This section has information about small stuff that doesn't fit in the other sections. (updated June 13, 2009)
Originally the cheapest way to go would have been to use a separate battery to power the system, but when I actually did this in my crazy moving with a controller scene, the head lights, wipers and all that stuff actually wore the battery down pretty quick, so I decided to get something that can power the whole system, which meant at least another 100 bux to dump into this.
To make a not-so-long story short, I ended up modifying my own IOTA 55A 120VAC-13.4VDC converter to run on 144VDC by simply shorting out the rectifier and connecting in the battery line. (through a 10Amp in-line fuse)
I still need to add a battery, in the event of a failure, or I pull the emerg disconnect, the DC-DC will also be disabled, so a small battery is needed for backup.
Hey, I live in Canada, gotta have heat right? I got to thank Gavin yet again for this idea, (most of this is because of him)
This was delayed because I wanted to keep the original heater core for future liquid cooling, but I doubt I'll ever go that far, so I decided to hack it up and put it to better use.
Below are photos illustrating how I assembled the heater, but I'll note on a few things first.
I couldn't find a relay that was rated for the value I needed, so I had to make my own using a momentary push switch and a solenoid. The switch is rated for 240VAC and 16 Amps. I also have an in-line fuse that is rated for 15Amps. I calculated that this heater shouldn't go over 12A for 144V. (It stays below 10A when on 120VAC [RMS]). Also, I kept the thermostat to turn off the heater (using the 12v signal instead of the high voltage line) in the event it gets too hot. Unfortunatly, it had to be installed near the floor where the heater core goes because it needs to be nearby the heating element.
Left is the thermostat, and on the right is the relay that I am using.
Converted EVs need a vacuum pump for the brake assist. Knowing that it is simply a small motor, a valve, and a switch with hysteresis, I didn't think it was worth $300, and researched cheaper alternatives.
After some discussion on the DIY forums, I found this pump on ebay. I thought it would be perfect, I even found the pinout and rating on this page (it had pictures/diagrams when I first found this website, but they since took them down).
I started with a single pipe, and I thought it was the reason I could only get 1 peddle press (less than 2L), but after upgrading it, the pump would still turn on in less than 2 peddle presses.
Currently, it is where the muffler used to hang.
Turns out, this pump was as weak as predicted in the forum. I put together a 1.5L reservoir (I thought it would have been 2L, but I made a mistake measuring the diameter of the pipe when I first got it). I was barely able to get a single brake peddle push before the pump came on.
After adding the large pipe in the middle to increase the reservoir volume to about 7L, I was still only able to get one and a half brake pushes before the pump came on. So I decided I had to modify the circuit that was in the vacuum pump. I thought I did nothing, but I must have accidentally touch a sensitive wire to 12V or something because I broke the whole thing. I had to come up with my own circuit to get thing working again.
I got a 1$ comparator chip from sayal, and got to work with a little reverse engineering.
Further reverse engineering allowed me to use the MAPS (manifold absolute pressure sensor) that came out of the truck. Before I blew up the original circuit, I was running tests on the vacuum pump and learned that it outputs a 5V square wave. It outputs 125Hz when a vacuum of 9in/hg is applied to it. (I don't own an oscilloscope, so at the time, I used signal generator program on my laptop and headphones) I recommend this free program as an oscilloscope.
Long story short, I got it working again with the right amount of hysteresis and an engine rated pressure of nearly 15 in/hg. (Improved over the 9in/hg that the pump was originally set at.)
The pump is powered when the key is in the run position. It gets it's power from a 10A fuse that used to enable the heated exhaust gas oxygen sensor. Whatever that is/was, I know its gone now as it was part of the old engine.
If this pump fails again, I'll replace mine with this pump (much more robust). I am aware that they say that this is no good with brake assist, but I'm pretty sure they don't expect users to add a large reservoir.
*Update Dec 15 2008; Success! The pump works great, I get about 5 full brake pushes before the pump turns on. (runs for about a min). I may add a reset switch to manually charge the pump if I know I am approaching an area where I need lots of brakes (like going down a steep hill).
I had originally wanted to turn the key to "start" and have a latch turn on the main contactor and then stay on while the key slides back to "run". However, there is a break in the signal in-between the start and run positions, nullifying the latch. (The main contactor turns off as soon as there is no signal to the latch).
I'm sure most conversion specialists would just have it setup for the key to go in the run position and then drive away, but I wanted it to be intuitive for new users. Plus with my way, if, for whatever reason, the inertia switch pops, resetting it with the key still in the ignition will not engage the main contactor.
I decided to go with large green "start" button that lights up when the key is put in the "start" position. I made a video to explain how this works.
I am getting the power for this system from the "low oil pressure relay" that was located under the glove box. (which is enabled when the key is put to "run".) I'm also using the existing wiring to run the "on" signal from the relay to the main contactor in the engine compartment. The power comes through a 15A fuse which also powers the instrument panel cluster.
Tachometer
This was one of the things I was a little worried about when I first started this project. Other people who have done conversions didn't write much about how they got their tachometer working (without expensive fancy motors and controllers, ie; zilla and warp9). I eventually learned that for a 4 cylinder engine, there are 2 pulses from the EEC for every RPM. (I don't know why, ICE engines are so convoluted to me anyways.) I found a project that used magnets on the secondary drive shaft of the motor to drive a HAL effect transducer or reed switch. I already had a reed switch in my old junk pile (I have idea where it originally came from), so I gave that a shot. Actually I have my doubts that this will work at high RPMs, but for now it is doing the trick. I simply wired one end to 12V and the other to the tachometer signal input. The 12V I am using is from the EEC power relay, (that does not have a fuse for some stupid reason, so I'll have to add one). I'll probably eventually replace the reed switch with a HAL effect transducer.
Update: March 14, 2009; You may have seen some of the videos on the test page, this thing actually works better than I had expected. I may just keep it they way it is.
Emergency disconnect.
I won't be driving this thing anywhere without some way of killing the power in the event of an accident (other than the main contactor). I've seen others do this, and I think it can be quite effective.
I have a pair of anderson connectors and I will bolt one to the chassis, and the other to a rod that will be attached to the clutch peddle. I will put some conductive grease on the contacts of the connectors to keep corrosion away and to make connection/disconnection easier. (I removed some of the grease because I thought I had too much and was causing a voltage drop, it does not conduct like metal.)
Now I know that some people would say that using the clutch peddle may be a mistake (for those who have a habit of using it). The best I can do is paint it red and put a label above it with the words: Emergency disconnect.
This can also be used when opening things up for showing or upgrades. It is installed, working, and shown in the video above. Just like the emergency brake, this will be used quite often in non-emergency situations
I picked up a pair of bolt cutters from the same place I got the welding cable. Not just to cut the cable, (can be done with a hack-saw) but to also crimp the lugs onto the cable.
I've seen a couple other EV converters do this too, (sorry I couldn't give credit, I can't remember who it was right now). So that's where I got the idea to cut the cat-ears shaped hole in the bolt cutters.
