One of the most sobering tests performed by a guy making his own BMS is here. His experiment showed that using the wrong parts can in deed cause a fire. Several designs out there use these same parts.

In another post, this poor fellow had his whole car burn to the ground. What a shame. He did a lot of work on it.

Here is a Prius fire story using A123’s. A bad connection was suppose to be the culprit of that disaster.

This P1 Dolphin board has the Mach220 chip that’s seriously damaged and the main relay fet vaporized from the board. Both instances left some low impedance paths between some traces. The Mach220 removal solved many of them. But the fet traces are damaged inner layers of traces. So the fet will have to be isolated and jumpered back into the circuitry.

All of the power supplies work with the Mach220 removed. So now the debug process starts. With a massive pile of projects on my plate, I don’t know how much more work this board will get until I have more of the projects completed.

This is how the board arrived. The 5v rail powered this Mach220 to death. Amazingly the 5v reg still works.

Here is what a correctly removed Mach220 location looks like. Zero lifted pads or traces. A socket will get installed here.

This fet had to have been jumpered to try and operate the main contactors directly. This is what happens.

The board did not squeal when it was tested again. It works fine now.

The #4 IGBT driver on the 4th board had a bad opto coupler on it. Now it’s in line to be tested in a truck.

Now for the squealer.

Three of the P4 50kw boards booted up without issue. Their next step is to be test driven along with some other boards.

The 4th P4 50kw board has an issue with IGBT driver #4, so it’s faulting. Disconnecting the IGBT driver allows the board to boot fully.

The 5th P4 50kw board squeals when powered up. Been down that road before.

The 6th P1 50kw board has a crater in the middle of the Mach220. I’ve de-soldered a few of the 68 pin Mach220’s and put down surface mount sockets, but there could be some toasted traces too since it took so much power to damage that chip.

Powered up one of the 65kw boards. They use the J1850-VPW bus for communication, so I could not watch the activity on Buscom without a J1850 to RS232 converter. Plenty of these on the market to fix that. More than a level shifter is needed here apparently.

One of the boards that nearly boots up, Is showing an IGBT fault during bootup. It has an issue in the #5 IGBT driver.

This evening I tested 5 of the 6 50kw Dolphin main boards. Three work fine in initial testing. 2 nearly bootup, but fail. The sixth board has a crater in the middle of the Mach220 chip. I’ve replaced 2 Mach220’s in the past. So it will be easy. But the chance of some board traces being damaged is very high.

Some weeks ago I noticed that my scope had the #2 channel not working. It’s a Tek THS720. Nobody has touched this scope except me. Measuring the bnc connector impedance on the scope probe inputs, found that the #2 channel was at 1/2 meg ohms and the #1 channel was 1 meg ohms. Both should be 1 meg ohms. Something was up. So I took a brave step and took it apart. What makes this brave is that the scope is all solid state and portable. So it’s compact. Every step of the way I kept checking the bnc connector impedance. Right after I unsoldered the two short pieces of coax from the board, the bnc impedance went to 1 meg on the #2 channel. I could not see what the cause of this was. So after a serious inspection I soldered the coax leads back onto the board. The #2 bnc’s impedance was now at 1 meg. Sweet! When I finally got the scope reassembled, the #2 channel worked perfectly!! Man was I relieved! It appears it was just a bad solder joint. Although the solder was very nice when I inspected it.

Was at Robogames during the last meeting.
– Took my self balancing scooter.
– Converted from 4 NIMH packs to 3 Lithium A123 packs.
– Charging it with my rack mounted 60v 10a CC-CV power supply.
– Just received a small 36v 10a switching PS for mounting inside the scooter for on board charging.
– Added a reclining camping chair and a joystick for steering in place of barstool.
– Used both barstool and recliner at Maker Faire due to poor solder inside the, brand new in the box, Joystick.
– Took the scooter to the Maker Faire as well.
– Will be taking it to Burning Man.
– Finally got a new wheel from the guys at the Tech Shop.
– Drunk employee crashed the scooter, cracked an aluminum hub and a wheel.
– I was never told of the crash.
– He rode it without consent.

Mapped all of the hundreds of components on the Dolphin board to a spreadsheet.
– This makes possible the ability to compare parts from one generation of board to another.
– Should help find the differences in parts between relaible boards and non-reliable boards.
– The goal is to find the source of the dropout issues.

Purchased a 60v 30a constant current constant voltage power suppply from Ebay.
– It was supposedly fully tested.
– The fan, one filter cap and a third part were shorted.
– Repaired it.
– Works great for recharging batteries during load testing.

Bill and I are building a Yurt for Burning Man.
– See Photo.
– Most are assembled with nylon strapping tape.
– We are testing Liquid Nails and canvas.

Scored a dozen important circuit boards for USE vehicles.
– Was suppose to be split up.
– Suddenly found boards on Ebay.
– Emailed owner and asked if I could buy them. He agreed.
– Pissed off a few people.

Got moderated on my own forum.
– 4 deals went bad. Me mad. So sad.

GV wants me to make them Lithium boards.
– Never seem to have any money.
– They want to own the schematic.

We need a place to meet on August 8th. Ana’s ??

Added note to SJEAA website that we won’t be meeting here Aug 8th.

www.frompatenttoprofit.com

Saturday Aug 29th, 2009 EAA Rally.

Today was all about cleaning house, so to speak. The spreadsheet that maps every component on the Main Dolphin board, is done. I also added many links for the schematics that cover the various circuits. It’s far more organized and quicker to look things up.

Due to the spreadsheet I found many differences in component values. This could help with the finding the dropout issue.

One thing I looked into long ago that I want to revisit is getting a board X-ray’d so that I can find out more quickly where the traces are going. If some are damaged an Xray may help to locate where the trouble is.

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