Guide Teardown and preparation of Polycab's 16A Wi-Fi Smart Plug for Tasmota

polycab_16A-01.jpg

This is a teardown and a guide about preparing a Polycab Hohm Lanre 16A Smart Wi-Fi plug model SLV1910001 for a Tasmota installation.

polycab_16A-02.jpg

A heavy vise can be used to clamp down opposing corners, the compression will cause the casing to separate.

polycab_16A-03.jpg

The tip of a box cutter can then be run around the edges to help separate the casing more.

polycab_16A-04.jpg

Further the separation by clamping down the other two opposing corners. Run the box cutter one more time and the bottom of the casing should separate cleanly.

polycab_16A-05.jpg

It takes a considerable amount of force but the bottom edge can be lifted up to separate the casing completely.

This pivoted motion is not advised for the 10A version, that model has an electrolytic capacitor along the bottom edge of the pcb that will almost certainly break away. For that model, pivot along one of longer edges.

polycab_16A-06.jpg

The next sequence of steps is to slice away at the heat-staking and desoldering the two input pins to separate the pcb from the bottom casing.

polycab_16A-07.jpg

Start with removing the earth pin receptacle which is simply unscrewed. It's very easy to overlook this step when reassembling the plug. Store the screw and receptacle in the larger housing so you remember to reattach it before sealing up the casing.

polycab_16A-08.jpg

There are four heat-staked supports, each one needs to be cut away cleanly.

polycab_16A-09.jpg

The left pin is the easier one to desolder, so it's a good place to start. A generous blob of flux helps with melting the solder. This is made easier with temperature of the soldering iron set to 350C.

polycab_16A-10.jpg

A desoldering pump (solder sucker) removes most of the solder, you'll need to do a few cycles of melting and pumping.

polycab_16A-11.jpg

The right pin area is crowded with a few components. Sometimes you can insert the soldering iron straight down, sometimes this ends up melting a nearby component like the fuse here. Bending the pin receptacle gives you a little extra working space.

Once the solder is molten, the pcb can be wriggled free. A heavy vise makes for a good third hand in this situation.

polycab_16A-12.jpg

With the pcb free, it's a good time to go in clean up the holes with the desoldering pump to make reassembly easier.

polycab_16A-13.jpg

Next up is removing the wifi module. For this, a generous amount of flux and a desoldering wick is essential. Soldering temperature should be lowered to 260C to minimize damage to the pads.

polycab_16A-14.jpg

This smart plug uses the Tuya TYWE2S module, which can be directly flashed with Tasmota using an usb serial programmer.

polycab_16A-15.jpg

Some kind of programming jig would probably make sense in the longterm but for now we can prep the pads for connecting the programmer with a little excess solder.

polycab_16A-16.jpg

It's not pretty but it works. Flashing is a simple process with Tasmota's web installer. Be sure to erase the device when asked.

Once flashing is complete, disconnect the wire from gpio0 and reconnect the programmer to usb to power up the module. Use a mobile device to connect to the ad-hoc wifi access point created by Tasmota (prefixed with the name tasmota). Your device will then prompt you to sign-in, in actuality you'll be configuring the wifi credentials for the smart plug to connect to your wifi network.

polycab_16A-17.jpg

When reinserting and soldering down the module, be certain there are no shorts between adjacent pads. Check for this using a multimeter with its continuity mode.

The plug can be then reassembled for testing without soldering the input pins or sealing the casing. Navigate to the ip address assigned to the plug and paste in the template command from below into the web console and press enter:

template {"NAME":"SLV1910001","GPIO":[0,0,0,32,2720,2656,0,0,2624,576,224,0,0,0],"FLAG":0,"BASE":18}

Navigate to Configuration and then Configure Module and select SLV1910001 (0) which should now be at the top the list and then tap on Save. This should prompt a reboot after which your tasmotized wifi plug is ready to use.

Finish with resoldering the pins, bending back the right pin receptacle, reinstalling the earthing pin receptacle and resealing the casing with your favourite low viscosity adhesive. Flex Kwik works well, allow a few minutes to cure.

The next step now is to calibrate power monitoring.
 
The wi-fi plugs continue to build-up heat over time, which suggests that these devices are not designed for continuous operation.

And if you wanted a reason to not do this:

photo_2024-11-06 11.45.46.jpeg

photo_2024-11-06 11.45.47.jpeg

photo_2024-11-06 11.45.48.jpeg

photo_2024-11-06 11.45.49.jpeg



The unit itself is fine, the electronics and circuit board anyway. Stresses on the socket in the smart plug by the 16A plug top I was using and swapping around (we have irregular electricity so I would switch a different wall outlet if one phase was down or fluctuating) eventually caused the receptacle inside the smart plug to bend and shift ever so slightly, creating a minuscule gap that might have started arcing occasionally.

And today, after a power outage, the power-on surge was sufficient to melt the plastic with the arc it created and neutral ended up being disconnected.

(If you're troubleshooting something like this, if both live and neutral show live or >230V then it means neutral is disconnected somewhere — weird, but that's just how AC works. It's because then live is flowing through the entire system/appliance and coming up at the neutral side and showing up as live since neutral is disconnected beyond that point)

Not sure what I'm going to do here, I haven't yet designed/made/found a better solution to monitor >1kW continuous loads.
 
Last edited:
And if you wanted a reason to not do this:

View attachment 212995

View attachment 212996

View attachment 212997

View attachment 212998



The unit itself is fine, the electronics and circuit board anyway. Stresses on the socket in the smart plug by the 16A plug top I was using and swapping around (we have irregular electricity so I would switch a different wall outlet if one phase was down or fluctuating) eventually caused the receptacle inside the smart plug to bend and shift ever so slightly, creating a minuscule gap that might have started arcing occasionally.

And today, after a power outage, the power-on surge was sufficient to melt the plastic with the arc it created and neutral ended up being disconnected.

(If you're troubleshooting something like this, if both live and neutral show live or >230V then it means neutral is disconnected somewhere — weird, but that's just how AC works. It's because then live is flowing through the entire system/appliance and coming up at the neutral side and showing up as live since neutral is disconnected beyond that point)

Not sure what I'm going to do here, I haven't yet designed/made/found a better solution to monitor >1kW continuous loads.
smarteefi node series. 16A with energy monitoring. heavy duty terminals. using a 16a+5a x5 retrofit node with my 2kw geyser+exhaust fan and bedroom lights.

 
Back
Top