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W1209 temperature controller not working

derekoak

New Member
Hi
The w1209 sensor is designed to show LLL on its 3 part display if the NTC sensor is not plugged in. This happens, but when the sensor is plugged in the display should show the temperature but now shows - - -. My continuity meter across the contacts of the sensor, when out of the w1209, shows just over 10 ohms at an ambient 23 C. Does anyone know what the - - - signifies?
As background, I made a diy lithium battery with Chinese cells 4 years ago. It has 8 cells in 2 sets of 4 cells making parallel13v batteries, recently I realised that at least one of my Daly battery management systems (bms) had died, so I took the batteries apart and replaced both bms with jk bms. The batteries now work again. At the moment we are in Austria and it is hot, but my problem is that my battery heating system depends on a w1209 temperature sensor which at the moment does not work. For 4 years if the batteries were below 5C I would switch a switch to activate the temperature circuit, the w1209 would come on and show the temperature of its probe. If it was below 5C the w1209 would illuminate a relay light, it would activate a more powerful relay and send 12Amps of current to 4 heater pads between pairs of cell in the battery. When the battery reached 9C the w1209 relay would switch off. The Bms would allow charging from my solar and the engine above 8C
It is possible that I damaged the w1209 sensor as I had to disconnect the sensor from the w1209 to get the heavy battery out of the car and that left an extended sensor probe wire trailing as I unthreaded it from the car to carry the battery to a workbench to disassemble.
 
The "---" display indicates an alarm condition. The sensor for the W1209 is a 10K NTC thermistor, and should definitely NOT be as low as 10 ohms. Sounds like you did damage it, probably the leads touched a live voltage point on the board while you were removing it.
All is not lost, however, as a new one is available from MPJA in the US. Surf over to https://www.mpja.com/Thermostats-Digital/products/589/ and you'll see the W1209 and the thermistor probe available, along with their datasheets, which includespecs and programming instructions. Might be easier in the long run to just but another thermostat (which includes a new sensor), just in case the W1209 itself is the culprit. Certainly cheap enough. Shipping cost & delays could be uncomfortable, but ....

Cheers,
DaveM
 
Thank you David, I feared as much. I can get another w1209 easily when we are next home, until then I will activate the heaters with a manual switch, when needed , with a timed alarm set to ensure I turn off the heat after 10 minutes
 

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