Thursday, January 28, 2010

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...


Gam0ra said...

"You know Bob, I like this compressor design but I think it needs something. I really think we need to build in an external electrical failure point so we have some easy reason to replace it. That way we make more money off of it more often."

"Well how about we just put a wire on the outside that just connects to itself? We can just disconnect it and say it failed. Nobody would expect a wire that connects to itself...that's just dumb."


Tim Catellier said...

Ha! I'm sure you're right. Except it would be Hans or Gunter, instead of Bob.