Now That's a Shunt!

There hasn't been a lot to report over the past few weeks.  I've been dealing with acquiring the hardware necessary for the Air Conditioning system. 

You may recall I'd ordered a Masterflux compressor and controller off a user on eBay for a bargain $200.  The unit was reported to be new but old stock.  In addition it required a 48 Volt DC supply.  I'd been looking for how I was going to supply the necessary current to the controller at the proper voltage.  Well the good news is that I've solved that problem, sort of.  It turns out the compressor was not new, old stock.  It was in fact used and not in good condition.  The compressor had been crammed into the box along with two poorly protected controllers.  Both had sustained damage while in shipment. Why the shipped two controllers, I have no idea.

Ultimately, I didn't trust either controller to work properly, and simply because of the circumstances, perhaps due to guilt by association, I didn't trust the compressor either.  Everything went back. 

Instead I have on order a brand new system that is designed to work directly off of my 160 volt DC system with no modifications required.  The upside is obvious; the downside is it was $1200 more than the other system.  Still, I'd rather spend the money and have a system that works.  I don't want to mess with it once it's up and running.

In the mean time, I've been working on the revised motor mount.  I cut and formed some steel and started dry fitting everything.  Sadly I ran into another road block on this front.  The problem I face is of course one of space.  I need to get adequate shock absorption material under the motor.  without any, it simply lays on the front steering rack with about 1/2" gap between the motor and the sub-frame right behind the steering rack.  I need to support the motor so it's at least 1/4" off the rack so that it doesn't hit it during any vibration.  More space would be better.  The problem is that if I push the motor up too far, I begin to ruin the alignment of the drive line. 

So, I need to find a way to support the motor in the proper position, with the proper attitude, provide shock absorption and tie it to the frame securely.  I could go back with the previous solution I had, but I'd really like to add more shock absorbing material.  The short story is that the pretty solution I drew up in the previous post simply won't work.  Back to the drawing board.

I also started working on a minor part of the A/C system, and that was how to turn it on and off.  The Z3 has a neat little button in the console with a picture of a snow flake on it.  When you depress the button, it glows orange and turns on the A/C.  I tried it out to make sure that it still sends a 12volt signal to the line that previously went to the compressor to turn it on, and no luck.  I don't know if the ECU needed other connections from the wiring harness that are no longer there, but there was no way I could get that to power up. 

Instead, I took the switch out, and started reverse engineering it.  That switch also has the button to turn on/off air recirculation within the cabin.  It has 8 points of connection.  In short order I figured out which blade had power to it when all the right conditions were met; the A/C button was depressed, and the HVAC system fan was on.  I simply spliced a new wire into that line so that I can draw 12V off it to power a new relay.  That relay will turn on power to a fuse box that will provide power to the Masterflux controller and the AC condenser fan and a cooling fan for the controller itself. 

I'm also taking this opportunity to swap out the Xantrex Link-10 meter I've been using, for a Xantrex Link-Pro.  OK, it's actually the e-Xpert Pro; same thing.  Why the change?  You can chalk this up to a rookie mistake.  In the beginning, when I was ordering all the parts for the car, I simply didn't understand how all of the component's specs needed to match up.  I ordered a Zilla capable of putting out 1000 amps, and the Link-10 capable of reading only 500 amps.  As long as I left the Zilla set to a 500 amp output or lower, then the Link-10 meter could measure the current accurately.  If I set the Zilla higher, it didn't hurt the meter, but it simply didn't read the current, which meant the usage it reflected in terms of the battery's state of charge would be wrong. 

Part of the package is a much bigger shunt, one that can handle 1000 amps vs. the 500 amp shunt for the old meter.  Check it out...

It reminds me of Crocodile Dundee, "that's not a knife..."  That thing is huge!  Which raises a concern as to where I'm going to put it.  I think I'll  be able to fit it where the old one was.  I hope.  Fortunately, the meter is exactly the same size and the leads I need to power it and provide data to it are identical, so it's a straight swap as far as that goes.  I did opt for one other thing when I bought the meter, and that is a temperature sensor that I'll be running to one of the batteries.  I'm going to pick one somewhere in the middle of the pack, one that is likely to get the warmest.  In this way I can keep an eye on the temperature of the pack during the summer heat. 

One other thing I've done was to remove the gaps between the batteries I have in the box under the trunk.  I'd put gaps between them so that I could force air between them if necessary.  I had installed a thermal switch that would turn on and force air over the batteries if they reached 125 °F.  It never came on.  Plus with the temperature monitoring I will now have on the meter, it's not really necessary.  But the biggest reason is that I intend to replace all the copper straps that connected the batteries with braided ones.  In order to do so, I need the batteries pushed together. 

So, I pushed all the batteries together and then carefully measured and cut some wood to push into the space created.  Mind you, this isn't to compress the cells, but merely to keep them from moving around. 

You can see it there over on the left hand side.  As I'd mentioned before, and as several people have discovered, the cells do not expand unless you over charge or over drain the, rendering clamping them together unnecessary. 

Good Progress

The batteries are all in place and anchored down.


Here's a shot of the front with all the batteries in place and anchored down. I've run new testing wires from each group of four batteries up to the little bus bars that are anchored on the back of the front rack and the front of the back rack. I've included a 2 amp fuse in line on each lead from the positive side. Any short will quickly blow the fuse and keep the wire from melting down and starting a fire.

Here's a shot of where I placed that one (ahem) extra battery. On the right is a shot of the battery box in the trunk as it was when I first finished it. On the left you can see the extra battery pushed down in the gap at the end of the box. It worked out very well, and was easy to get into place and clamp down.

After I hooked them all up, I went through and took a voltage reading on all the batteries. After sitting for over two months, with 2/3's of the batteries sitting in a box and the rest still wired up in the car, they each read 3.29 volts. I suppose I had no reason to expect anything different, but I couldn't help being impressed. These really are great batteries.

I want to go through and re-verify and recheck all the connections for the high volt system and the 12 volt system before I replace all the fuses and throw the breaker. I should be able to get that done early tomorrow. There are still a few things I need to do after that and before it comes off the jack stands, so a Friday launch is looking unlikely. But that's OK, I should be back on the road next week. Can't wait to feel that EV grin again!

The Home Stretch

I took care of a few more odds and ends today. Installed the new radio.

There's the new radio. Just above the gear shift is the Link 10 I've mentioned in other posts. It's reading 160 Volts at the moment. I can cycle it through the current Amps being drawn off the pack, the total number of kWh's drawn since the last charge, and the percentage of charge left. The little green lights across the top are the "fuel gauge". The switch just to the left of the Link 10 is the new switch for the heater.

I also ran all the wires that go from the back of the car to the front, or vice-versa, in a wire loom. Those wires all go under the car in the transmission/drive shaft tunnel. I then anchored it, as well as the battery cables that run up front, to the chassis. That was long tedious work that I'm glad I only had to do once.

To protect all that wire, and to help make the car a bit more slippery through the air, I covered up the tunnel as best I could with some left over sheets of aluminum.

That first seam there looks crooked, but it's not really. The front piece was slightly longer on one side. To get each plate to stand off from the chassis evenly, I used a 1 inch nylon dowel, cut into the proper lengths as stand offs. There were several screws and bolts sticking down from the chassis that had been used to hold either heat shielding for the exhaust or the fuel system. I simply cut a proper length of dowel, drilled a hole in it on one end and then screwed it onto the existing bolt or screw. Once they were all event I screwed the aluminum to them for a nice flush surface. I don't know if it will make any difference in the drag coefficient of the car, but it protects the motor and the wires.

I also finished cutting the carpet and the plastic trim pieces that had been in the trunk and refit them as best I could.

I need to get some Velcro to hold down the back corners of the flooring, but it turned out pretty good. The floor of the trunk is about 1/2" higher than it was and it's a bit wobbly. I'll see if I can't shim it later on sometime. Eventually I'm going to have to figure out some way to keep groceries from falling into the equipment in the back. For now, I'll probably just get a plastic crate or two.

Well, that's just about it. The only thing left is to install the new tachometer when it arrives, and then re-assemble the dashboard. I desperately want to drive it around, but it will be easier to do all that while it's still up on the jack stands. So, for now, it stays put.

Installing Batteries Part II

In the last post I mentioned that I'd finished the mounting brackets for the A/C compressor and here is the picture I promised of the whole assembly.

You can see there are two aluminum angle pieces that are mounted to the face of the motor. The bottom one supports the compressor directly while the top one is bolted to the black bracket attached directly to the compressor. There is a slot in the top aluminum piece that allows me to adjust belt tension by pivoting the assembly back and forth. Now I need to get a belt.

The last thing will be taking the car down to an A/C shop to have some custom hoses made. Truthfully, I'm kind of worried about that. The space is so cramped that it will be hard to work in unless I dis-assemble parts of the car. That means driving it there, taking it apart at their garage, and then re-assembling it when they are done. Hmmm.... we'll see how that goes.

The big news today is that I finished the work on the back battery box. All the batteries are securely mounted in the box. There is plenty of room to allow air to move through them to cool them. And I have all the interconnects wired up.

I ended up putting 17 batteries in the back. Such a strange number, but there is that one space up front where I had intended to put a stack of 4, but can only fit 3. So, the extra one goes in the back. Notice up in the top left hand corner, there is an unconnected + terminal. That is the start of the battery pack. Below and slightly to the left, you will see an unconnected - terminal. I will be running a line from that terminal to the next positive terminal at the front of the car, continuing the series.

Truthfully, I'm not too happy with all of this. It's way too complicated. While it's strong and there's no way any of those batteries are shifting around, I approached the whole endeavor of securing the batteries as an after thought; I hadn't planned it from the onset. I don't know that it would have made much difference if I had, but I'd like to think that I could have come up with a much more elegant solution. But, at least it's done.

One thing I don't have in place yet are some "testing" lines that I'll be putting on each group of 4 batteries. I'll attach a small wire at the start, or + terminal of the first battery, and then another on the negative terminal of the fourth. I'll be doing that from start to finish, which will give me a total of 12 groups of 4, so 12 pairs of wires (a negative and a positive for each). I'll attach each to a terminal, paired up next to each other. This will allow me a handy way of checking the voltage of each group of 4. If the voltage on one battery in the group starts to get too high, or sag behind the others, I can more easily locate it and deal with it.

The real danger with these LiFePo4 batteries lies in the extremes. The closer you get to fully charged, the more likely one or more batteries is to run away, accepting too much of a charge and in the process, frying itself. The closer you get to draining the batteries, the more likely one takes a dive in voltage before the others and dies an early death. They are extremely finicky at the extremes. However, kept in the middle of the range they are stable. I'll be setting a charging scheme that will charge them to approximately 95% full, avoiding the top end where one can run away. And as I've said before, I won't be taking them below an 80% depth of discharge, meaning that they will always have at least 20% capacity left, avoiding the death spiral. It means that I'm leaving some untapped potential in the batteries, but it also means I should extend their life by not pushing them to their limits.

At some point in December, someone in my family decided to make a commentary on my progress. Well, they were probably just trying to be cute, but I took it as a comment on the progress I've made. Or rather on the slow pace of the progress I've made.


I had hoped the project would be done sooner, but with the delays I've faced waiting for components, it's pushed things back a bit. Still, when it's done, there should be few things I have to re-address. In either case, I took vengeance upon them all just to be sure I got the guilty party.

Installing Batteries Part I

I've fallen a bit behind in posting what's going on, so let's catch up. I gotta warn you, this one's a bit long.

The copper straps, or interconnects, for the batteries arrived Wednesday. The suppliers found some in their warehouse after all, so they didn't have to come from China. They are composed of 5 strips of copper, held together with head shrink tubing and are a total of 3/32" thick.

I fit most of the batteries in the back box in the trunk, 12 across, with room above for up to 9 more. With all those batteries in there, it would be a very tight fit and almost impossible to route any sort of cooling air flow around them. I only need to fit 18 in that space, so I decided I'd better start playing with the spacing to help promote better air flow. Rather than 12 across in the back row, I decided to go with 11 and space them a bit. But since the interconnects are made to fit properly when the batteries are snug against each other, that meant I was going to have to make my own. I already had some 1/32" copper strap, so I simply cut, laminated and drilled a few that are about 1 centimeter longer than the others.


You can see I'd put one in place just to test the spacing. Once I fit the rest of the straps, there will be about 4 mm between each battery. Plenty of space for air flow. Above, there will be 7 more, two stacks of 2 and one of three at the far right side. In the midst of the 11 batteries I'll be putting a temperature switch that will turn the fan on when the temperature reaches 122 °F. Although I don't have any of it built yet, I know just how I'll be anchoring all those batteries to the box and the chassis so they don't fly around. Oh, and notice the larger black wire laying across the batteries at the bottom of the picture? That's for the XM Radio tuner that I've installed in the back. Gotta have music!

Today I spent time building out part of the system that will allow me to anchor the batteries in the larger tray that will go under the hood.


The strap in the middle of the box is bolted to the tray underneath. All of the rest of the bolts go through the box, through the tray and into the supports that my friend Tim and I welded to the chassis this last summer. The whole thing is as sturdy as a rock. This box will hold a total of 14 batteries (138 lbs for those of you keeping score). There will be two stacks of 4 laid flat in the front (bottom of the picture), and two stacks of 3 in the back. I had planned to stack 4 in the back as well, but I ran into a snag. One of those snags where if I had to build the car again, I would know to look out for it.

When Tim and I welded those supports to the frame, I specified more clearance over the motor than I needed. Only 3/4", but it turned out that I could have used that space. You can't see it in the picture, but when you close the hood, the two nozzles for the windshield wiper fluid come down right into the back corners of the boxes. They would interfere with closing the hood, but only just. How tight you ask? 1/4". That 3/4" clearance I left seems pretty silly now. It's not that big a deal, it just means 18 batteries in the back instead of 16.

Before I mount the two smaller boxes in front of the large one, I need to sort out two things. One is the rpm sensor mount and the other is the A/C compressor. The mount for the rpm sensor will be easy enough, but there's more to the story. Since there isn't enough room in the engine compartment to run the A/C compressor off of an auxiliary motor, I have to run it off the tail shaft of the main drive motor. I had purchased a rpm sensor that mounts to the end of the tail shaft, but if the pulley is in place it interferes with the sensor. It was beginning to look like I would have to choose one of the other.

Along came a new sensor that is designed specifically for the WarP motor I'm using. It mounts flush to the motor and I could use it and the pulley at the same time. The only problem is that no one is sure if it will work with the Zilla controller. The controller expects 4 pulses per revolution and this sensor can deliver that, but only testing it will tell for certain. So the bottom line is that I have to build a mount for the first sensor and test it out, and then mount the new one and test it to see if the Zilla interprets them the same. That will be part of the testing that I'll be doing before the car comes off the jack stands.

Either way, I need to have the compressor's mount built and ready to go in case I can use it. Other wise, I'd have to disassemble the battery boxes I would have installed by that point so that I could work in the space. Taking the compressor out if I can't use it, while the batteries are in place won't be difficult.

Speaking of the compressor, I'd been sweating one detail, and that was how to hook it up to the electrical system. There are three wires on it. Take a look...

Notice the big black harness at the top. That contains one wire, and the matching harness is on the car, so no problem there. But take a look at the side there, and you'll see two wires, one with a male the other with a female plug. There is no place to plug those in. No dangling wires left in the engine bay that might accept those to plugs. Baffled, I went to talk to the guys that took the engine out. They showed me that those two just plug into each other. Josh, the mechanic had a car on the lift and showed me. I'll be damned. I would have never thought that they'd build a compressor with an external wire that has a connector in it. The only reason I can guess for that is if you needed to pull it apart to do diagnostics on the unit.

Anyway, thanks to them, I've got all the wiring sorted for the A/C system. Now if I can just get it in the car, with a functioning rpm sensor...

12 Volt System Tests Done (I Mean it this Time)

I got the replacement relay for the heater switch, dropped it in and it works just like it's supposed to. So here's how it works. The Car must be on for the heater fan to work. The heater fan must be on in order for there to be power delivered to the switch on the dashboard that turns on the heater. If the cars not on, no power to the switch. If the fans not on, no power to the switch. So there should be no way for the heater to be on unless the car is running and the fan is on. I'm trusting that means no exciting fires in my dashboard.

I got a bench power supply the other day. "What's that" you say? I'll explain. If you build any sort of electronic devices, you need some way of providing power to them to test them or operate them or whatever you have planned. Well a bench power supply lets you set the precise voltage and current (amps) you want to deliver to the equipment. "But Tim, you're not bright enough to build any high end circuitry" you say. Well, you're correct. But the great thing about these is that they can function as battery chargers.

You say "Well then, why don't you just buy a battery charger you dimwit?" Whoa, that was kind of harsh. The thing about these batteries that I'm allegedly getting someday is that they are 3.3 volts apiece. Not exactly your standard charger voltage. If one of them needs to be charged by itself for some reason, say it lags behind the others in the pack during a normal charge, then I can catch it up with this. I don't expect that to happen much because I plan to follow a fairly conservative approach to charging. But you never know.

Anyway, with that, I was also able to charge the 12 volt battery I'd installed a few weeks ago and have been running down ever since. With it nice and charged up, I felt it was safe to try that energy hog of a power steering pump. I'm pleased to say that the whole system worked flawlessly. I turned the wheels and the pump comes on right away. It stays on for 10 seconds after the wheels are straight again. If during that 10 seconds I turn the wheel again, the timer restarts. Plus no leaks! I'm very happy about that.

I also started modifying some of the carpet that lined the trunk, so that I can put it back in place. I have to cut out holes to accommodate the new equipment, but so far so good.

And you guessed it, still no word on the batteries.

Odds & Ends Part VI

Today was a day to take care of some smaller things.

I cut a hole in the trunk's battery box and mounted the ventilation tubing in it. I also ran the tubing to the fan mounted under the box that occupies the space where the gas tank was. I routed the tubing where I need it to go and secured it to the under side of the chassis so it doesn't move around and run into the suspension.

I also secured the wire loom that had been hanging in the trunk to the box mentioned above. Here's a shot of the trunk as it is now.

Notice the nice clean appearance, and the tubing inlet in the lower left corner of the picture.

I marked and drilled several holes in the tray that will hold the Zilla controller. Once I sort out the position of all the other electrical components, I'll be able to just mount the Zilla to it and then drop the tray in place and bolt it down.

That's all for now, back next week.

The Charger and a Home for the Zilla

I finished installing the charger in the electrics box in the trunk. I connected the charger to the power line that comes in from the gas door, and mounted the charger itself to the floor of the box. I also mounted the DC to DC converters in the box, simply bolting them down into place, and I sealed the perimeter of the box where it meets the chassis, to be sure that any water that splashes up can't get in the trunk area.



I still need to finish up the wiring on the for the converters and connect the charger to the batteries, but as I don't have them yet, that will have to wait. One of the things you can't see is a port in the back of the box that will vent fresh air into the compartment. When the car is running, or when the charger is on, a fan will kick on to force fresh air into the box, helping to keep everything cool. I also need secure that wire loom to the top of the box and eventually cut the carpet that was there to accommodate the opening.

I mentioned yesterday that I'll be using the original location that was used for the car's electronics as the home for the Zilla and anything else I can squeeze in there. Here's a shot of that space complete with an aluminum sheet I cut to fit.


That sheet will act as a tray that I can mount the Zilla and the hairball to. I still need to build the support for the sheet, it will sit a little higher than where it is in the photo. I'm a bit concerned I'm going to run out of room for all of the electrical doodads that I need to install. Some of them I can put under the tray because I won't need to access them unless they fail. Others I may end up running into the cabin and mount under the dashboard. I'll just have to play it by ear.

Never Say it's Done

Last Friday I mounted, for what I thought was the last time, the aluminum tray under the motor. Well, over the weekend, I realized that with a few modifications I could improve the way it fits into the chassis. It nagged at me all weekend until I could bear it no more. Today it came out. Again. I made the modifications, wrestled with it again and finally got it back into place. While I'm not saying that it's permanent, I did put thread lock on all the bolts that hold the cross brace that it sits on into place.


I mounted the water pump as well. Not that exciting or time consuming, but one more step closer. Notice the nice brass housing.


I also permanently mounted (doh! there I go again) the back box that will house the charger and DC to DC converters. Next I'll be mounting all the components in them. I can't begin too much of the wiring at this point, but I'll do what I can before the batteries arrive.

I also sorted out how to mount the Zilla controller. There is a nifty little water tight area back near the firewall, right in front of where the passenger sits. It held the car's ECU and many other electrical connections. Most of those are gone now. I'm going to have to build a little tray to hold the controller and the hairball, but there's plenty of room, some good places to anchor the tray and it shouldn't take too much work.

Back Component Box

Pictured above is the box in the trunk with three of the cars components in it. The charger on the right, and two DC to DC converters. None of it is wired up yet, or even bolted in for that matter. This is just a dry fit test. Though you can't see it, there's a cord that runs out of the back of the box on the charger's side. That runs to the fuel door on the passenger side of the car. One of those cables you see will be routed back to connect to that. The other cable will be connected to the batteries in the box that you can barely see at the very bottom of the picture.

Also on that side is a 2" tube ducted into the box to provide fresh air to the charger when it's operating. The charger has two fans in the back that vent air out the front into what will be the interior of the trunk. I need to make sure fresh air can get to those fans, and that stale air has a way out (that vent will be elsewhere). Once I've put some paint on the steel I cut to make room for that, I'll be ready to bolt it all into place.

The DC to DC converters will be wired in parallel and will put out the 12 volts needed for the car's normal electric systems, and about 80 amps continuous, 100 amps peak.

Odds & Ends Part V

Well, it's been a very busy week and today was the first chance I've had to work on the Z3. Let's tally up what I did, shall we?

1. Finished the mount for the box that's going in the trunk. It will fit through the hole I've cut and into the cavity that was occupied by the fuel tank. Luckily, there was a mounting bracket welded to the chassis in very nearly the perfect spot for use to support the box. I cut a piece of light steel to bolt to it, and the box will simply rest on it, kind of wedged into place. I'll clamp it down on the front edge, and that will prevent it from moving at all.

2. I also cut a 2 inch hole in the back of the box. I will connect some ducting to it and it will do one, possibly two things. It will provide fresh air to the fans of the charger while it is running, and it may also be the conduit for the AC power line to the charger. I might just drill a separate hole for that so there is nothing in the tube obstructing air flow.

3. I figured out how I'm going to mount the power steering pump. I had decided that I would simply suspend it from the front battery box making use of the room there. Today I cut and fitted all the steel needed to support it. Next up for that is simply weld the steel up and then drill out a few holes so that I can mount it in place, easily removing it if necessary.

4. One of the biggest pieces of news this week is I've opted to scrap the idea of lead acid batteries in favor of Sky Energy LiFePo4 batteries. I'd come across a fabulous series of videos put together by a gentleman by the name of Jack Rickard, in which he talks about how best to treat LiFePo4 batteries. All fascinating stuff, but what really caught my attention was the price he mentioned that he paid for the batteries. When I started looking into the project a year and a half ago, a similar pack of Thunder Sky's would have run me over $20,000. Well they've come down substantially, making them much more economically viable. Jack was kind enough to answer some of my questions, and encourage me along. If you care to check out his project, you can see it here. First rate stuff!

The Sky Energy's will weigh in at 475 lbs, versus the 737 lbs that the lead acid I had intended to use would have weighed. In addition, if handled properly, they are rated to handle 3000 charge/discharge cycles. That amounts to approximately 150,000 miles, or for all practical purposes, the life of the car.

5. To that end, I need to redesign one of the battery boxes and the tray that holds it to accommodate the different shape of the batteries. Fortunately, there is no need to adjust any of the bracing that we'd welded up over the past few weeks. However, I will be able to reduce the weight of two of the trays used to hold the battery boxes. The two trays weigh in at about 32 lbs, and I should be able to drop that to about 10. Today I took all the necessary measurements and began cutting up the new lighter steel to hold it all.

That's all for now. Hopefully next week, I'll have more time for the project.

More Cutting in the Trunk

Today was spent cutting out the bulk head in back of the trunk, that separated the trunk from the fuel tank area. Here's what it looked like before:


And after:


I have a bit grinding to do to get the opening nice and even, but that won't take too long. I'm going to have a plastic box built, just like the battery boxes, to fit in that space. I built another mock up out of cardboard to make sure it all fits.

This new box won't hold batteries (not enough room). Instead I'll be mounting the charger and the DC to DC converters. After giving it lots of thought, I decided to go with two DC to DC converters. Each one can put out about 40 amps at 12 Volts DC. The power steering pump alone can pull up to 75, so clearly one just wouldn't be enough.

I had thought that I'd put in an auxiliary 12 battery to handle the extra load, but realized the battery alone wouldn't be a good plan. Instead I'm going with two converters AND the battery. It just keeps getting more complicated. But that's ok, I'm trying to build this so that I have as few compromises as possible.

By the way, thanks to my good friend Len in Malta for the great suggestion of using the back of the trunk and fuel tank cavity in such a productive way. Hope you're well Len!

The Back Battery Box is Complete

I said I'd try and finish it today and I did. It's late at night, but the rear battery box is done. Here is a shot from inside the trunk. You'll notice the foam insulation surrounding three sides of the box. That's to keep water out. I ran out of foam, so I need to get a bit more to finish up the front edge.

Here is a shot of the back bumper from roughly ground level. You can see the battery box from underneath. It's about even in height with the trans axle. Once the car is on the ground, I should have plenty of clearance for normal driving, but I think I will have to go down steep curbs carefully.

My God, Man! What have you done?!

BMW lovers, you may want to look away for a moment. You've been warned.


I prepared the trunk for some serious brutality this morning. Measured out the space where the battery box will go, got out an angle grinder with my best diamond bit and went at it.




It went surprisingly well. Lots of sparks, a little smoke and no blood. Sounds like a near perfect date. I'm considering using carbon fiber to make the battery box that will fit in that hole. Of course it's lighter than steel but also many times more expensive. But how cool would that be?!



Here you can see a mock up of how the batteries will fit in the space. Each of the boxes is slightly bigger than one of the batteries I intend to use. See, I've conveniently drawn battery terminals on one of the boxes to show it's supposed to be a battery. Isn't that clever? No... it really isn't is it. Lets move on.

Once I build the box to hold them and mount it in place, the tops of the batteries will be just below the surface of the trunk's floor, and yet several inches above the bottom of the bumper and the rest of the under-carriage from underneath.

Odds and Ends: Part I

Spent the whole day doing a variety of tasks, and yet it felt like I made no progress!! In retrospect, I guess it wasn't all bad. I worked on getting the gas tank out. I mentioned earlier that I'm going to be cutting it to pieces rather than taking apart the entire back half of the car. It's plastic after all. Crazy, perhaps, but so far so good. Oh and yes the tank is completely empty with no smell of gas what-so-ever. Even so, I have two extinguishers at the ready.

I spent a couple hours cleaning and degreasing the engine bay. 134K miles of road grime! Now I can work in the space without looking like an oil rigger from the 1800's.

I carefully measured off and marked the area that I'm going to be cutting from the floor of the trunk. Once I get a box built for the space I will be able to suspend 4 batteries below the floor of the trunk. I can put the carpet back over it and still have space to haul lumber and what-not.

Last, I drained the power steering system. I need to remove the old power steering pump, but there's a problem. It's not attached to anything anymore and the nut that holds the high pressure hydrolic line on the pump was tightened by an angry gorilla. The bottom line is that I can't hold the pump still AND put enough torque on that bolt to break it free. I'm going to need to start pumping some serious iron, or try channeling the spirit of Archimedes.