30 votes
Accepted

Battery drops to 10.5 volts after charging

Yes, this is a bad battery. One of the cells has most likely shorted. Each cell is a little above 2vdc. A fully charged battery will usually be ~13vdc. If you lose one cell, it will drop it down ~2vdc,...
Pᴀᴜʟsᴛᴇʀ2's user avatar
17 votes

Why don't some modern cars automatically turn off headlights when stopped?

This is another of those questions that can only be answered by a few people at VW, clearly the car could turn the headlights off after it is stopped; or after it is stopped and a certain amount of ...
dlu's user avatar
  • 14.5k
13 votes
Accepted

Nearly drained battery for 2 weeks - how much damage was done?

Considering car batteries usually have a lifespan of between 3-5 years, I'd say "yes" you should probably think about getting a new battery. As far as damage to the battery, you should have ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
10 votes
Accepted

How do I keep an idle/unused battery ready for immediate use?

Similar batteries are used for motorcycles, and many people don't use those very often at all. They sit in the garage for months at a time until the weather is just perfect for that 20 minute ride. ...
JPhi1618's user avatar
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10 votes
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What would cause a short to ground while driving - how to locate the problem?

The most likely cause is that the cable that runs down to the starter motor has been rubbing against the body or the engine and has worn through the insulation.
HandyHowie's user avatar
  • 25.2k
10 votes

Is my car battery charger not working?

12.45 to 11.94 in 6 days seems like a significant discharge. You should be able to leave your car for a month or longer and still have enough power to start. At your current discharge rate, I wouldn'...
rpmerf's user avatar
  • 8,403
9 votes
Accepted

What would cause a slow drain of a battery?

There a number of possible causes: An old battery that can no longer handle the load of the "always on" accessories (clock, alarm, etc.). A new load (like the inverter my son left plugged ...
dlu's user avatar
  • 14.5k
8 votes

Car battery dead for a while... now it won't charge?

I'm not going to tell you to try and utilize a battery charger to fix the issue as @MoveMoreCommentsLinkToTop has suggested in the comments, but it has been my experience when a battery has sat for an ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
8 votes
Accepted

Why won't my car even crank?

That wire will have been the main power connection from the alternator to the battery it is used for powering the car and charging the battery while the engine is running. By forcing this onto the ...
HandyHowie's user avatar
  • 25.2k
8 votes
Accepted

Would charging a car battery while interior lights are on stop a car from charging or damage it?

It didn't damage your battery or the charging at all. Because: All batteries in automotive created for simultaneously charging and discharging otherwise your car will not have an alternator in the ...
Cubic273.15's user avatar
7 votes

What would cause a short to ground while driving - how to locate the problem?

Sounds like a dead short, one large enough like that should be easily visible, either through burn marks on a metal edge or bracket or a hole in the insulation. Check and follow all the main or thick ...
Solar Mike's user avatar
  • 34.6k
6 votes

Starting Enfield with low/dead battery

Many times you can start a motorcycle with a low battery This answer has a push start method You can also coast down a hill and let out the clutch with the ignition 'on' and the start switch set to '...
DucatiKiller's user avatar
  • 32.9k
6 votes

battery fully discharged, got a jump-start, but what do I do now?

It is very important to charge back the battery as soon as possible. As per how fast does the alternator charge the battery?, it may take as much as 10 hours or more for the battery to be re-charged ...
cnst's user avatar
  • 1,515
6 votes
Accepted

Why don't some modern cars automatically turn off headlights when stopped?

All of these other answers go into weird philosophical directions... The answer is much simpler than that: Yes, it is possible to have the car turn off the headlights when the car turns off - many ...
SnakeDoc's user avatar
  • 176
6 votes

How do electric car batteries cope with the car standing idle?

As an electric vehicle owner for many years, I've found that the traction battery does not have problems with long duration idle state. If you top up the battery before heading to the airport, it will ...
fred_dot_u's user avatar
  • 4,465
5 votes
Accepted

How long can a car battery be uncharged before it is ruined?

There's no specific time that will determine how long a battery will last without damage. There are a number of factors, not limited to temperature, age of the battery, what the "open circuit voltage"...
SteveRacer's user avatar
  • 12.4k
5 votes
Accepted

2010 Hyundia i30 - Should I keep the batter lead removed in order to prevent the battery from flattening out?

You're probably better off starting and driving the car everyday or leaving a battery tender on the car. Some cars learn and store values like idle, etc... When the battery is disconnected it loses ...
Ben's user avatar
  • 10.7k
5 votes

Motorcycle won't turn over immediately after a pit stop

You may have a bad stator As @paulster2 stated, you should have your battery tested. You could have a lead plate the broke free inside the batter and grounding out that cel to another cel. Your ...
DucatiKiller's user avatar
  • 32.9k
5 votes
Accepted

Emergency flashers drain the battery in 5-10 minutes

A battery should be able to run the flashers for several hours and still start the car. There should be a sticker on your battery which tells the month and year it was manufactured. The sticker will ...
the_storyteller's user avatar
4 votes

Help with Strange Intermittent yet predictable parasitic battery drain?

Since the drain is very repeatable, connecting an ammeter in series with the battery and disconnecting each fuse in turn is a good idea as @jphil1618 suggested. You could find that the problem is ...
HandyHowie's user avatar
  • 25.2k
4 votes

1998 Nissan Altima Slowly Discharging Battery with New Alternator

Welcome, Mike. I hope you kept your receipt as you likely have at least one defective diode in your new alternator. If you replace it and experience the same problem, you will want to check the ...
Mustangguy809's user avatar
4 votes
Accepted

1999 Ford Ranger Battery Drain

So after looking up what a GEM was (its the Ford name for the thing that controls the majority of the interior and some of the exterior electronics, if anybody else was wondering), A reasonable first ...
Zshoulders's user avatar
  • 1,646
4 votes

Why don't some modern cars automatically turn off headlights when stopped?

Basically: sometimes, you need your headlights on even though the engine is off cars with "smart" systems like this are annoying if you i) don't know how to operate/disable the "smart" system or ii) ...
tlhIngan's user avatar
  • 12.2k
4 votes
Accepted

Temporary loss of engine power when headlights flashed after jump start

To put it simply; Your alternator was working very hard to charge the battery while you were driving. The additional load of flashing your high beams added to the amperage draw which in turn added to ...
CharlieRB's user avatar
  • 9,015
4 votes

How often do i need to drive my car when it's cold?

You are asking the wrong question. The question should be: for how long should you drive the car, once you have started it? A battery in proper condition should last for at least a month in a car ...
juhist's user avatar
  • 14.5k
4 votes

Is my car battery charger not working?

Solar chargers are impacted by many factors: Glass: especially tinted glass filters light, you won't get maximum charge behind glass Direction: solar cells work best when pointed at the sun Sun ...
GdD's user avatar
  • 16.9k
4 votes

Acceptable battery voltage drop overnight

Given your driving history, I would guess this isn't a "parasitic draw" problem at all. If you have had the battery continually undercharged for 6 months, it may have lost a lot of capacity. If you ...
alephzero's user avatar
  • 2,944
4 votes

Battery voltage drops from 12.3V to 11.2V in 5mins

When the battery goes through charge/discharge cycles, the chemical composition of the internal plates changes, and they have different volumes. Eventually the swelling/shrinking will cause little ...
Arthur Kalliokoski's user avatar
4 votes

Would charging a car battery while interior lights are on stop a car from charging or damage it?

You probably did no damage. Most chargers have built-in protection for excessive amperage drain. Courtesy lights do not draw very many amps and the battery probably was taking a charge. Turn off all ...
Jupiter's user avatar
  • 3,187
4 votes
Accepted

Vehicle dies for a couple minutes when I try to start then turns back on

First thing to check is the battery terminal connections. It sounds like you could have a bad connection. A high resistance would allow some of the low power circuits to work, but when you try to ...
HandyHowie's user avatar
  • 25.2k

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