Automatic car alternator not charging battery

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Fri 30 Oct 2020 09:09
Automatic car alternator not charging battery - James de Budé
When driving a automatic car battery dies due to alternator failure when driving up a steep hill, car cuts out and rolls downhill. Brakes do not work, steering neither, handbrake disengages, all due to battery being completely dead. My question is how do you stop the car, Why does it continue to roll backwards even though it is in gear?
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Fri 30 Oct 2020 09:24
Automatic car alternator not charging battery - bathtub tom
Brakes do not work

I suspect hey just feel like they don't work. Due to the engine not running you lose the vacuum to the brake servo and hence the power assistance. It feels like someone's stuck a brick under the brake pedal. You just have to press HARD.

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Fri 30 Oct 2020 09:43
Automatic car alternator not charging battery - James de Budé
The brake was pushing back on me, only on the mild gradient did the car stop.
I agree with your post as I have had many a time been towed where I had to push hard on the brakes to slow down, but this time was very different. The automatic handbrake would not engage either due to battery being dead. Even when I manually tried to set it.
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Fri 30 Oct 2020 09:44
Automatic car alternator not charging battery - Andrew-T

What sort of car is it where the battery 'goes dead' when the alternator fails ? Unless the electronics cut out the whole system, which seems a bad idea safety-wise, especially if an electric handbrake is involved.

Steering and footbrake revert to manual when the power assistance fails, so as has been said, you just have to work harder.

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Fri 30 Oct 2020 10:28
Automatic car alternator not charging battery - James de Budé
Brand new car had it 3 weeks, do not want to name manufacturer as my concern is with all automatic cars. In the morning a battery error came on, restarted the car and no more warning lights. Drove to work, on the way home going up this steep hill it cut out. The alternator must of stopped working in the morning, so when driving home with all the lights on I drained the battery and all electrical stuff stopped working. When pushing the brake I could feel the hydraulic pushing back on me.

I totally accept the point of working hard on the brakes, strong people might be able to hold onto the brakes for a while. However I had to push the button to call the AA who took an hour to turn up, not sure many people would be able to hold the brake for that amount of time.

Also I understand this must be very rare thing to happen, hence me asking on this forum.

Edited by James de Budé on 30/10/2020 at 10:44

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Fri 30 Oct 2020 14:11
Automatic car alternator not charging battery - Andrew-T
... I had to push the button to call the AA who took an hour to turn up, not sure many people would be able to hold the brake for that amount of time.

I don't drive autos, but if the normal brake fails, can the car not be braked by selecting Park ?

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Fri 30 Oct 2020 14:47
Automatic car alternator not charging battery - Falkirk Bairn

There are 2 batteries in a hybrid - the one the can propel the can form 1 mile to maybe 40 miles.

Then there is the lead acid battery which is charged by braking - if the car is run for just short trips the Lead Acid battery will go flat.

OP - what sort of mileage has the car done in 3 weeks? and how many miles will it be driven on any one day? - a series short trips of a mile or so will kill the car battery.

If you make a lot of short trips a Hybrid was not the car to but - a straight forward petrol only car would have been a better buy.

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Fri 30 Oct 2020 14:56
Automatic car alternator not charging battery - Bromptonaut

Seems odd to me that if the alternator failed and the battery was discharging there was not a festoon of warning lights. Even my Mother's Mini c.1966 would show a red warning light if battery draw exceeded the dynamo's output.

I've only very rarely driven automatics and most of those were TC types many years ago.

Once the engine stops then you'd lose the manifold vacuum (or on a diesel the vacuum pump) and power to the brakes would fade but there should be enough to stop. Even without any servo assistance there should be SOME braking action. Once stationary, if the electric parking brake will not actuate then selection of P should lock the transmission. I wouldn't expect P to act as a brake on a rolling vehicle and would rxpect selecting it while moving to cause damage.

The OP needs to ask the supplier of his new car some searching questions.

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Fri 30 Oct 2020 15:12
Automatic car alternator not charging battery - elekie&a/c doctor
A three week old car with major faults ? I would be sending it back for a refund . We don’t know what car this is . No mention of it being an EV or a hybrid . You can’t engage Park with the car in motion . Is this post for real ??
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Fri 30 Oct 2020 17:30
Automatic car alternator not charging battery - Andrew-T
You can’t engage Park with the car in motion . Is this post for real ??

When I mentioned in my post above the 'normal brake' I meant the handbrake, which we were told was not working - presumably being electrically operated ?

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Fri 30 Oct 2020 15:13
Automatic car alternator not charging battery - Miniman777

While make of car/model not confirmed, both my X3 (TC auto) and Qashqai (manual, with elec parking brake) have the brakes apply themselves when the engine stops. The can cannot move, ie: fail safe. The X3 goes into P too.

Question OP needs to ask dealer is why this does not happen to his car, where is the fail safe for the auto? Conversely, could brakes release unbeknown if battery fails when car is unattended?

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Fri 30 Oct 2020 19:44
Automatic car alternator not charging battery - bathtub tom

This doesn't sound true. I suspect we'll get a spam link soon.

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Fri 30 Oct 2020 19:59
Automatic car alternator not charging battery - elekie&a/c doctor
Exactly, waiting for the “problem solved “ response.
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