Battery Bits

Had four days with a clear schedule - no rehearsals or concerts. Last weekend I performed in three concerts, the weekend before played two concerts with six rehearsals in between. That doesn't leave a lot of time to spend on the car, but this weekend I have the luxury of uninterrupted work time. It was great to get some things accomplished.

I mentioned in an earlier post that we've finalized the placement of the batteries, all in the rear. Two of the banks of batteries are just as received with sixteen modules all built up into a unit. Those we had figured out some time ago.

Since the charger is moving under the hood, that leaves a nice opening between the full banks over the transaxle. Four battery cans stacked are just the right height and will allow for a deck covering the batteries under the hatch with no loss of storage. So I built a four-pack in that configuration that should mount in the center of the battery bay.

That leaves eight modules, so after consulting with Robert, we decided to keep all the batteries together in the rear of the car. I proposed pulling out the rear seat and installing them there, but Robert made a good case for keeping the back seat and placing that group on the remaining deck behind the seat back.

Once again, four of the battery cans stacked flat was just equal to the height of the seat back above the deck, so I built an eight can module in two sections electrically tied together by one of the original flat connector straps from the Better Place pack. The strap is solid copper, plated with a silver material. It is insulated with a very tough plastic jacket (mylar maybe?) that is adhered to the strap and very hard to remove. Don't ask me how I know.

These will go over to Pro Automotive on Monday to get fitted to the car. They are built up with six inch carriage bolts in 1/8" aluminum bar stock passing through the holes in the battery cans and mounted to the aluminum sheet with metal lock nuts. It feels very secure and can be mounted by drilling and bolting the base to the battery box structure and deck. I need to bring the remaining four pack that is behind the transaxle home for the same treatment.

UPDATE April 27, 2015:

Dropped off the finished battery modules this morning. The center pack looks real nice in its new home. Robert plans to build a tray to secure the eight pack behind the rear seat. He's also working on the motor mount and Dave the machinist is preparing the coupler for installation on the motor. Things are beginning to come together.

And Now For Something Completely Different

I'm going to wax nostalgic here for a bit, so move on if you don't want to hear an old guy sobbing in his beer. If you choose to indulge me, read on:

I went to the local hardware store today and found it was closed - no signs, just brown cardboard covering the windows. I suddenly got all weepy and felt a little bit guilty. Let me explain. This was an old fashioned, real life hardware store at Spicewood Springs and 183. I don't know how long it had been there, but walking inside was entering a time warp. They sold denim overalls, fertilizer, guns and ammunition, water heater elements, brass pipe fittings, chain and hose of all sizes cut to whatever length you needed, paint and stain, hand tools and wheelbarrows. They had walls of nuts, bolts, and washers of all sizes in little yellow bins and you could buy just one if that's all you wanted. Assortments of O rings and the odd sized furnace filters you couldn't find anywhere else. 

The guys who worked there were old and a bit cranky, but they knew what they had and where it was stashed and could figure out from your description what you were trying to accomplish and how to jerry-rig bits and pieces from all over the store to get it done. And their hands! Gnarly and rough, one guy was missing a finger or two, but you knew these were guys who built stuff!

They had a mechanical cash register and seemed to deal mostly in cash - credit cards took a lot of head scratching and a very old dial-up terminal. But it was ok because they knew how to make change and had the most amazing assortment of small brown paper bags to hold precisely the two bolts and three washers you were buying.

But the thing that took me back was the smell, a sweet aroma of leather, rubber, cosmolene, tobacco, steel, paint, 3 in 1 Oil, and a thousand other hardware store smells. Oh and maybe a little sweat, too. That hardware store perfume is what took me back to some special times.

On Saturdays around our house, there were chores and repairs to be done. Often Dad would load my brothers and me into the family station wagon and head to the hardware store for some odd bits to repair whatever we had broken that week. To me that hardware store was wonderland. They had a small hobby shop section where I could see all the parts for the world's best model airplane I was planning to build: the balsa wood and tissue paper Ringmaster kit, McCoy Red Head .35 gas motor, wooden or nylon Top Flight propellers, glue and paint and a thousand other specialized model airplane parts. I had calculated exactly how many lawns I'd need to mow to pay for each precious component, but never seemed to actually get there.

And the smell in that boyhood hardware store sixty years ago was the aroma that struck me whenever I entered the one on Spicewood Springs. I was usually going there for some obscure bit for one of my electric car projects that I knew they'd have. Suddenly I'm that little boy again dreaming of the things he'll build someday.

I'm going to miss that store. Sure, the big box stores have so much more, but Lowe's and Home Depot lack the things that made the home town hardware store so special; the ability to buy just one of something for three cents and get change back, the wisdom of the old guys who knew how to build stuff out of old crates and tin, the blissful lack of marketing and product placement. And I don't think they'll ever figure out how to synthesize that authentic hardware store smell. Sorry I never got to say thanks and goodbye.

Quick Update

Quick update here: things should pick up now that Robert can focus on the Porsche EV project a bit more. He and Keith picked up the motor and a battery pack from my place, and the battery box is getting more populated.



Two banks of 16 modules flank the transaxle with a bank of four behind. Another four pack will be installed above the axle and two more four packs will go where you see the black carpet against the rear seat back. That puts all the batteries in close proximity in the rear and frees up space under the hood while preserving the rear seat. All good. That puts about 400 pounds over the rear axle. While the rear has settled, it doesn't appear to have lost too much in ride height.

Note also the maintenance disconnect with the green handle. It is positioned to split the pack as it did in the Better Place arrangement. It also contains the traction pack fuse. Finally, I've installed the plastic protective covers over the terminals to prevent a repeat of the welded chain incident.

Next step is to have the machine work done on the motor coupler so the motor can be installed. More to come ...

New Charger, New Plan

The new Lear charger arrived from EVTV yesterday, and it's pretty impressive. It's the charger used in a Chevy Volt, and this one appears to be brand new. The part label on the box was partially covered with shipping tape, but the label instructing that the core should be returned in the same box indicates it probably came directly from Mr. Goodwrench.

The two orange wires on the left connect to the battery pack while the orange bundle coiled on the right will go to the J1772 inlet port. It's 12' 10" long so there's a chance it might stretch all the way from the motor bay to the old gas filler on the passenger rear fender. The real magic is in the little black box behind the coil. It essentially contains a small computer that sends CAN bus messages to the charger to set its operating parameters. Mark Weisheimer deciphered the CAN message stream and Jack Rickard programmed the Arduino Due chip set in the black box to spoof the OEM charger into thinking it's getting instructions from the Chevy Volt ECM. It's all very slick and part of the EVTV strategy of making OEM quality parts available to do it yourself converters like me.

On either side of the orange input/output connectors are the liquid cooling ports. The Lear charger is water cooled which allows it to be somewhat smaller than the air cooled TC Charger it replaces.

You'll recall that I learned that my Better Place battery pack really wants to be charged to 4.2 volts per cell (403.2 volts pack total) to get its full capacity. The TC Charger at 389 volts just wasn't going to get me there. Given that the Lear charger is water cooled at a smaller footprint it will go in the motor bay, allowing four more cell modules in the rear battery box in place of the TC Charger. That leaves eight cell modules to put somewhere, maybe in place of the rear seat cushion.

Now we'll be rethinking the motor bay arrangements to accommodate this Lear charger along with the DMOC 645 inverter, cooling system, and precharge/contactor box. That will have to wait until we have the Siemens motor in place and can assess the space available. The project plan now looks like this:

Remaining work items: Pro Automotive

• Rear battery box
• Motor to driveshaft coupler
• Driveshaft tube to motor adapter
• Front motor mount
• Inverter mount
• Charger mount
• DC/DC converter mount
• Radiator mount
• Power steering and air conditioning hoses
• Front paint and bodywork

After that is all complete, it's coming back to my garage. The ONLY (?!) things left will be all the HV and 12v wiring, instrumentation, and interior work. Our June 30 target date is looming very large indeed.