What Not To Do With A HS-110

brian5 · December 11, 2020, 7:49pm

I recently received two KP-115s from BLT. I decided to put one on my brand new washer (see my thread about modern washers being detected) but there was a problem. I already had a HS-110 on my dryer since my original washer was detected. The 115 doesn’t fit with a 110 on the other outlet. I looked to see by how much they were off, and it wasn’t much, less than a half inch. I decided to modify the 110 to remove its chin and have it fit. I looked up the internals via this teardown: https://www.edn.com/teardown-a-wi-fi-smart-plug-for-home-automation/
but got a piece of info wrong. I saw that one board had an open bottom, so “knew” I had room to spare on the bottom. I used a miter saw to remove the bottom half inch…until I sliced into part of the main board. Looks like all I did was sever two copper leads, but the unit is dead. I plugged it in to see what would happen, and thankfully there was no fire or even sparks, the breaker didn’t even trip, the unit is just stone cold dead.

If anyone wants a completely dead, easy to disassemble HS-110, let me know. Maybe we can cobble two dead units together into one functional one. I’m thinking positively, now this gives Sense more time to natively detect the dryer motor.

kevin1 · December 11, 2020, 8:46pm

Since you have effectively done a “teardown”, perhaps you can give us a rundown of the make and model of the chips onboard

drjb · December 11, 2020, 10:41pm

can’t travel back in time … but would have been easier to put the two KP115 together, and move the HS110 elsewhere. Granted, there’ll be some work renaming/merging the already detected devices, but reaching for a hacksaw is always my last resort … obviously you’re more brave and curious than I am.

obscuredtrip · December 11, 2020, 11:24pm

For next time: https://www.amazon.com/FIRMERST-1875W-Profile-Extension-Black/dp/B073F8NY83

I use a bunch of the thinner gauge ones to to fit wall warts in power strips.

brian5 · December 12, 2020, 1:20am

Oh heck, I could’ve just gotten a straight plug extender. There’s hundreds of ways I could’ve gone about this that would’ve been better than what I did, but I’m definitely one to occasionally go overboard. It usually works out as well as this.

drjb · December 12, 2020, 1:16pm

In all honesty, this is not a waste, so let’s turn this around. Many of us are very curious about the inner components of the plug and how current sensing is done (along with other aspects). There are 2 options I know of (maybe more): CT (current transformer) and solid state (many chips available, look up Arduino-based current sensing). If not too much, can you continue what you started, take the thing further apart, take many pictures, and enlighten many of us? It’ll be your contribution to the community

kevin1 · December 12, 2020, 5:11am

There’s an HS110 teardown at the link below, but the labels on some of the chips are covered. I know from another link that the power monitoring chip is from Maxim. But it would be nice to have @brian5 confirm.

https://fccid.io/TE7HS110/Internal-Photos/HS110-Internal-Photo-2822789

brian5 · December 23, 2020, 10:27pm

Here are a couple close ups. If there’s specific chips anyone wants a close up, I can get my DSLR out.

kevin1 · December 24, 2020, 12:21am

Thanks for the photos… Your pictures are good enough to id the two devices I was interested in.

Maxim 71020 (in magenta) that is essentially the CT, voltage and power meter for the HS110
Omron relay (in red) - notice that it is rated to 250V AC at 16A