Paul & Sabrina's cheap DIY 144v motor controller - Page 102 - Fuel Economy, Hypermiling, EcoModding News and Forum

edown · 04-20-2009, 11:20 PM

Paul, Check out this site, they send quotes to many companies.. I got quotes for your mosfets as low as $2 each for just 12 pieces.. Overseas of coarse..

Electronic Components Marketplace - Hong Kong Inventory Limited, China, Home

Evan

MPaulHolmes · 04-20-2009, 11:34 PM

Holy crap! That would be awesome! When we're ready to order a bunch maybe we should go through them?

MPaulHolmes · 04-21-2009, 01:30 AM

I de-soldered all the capacitors on the old controller. Now, if I can remove all the diodes and mosfets safely, that would be really nice. I know all the diodes are fine, and the last 7 mosfets seem to be good too. If I were to hook up the control section again, it would be a perfectly working 300-350 amp controller. Well, except for the fact that I took out all the capacitors. haha.

edown · 04-21-2009, 08:33 AM

Paul, the quotes just keep coming in! Just got one for your mosfets made in 2007: 12 for $7.00. I've had about 15 quotes so far..

MPaulHolmes · 04-21-2009, 10:02 AM

Careful, edown! I just spoke with an engineer that told me his company now never buys directly from china because the parts kept failing, and then they discovered that the part numbers had been sanded off, and a new part number had been added! I'm just passing on what he told me. But if they are bad, it's only $7. You could try it?

MetroMPG · 04-21-2009, 10:04 AM

CSI: EcoModder

Wherewolf · 04-21-2009, 10:17 AM

I would agree with the "be careful" in buying direct from China. I've personally purchased some "Cisco" products out of HongKong....it's said "Cisco", had the logo's and everything, but when held side by each with a real "Cisco" product, it was obvious that it was a cheeeeep imitation. Probably parts rejected by QC (which isn't very high in China to begin with) and just silkscreened with logo's and re-sold. I don't know if it's worth the having to rework a controller when the parts fail - I think our respective labor in assembly is worth some $$$ - it would be a PITA to keep having to remove and replace because we bought rejected and re-silkscreened parts.....I want a quality controller.
Wherewolf

MazdaMatt · 04-21-2009, 10:57 AM

I work in electronics. Now and then we get dinged because one of our suppliers bought a cheap lot from someone who bought it from china or ebay via china. Most recently we had a lot of supposed op-amps that were not what they claimed to be.

Also, i went to lunch with some salesmen from Avnet (our Freescale supplier). One of them was at an electronics trade show in Hong Kong. There were booths from all the major players in electronics - microchip, freescale, motorolla, TI, maxxim, etc etc... and then there was one booth that had ALL of company logos at it. Right there at the trade show, in the face of all of the other companies, this business was advertising chip re-marking. They said that they could take any chip, shave off the top and put any other company's logo and part number on it. That was actuallytheir idea of a legitimate business. Much of the time, those parts are coming from disposed electronics that have landed in china. Poor dirty children desolder the parts over open fires, trade them in for some food and then they are sent for cleaning and re-marking. Then they sell them to you for 7 dollars for 12

MazdaMatt · 04-21-2009, 11:05 AM

Paul, was the gate-source resistor blown up due to proximity to the blowing source lead? Or was there some insane current going from gate to source? Are your gate drivers still pushing current? (you could test by pulling up the gate driver pin and attaching a resistor to ground and checking voltage across it).

Let me know about that part I was questioning above, too... the opto/mosfet chip.

MPaulHolmes · 04-21-2009, 07:04 PM

Hey Matt! Yes, we can do without that part. Just an optocoupler and mosfet will be fine. We're going to do that instead. The guy that's helping me wanted me to thank you for mentioning that! He had included it because he had some other ideas that required some sinking and sourcing of current, and then just went back to something that a mosfet/optocoupler could do.

Only the right side of those gate to source resistor legs were vaporised. The left side was essentially unharmed. I'm thinking it was because there were so many electrons going from source to drain. Hey! Real life proof that current really does flow from negative to positive! It also got progressively less damaging as I moved away from the B- connector.

Maybe it would be better in general to have the furthest away mosfet turn on first?