Modding Dyson (DC16) handheld vacuum cleaner for wall power - Page 1
Forum section: electronics / beginners

author: aurmer
author_rank: Regular Contributor
timestamp: May 13, 2016, 10:34:37 pm
content: Hello, I am new to the community! I am an undergrad EE student with a head full of home/pet projects, but I am not quite learned enough to complete them on my own.on to my work...I bought my Dyson DC16 years ago. It is a great piece of equipment except that it has always run out of battery power before I am done cleaning. This unit is designed to only run on battery.=) So it is time to design a new power source. I will trick the IC (which Dyson designed) so it thinks that it is running from the battery, when actually, it is hooked up to a dedicated power supply.Things I have already done (aka things I know):- I considered bypassing the motor control circuit and safety measures installed in the the embedded IC... basically just connecting power to the motor, with a switch. It seems easier (and probably safer for the equipment) to just use the connections designed for the battery pack.- The battery has 4 pins. Two were clearly marked for power, and after researching and probing for resistance, I found the last two pins are basically a thermistor circuit which provides safety cutoff for an overheating battery.- The battery has a printed label declaring an output of 21.6V and a capacity of 1080mAh.- When I test the voltage across the battery at "full charge" (on the charger for a day), it is indeed 24 volts.- The LOADED voltage across the battery is 18V. This is me watching the multi meter while the motor is running.- For testing-I breadboarded a passive 8.5k ohm circuit, connected it to the what the IC thought was thermistor.-Hooked up my 0-30V 0-5A lab power supply to the power pins.-The IC rails my power supply at 5A, and while it is operating the motor, it is not running with the same suction as with the battery.Clearly I will want more than 5A in my dedicated power supply. I have ordered more equipment to try to get an accurate read on how many Amps the motor will draw when uninhibited, but a few online resources indicated to me it will be around 8-10A.I have tried to do my homework on this, but I am a novice in the subject of "power circuits".What is a good next step for me? Find an existing power supply matching my specs? Is it possible to design a custom one for cheaper?

author: amyk
author_rank: Super Contributor
timestamp: May 14, 2016, 02:42:05 pm
content: http://www.mikrocontroller.net/topic/283477Looks like a standard brushed DC motor, similar to what's used in cordless drills. Those can draw several times their running current on startup.

author: aurmer
author_rank: Regular Contributor
timestamp: May 14, 2016, 09:33:31 pm
content: This helps! I did want to see the motor, but I didn't want the headache of desoldering it and trying to put it back.Ultimately, though, brushed or brushless...My goal is to create or identify a power supply to drive the device. I know my voltage, and I will report back the max current it will draw (as soon as I have the right equipment).Maybe I should ask more plainly... How is a dedicated power supply designed? I know Input is 110VAC, and my output is 24VDC + 10A.I know there are resources for this, but I my Google search results are cluttered with "variable lab power supply beginner projects".Thanks!

author: IanB
author_rank: Super Contributor
timestamp: May 14, 2016, 10:46:15 pm
content: Laptop power bricks typically have an output of 19 V DC and a power rating of 80 W upwards. (Obviously they are truly brick-sized once they get into the 200 W range.) It seems like one of these might be an ideal surrogate power source. You might look around for one on the surplus/thrift store market and try it out.

author: aurmer
author_rank: Regular Contributor
timestamp: May 15, 2016, 07:39:41 am
content: Brilliant! You are right, our world is saturated with these things because people get new chargers with new computers. I will be on the hunt for one.And in the meantime, I think I figured out how to properly search for what I needed... Here is something I think will work for me.http://www.amazon.com/Transformer-switching-transformer-Universal-Regulated/dp/B00QCJ9FAYLots of PSU's being marketed now for LED strip lighting, and I think this will work for me as well. I would just want to 3d print a decent housing for it to mount to the vac.

author: amyk
author_rank: Super Contributor
timestamp: May 15, 2016, 02:52:15 pm
content: Quote from: IanB on May 14, 2016, 10:46:15 pmThe inductive (and very noisy) load of a brushed DC motor might not work well with the control loop of those.

author: aurmer
author_rank: Regular Contributor
timestamp: May 16, 2016, 05:48:16 am
content: You make a really good point. I am hoping (fingers crossed?) that the existing motor driver circuit already has the inductive spikes handled.I suppose I can properly test the voltage across the battery during normal operation and watch for any crazy fluctuation when cutting the motor off.