Sounds like a nasty fall. Hope your ok. You could take a spot next to @psychotiller to recover. I took a nasty spill at 25mph in San Diego and messed up my hip for two weeks. Luckily I was wearing gloves so I didn’t mess up my hands too much. My hip took all the impact.
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Feel better soon brotha!
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ur phunny…
If you are building from scratch, lap both flat 1st, it works better for thermal adhesive. You can lap it flat with a 500-1000 grit sharpening stone, wet and dry sandpaper works well if it is on a flat surface. FET’s are made from silica (glass), so they take this treatment well, Not too smooth, you want the thermal adhesive to have some purchase on both surfaces.
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I thought these switches, when they failed, usually go closed circuit (ON)? Scary shit.
Depends on how they fail. Mine was stuck ON, the solder bridged the MOSFET leads, that’s not a problem, the motor is controllable. Having it power off as you prepare yourself for acceleration … Not Good.
yea going to start wearing gloves for sure, have been using a helmet.
would the directfet switches that goldenHusky’s been building qualify?
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@thisguyhere Sorry to hear about your fall. Wishing you a speedy recovery!
On the topic of failing anti-spark switches…
It seems as though most of the switches on the market are only using 2 parallel IRF 7730 FETs. Which really should only be used for 30A continuous, 40A max. Adding heatsinks helps, but I just don’t think it is enough when you’re drawing 80A. They are each dissipating about 3.5W per FET, and you want to keep it under 1W generally
I’ve had a heatsinked dual-FET Vedder/Fechter switch fail twice already, and I usually never pull more than 30A. Leading up to both switch failures, I also experienced the slow 10 sec power on you mentioned. I think it is a sign that your switch is about to blow
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We should inspect the switch Joe. Typically, (always as far as I know) the switches fail in the on position which wouldn’t have cut power to your board. Voltage sag can cause your bms to reset though which does shut the board down for a split second.
When you feel a little better lets get together.
yea for sure, i’ll come by maybe in a couple weeks, pretty busy this weekend. i wanted to pickup a couple things anyhow. i’ll let you know.
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… Removable hip and knee pads.
Lots of different styles and prices out there. https://www.aliexpress.com/item/2016-KOMINE-MOTORPOOL-UBS06-Jeans-Leisure-Motorcycle-men-s-off-road-outdoor-jeans-cycling-pant
Maybe this too
To be serious, after having one nasty fall, helmet and front hand glove minimum. No watch (ouch!), and I’m considering one of those kevlared flannel shirts. Long sleeves anything helps.
Pics or it didn’t happen!
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This is a great point. Most of the times that my board has cut out under hard acceleration or big hills was due to voltage sag, and the BMS cutting off power for a few seconds. It’s a very hard cutoff. 30A to 0A was drastic. I can’t imagine a cutoff at 80A
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i was thinking about this while walking my dogs, and yes this seems more likely. a switch wouldn’t / shouldn’t cut the circuit, right?
per cell voltage was at about 3.25v, max sag i saw at 80amp draw across the pack was 0.5v per cell. bms lower cutoff is 2.9v, so 3.25-0.5 = 2.75v, below bms cutoff. so bms must have cutoff before the vesc had a chance to limit current draw, right?
so…there you go. lesson learned, don’t haul ass when pack is below 40%.
one benefit of getting fucked up is my girlfriend is surprisingly pleasant and isn’t being too judgmental about me getting drunk.
c’mon! it’s like five posts above.
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You’re a lucky guy! My Lady Friend hates my guts lol
u mean your wife? or the one of many side hoes?
edit - this is incredibly misogynistic, pardon me it’s meant for comedic effect.
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wasnt too far south…heehee
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fkn awesome…
The well dressed rider…
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Why are you cringing? 