Thursday, May 30, 2013

Down the Drain

Still working on the voltage sag on the 12 volt system. The symptom is that the controller error light blinks when both the brake lights and turn signals are on when the headlights and cooling pump/fans are running. Swapping the 30 amp DC/DC converter out for a 44.5 amp version reduced the incidence of the low voltage warning, but when headlights, brakes and turn signals were in play, it remained an issue. I found these at the local auto parts store:

They promise to drastically reduce the current draw while giving a brighter light than the old fashioned filament style bulbs. With resistors built in, there's no need to add a load to work with the existing flasher. 

Installation is easy, just remove the tail light lens and replace the old bulbs with the new LEDs. They look clear, but actually give a red light when powered.

The new LEDs are on the left and the old bulbs still on the right. I can't say that the LEDs are that much brighter in the daylight, but they are certainly no worse.

The proof is in the testing and early results are good. The first thing I notice is that when flashing there is no fluctuation in the voltmeter reading, where there was a very clear "tic" up and down on the needle before.

A quick drive on my favorite test route with the headlights ablaze got the cooling pump and fans running. The voltmeter was showing a constant 12.5 volts, and it held steady at that level when the turn signal and brakes were applied, so I'm going to declare success.

The next step will be to swap out the old sealed beam headlights for LED replacements to get a brighter light out front. At around $260 each ($520 a pair) though, that will have to wait a while.

Monday, May 6, 2013

Helping to Keep Austin Weird

When we first moved to Austin, we saw a lot of these bumper stickers:

We thought it a bit quaint, but it's true! Sunday I got to be a part of some of the weirdness. The AustinEV club sponsored a display at the Mini Maker Faire at the Palmer Events Center on the south shore of Lady Bird Lake.

The list of exhibitors was long and eclectic: everything from vintage costumes to making mud bricks to a huge Lego railway to weaving to robots to home composting to an inflatable planetarium. Click here to a see the exhibitor list. Here's a video that captures the variety of stuff that was going on:

There were all kinds of activities for kids - they could get their faces painted and ride on a big butterfly bike, see a Star Wars Jedi Fighter, and create their own custom bars of soap:

And of course there were the electric cars!

evTD on display

Also on display were a Saturn and a Jeep, so we had a cross section of cars from off-road to sports car to family sedan.

There was a steady stream of interested visitors, almost universally positive about the conversions. This was a very "green leaning" crowd, so there were very few of the critical questions we often field about return on investment or perceived shortcomings. In the case of the evTD, mostly wonder at how a classic like this could be made electric.

Photo courtesy of Mary Jackson
I did chat with one lady who said they were expecting their Tesla Model S delivery in a couple of weeks and several Dell employees who said that there were new charging stations at work so driving electric was starting to make sense. I'm not sure if we moved the EV ball forward much, but there was certainly a positive vibe around this show.

We were positioned right next to the bandstand, so it was a bit rough carrying on a conversation at times. The highlight of the music scene came when the last musical group made their appearance late in the day. The Dead Music Capital Band marched(?) from the main entrance to the stage and gave a concert that had everyone asking "Huh?!"

Austin bills itself as the "Live Music Capital of the World", so the DMC band is - you guessed it - zombies playing tunes to wake the undead. Here's a sample:

Did I mention "Keep Austin Weird"?

In other news, This is the longest trip I've taken to date in the evTD, 39 miles on 57Ah. That's 1.45Ah/mile and extrapolates into a real-world range of 55 miles to an 80% depth of discharge. I'm actually pretty pleased with that given that the evTD has the aerodynamic drag coefficient of a cinder block.

Saturday, May 4, 2013

Spec Sheets and Handouts

I'm taking the evTD to the "Maker Faire" show tomorrow, and based on a comment from Jarkko Santala, I'll be adding a clear acrylic cover to the component box so people can satisfy their curiosity about what's in there. It also occurred to me that I should put together some info sheets and signage to answer some of the recurring questions that are likely to come up.

First I printed out the contents of this blog and organized the pages in a three ring binder.

That way I can show the steps involved from beginning to completion. Or people can leaf through at their leisure if I'm in a conversation with someone else.

I also put together some placards that give basic information at a glance. These can fit against the front of the windscreen, held in place by the windshield wipers.

It also occurred to me that it would be nice to provide a take-away sheet for people who show real interest and might like to follow up. I'm only printing twenty five, so these are not for everyone, and I'll have to be a bit selective on how they're distributed. Here's the front and back:

and the inside:

I'm also designing some simple business cards that point to this blog for further information. Seems the last time I did a car show I had to write it down about a hundred times.

Wednesday, May 1, 2013

It's the Little Things

Continuing the refinement process, I added two little neoprene bumpers to the motor hatch in back to stop the rattling - not much to see there. Also devised a way to lower the soft top without pulling all the snaps off the back (which is a real pain, literally). Securing the folded top with velcro straps keeps it from flapping around in the slipstream.

The straps are attached to the spare tire supports by simply wrapping the velcro around the support tube.

The corners still tended to lift at speed, so another velcro strap on the diagonal from the folded top frame to the spare tire support got that under control.

The evTD is taking part in the "Maker Faire" show this weekend at Austin's Palmer Events Center. This show is about DIY activity of all sorts. Because it will be a crowd that isn't familiar with electric vehicles, I wanted to complete something I started eight months ago and never quite got around to. You may recall that I originally configured closed boxes to contain the miscellaneous electric bits where the most positive and most negative cables attach to the pack. In the crunch to get the project finished for EVCCON, I took a shortcut and attached the shunt, fuse, and current sensor directly to the front platform.

It seemed OK for EVCCON where everyone is knowledgable about circuits and wouldn't be touching exposed 230 volt connections, but I felt it needed to be "finger safe" for a more generalized audience. The negative component box was pulled off the shelf and configured with the shunt, fuse, and current sensor inside.

I remembered why it didn't get done the first time - I needed to re-build the current sensor link so it was about an inch longer and had the gland nut in place before crimping on the lug. With that done, it went together nicely.

It fit the space well and tidied up what had been a busy looking, somewhat cobbled up area. With the cover installed it looks almost like I planned it that way.

The other new item you'll notice is the maintenance switch on the upper platform. It's become apparent that the DC/DC converter needs to run full time to keep up with the "always-on" 12 volt loads; the GPS speedometer, radio, BMS, and JLD 404 amp-hour meter. The maintenance switch gives me another way to disconnect the pack in addition to the emergency contactor.