Alternator question
Asked by Timothy Nov 16, 2017 at 08:21 PM about the 2009 Chrysler PT Cruiser Wagon FWD
Question type: Maintenance & Repair
My brand new alternator reads about 0.3 volts when the car is on. There is
also a 12 volt drop from my alternators positive connector to the positive
connector on the battery. Will an alternator put out a bad reading like this if it
is not connected to the battery?
Also my battery dies when sitting for a day or two. Will a bad alternator or
bad connection to the alternator cause the battery to drain just from sitting? It
seems like this shouldn't effect the battery while it's just sitting there. The
battery is brand new.
11 Answers
I would test the alternator at the battery. When the car is running the voltage should read between 13.5 and 14.5 volts more or less. The battery dying may be from lack of charge or from a parasitic battery drain.
Thanks for the reply. I also checked at the battery. Voltage was 12.8 with car off and 12.4 with car on. However if the wires are bad from the battery to the alternator wouldn't checking at the battery be pointless? Checking at the battery would just tell you the alternator is bad or the wires are bad. I already know the wires are bad so it's going to read bad. I don't know why the voltage drops when the car is on though.
Either the alternator is not charging or like you say maybe there is a wiring problem. Either way you don't have charging. Have the alternator tested at your local auto parts store and inspect the wires and repair them if they are bad like you say. The voltage drops because there is a load on the battery.
Any idea why it would read bad at the alternator? Does the battery have to kick start it for it to read correct voltage?
Without a load on the alternator you will not get accurate results.
If you have a 12 volt voltage drop on the alternator wire then there is a problem. Check the voltage at the battery engine running as suggested above.
I've checked it at the battery as stated above. FOR answered my question of why my alternator is reading bad at the alternator. I wasn't sure if it would put out voltage without being connected to the battery.
enginecreator answered 7 years ago
My excellent advise is to replace those known bad wires and then test like normal at the battery.
I have a 2006 pt cruiser o had my battery check and it's fine every few days my car want start are I can drive it come home that it off and try to restart my car and it's just like it's dead