Motor Vehicle Maintenance & Repair Stack Exchange
Motor Vehicle Maintenance & Repair Stack Exchange

Questions tagged [voltage]

73 questions
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4 answers

Do month-year coloured dots on batteries signify install-by expiration date?

As per How do you know if the replacement battery is a good one?, it may be the case that I've purchased a battery that may not be at its best. I got it from a VW dealer installed on 2016-10-01; it had the coloured dot of "9/16", but also an…
cnst
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Can the amount of ampere hours in a car battery be determined by it's output in volts?

Let say an average car battery has a 48 amp-hour capacity. Is it possible to determine how many ampere hours are left in a battery if the volts are known? What about if they are lower (e.g., 8 V) than a completely discharged battery (i.e., 11.9 V)?…
Narcotixs
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Battery resting voltage drop after trying to start

My girlfriend's 09 Camry is not starting unless it gets jumped. She took the car to Autozone where they tested the battery and alternator and said both were fine. I measured the voltage across battery posts to be 10.6V. After jump starting it and…
Mirza Dobric
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No Start: Bad starter solenoid, bad wiring, or a defective anti-theft system?

The vehicle is a 2010 Fiat Ducato (x250) 2.3L Turbo Diesel with an old third party Ituran anti-theft system. There are two codes U1602 CAN Line, Bus Off in the Instrument Cluster - intermittent D602 CAN Line Error, Bus Off in the Body…
Robert S. Barnes
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Alternator squeal

98 rav4. I have a bad squeal, however I tried a new alternator and it did not go away. The charging voltage does not go above 12.3 and when I unplug the plug on the back of the alternator the squealing stops but I lose voltage. Revving the vehicle…
Lane
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How is alternator directly connected to vehicle electronics?

I've tried a lot of research but I can't find specifically what I'm looking for no one has actually mentioned this and I've looked at various wiring diagrams which still don't prove how this is possible: I understand that the alternator supplies…
TMax
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Acceptable battery voltage drop overnight

This is a follow up to this question that I asked previously. Since asking that question, I have kept my same commute, but have been driving consistently 30+ miles on the weekend. In addition, I have brought my car to the dealership where they…
hchc1992
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Safe voltages for jump starting

For various reasons, I keep several very large four cell lithium-polymer batteries in my vehicle. Each of these batteries is rated for over 100 amps of constant current, with 10 second burst ratings of twice that. Wired in parallel, they could…
Anonymous
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ECM voltage, spark spike

When the car was idling in the garage this morning (hooked up to HP Tuners), I saw a spike on the "Spark" graph at the same time as the car stumbled. "Control Module Voltage" also went from > 14 down to 13.69. Not a massive difference, but I don't…
3Dave
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Why does my car's switched 12V drop to 5V when I add an accessory?

Disclaimer: I have very little electrical knowledge. I have wired electronics (radar detectors, dash cameras, GPS units, etc.) to about a dozen vehicles in the past, but have ran into a strange issue with my 2016 Toyota Tacoma (which, I'm told, uses…
Yuriy Babenko
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2015 Kia Forte Intermittent Low Voltage Occurrences - P0562

2015 Kia Forte I’m hoping people can throw some ideas to this one, we are really struggling to pinpoint the issue. Many thanks in advance. Issue Summary: Intermittently, while driving, my car will experience a low voltage incident (seemingly no…
jenhil34
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Connecting Fuse Tap to another Fuse location

This question is similar to can i split off another circuit from fuse box to run power to cigarette lighter?, however I want to know the mechanics of mismatching amperage when it comes to fuse tapping: Let's say I have 2 fuses in my vehicle, a 20…
Moshe
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12V AGM battery charging voltage

I have the following 12V car battery: Varta Silver Dynamic AGM 595901085 (12V/95Ah/850A), and the following car: Jaguar S-Type 2.7D. In the technical cars manual it says this: So in cold winter mornings, when I initially start the car, the…
mariusmmg2
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Is my car battery health bad and should I replace it?

I bought a 2010 Golf in march and I do not know how old the battery is (no dates on the battery) and with winter coming in I feel a bit nervous. Usage I do not use the car very often but I try to give it a 30min ride once a week. The car is parked…
Thibault D.
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Is 15 Volts too high of a voltage to run on automotive electrical systems?

Is 15 Volts too high of a voltage to run on automotive electrical systems? And if so, would filtering the current thru an old style voltage regulator work to lower it to an acceptable voltage ???
David Diaz
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