles away and we decided to take the interstate part of the way. It was a fairly warm day and we cruised to Minor's with no problem. We shopped around and picked up some plants Elizabeth had been wanting, then took off for another garden center in Cedarburg, 8 miles north. Parking at the nursery and shutting off the car, I noticed that the cooling system was running. Excellent. The driving activity had warmed the batteries up enough that the car decided to cool them off.
Next, we headed up to Grafton, another 5 miles, and stopped at the grocery store. The cooling system was still running, no problem. Finally we headed on home. The total trip was around 44 miles and used around 50 amp-hours, more than our lead-acid pack could have done, but not close to the capacity of the NiCD pack.
When I got home and pulled into the garage, the cooling system ran for a minute or so and then shut off, as the batteries got cooled down to an acceptable temperature. The system was working as it was supposed to.
I plugged the car in and the charger didn't start up. Hmmm. Not good. A quick troubleshooting showed that the interface between the amp-hour counter and the charger wasn't working, and the charger didn't think we had drawn any energy from the pack! With some help from the guys on the Saft mailing list, I was able to get that working and the car charged right up. My year-long odyssey to upgrade the car was over. Well, nearly. I still had to put that rear battery box cover on.
It's now August 5, 2002. We've been driving the NiCD Force for over two months, and it's been working flawlessly. I've taken it on some long trips, using just over 60 amp-hours of energy. I haven't pushed it much beyond that, though I'm sure it could do it. In the latter stage of these drives, I've noticed that the pack doesn't want to put out more current than the "Normal" power selector on the car will allow -- Putting it on "Power" doesn't seem to draw more power. I'm not sure if this is a limitation caused by the batteries being warm, or what. I did notice that after this happened, and I had gotten into a lower speed limit area and reduced speed and power demand for a few minutes, when I again called for more power, I got it.
Overall, I'm really happy about the conversion. Of course, having done it once, if I had to do it again I could do it in a fraction of the time. A lot of time was spent trying to figure out how to do various parts of the project -- How to make the parts I had do what I needed, or how to configure things so the conversion would be long-lasting. I'm very thankful to the people at Solectria, who provided a couple of key components (LED box, cooling system control box) and helpful information on the conversion.
As I suspected, I use our Honda Insight a lot less now, because the Force now gets the job done for intermediate-range driving tasks. The only reason it hasn't been used more in the last few weeks is because it doesn't have air conditioning, and it's been incredibly hot here.
Hmmm. Maybe I ought to add AC to the thing... That's another story for another time!
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This page last edited August 06, 2002