1994 US Electricar Repair Blog by Mike

Today I just announced the opening of the US Electricar store to the US Electricar Yahoo group.

If you have not noticed or heard, I’ve opened the US Electricar.net store for USE owners so they can get repairs and parts to keep their vehicles running. There are links on this blog to take you there. Enjoy!

Today I finally got a fixture together to wind the T1 transformers that fail on the Dolphin chargers. I used an IR led pair tied to a counter to tell me how many windings were made. I wrote several types of G-code to have the cnc mill help in the winding of these parts. It worked out well in the end after several iterations. I settled in the 532-540 ohm range after they were wound. This was a few turns under 3k. I have one more transformer to wind. I’ll take some better video with a better source. It took days to figure all of this out and get it built and tested. The original estimate for rewinding was 15 hours. By working on the G-code and the cnc hardware I knocked is down to just over 2 hours. But last night I had a better idea. Now the full rewind takes 5 minutes while the hardware counts every turn. Sweet!

The brightness of this IR led was too high. The Rx led did not like so much light. These pics were taken with my G1 cell phone since the human eye cannot see Infra-red light. Thanks to Bob at Halted for that great tip! Video camera with night shooting have the same capability of seeing IR.

This brightness worked well. I might even be able to drop it a bit more, but for now it worked fine.

Here is a winding video from my G1 cell phone. You need Quicktime to play it. I didn’t sit still long enough to show that the transformer is moving up and down via the cnc. It spaces the windings out very nicely. I borrowed the counter from my automated battery load tester.

It occurred to me today that I could design a dropin replacement for the Dolphin’s filter caps, HV buss, and IGBT hardware under the main board. It would be put together a lot like the ACP cars. Separate igbt’s in parallel for each phase. Several filter caps too. This would make getting parts far easier. There is a a lot of volume to work with under the main board. I’ll have to draw it up in cad sometime to see how it will physically fit. I should dig up the ACP pics I have as well of their hardware.

After delivering several more Dolphin boards it was time to assemble my system. I turned the key and as soon as the ready light comes on there was a gun like pop! I had forgotten to connect the igbt driver cables. At least the main board was not affected. All 3 igbt’s are shorted. I am lucky that my last customer was willing to give me his 3 spare igbt’s.

The #2 and #3 main boards that have received the Classic Dropout mod shipped today. They work very well compared to when I first got them running. What a thrill to finally see such great success with a problem that plagued these vehicles for years.

The first main board with the Classic Dropout mod shipped today!! Two more have
been modified and are ready to ship as well.

The Dolphin passed a 17psi coolant system pressure test in the truck today.
It’s running very nicely now. Since I have to spend to much time under the hood I
added a toggle switch to the power steering pump relay. Man it’s a lot quieter
in the garage!

So now it’s time to test drive this 1 of the 4 boards that are here with the new
Classic Dropout mod. So far it’s worked perfectly.

Some wonderful people sent me a pair of Dolphins to repair. Someone before them
had been into both of them deeply and did some serious damage. Pins were not put
back into connectors properly. The fets on the charger board were not even
parallel to the base plate. Both main boards and chargers were toasted. Even the
GFI hardware was missing from both units. Parts were missing from one of the
dc-dc boards. So when these systems arrived they had one board out of 6 running.

The one charger was the very latest revision from USE as it had a new board and
revision I’d not seen before. Only one fet was shorted, the other was fine. My
standard rebuild is to replace both fets, both relays and the diode weather they
are bad or not. So that’s what it got. I was very happy to see that the T1
current transformer survived the onslaught of failure.

One main board had the standard shorted bridge rectifier that goes along with
the shorted charger fets. The fet driver pwm output was fine however. But it had
happily open circuited the traces that usually just get shorted to other things
and cause a whole other set of issues. So some jumpers were added to the new
bridge rectifier. The board made it through my long QC list of tests and runs
well in the truck. Both boards got the regen upgrade (I modify the Dolphin to
increase the regen output by 40%) and the Classic Dropout mods for vastly
improved reliability and a better driving experience.

Once the charger was supposedly rebuilt, and the main boards repaired, It was
time for a test run. The Dolphin booted fine. But as soon as the throttle was
pressed the Dolphin faulted with a sizable thunk and gave an IGBT fault. It
turned out that the large diode on the charger board, when shorted, ties the
motor’s neutral line to the pack negative. That’s essentially a short across the
output of the Dolphin. It was odd at the time that none of the Dolphins IGBT
fault circuitry was triggered. All of it was normal. Yet I got an IGBT fault. It
turns out that the software looks for a reasonable load at various throttle
positions. Since the load was nearly infinite at low throttle it protected
itself by disabling the IGBT’s by not energizing them rather than the IGBT
circuitry sending a fault.

Then there are the mice that got in these Dolphins. They love eating insulation
off of wiring. Especially teflon wire. Then of course they have to use the HV
section of the Dolphin board as the bathroom.

After all of the repair work, and the passing of the many bench tests, it was
time for a test drive. The first board had dropouts so badly, that it could not
even pull itself back into the garage. I would say a dropout every second. The
next board dropped out every 15-20 seconds. After much studying and testing over
4 years, this really bad board made it a little bit easier to diagnose what was
causing the classic dropouts. Thankfully I figured out the dropout issue as
these boards were destined for the scrap bin! I pulled a 3rd board out of
mothballs that had bad Classic Dropouts, and it too was cured of dropouts with
the mods I had made to the other two boards.

After performing the Classic Dropout mod, I took both Dolphin boards for another
ride in my truck. Zero dropouts at very high regen or very high acceleration.
Nice improvement! I went for a walk at the park to enjoy the rare sunshine. I
noticed a bad coolant leak as I walked back. The bottom plate on the Dolphin
chassis is just .125″ thick aluminum glued and screwed on. The glue is very
brittle. When I used my cooling system pressure tester on the radiator, the
Dolphin cooling plate squirted coolant all over. It’s almost impossible to get
the tiny red-loctited screws out. It takes quite a while to scrape all of the
adhesive off too. I’m about 60% done. Makes me think this is another ticking
time bomb. This is the second Dolphin I have had that has cooling plate leakage.

Time to get to it!

Since I am swapping around complete Dolphin systems for testing, it made it very
easy to reach down and pull out a water pump brush. Was I surprised. The brush
still had about 85% of it’s length left after over 10k miles were put on it. The
originals only lasted a total of 10500 miles! What an improvement! If you look
at my photo album there are pics, descriptions and part numbers of the brushes I
bought and mdified for my water pump. They were only around $15 or something
compared to the $75+ factory brushes.

I thought for sure I’d be replacing them again. Some day I’ll pull the motor out
to check the commutator for wear since these are obviously harder brushes. Rough
math shows they will last about 60-70k miles.