maydog Posted January 11, 2005 Report Share Posted January 11, 2005 Hello, The Mrs. aurora (96) was yelling at her the other day. I scanned the codes and found none, but the charging system monitor displayed 17 volts. It has always had the voltage on the upper end of the range but 17 is a bit to high. I double checked at the battery with a multimeter, sure enough 17+ volts. I went ahead an removed the alternator (the removal / install was a bigger pain in the rear than my 97 sts), I had it tested at a parts store where it failed. I should have paid more attention to the nature of the fail, but instead just bought a new one. I spent most of the night installing the new unit, as soon as i started the car back up the voltage jumped to 17? What the hay - what elese could be the culprit? The battery is at 12.2 without the car running and it has no trouble cranking. I am reading about a battery thermistor and other stuff on alldata - any ideas? Thanks, Maydog Link to comment Share on other sites More sharing options...
yenko Posted January 11, 2005 Report Share Posted January 11, 2005 My volts usually stay around 13.0, but 17 sounds very high! IMPORT CRUSHER Link to comment Share on other sites More sharing options...
maydog Posted January 11, 2005 Author Report Share Posted January 11, 2005 I just shorted out the battery thermistor and the voltage stays low around 12.0 volts. If this is indeed the problem I may just hardwire an appropriate resistor for the winter. I cannot seem to find the part number for this thermistor anywhere? Link to comment Share on other sites More sharing options...
maydog Posted January 11, 2005 Author Report Share Posted January 11, 2005 I have a small favor to ask someone out there. I need to get a resistance reading of the battery thermistor at around ambient temperatures. Digikey carries several thermistors but the resistance ranges vary greatly. Also, I think that the thermistor does not have its own part number since it is integrated within the positive battery cable - the cheapest I can find is $110. I should be able to acquire a thermistor and hack it into the cable for $5. Much thanks. Link to comment Share on other sites More sharing options...
JimD Posted January 11, 2005 Report Share Posted January 11, 2005 I have a small favor to ask someone out there. I need to get a resistance reading of the battery thermistor at around ambient temperatures. Digikey carries several thermistors but the resistance ranges vary greatly. Also, I think that the thermistor does not have its own part number since it is integrated within the positive battery cable - the cheapest I can find is $110. I should be able to acquire a thermistor and hack it into the cable for $5. Much thanks. 1998 Seville (battery under the rear seat): using a decent Fluke DVOM, I measure 1.7K ohms at 47 degrees. Good luck...... Jim Drive your car. Use your cell phone. CHOOSE ONE ! Link to comment Share on other sites More sharing options...
maydog Posted January 11, 2005 Author Report Share Posted January 11, 2005 Thanks for the info, I was able to drive the car today buy using a 1.1K fixed resistance. At that value the battery hangs around 13.8 volts. I will acquire a thermistor and post up a small how-to on my website. I am really surprised that such a simple thing led me to replace my alt. Link to comment Share on other sites More sharing options...
maydog Posted January 15, 2005 Author Report Share Posted January 15, 2005 Well, I got the parts. Before I went on to bastardizing the thermisor on the battery I double checked its operation. (by the way, it is a separate unit and I have not been able to find its part number) It was at 6.5 K at 0 degrees f - which is a normal value. I plugged it back in and now everything seems to work ok. The connection must have opened up due to the cold and maybe a little corrosion. I bent the terminals a little and plugged it in. So I spent about $215 on a repair that required only unplugging a sensor and then plugging it back in. darn Link to comment Share on other sites More sharing options...
Oldgamer Posted January 15, 2005 Report Share Posted January 15, 2005 I didn't know a positive cable has a termistor! It's really interesting to know. Thanks. Link to comment Share on other sites More sharing options...
msilva954 Posted January 16, 2005 Report Share Posted January 16, 2005 Our BMW was over charging by 1.5volts........replaced under warrenty for get this....a remanufacutred one.......$600....!!! Link to comment Share on other sites More sharing options...
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