I read through this Thread, I'm confused did I miss something? No, offense, but when did it change from a blower at 6amps to 19 running amps? If the blower came out of a BMW I would think it should run on a 12v battery, I get you need to charge the battery during run time, but I'm just not sure where your going with it?I've only recently learned about snubber RC's. The two concerns would be what the proper values are AND if they can handle the current. Startup is approximately 36 amps. Full speed running is around 19 amps.
The more I think about this the more I'm realizing I'm going to need a heck of a power supply for those currents. I have a 40 amp battery charger / engine starter in the garage. It's not small. And running this from a car battery will require a big battery and time to recharge in-between usages.
I questioned because it just seemed the amperage was a bit excessive, 10 gauge might be in play because of out of control amperage for what ever reason. I looked around on some forums and found 5 to 6 amps is the suggested operating amperage for a BMW Blower Motor. The kid might just be telling the truth, if the blower is drawing that much amperage go get your money back. Here is the site I pulled the info from, it might give you some ideas, while speaking directly about the type of blower itself.Going with SBR60A45CT Schottky Diode, 60A 45V LOW VF.
Was reading an older thread where people have been buying from E-Bay and Amazon and getting factory rejects sold by unscrupulous people. Went with Mouser. Little higher price, but at least I have confidence I'm getting a good part. With shipping I decided to get a few extra so I'd have them if ever in the future I tackle a similar project.
@killivolt: When I picked up the blower I was told it drew 6 amps by the kid at the scrap yard desk. Knowing as I do that kids often speak with authority but without accurate knowledge, I set out to discover the true draw. One giveaway was the 10 gauge stranded wire. YOU DON'T NEED 10 GAUGE FOR 6 AMPS! So after finally coming up with a reasonable test rig I determined my starting amperage is approximately 36 amps and running around 19 amps. IF I were to power it from a power supply - it would obviously need to be quite a large supply. I have a RadioShack 13.8V 19A supply but it's far from capable of pushing the blower. It repeatedly goes into overload protection (something remarkable for a RadioShack product) but it just doesn't manage running the motor. Even with a small 12 volt battery on it - the PS from RS is just BS. So it's more than likely I will end up powering this from a spare car battery I have. I will keep it charged so it doesn't sulfate away. But finding a 40 amp PS - like I mentioned, I have a HUGE battery charger that is also rated to jump start a small car. That has a 40 amp setting. But I've never tested it out to see.
Anyway, I think I have a handle on where I'm going with this. I hope if anyone sees a potential problem they'll point it out. Believe me - I don't think of people being offensive toward me just because I don't know something. I consider the "Dumbest" question is the one nobody wants to ask. And THAT is dumb.
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by Jake Hertz
by Robert Keim