La Crosse BC-900 indicate temperature in the LCD display

[twolf]

from a german post:
http://forum.penum.de/showthread.php?id=24339

At power on the bc-900 (Firmware 33 and Board Rev. 06) indicate the temperature of the two sensors (for a moment)
The temperature is shown in decimal (RAW). The hundreds omitted. Supplements the hundreds arises the following table:

Raw  Temp[°C] Temp[°F]
231	9	 48    
183	14	 57    
142	18	 64    
131	20	 68    
110	25	 77    
81	30	 86    
71	35	 95    
64	37	 99    
60	39	 102    
56	40	 104    
54	42	 108    
47	45	 113    
43	48	 118    
36	52	 126    
->     Shut down at 53°C = 127°F= 35 RAW

as a chart

The temperature was measured on the contact pins to the accu.

If I count the pins I see that the the BC-900 contains a 8-Bit micro-controller with 4x32 LCD-support, ADC with 10 or 12 Bit and Pulse Width Modulation (PWM) output. On the board a contacts for TX/RX
Which micro-controller is inside the BC-900??

 

[paulr]

Re: La Crosse BC-900 shows temperature in the LCD display

Sehr interessant (very interesting)!

 

[glire]

Re: La Crosse BC-900 shows temperature in the LCD display

Which micro-controller is inside the BC-900??

Custom, likely.

Main LaCrosse business is weather stations, from basic to complex. They should have the skils to design from zero a micro-controller based circuit IMO.

 

[SilverFox]

Re: La Crosse BC-900 shows temperature in the LCD display

Hello Twolf,

I wonder if La Crosse has changed things. My version is 32. I have no number that indicates temperature readings.

Shutting things down at 53 C (127 F) is a lot better than what I have been told.

I took my charger apart and looked things over. I see that others have also noticed that the thermocouples are stuck up inside the metal strip that contacts the battery cells. Mine had a little thermal paste on it. I added some thermal past and made sure the thermal couple was in good contact with the metal strips.

Perhaps our high temperature events are a result of a bad connection in this area...

The other thing that bothers me is that at 0.2 A charging current, a 2500 mAh cell should be able to be left on the charger for a long time without any damage at all. This leads me to consider what JTR mentioned. Perhaps there is some electronic noise that is causing the charger to malfunction. If we add confusion due to electronic noise to improper thermocouple contact, we could end up with melt downs.

Tom

 

[wptski]

Re: La Crosse BC-900 shows temperature in the LCD display

Tom:

I ordered this power supply which is supposed to eliminate the noise source: http://www.allelectronics.com/cgi-bin/category.cgi?category=480&item=PS-334&type=store