In theory, if your alternator is providing adequate power to the car while charging the battery,
then once the car is started, disconnecting the battery should not cause the engine to stop running
. …
Can you disconnect battery to check alternator?
If you're tempted to test an alternator by disconnecting the negative battery cable,
don't do it
. A good alternator may indeed keep the engine running without the negative cable, but this was never a good test. In the pre-computer days, you could pull it off without damaging anything.
What happens if you disconnect your car battery?
Disconnecting your car battery will not cause any permanent damage to your computer or ECU (electronic control unit), but it can have some adverse effects. Those include
canceling your preset radio stations
, forgetting learned shift points, and your car's ideal fuel/air mixture.
How can I tell if its my battery or my alternator?
If your engine won't turn over or takes far longer than usual, it's time to grab the jumper cables and attempt a jump-start. If your engine starts and stays running but won't start again later, it's likely a battery problem. If your vehicle immediately stalls, it's probably a bad alternator.
What happens if you disconnect the positive terminal first?
It's important to
disconnect the negative side of the battery first
, otherwise you can cause an electrical short if the positive is removed first.
Which terminal do you disconnect first on a car battery?
When disconnecting the cables from the old battery,
disconnect the negative first, then the positive
. Connect the new battery in the reverse order, positive then negative.” When you are replacing your car battery, It isn't always easy to remember the order in which to disconnect and reconnect the terminals.
What happens if you don't disconnect the negative battery cable?
Contact between the negative battery terminal and the battery, even if the cable is not clamped onto the battery,
may reactivate the electrical system within the car
. This would negate all the reasons you have done this much work to ensure the cable is disconnected.
How do I reset my car after replacing the battery?
Switch off your vehicle and unplug all fuses once it has completely warmed up, then detach the battery to cut power. All of the old data should be reset after a few minutes, so reconnect the fuses and restart your engine.
What are signs your alternator is going out?
If you ever hear
growling or whining noises coming
from under the hood, you could have alternator problems, which should be checked out by a professional ASAP. This growling or whining sound happens when the belt that turns the alternator's pulley becomes misaligned or rubs against the side of the pulley.
Can a bad alternator destroy a new battery?
Can a bad alternator kill a new battery?
Yes, very easily
. A failing alternator can overcharge, which will damage the battery. An undercharging alternator will leave the battery flat, which speeds up its failure.
How do I check my car alternator?
- Get a multimeter.
- Set your multimeter to DCV (DC Volts) above 15.
- Make sure your alternator's positive and negative terminals are clean.
- Put the multimeter's black cable to the negative terminal and the red cable to the positive terminal.
- Look for an ideal alternator reading of around 12.6.
Is it OK to just disconnect the positive terminal?
You will be fine.
Disconnecting either cable works
. The reason they say to disconnect the negative and not the positive is because while taking the positive connection off with a wrench if you happen to touch anything with the wrench while it's on the positive terminal it can arc and be dangerous.
What terminal do you disconnect when working on a car?
Make sure you disconnect
the negative terminal first
. Lay the disconnected negative cable carefully to one side, making sure it's well away from the battery terminal. Disconnect the cable from the positive battery terminal in the same way, then lay it to one side.
Why do you connect the positive terminal first?
Connect positive first, negative having
less potential won't arc
. The higher the voltage, the greater the chance of arcing and fusion. On a car if negative first and you are touching any metal part of car, when attaching positive there is possibility of arcing through you. Your body becomes part of the circuit.
What happens if you connect positive to negative on a battery?
Connecting the positive terminal of each battery to the negative terminal of the other battery will result in
a huge surge of electrical current between the two batteries
. … The heat can melt internal and external battery parts, while the pressure from the hydrogen gas can crack the battery casing.
How long will a car battery last if disconnected?
When the battery is removed, it can stay for
six weeks to 6 months
. However, you need to keep recharging the battery over time. Ideally, the battery should be recharged every 12 weeks when the battery is disconnected.
