A short video showing the main features of the Volt914, and giving a good sense of what it sounds like to drive around in it:
Youtube link
Tuesday, January 8, 2008
Thursday, December 20, 2007
A *Five* Speed Transmission
This morning, I had a spare hour, so I decided I was finally tired of only having a 3-speed transmission. Fixing it was simpler than I expected. I lifted the carpet over the center tunnel, made sure the transmission was in neutral, loosened the shifter bolt (shown below) with a 13mm socket, pushed the shifter as far right as I could, then tightened it again. Now, it's a five speed as originally intended!
At first, I tried pushing it to the left as far as it would go, but that did not help. Fortunately, right did it. I took it up to 65 MPH (above 100 KPH) just for fun, and was impressed with how smooth the ride is - a low car with a very low center of gravity makes for a pretty stable ride. And, best of all - this makes it harder to nick "Reverse" accidentally on the way to 2nd.
Also, today I passed 250 miles as an electric. 1/4 of the way to 1000...
At first, I tried pushing it to the left as far as it would go, but that did not help. Fortunately, right did it. I took it up to 65 MPH (above 100 KPH) just for fun, and was impressed with how smooth the ride is - a low car with a very low center of gravity makes for a pretty stable ride. And, best of all - this makes it harder to nick "Reverse" accidentally on the way to 2nd.
Also, today I passed 250 miles as an electric. 1/4 of the way to 1000...
Monday, December 17, 2007
A *Two* Car Garage
After two and a half years of being patient with my monopoly of the garage, my wife decided she wanted a space in the garage for Christmas. So, I spent yesterday afternoon organizing and cleaning, making space for our 2000 Saturn SL1. It fits pretty well, as you can see. I backed the Volt914 in so that the driver's doors face each other, so both Jill and I can easily get in.
The oil spot under the Saturn is actually where the Volt914's transmission had been slowly leaking. At some point, I need to fix that...
The oil spot under the Saturn is actually where the Volt914's transmission had been slowly leaking. At some point, I need to fix that...
Wednesday, December 5, 2007
Heater Installed
Although I was originally considering putting the heater in the rear trunk near the controller, after further reflection, I decided to put it in the passenger compartment, below the dash, between the driver and passenger. The main reason was to simplify the wiring. A secondary reason was that the heater did not fit especially well in the rear trunk. First step was attaching the heater mount to the firewall. I used rivets:
I then mounted the heater on the mount. I made sure when placing the mounting point that the heater did not interfere with any of the pedals or the steering linkage (it's hard to tell from this picture, but the steering linkage is not all that close to the heater blower):
I used 10-gauge red and black wires to deliver power from the 144-volt pack to the heater. I routed them through the original (now useless) windshield sprayer hose grommet:
Next up was work in the middle compartment. I mounted a power post so I could attach several negative cables (the original negative cable from the most-negative point, along with negative cables to the charger and to the heater):
Next, I took the contactor I ordered...
...and mounted it on a piece of polyethylene along with the large fuse which protects the 144V heater circuit:
I hung the board from the middle battery box using tie wraps (also visible in this picture are the three wires going to the negative terminal post):
I then ran a yellow wire from the +12V input to the contactor to the switch location on the dashboard. I also ran a brown ground wire from the contactor to the grounding stud in the gas tank compartment. Note the yellow rubber cap on the negative post - I have a story to tell about that down below...
Here is the switch that will go into the dash to control the heater. The red wire goes directly to unswitched +12V (because I want the heater to be able to run without the key in the ignition). The yellow wire is split to drive the contactor and a relay for the heater blower motor in parallel:
This is the relay - a standard 12V 40A automotive relay, normally open. The yellow wire is from the switch above, the red is directly from unswitched +12V (I used 12-gauge wire since the blower pulls a fairly large current). The brown wire ties into grounding wires behind the dash. The black wire is +12V power for the blower, and the orange wire is ground for the blower:
Here's the wiring around the heater - I wrapped the contacts of the relay in electrical tape (to avoid shorts) and tucked it up above the heater:
It all works pretty well. You turn the switch on, and hot air blows out of the heater. Originally, I was going to attach hoses from that to the original heating system. However, I tried that, and the warm airflow was unsatisfactory. Fortunately, the heater is well-positioned to keep my feet toasty. I may install the flappers that came with the heater so the driver and passenger can independently control airflow.
Last, here is a wiring diagram of the heater circuits. Originally, I had the contactor and relay in series with the switch. However, this led to an excessive voltage drop which meant that the contactor did not close. So, I changed and wired them in parallel as shown here:
Remember the yellow rubber cap on the negative post I was telling you about? This is why it is here. I was tightening the bolts on the most-positive post, but my normal electric-tape-wrapped wrenches (that I use on the batteries) were not the right size for that bolt. So I used just a plain wrench. I managed to brush the top of the negative post while the wrench was touching the positive post. It resulted in a most exciting spark, including blast damage around the positive post and a flash burn on my hand that was holding the wrench:
Moral of the story: be very careful when working with high voltage... If you think you are being careful, think again, and find another way you can be even more careful. I was very lucky not to have damaged myself more than that flash burn on my left hand. I really need to get around to purchasing and installing that high current circuit breaker I've been thinking about...
I then mounted the heater on the mount. I made sure when placing the mounting point that the heater did not interfere with any of the pedals or the steering linkage (it's hard to tell from this picture, but the steering linkage is not all that close to the heater blower):
I used 10-gauge red and black wires to deliver power from the 144-volt pack to the heater. I routed them through the original (now useless) windshield sprayer hose grommet:
Next up was work in the middle compartment. I mounted a power post so I could attach several negative cables (the original negative cable from the most-negative point, along with negative cables to the charger and to the heater):
Next, I took the contactor I ordered...
...and mounted it on a piece of polyethylene along with the large fuse which protects the 144V heater circuit:
I hung the board from the middle battery box using tie wraps (also visible in this picture are the three wires going to the negative terminal post):
I then ran a yellow wire from the +12V input to the contactor to the switch location on the dashboard. I also ran a brown ground wire from the contactor to the grounding stud in the gas tank compartment. Note the yellow rubber cap on the negative post - I have a story to tell about that down below...
Here is the switch that will go into the dash to control the heater. The red wire goes directly to unswitched +12V (because I want the heater to be able to run without the key in the ignition). The yellow wire is split to drive the contactor and a relay for the heater blower motor in parallel:
This is the relay - a standard 12V 40A automotive relay, normally open. The yellow wire is from the switch above, the red is directly from unswitched +12V (I used 12-gauge wire since the blower pulls a fairly large current). The brown wire ties into grounding wires behind the dash. The black wire is +12V power for the blower, and the orange wire is ground for the blower:
Here's the wiring around the heater - I wrapped the contacts of the relay in electrical tape (to avoid shorts) and tucked it up above the heater:
It all works pretty well. You turn the switch on, and hot air blows out of the heater. Originally, I was going to attach hoses from that to the original heating system. However, I tried that, and the warm airflow was unsatisfactory. Fortunately, the heater is well-positioned to keep my feet toasty. I may install the flappers that came with the heater so the driver and passenger can independently control airflow.
Last, here is a wiring diagram of the heater circuits. Originally, I had the contactor and relay in series with the switch. However, this led to an excessive voltage drop which meant that the contactor did not close. So, I changed and wired them in parallel as shown here:
Remember the yellow rubber cap on the negative post I was telling you about? This is why it is here. I was tightening the bolts on the most-positive post, but my normal electric-tape-wrapped wrenches (that I use on the batteries) were not the right size for that bolt. So I used just a plain wrench. I managed to brush the top of the negative post while the wrench was touching the positive post. It resulted in a most exciting spark, including blast damage around the positive post and a flash burn on my hand that was holding the wrench:
Moral of the story: be very careful when working with high voltage... If you think you are being careful, think again, and find another way you can be even more careful. I was very lucky not to have damaged myself more than that flash burn on my left hand. I really need to get around to purchasing and installing that high current circuit breaker I've been thinking about...
Legal to Drive, Part 2, and 12V hack
As you may recall, I registered the car so it is street-legal. The State of Colorado followed up with a new title issue, which arrived today - note the FUEL option. Hopefully this will be all I need to claim the Colorado alternative energy vehicle tax credit. I've scribbled VOID over this to make it harder to use this image for nefarious purposes:
I also engaged in a little 12V hackery this week. Like TimK, I was bothered by the voltage drop caused by 20+ feet of wire between the aux battery and any devices. So, I hacked mine. I took a different approach than Tim. Figuring that the two wires were connected in the engine compartment, I just cut them at the front firewall:
And then I put ring terminals on the end of all four wires and put a 1/4-inch bolt through them. This shows two of them bolted together:
This also provides the power takeoff point for my heater. I want to be able to run it without the key inserted (on those cold winter days), so I need unswitched power. I wrapped this securely with electrical tape once I had all the wires installed on the bolt.
This helps because instead of the 20-or-so feet of wire between the aux battery and any devices (because the wire runs to the engine compartment and back before plugging into the 12V system), the "short" introduced by the ring terminals and bolt provide a much shorter current path which results in a much lower voltage drop. Previously, the 12V system was dropping to 10.3-ish volts with the lights, brake lights, and a turn signal on. Now, it stays at 11.5 or better.
I also engaged in a little 12V hackery this week. Like TimK, I was bothered by the voltage drop caused by 20+ feet of wire between the aux battery and any devices. So, I hacked mine. I took a different approach than Tim. Figuring that the two wires were connected in the engine compartment, I just cut them at the front firewall:
And then I put ring terminals on the end of all four wires and put a 1/4-inch bolt through them. This shows two of them bolted together:
This also provides the power takeoff point for my heater. I want to be able to run it without the key inserted (on those cold winter days), so I need unswitched power. I wrapped this securely with electrical tape once I had all the wires installed on the bolt.
This helps because instead of the 20-or-so feet of wire between the aux battery and any devices (because the wire runs to the engine compartment and back before plugging into the 12V system), the "short" introduced by the ring terminals and bolt provide a much shorter current path which results in a much lower voltage drop. Previously, the 12V system was dropping to 10.3-ish volts with the lights, brake lights, and a turn signal on. Now, it stays at 11.5 or better.
Monday, December 3, 2007
Brief Maintenance Note
I got bit by a Blogger image upload bug with the last few posts. I've patched them; if you're curious what is involved, see this link.
Apologies for any inconvenience... let me know if you run into any broken image links on my blog.
Apologies for any inconvenience... let me know if you run into any broken image links on my blog.
Tweaking Regen Braking
I tweaked the regen braking this morning. As I mentioned earlier, the default parameters caused an oscillation or "lurching" during regen braking. I exchanged email with the support folk at Azure Dynamics about my theory - that the default 150-volt EE2NoRegenBat caused the controller to turn regen off and on as the voltage hovered near that value. The tech people agreed that setting NoRegenBat higher would be a fine workaround. I don't want to overcharge my batteries, so I decided to go with a higher NoRegenBat but a wider ramp (set by EE2RegenRamp). This chart illustrates what I did:
EE2NoRegenBat is set to 160, instead of 150, and EE2RegenRamp is set to 34, instead of 12. This had a great effect, as the following chart shows. It plots braking as a percentage of max torque (which is 53Nm with my current 100A power max for regen):
Despite the fact that the sampling period (1 second) introduces some aliasing, you can clearly see the oscillations in the old, default parameters (the blue line). The red line shows a much smoother curve, with substantially reduced lurching. I plan on leaving regen enabled from this point on to see what it does to range.
EE2NoRegenBat is set to 160, instead of 150, and EE2RegenRamp is set to 34, instead of 12. This had a great effect, as the following chart shows. It plots braking as a percentage of max torque (which is 53Nm with my current 100A power max for regen):
Despite the fact that the sampling period (1 second) introduces some aliasing, you can clearly see the oscillations in the old, default parameters (the blue line). The red line shows a much smoother curve, with substantially reduced lurching. I plan on leaving regen enabled from this point on to see what it does to range.
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