Archive for November, 2010

Tricycle

It’s raining today but I did add a cool option to my car. The iPad mount! I was originally going to make my own mount, but that would take days of machining time and would not probably work all that great. I decided to search for options and quickly found Ram Mounts. I bought the basic iPad mount and the long arm (along with 2 balls) for $40 or $50 (I forget now). I figured out where I wanted it and drilled a few holes under the dash. I then mounted the ball end with 3 M5 cap head bolts that I had lying around and voila! In car navigation on a huge touch screen:

It moves around quite a bit and has a lot of position options.

Totally sweet! Now I can watch “Who Killed the Electric Car” while I drive my electric car.

I got my heater installed; I can test the fan and make sure the contactor comes on, but heat won’t come out until I actually have my battery pack installed.

I cut a hole on the dash (opposite the emergency blinker sign, to the left of the ash tray) for the switch. I had to grind down the back area a little bit to make sure the contacts didn’t touch the frame and short anything out.

The front 3-speed switch is then mounted to a little face plate that shows off/low/med/high. No picture (I forgot to take one). The fan and box containing the ceramic heater is mounted to the left of the motor. I simply drilled two little holes in the box frame and tapped it with 1/4-20 threads so I could just screw it on from underneath. The box has two outlets; one going towards the front of the car and one to the back. There is a hole for the heater hose under the DC-DC converter and it runs directly into the existing heater vent hose for the car’s vent system. The other side I covered up with foil tape; I’m not sure the heater will put out enough heat to power both sides of the car, so I’m going to try it with one side first. If I decide to do both sides, I’ll uncover the hole and drill another hole directly in front of it to run the tubing through and over to the other side.

The contactor will power the ceramic heater core. For safety reasons, I want it to turn on automatically with the fan. The trouble is, I have three fan speeds and I needed to somehow tap the power to a single 12 volt lead to turn on the contactor. I tried to figure this out myself, and I thought “man, this would work if there was some way to limit current flow in only one direction…”. I emailed Randy from CanEV.com (where I bought the heater kit) and asked. He said to use some diodes, and a quick google search later I realized those were effectively electricity check valves. It makes me wish I would have taken at least one EE class in college!

I still wasn’t sure what kind of diode to get and what size, and how exactly I should wire them. So, I asked on DIYElectricCar.com. Apparently you can just put them inline, and Sam on the forums also said to use an extra diode on the back ground side to snub off extra voltage. I’m glad I asked, since I didn’t know that was recommended practice, and now I wonder if I need to do it for my other contactors (although, they have some little diode thing on them already).

I split my three input wires and used 3 diodes to merge them into one wire to power the contactor. The contactor is a little guy on the right of the right hand (positive) contactor. It is close so I can wire up the positive side of the pack to it.

In between the contactor and the heater core is another HV fuse (important!).

The fan works great and flipping on any three speed correctly turns on the contactor. Sweet!

The car is effectively all wired up, and I only need batteries. I do need to some weather sealing on the rear to let me be able to drive when it is raining out.

I’m still waiting for batteries, but i’m getting a lot of the little details done. The car could be drivable if I actually had a battery pack. I can turn on the key and hear a satisfying “click” of the negative contactor closing. Hopefully the batteries are down in LA on a big boat that is about to come up to the Bay Area. I’m crossing my fingers hoping I get them before my week long thanksgiving vacation.

Here’s a shot of a bunch of stuff wired up. I’m using 2/0 welding wire for the battery interconnects. I may upgrade to 4/0 (which is recommended for the motor connection) at a later point if they get excessively warm while driving. I’ll be using 2/0 for wiring the battery packs together.

What is in the above picture? On the right side you can see the two fans covering a small water cooled radiator that cools the controller. The pump is underneath the reservoir, as previously mentioned on other posts.

Above it is the positive side contactor. This one is hooked up to the controller, and it will turn the High Voltage (HV) on and off. (A contactor is a way of turning HV on and off by applying a 12volt power to it)

For extra safety, I have a secondary contactor on the left side for the negative side of the pack. This contactor is controlled by “key on” and is the one I first hear click when I turn on the key. By physically separating them I ensure there won’t be any accidental way of completing the circuit.

Beneath the left (negative) contactor is the IOTA DC-DC converter. It is hooked up to the battery side of the positive and negative contactors. I initially thought “hey, why not hook it up to the other side, that way it gets turned on with the controller”. It turns out that is a bad idea; the Netgain Controller says to not do it because of voltage drop (or something like that). So, instead I use a 60 amp relay that is powered on when the “key on” comes on. This will power on the back “key on” accessories and allow the DC-DC charger to start charging the accessory battery. It will also provide power to accessories. The little white thing on the top of the left contactor is a High Voltage / 20 amp fuse for the DC-DC converters power. The wires feeding it are only 12 gauge, which good enough for 20 amps. The output wires are 10 gauge to the battery, which should be enough (it was what was originally used by the alternator).

Coming out of the motor are two little wires. These are a normally closed circuit that opens when the motor overheats. It is used to wire up a “check engine” light. The bug already had a powered wire coming in the back from the oil pressure light, and the light would come on when grounded. So, I hooked up “key on” power to the motor’s wires and input it into a 12volt/20amp relay. The relay does nothing when on, but when off it grounds the oil pressure light line and turns on the warning light. I was happy I figured this out, considering I didn’t know what a relay was just a few weeks ago.

On the left side is a wiring mess that I’m going to clean up one I have everything in its final place. I have two fuse boxes; one is a “key on” power source (directly from the DC/DC converter and battery) that goes to the controller, fans, water pump and reverse lights (which hooks up to the transmission). To the right of that is a regular fuse box for fusing other things that don’t need key-on power but do need a fuse. For instance, the controller has an “always on” power directly from the battery, and this is protected with a 5 amp fuse.

I have some other wires coming in for the heater. I just cut a hole to the left of the ash tray that I’ll use for the 3-way switch:

….more later!