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James and the EV, IV · 15 January 06

Brace Welding

Time for an update on James May’s EV. Last time I posted he was on the brink of his first test run and then…silence.

Uncomfortable silence…

And then he started posting in the comments section on the site, so we knew that he was still alive. Thanks for leaving us hanging, James!

Still, the comments didn’t let us know how alive the EV was.

The good news is that he’s been driving the EV and it sounds like he’s having a blast. The bad news, well, we’ll get to that later.

First let’s go over the last batch of photos James sent along. The first photo up top (click for larger view) shows that he’s a steady hand at welding. Nice work!

According to James he picked up a little MIG welder when he was 16 or 17 to help repair his aging, but beloved, Mazda B100 pickup. The truck finally ended up in truck heaven (or wherever it is trucks go when they die in England) and he moved on to making an EV.

Having weeded through a number of blurry photos from James I’m thinking he should apply his welding skills towards making a camera tripod! ”:^)

Braced with Plexiglass in place

Next up we have a closer view of a completed battery hold-down along with plexi-glass safety cover.

I created one of these to cover the electronics control board on our Mazda EV, but didn’t do as good of a job making hold downs like James has done here and it eventually snapped off. These covers keep the curious hands and/or wayward metal wrenches away from high voltage terminals.

The black stuff coating the metal brackets is an anti-chip paint which is somewhat rubbery. He hopes it would help prevent a short if he’s working on the pack and drops a spanner. Wrapping the, uhm, spanner in electrical tape is another common safety approach.

Back Battery Mounts

And finally we have the view from the trunk of the back batteries with all of the hold-downs and covers in place.

The “top” three batteries are actually under the back seat and you wouldn’t see them on opening the trunk. At the very bottom of the picture, almost out of frame, is a small muffin fan and I’m guessing the charger.

I suspect the thinner red and black leads are from the charger, one attaching to the “end” of the rearward battery pack and the other snaking to the front to attach to the “start” of the pack. The fan most likely keep the charger cool.

Time for the bad news…

Melted Battery Terminal

Here’s unlucky battery #13 after having a terminal meltdown. James was driving along and the terminal overheated and melted down. He has since been able to fish out the molten slag, re-seal the case, affix a new connector to the terminal, and all is well again. I’m sure it was a tense moment.

Some folks on the EVList say not to get this type of terminal, that it can’t handle the needed torque and is too thin. I’ve used this terminal type with both of the Trojan SCS225 packs used on the Mazda without any problem. Maybe Trojan changed the specs since then?

When putting your EV together you do need to be overly zealous in checking and re-checking connections. Just a little bit of resistance can quickly turn into too much heat when a few hundred amps of current goes through it.

For batteries I clean all of the lugs and cable ends before assembling, then firmly tighten while holding the cable, so as not to over-torque the battery terminal.

Then, after a short test drive, quickly touch each connection with the back of my hand to feel for any warmth which might point to a bad connection. Repeat this process as often as your paranoia dictates for the next week or so.

I haven’t tried one yet, but you can buy infrared thermometers which would do a much safer and quicker job of measuring connection temperatures than the average un-calibrated knuckle.

Comments 2
  1. — James May    Jan 16, 2006 08:23 AM    #
    yes sorry about Tte photo quality. A lot of the problem is that the photos were taken in very low light after work. the shutter times are long.
  2. Jerry Halstead    Jan 16, 2006 09:04 AM    #
    No problem, just razzing ya. ”:^)