Bar heaters- home made

[Wizard]

I got the RF PWM Controller. $8 delivered to the door,,.. amazing.

You can see the 2 N channel MOSFETs at bottom right, switching the Negative side (cheaper than P channel MOSFETs).
I checked their numbers and they have almost ZERO conducting resistance,,.. also amazing,,..
When operating at 100% there is almost no voltage drop across the device.
But,,.. there is a constant 30ma current draw, even when OFF. I figure its that 3 pin 7805 5V regulator and RF circuit always listening.

30ma means a battery draw of 5Ah over 1 week.
Since most bike batteries are about 12Ah, with natural leakage and cold, it could mean the battery is 1/2 drained in 7 days,
the remaining 1/2 charge may not be enough to start the bike.
I would put a Master Switch in front of it. Or your Ignition Relay idear fixes that.
I was too lazy to set up a scope, so I set the digital camera to 1/10 second exposure, set the Led Controller to 50% duty cycle,
and took some pics while waving a 1W green LED around;

Got 12 pulses, which means the unit Duty Cycles at 120Hz.
I would also put an inductor/choke in front of it.
Not sure if I'll use it on the bike, but then it will end up in the Travel Trailer.
Fun Stuff Normk, I like the way you think,,..
Rich.

 

[Normk]

Thanks for that, Rich. I hadn't gotten to pulling the controller out of the box as yet as planned to run it for a season to try. Good info.

Maybe I'm blind but can't see if you listed the MOSFET numbers as it would be interesting to look up the maximum current rating, etc.

I like to fool around with adapting things as that often produces a very economical option and always teaches me something. Maybe only, "Don't do that again!" (VBG)

My controller is powered from an ignition switch controlled relay which now powers the accessory fuse. That way the unit is definitely off.

Off to son's season end soccer wind-up.

Best,

Norm

 

[Wizard]

They are both MDD1653. 30V/50A. Rds of 10 milliOhms :!:
They are Surface Mount Style (TO-252) so you'll want the style with Heat Sink Tab (TO-220?).
I figured they used 2 in parallel cause the PCB copper kept curling up and going off like a Flash Bulb.
My unit never goes to 0%. Seems there is at least 1% present at lowest setting.
I need to find a High Voltage version of this to fix a Lapper Charger. Its got a cheap MOSFET that gets so hot,
its melted the case.