The target for last week was to get all of the pieces arranged on my garage floor, get things wired together, and to make sure everything works. I got to that target this week.
The existing/recycled battery cables that I am using have corrosion on them. Some of them have a LOT of corrosion. The corrosion is a pretty good insulator, increasing the resistance in the cable connections. Increased resistance means increased heat as well as less power being delivered to the motor. So, I dug out of my painting supplies an emery cloth block. It looks like a sanding block, but the abrasive particles do not fall off when you are using it, so there is no residue of sand in the threads of your battery connections, or between the contacts of your cable lug and the battery post.
Removing the corrosion is not difficult. Even the very corroded cables took only a few minutes to knock off the corrosion. I took video of it. It's pretty boring, even for me. I'll get sections identified that illustrate each type of connection and get it put together and posted ... but it's not a big priority for me. I knocked the corrosion off EVERY cable ... or every POWER cable I guess ... even the 'new' cables have corrosion. It's just not as easy to see. Alunimum, copper, tin, they ALL corrode almost immediately in air. Most of the time it is a thin coating, and that coating is a barrier to more air, so the corrosion stops. So EVERY time that you put in new cables, or when you take apart your cables to remove a battery or add another, change controllers, etc you SHOULD knock the corrosion off before putting the connections back on. This is only necessary for the high current connections like the batteries, controller and motor. This same effect happens to all of the rest of the cables used for signals and low power ... but the increased resistance does not lead to drastic issues with heat unless there is a lot of current going through the increased resistance.
The emery cloth would not take off the corrosion inside the holes of the cable lugs - because it won't fit into the holes. There should not be current passing through that part of the lug, and then through the bolted connection, to the battery or controller or motor. But I put the cables on my bench and used a battery cleaner wire brush to scrape them out a bit. I don't think I'll do it every time. I think that the little wire pieces that break off the brush would do damage by being dropped into the rest of the electrical connections and batteries, or get into the bolt threads.
The cables are important, but so are the connections on the controller, the motor, the HVJB and the batteries. The corrosion was knocked off ALL of these. The corrosion on the bus bars, terminal posts and fuses in the HVJB were knocked off during the assembly process some time ago, so the only parts that were re-cleaned were the terminals into and out of the HVJB.
With everything arranged on the garage floor and the cables newly cleaned, I began connecting things together. I started at the load and worked backward. Motor terminals first, connected to the HVJB. Then the Controller connections to the HVJB. Make sure that the HVJB maintenance switch is open. Connect Pack+ and Pack - to the HVJB.
From there, I switched to the LVJB. The cabling from the HVJB to the LVJB was done. Then from the throttle (potentiometer) and pedal switch (mini breaker) to the LVJB. Then the LVJB to the Controller. The final connection to the 12V battery was left undone. The ignition switch (mini breaker) is turned off.
Wiring the pack together, I connected the longer cables between battery packs first. The packs are set up as three pairs. So HVJB pack - to pair 1 -, pair 1 + to pair 2 -, pair 2 + to pair 3 -, pair 3 + to HVJB pack +
Then I added the connections between batteries with each pair. Pair 1 battery 1 + to a 6 inch cable to a fuse to a 6 inch cable to Pair 1 battery 2 -. Pair 2 battery 1 + to an 8 inch cable to a maintenance switch (turned off) to a 6 inch cable to Pair 2 battery 2 -. Pair 3 battery 1 + to a 6 inch cable to a fuse to a 6 inch cable to Pair 3 battery 2 -.
Check voltages on the batteries. Each is 12.5 - 12.6V. Check resistance of connections and cables between batteries. Each shows 0.0 ohms, or less than my meter will read - this is a GOOD check, but not accurate. To get an accurate measurement I'd need to use a high current measurement device like a ductor. A ductor uses 5 or 10 amps of current through the probes so that the voltage drops can be measured more accurately, and the resistance calculated. They measure milli-ohms (thousandths of an ohm) and micro-ohms (millionths of an ohm). They are a bit expensive for a hobbyist. I'll sign a ductor out of the tool crib at work and take video of checking the connections when I get everything set up in the test car.
I set up the video camera ( my phone), got my green laser pointer, and started taking video of each piece of the setup. Besides tripping on the tripod legs a couple of times (no damage to me or the phone) it went pretty well. After looking at the video, I think I'll set up some extra lighting next time.
Now for the moment of truth - turn it on. I started by plugging in the 12V battery for the 'car'. Again, video camera set up and I went through 'turning on the ignition', verified the correct contactor in the HVJB closed, saw the controller turn on and give me some blink codes for low voltage and accelerator active. So I turned down the accelerator to 0. Then I turned on the maintenance switches for the pack and the HVJB, measured the pack voltage at the HVJB, then pressed the 'pedal' to close the contactor across the precharge resistor. The controller is OK to go, so I turned the 'throttle' and the motor started!
There were a couple of problems - blink codes on the controller that I needed to look up before I continued, a bad crimp on the 12V 'car battery' so the controller would not turn on ... as well as a couple of checks that I did since things were powered up - measure the resistance of each contactor and each switch in the ON state ... those ARE on video somewhere but I did not go through the effort of taking parts of several videos and splicing them together. Most of the video that I have posted is from one file, with the silences and muttering to myself parts removed.
I added a piece of tape so that the video would show the motor turning. I stepped on the motor the first time I started it since I don't have it on a mount and if it started with a lot of torque, it could 'roll away'. I think I did that in later videos as well, just to be paranoid.
After some run-up testing with the smaller motor, making sure that everything was working as it should, I connected the Netgain motor. The first time it turned, I was surprised at how much throttle it took to start. There were SPARKS coming from the brushes ... and the motor did not sound as it should. I repeated the run-up, but not to a very high speed in case there was something wrong in the motor - I did not want to damage it, but I wanted to see if the sparking and the noise would go away with a bit of runtime. As it turned out, the sparking lessened but it was still visible. The noise did not get any better at all.
So - what can be wrong?
1. The brushes may be new even though it is a used motor. If the brushes are new, they are not worn into the shape required to make good contact with the armature, so they spark a bit until they are worn in. There is a noise that the motor will make when this is happening, but the video that I have seen and listened to does not quite sound like this.
2. The brushes may be in backward. If someone worked on the motor that was not familiar with DC motors, the brushes DO fit backward and only a very small part of the brush would be contacting the armature. The angles would be wrong, so the leading edge of the brushes would wear quickly and make some noise.
3. It could be turning backward. If the brushes were worn in going clockwise and it is now going counterclockwise, or if the brush position is advance for clockwise and the motor is turning counterclockwise .. I'll have to check. This may explain the sparking but the motor should not sound like that.
4. The bearings could be making that noise and making it hard to spin the motor. That would explain the noise but not the sparking.
5. The armature (part that turns) could be damaged and could be rubbing on the stator (outside part that does not move). That would be bad, and hard to fix. I won't talk about that one any more.
6. Something else that I have not thought of could be wrong. I'll need to take it apart and inspect it to see. Perhaps a cleaning will help?
In any case, that's it for today.
I stopped the video and took pictures of each piece and the overall connections for documentation. If I can get the pictures compressed enough to post, I'll add them to this update.
I'll be away from home for the next couple weeks, so there will be no progress on the motor inspection but I'll try to get some items off my todo list, like editing the video.
Video link
Video Update 2013 Feb 28 + test run - YouTube