Monday, August 30, 2010

Completing the main battery box

The batteries have been loaded into the main battery box.  Here's how it went.

I previously showed connecting the exhaust vent and fan to the rear of the box and to the back of the trunk.  On the front side of the box I had previously made a cutout for the battery cables to run through.  Using a hodge-podge of electrical and plumbing fixtures and adapters, I cobbled together something which connects the conduit which I had previously installed in the hump and the front of the battery box.  Here's a picture of the hodge-podge in place.
Next I caulked around the edges of the wood pieces inside the box.  I will probably regret this later when I decide to rebuild the box, but I used silicone caulking (white, no less).  Hopefully it won't be too ugly to remove.  Once that was cured I started loading batteries, starting with the batteries in the rearmost positions.  It was a pretty awkward situation, and since the batteries weigh 87 lbs each I could not lift them into the back box.  I considered some elaborate hoist that could levitate the batteries into position, but then snapped out of it and placed a piece of plywood to act as a ramp from the forward lip to the rear of the box.  Worked like a dream.
I had previously designed battery tie-downs to keep them from jumping and sliding around while I'm driving, but I also want to constrain them from the bottom as well.  I bought some rectangular HDPE extrusions (3/8" x 1") to use as guides - I figured I'd screw them in to the bottom wood to give myself a positive stop when positioning the batteries.  Here's a view of the guide at the back of the box.
Here's a view of the "side guide" for the back of the box.  I hung this one from the side because the gap was too narrow to use the full width on the bottom.
Here's a view of guides that are just wedged in between the batteries.  (Not a press fit, just snug)
Here's a view of the front guides in the rear section.
I used the same technique to create guides in the front section as well.  Some screwed into the bottom wood before the batteries are installed, others slid into place after the batteries are loaded.  In this case, the batteries were designed to be snug against the front wood so no shims were required there.
With all the batteries in place, it looks like this:
Here's a close-up of one of the tie-downs:
So, now that the car is fully loaded I can see how good my calculations were for the strength of the new rear springs.  The rear end is about an inch taller than the front.  Not too bad.  I may have to adjust those at some point - just have to wait and see how it looks from a distance.
Next stop: battery cables.

Wednesday, August 25, 2010

Battery box ventilation

In order to remove hydrogen gas and other unpleasant odors which might be generated by the batteries during charging (and possibly discharging) I wanted to install a ventilation system.  The overall plan is to be able to seal the battery box as much as reasonably possible and then vent the box through a hole somewhere in the back of the car.  The fan should be installed as far downstream as possible to minimize the "positive pressure" parts of the ventilation; that way if there are leaks air will be drawn in to the box rather than out into the passenger compartment.

Step 1: cut a hole in the back of the battery box (as high as possible without compromising the structural integrity of the box, i.e. don't cut into the metal).

Step 2: cut a hole in a convenient place in the back of the car.  In my solution to this problem, I cut the hole in the back of the spare tire well, the only place I could find with a reasonably flat section for the fan assembly to seal against.  View (upside down) from inside of trunk.  So, the fan will blow air into the space behind the bumper cover.

View from behind the car (bumper cover removed).
 Step 3: make a fan sandwich between pieces of plywood.  A double thickness of plywood was used on the "upstream" side of the fan so that the wood pieces contacting the fan could have an opening as large as the blade diameter.  The hose being used to connect the box to the fan is smaller in diameter.  The bottom plywood is larger to leave room for screws to attach it to the trunk wall.  The sandwich is held together with #6 machine screws threaded into "T" nuts driven into the back side of the larger plywood.

Step 4: attach the large plywood to the back of the trunk with sheet metal screws so that the wood cut-out is sitting directly over the hole cut in the trunk wall.  Since this joint will be positive pressure, I used a thin silicone gasket to ensure it is air tight.

Step 5: create the fan sandwich and attach wires to the fan (power taken from cargo light [always on], ground wire attached to ground terminal in rear enclosure).  The joint between the fan and the large plywood is also positive pressure, so another silicone gasket was used here as well.

Step 6: cut the rib off the end of the hose fittings and jam them into the holes (battery box and fan sandwich).

Step 7: connect the accessory battery, and confirm that the fan is blowing out of the back of the trunk.

Air flow confirmed.

Wednesday, August 18, 2010

The Saturn has landed!

Major milestone!  Not to say that they'll not be coming off again, but for the first time since April 2009 the Coupe de Volt is sitting on wheels again.
No batteries in the back yet, so my mega-stiff springs in the rear are holding the car up high!

Note to self: Those aluminum wheels are looking pretty scuzzy.

Batteries in radiator box

Two of the batteries are in place!  Because of the placement of the front battery box (where the radiator used to reside) it is not possible to load the batteries in from the top.  So the box is designed to be loaded from the bottom.  Here's the 2 batteries loaded on the box bottom.  Have to be careful to keep them balanced on the jack!
Next, I pushed the jack under the car and start pumping.  It was a little tricky aligning everything on the way up (partly because the jack doesn't lift straight up) but it fit eventually.  In order to hold the batteries in place, I put little pieces of 1" square tubing (painted with epoxy and with the ends closed with polyethylene caps) across the top so they get sandwiched between the battery and the top rail of the box.  It's a little tough to see in this picture, but the tubing is set in between the trio of filler caps.

Here's a view of the loaded box from the bottom.  The bottom of the box is actually about an inch above the bottom of the bumper, so I shouldn't have any problems with ground clearance.
Ready to be wired.

Monday, August 16, 2010

AC wiring

My plan was to use the "fuel filler" area for getting AC power to the battery charger.  Because the body panels are plastic, mounting options for the receptacle are limited.  The only real solid place to attach a receptacle is a single "speed clip" attached to a metal bracket in the upper right corner (where the original gas tank filler pipe was attached).

I cut a crudely-shaped piece out of some scrap aluminum sheet (1/8" thick) and cut a hole in it to accept the body of the receptacle.  I drilled and tapped 3 holes situated around that hole that matched the mounting hole pattern in the receptacle flange, and then drilled a clearance hole for a #10 machine screw to mount the aluminum piece to the metal bracket's speed clip.  Once mounted in place, it looks like this:

It's an L14-30 receptacle.  I chose the L14 style because I wanted a turn-lock style (as opposed to the dryer style) for a more secure connection and I decided it would be a good idea to bring in a neutral line in case I have components on the car that run on 110VAC.  Like, for instance, a little trickle charger for the accessory battery, or blanket-style battery warmers.

So, from this receptacle I ran 4 10AWG wires (2 black wires for the hot lines, a red wire (with white electrical tape wrapped around it - I ran out of white and had plenty of red) for the neutral line, and a green wire for ground) through the body at the top of the inner fender wall and into the rear electrical enclosure.  Here's a view from behind the receptacle:
I'll wrap the wires and the back of the receptacle to protect them from the elements.  Here's a view of the wires coming out of the fender wall:

Here's a view of the fully-wired rear enclosure:

I have the power coming in from the right side and leaving the left.  The blue and red wires are the AC input to the Zivan NG3 battery charger.  There is an additional green wire that connects to the chassis and serves to tie the chassis ground to the AC power ground line (earth) while it's plugged in.  Two of the small black wires connect the AC power to the Primary AC Interlock Relay in this enclosure while the others run between this relay and the other relays in the relay enclosure in the engine compartment.

Thursday, August 12, 2010

Electric Schematics

I thought I'd publish my electrical schematics for posterity.  Then if my hard drive and memory sticks all crash I'll at least have some record of what I did!

In these schematics, the "light blue" numbers (cyan, actually) are my wire numbers.  The purple (pink?) text denotes which opening in the box the wire goes through.  If a wire has no number that means it is an existing (pre-conversion) wire.  On page 5, the wire color denotes the wire gauge.

I also created a schematic of the "High Voltage" wiring (though my electronic hobbyist friend claims nothing less than 1000V can be called High Voltage!).

I reserve the right to update these at any time, and make no claim as to whether they are correct.  (After all, I haven't even connected my 12V accessory battery at this point!)

Wednesday, August 11, 2010

DMOC installation (3-phase wiring and grounding strap)

More wiring fun.  The AC24LS motor comes with a giant pigtail already installed containing 3 #2 awg wires which will carry the 3 phases of AC power from the DMOC.  The pigtail is supposed to be fed through a bulkhead fitting in the DMOC enclosure, then the cable lugs are attached to terminals in the enclosure.  In order to make the proper connection to the DMOC I had to pay careful attention to how the shielding connects to the metal enclosure which houses the terminal posts (minimize electrical noise).  The instruction manual makes it sound relatively easy.  Peel back this, cut away the excess that, slide the shield over the grommet, tighten the nut.  Great.
(Preceding photos taken from Azure Dynamics' DMOC Instruction Manual)

Well, not so great.  I didn't take pictures of the process but suffice to say that it was not as easy as they made it sound.  The shield is stiff, and the rubber grommet has to be placed in exactly the right place before you start because it will not slide on the heat shrink covering the 3 wires, and the lugs have to be bent exactly just so in order to match up to the terminals.  But the worse part was the nut that holds it all together.  It's a stamped piece with regular raised portions around the outside for gripping with a pipe wrench.  The problem is that because it is stamped all those raised portions correspond to recessed portions on the inside.  So, when they went back in and cut the threads for the nut the threads disappear over the recessed portion.  So, if the nut is not exactly straight when you're getting it started on the bulkhead fitting it will cross-thread.  And, did I mention that this assembly is stiff?  It was right near impossible to keep the nut straight when trying to get it started.  As a matter of fact, I gave up.

Fortunately, my helper friend didn't give up and had the great idea of unscrewing the bulkhead fitting, putting the shield/wires/grommet/nut assembly onto the bulkhead fitting, then putting the bulkhead fitting back on the enclosure.  Removing the bulkhead fitting allowed us to make sure everything was perfectly straight when starting the nut, so it went on.  Finally.  Whew!  3 hours just to connect three wires.

Here's what it looked like after the saga was complete.

I also connected the grounding strap that came with the DMOC.  The instructions called for it to be connected from one of the mounting feet to a good chassis ground.  Well, I couldn't get it to reach to the chassis, but it would reach one of the big bolts holding the adapter to the bell housing of the transmission.  Here's a horribly out-of-focus picture of the grounding strap attached to the adapter bolt.  The other wire with the yellow lug insulation is a #10 awg wire that runs to the main chassis ground bolt near the accessory battery.
Here's the view from a different angle showing where the grounding strap attaches to the DMOC mounting foot.

Tuesday, August 10, 2010

Low voltage wiring (engine compartment)

Now that the Primary AC Interlock Relay has been installed and the wires have been run up to the engine compartment, I can start wiring the engine compartment relays.  The EA kit that I purchased includes detailed instructions on how to make all the electrical connections necessary.  The instructions are a little out of date, unfortunately, so they don't exactly match the components that came with the kit.  For instance, the DC/DC converter supplied with the kit (Elcon ####) doesn't need the input voltage filter that is specified in the intstructions (originally for PFC DC/DC converter).  In addition, I added a "DMOC Kill Switch" within reach of the driver, necessitating an additional "DMOC Relay" wired to that switch.  So I adapted the electrical schematic provided to depict these changes, as well as adding details as to where I'm pulling power from the existing 12V system and locations of the various components.

I'm working on being able to load the electrical schematics to the blog, but in the meantime here are some images of the wiring as it was being completed.  First, a view of the passenger side of the engine compartment.

This electrical enclosure in the middle of the picture contains:
-Secondary AC Interlock Relay
-Key Switch Relay
-Neutral Switch Relay
-Regen Relay
-DMOC Relay
-Vacuum Pump Relay

To the right of the enclosure is the DMOC controller.  Directly behind the enclosure is the water heater.  Barely visible in the upper right corner is the brass tee at the top of the vacuum pump.  There are wires in the red corrugated wire-minder running from the enclosure to both the heater and vacuum systems.

On the driver side of the engine compartment is another electrical enclosure which houses 3 shunts for measuring current.  The large shunt in the center measures the current going to the motor controller.  The 2 smaller ones measure the current being supplied to the water heater and accessory battery.  This picture shows the enclosure with all the wiring except the big battery cables.

The new accessory battery (lawn tractor size U1, since I won't need the "cranking capacity" of the original battery) resides next to the "shunt" enclosure.  This picture shows the wiring coming into the battery (Ground not connected! - I'm scared to connect it right now...).  The "bundle" of white wires attached to the chassis next to the junction box are the ground lines from the relay box, the DMOC controller, the vacuum pump, and the transmission.  The thick black wire (#4 awg - I know, overkill, but it had the right size ring lugs) connects the chassis to the battery ground.
Notice the coil of many-colored wires nestled next to the junction box?  That's what's left of the original engine wiring harness.  I conscripted 2 of the wires as "keyed 12V" lines for the various relays/DMOC/Vacuum, so the rest are unused in this conversion.  However, rather than trying to dismantle and remove the wires individually I electrically isolated the ends/connectors and left them in the car.  Never know when I might need to commandeer another of the old circuits!  Here's the wire bundle before I coiled it up.  Ugly!  And a lot of it covered with oil....
Finally, to round out the 12V wiring, the last component to be installed is the potbox which converts the accelerator pedal position (not the "gas" pedal - tee, hee) into a resistance which the DMOC controller can interpret as a throttle request.  In the ICE, pressing the pedal pulled a cable through a sleeve which controlled how much air was sucked into the intake manifold.  The end of the cable was held in place by a bracket which positioned the cable properly.  In the EV, I needed to duplicate that positioning in relation to the potbox.  My solution was to put it in an electrical enclosure with the potbox mounted in such a way that the side of the box acted as the positioning bracket.  Also, an additional return spring was attached to the potbox arm from the opposite side of the box as a redundant feature.  Don't want the potbox throttle stuck in the "on" position!

A small metal rod is attached to the end of the accelerator cable, forming a "T".  The rod nicely fits through the pre-drilled holes in the potbox arm (coincidence?  I think not.).  I needed to come up with a way to keep it in there, though, and I forgot to look at the original installation to get ideas.  I found a small aluminum piece (from a toy Erector set) that was the right width and had slightly-too-small holes drilled in it at about the same pitch.  What luck!  So I opened one of the holes up so that it could hold the other side of the "T" and bolted it to the potbox arm.  Here's a side view:
Here's the top view, with the potbox mounted in the box.  The supplemental return spring is connected to a "spring connector stud" I found on McMaster-Carr (what a great place that is!).
Because of the length of the accelerator cable and because I was limited in where I could mount this box, I had to mount it on the relay enclosure at a bit of an angle.  Once the lid is on and everything is buttoned up, it doesn't look half bad.  At the moment it is only attached to the lid of the relay box, which may or may not hold up over time from the jolts of driving, but I can always reinforce it with steel later.