Alternator Question

[NLI10D]

Got a VW Beetle that's having issues.

When I first test drove the car, it had to be boosted to get it started and I was told while test driving not to stall the car (standard) because I would need another boost to get it started. Later in the day the battery was charged, but it didn't hold charge and to start the car it had to be boosted to get it going. Replaced the battery and it would start without a boost but it would take a number of key turns before it starts, atleast 10 key turns. When trying to start the car, there is no sound, no turning over, no lights then it would just start normal after so many key turns. Everything points to ignition switch but someone told me alternator might be bad.

Here's the question:

When the beetle had a battery that would not hold charge but still ran doesn't that mean that the alternator is still good?

[starboy869]

A battery stores power and an alternator produces power.

Your alternator isn't recharging the battery. The car still requires power to run ie. Ing coils, ecu, lights, fan, etc.

[Maymybonneliveforever]

At minimum the main purpose of a auto battery is to turn over the starter and create enough voltage to create spark to ignite the fue and run the computerl, but it does far more then that. The altermator creates around 13.8 volts at a certain rpm in order the charge the battery as well as run all the other electrical functions. It's been said that once the car is started if you disconnect the battery the alternator should keep the car running if enough rpms are present to create enough voltage to operate all necessary functions pertaining to the function of the engine. Do Not Attempt This as it can blow your alternator.

One way to test the alternator is by way of a standard multimeter to check charging voltage either at the alternator or the battery. You can also check voltage battery to see if it's at least 12 Volts.

Your problem seems to be a bad connection somewhere in the electrical system, whether it be at the battery, starter, ignition switch etc.

If a alternator is overcharging the car will still run after a boost but eventually damage the cells in the battery depending on the amount it's overcharging. For e.g. a higher output alternator will overcharge more when the voltage regulator is not functioning properly.

[jimmy-j]

It's been said that once the car is started if you disconnect the battery the alternator should keep the car running if enough rpms are present to create enough voltage to operate all necessary functions pertaining to the function of the engine. Do Not Attempt This as it can blow your alternator.


i've always tested a suspect alternator this way and haven't run into any problems. i've never put extra load on the car though.. only during idle with all acc/lights/radio off.

[afretes]

Here's the question:

When the beetle had a battery that would not hold charge but still ran doesn't that mean that the alternator is still good?

Yes, if the vehicle runs then the alternator is charging.

[starboy869]

However rethinking this

Your battery could be toast. However it would be best to check the charging system by a professional. An overvoltage charge could've baked the plates in the battery.

[NLI10D]

i know the battery was toast, it wasn't charging. Part in question is the alternator. The car started after being boosted so my logic tells me that the alternator is good because the car is still running. So am I right?

[l69norm]

No. Alternator might have a bad rectifier so it won't put out enough amps to both run the car and charge battery.

Take it in for service if you don't have the gear to diagnose the problem yourself.

You can easily get into a death spiral otherwise. A dead battery can easily kill a good alternator. Replace the battery and now the newly dead alternator kills the new battery. Replace the dead alternator and the cycle starts over

[NLI10D]

No. Alternator might have a bad rectifier so it won't put out enough amps to both run the car and charge battery.

Take it in for service if you don't have the gear to diagnose the problem yourself.

You can easily get into a death spiral otherwise. A dead battery can easily kill a good alternator. Replace the battery and now the newly dead alternator kills the new battery. Replace the dead alternator and the cycle starts over

i'll get them to test the alternator. Since i just put in a new battery, last thing i need is for that to be ruined. A new starter is already ordered. I'm not mechanically savy but to me the problem I'm having, multiple key turns to start the car, means its something closer to the key. When I open the door, cab light goes on and alarm also enables/disables so battery is juicing up the car.

[packardbell]

doesn't anyone have a multimeter these days? Geez, just put the red probe to the positive battery post and the black probe to the negative and see what the reading is with car off? then take a reading with the car on and running. The alternator should be charging once you started it so you should read over 13.5 volts or if your reading is more close to the battery voltage (when you took the measurement with car off) then the alternator is not charging.
for the ignition switch issue, the switch is under 15 bucks and takes like 15 minutes to replace. If you want info message me about it.