Battery Voltage

[RSD]

Curious thing i noticed with my 2006 dts LIII. Took a 3 hour trip out and back last Saturday and noticed that while driving the battery voltage was between 12.8-12.9; it is 14.4-14.6 when the car is just started. On Monday, i drove the car on four ten miles trips, same route back and forth. first two trips, the voltage stayed between 14.4-14.6. the second two trips later in the day, the voltage started at 14.4-14.6, but quickly dropped to 12.8-12.9. Tuesday and Wednesday, voltage stayed at 14.4-14.6 when driving.

Is this sporadic drop in battery voltage normal?

Also, the battery is very weak when starting the car, dont know if this is related to the voltage fluctuation.

Ideas? Thanks, Scott

[Superjim]

If the battery is weak when you start it...I would take it in and have it checked.
The battery is covered under the 4 year/50,000 mile warranty.

As for the voltage...mine is usually at 14 something when I first start it, but drops back to the mid 13's pretty quick...than after driving for a while...it stays in the high 12's.

Texas Jim

[RSD]

ok, thanks. i bought a new battery and will put it in; car has 43,000 miles and battery is probably original. sounds like the voltage drop is normal

[z06bigbird]

These amp gauges are about as accurate as the old analogue fuel gauges.

My amp gauge was showing 14.7 regularly.

Dealer tells me that I need to worry if my alt charges at the rate of anything above 14.4.

I take vehicle in--under warranty; new (not rebuilt) alt also routinely charges at 14.6 or so. That was a couple of years ago. Car, alt, and batt are much stronger than me.

[Superjim]

Originally Posted by RSD

ok, thanks. i bought a new battery and will put it in; car has 43,000 miles and battery is probably original. sounds like the voltage drop is normal

If the battery is weak..it is covered under warranty for 4 years or 50,000 miles.
Looks like you are still under warranty...save your money and let the dealer replace it.

Texas Jim

[tedcmiller]

Obviously some people don't know the difference between current and voltage. The use of "amp gauges" went out with generators. The reading provided by the DIC is the system voltage.

[z06bigbird]

Originally Posted by tedcmiller

Obviously some people don't know the difference between current and voltage. The use of "amp gauges" went out with generators. The reading provided by the DIC is the system voltage.

Yes, mother!! LOL

BTW, why did my 64 Lincoln have 'amp' printed on the gauge? Ford started using alternators in 62, methinks. At any rate, my Lincoln had an alternator.

What is the difference between current and voltage? I suspect others want to know.

[RSD]

i know that i dont know the difference, the electrical part of vehicles has always left me behind. i gather a generator produces amperage and an alternator produces voltage? where does current come in? i am stupid about this. but I am fairly good with replacing carbs and exhaust systems.

[z06bigbird]

[quote=RSD;1956844]i know that i dont know the difference, the electrical part of vehicles has always left me behind. i gather a generator produces amperage and an alternator produces voltage? where does current come in? i am stupid about this.

Should we agree with your last statement or not???? lol

[tedcmiller]

Current is the flow of electrons produced by voltage. Amperes (A) are the units of measure of current flow. Volts (V) are the units of measure of voltage. In old generator systems brushes on a commutator produced direct current and voltage when the engine was running fast enough to run the car and charge the battery. Typically when engine RPM went down, as at idle, the generator would not produce enough output to run the car and charge the battery. In this case, the battery took over and provided the necessary current until engine RPM again went up and the generator could supply the car's needs and charge the battery. The so called "amp gauges" were placed in the supply path for the car's system, but not in the supply path for the starter motor. These meters were centered at zero and showed the current flow to (+) or from (-) the battery typically in amperes. When generators were replaced with alternators, the problem with insufficient output at idle was essentially solved so that the battery was charged even at idle and the "amp gauge" was no longer needed. The battery in modern vehicles is used only when the engine is not running, as in starting or listening to the audio system while parked, or the charging system is defective.

Alternators produce alternating current (AC) and voltage which is converted to direct current (DC) and voltage using solid state diodes. This is followed, as was the old generators, by a regulator to keep the output from becoming excessive. Old style regulators were separate items, but are now typically part of the alternator. Today's alternators typically can produce 100 A or more of current at 15 V. A typical, fully charged battery will indicate 12.5 V under no load. Most car electrical parts are rated at 13.8 V. This is the average voltage most devices will see in a car system in which a partially charged battery is being charged and the rest of the current from the alternator is being used to run the system. As conditions vary, so will the alternator output and the system voltage.

This is very short primer on low-voltage systems (now 12 V - they used to be 6 V) as typically found in today's cars. If you have any more questions post them here.

[RSD]

thank you TedC, that was very easy to comprehend. i know that in restorations, many times the generators are replaced with alternators, such as in old Harley Davidson MC, i understand why now.

I am still suspicious that my 2006 DTS has a charging issue. do these cars have some type of 'assisted' starter motor? when I start the DTS with the ignition key, i only have to touch it the key to the start position, and then it seems that the starter takes over and goes on spinning. knock on wood, the car starts every time, but sounds like a weak battery none the less.

i have owned the car for the summer now, and its great. just got back from a trip to Daytona/Orlando and have several day trips to Lexington VA also this summer. Looks good, rides great and plenty of torque when desired on the highway.

[Justbob]

RSD, ya know your car could have a build date in 05. Your battery may be close to five years old. Could be you may need a new battery. Starting your car is the heaviest load you can put on a battery.
Bob

[ewill3rd]

Don't stare at your voltage readings on these newer cars.
If something is broken a red light will come on, staring at the voltage can cause madness.

These systems use pretty complicated software and sensors to control charge rate and battery state of charge. Lots of stuff is taken into account including the temperature of the battery.
The voltage will normally flucutate all over the place. 12.8 to 14.x is all perfectly fine.
These are externally regulated by the engine controller, some use other modules to help monitor the state of charge for the battery also.

[RSD]

Thank you gentlemen, all very good advise for a new DTS owner.

EWill3rd, turns out i bought this used certified 06 DTS L3 at Lindsay in Alexandria. one reason i went back to Lindsay to purchase was the fine treatment i received when needing work on my 10 year old Eldorado last year and this year. Thanks to all for your help.

i will put a new battery, hopefully in a week or so. with the daily commute to DC, etc, i have decided to eat this one, and not ask the warranty to cover the battery, still not sure if its bad yet. Heading out to Lexington VA again this weekend, and am keeping a portable jump start box in the trunk, plus cables.

[tedcmiller]

The correct word is "advice," not "advise."