Cadillac Owners Forum banner

1 - 4 of 4 Posts

·
Registered
1
Joined
·
64 Posts
Discussion Starter #1 (Edited)
Hello again

Installed a new bosch battery. The old one failed the other day, it sat at 9 volts, NO start... So I installed a brand new one.

But now it's running at 15.1 volts when the car runs. Is that ok, or is that too high?

someone said I may need a new voltage regulator? If so - where can I buy it and where is it in the engine?

Please and a BIG thanks! :)
 

·
Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
Joined
·
68,458 Posts
Mine runs at 15.1 for a while after start, particularly after a cold night. Then it slowly ramps down to 14.6 or so as the battery comes up to full charge.

The voltage regulator senses battery charge state, and as soon as the engine starts and electrical loads stabilize it begins charging at an elevated voltage (which we can see) and elevated amperage (which we cannot see). As the battery recovers from sitting idle and the starting cranking sequence, the regulator "sees" this and begins lowering charging amperage. After a while, near full charge, the amperage lowers to that required to run the engine and electrical loads and voltage lowers to the mid-14s. Automotive voltage regulators always maintain output voltage at some value above the 13.2 - 13.4 volts required to run the car as well as maintain full charge. A fully charged battery, disconnected from anything for an hour will show 12.6 or 12.7 volts - each cell is 2.1 volts, so 6 X 2.1 = 12.6.

A brand new off the shelf battery is NOT fully charged. Find an excuse to drive 45 minutes, open road, for lunch.

The voltage regulator is inside the alternator. Lotsa bucks and magic words and patience and tools.
 

·
Super Moderator
White Diamond '03 DHS (with DTS floor shift)
Joined
·
86,783 Posts
:yeah: Mine also runs at 15.1 or 15.2 after a start, especially when all accessories are on (heat, lights, seat warmers, radio).
 
1 - 4 of 4 Posts
Top