Contour Enthusiasts Group Archives Forums Modifications General Mods battery voltage

can someone tell me what the battery voltage should be w/ car on and off? i have a v6 auto if that makes a differance. mines like 12.5 off and alittle over 15 on. my friend says thats too high.

Seems about right to me.

the 12.5 off sounds right. the 15 on i've never heard any tour owner say they get. i think mine goes to 13.8 13.9.

12.5V with the engine off is spot on, but 15+ with it running is bad and will eventually damage the battery. Sounds like the regulator is bad on the alternator. We were just having a discussion on this in the Audio forum, and I posted this link:

http://www.contour.org/ubbthreads/showthreaded.php?Cat=&Board=trouble&Number=426586&page=&view=&sb=5&o=&vc=1

12.6V is a fully charged battery (there are 6 cells 2.1V each) After driving a car for a while it builds up a "surface charge" which can range I think like 13.9-15.9, Also I am not sure if this makes a difference but on all ford vehicles after you shut off the car cetain modules will still read outside temp, engine coolant temp etc... obvisouly flowing small amounts of electrcity there for you cannot do a parastic darw test on a ford untill the car has been shut off for 45 min. Like I said I am not sure if that will affect a battery voltage test to much. But to get rid of a surface charge turn the car off and leave the headlights on for one minute, turn them off then check your voltage. 12.2V is a dead battery the car will not start but you can charge it. After you turn on your headlights for one minute then check battery voltage and it reads something like 15V's , I am not sure if a contour has a voltage regulator if it does yours has gone bad, usally it is inside the alternator if this is case buy a new one, rebuliding it is too hard I have tried! Also what kinda of tool are you reading battery voltage with?

-Jeff-

I hooked up my laptop over 2 and a half hours after the car was off tonight and still got readings from the MAF, ECT (126 degrees), etc.

The charging voltage will vary depending on the state of charge of the battery. If the battery is low, the charging voltage will be low. If the battery is well charged, the voltage will be high. This is part of OHMS law. When the amps are high (charging) the volts will be low, and when the amps are low (not charging much) voltage will be high.

The rule of thumb for the increase in voltage over the base battery reading (after the surface charge has been removed by turning the lights on for about 30 seconds) is between 1/2 volt and 2 volts.

12.5 volts (your base battery voltage reading) plus 2 volts equals 14.5 volts.

My experience has been that if you are much above 14.6 or 14.7, there may be something wrong. 15 volts is suspecious.

I just checked the shop manual. It says usually charging voltage should be between 14.1 and 14.7. It also says if charging voltage is more than 2.5 above battery base voltage you may have a voltage regulator problem. It sort of leaves a grey area there between 14.7 and 15.2.

I think the style of battery may make a difference. Are you running an Optima?