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Author Topic: Charging a flat battery by driving  (Read 13770 times)

dw

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Charging a flat battery by driving
« on: 24 March 2013, 05:22:50 PM »
As a result of car battery abuse - ie too many short journeys, inflating the tyres with the car battery powered tyre pump, and cold weather, the Aero would not start today - I jump started it and it ran smoothly, I then took it for an 80 minute drive with no restarts. 
The battery voltage was so low that it had cleared the SID memory information and the Clock time in the radio prior to the jump start.

When I got home I connected the battery to a standard mains battery charger and the charging meter indicated that it was not putting any current into the battery - can I now assume the battery is really full.
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sgould

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Re: Charging a flat battery by driving
« Reply #1 on: 24 March 2013, 06:13:34 PM »
I wouldn't bank on it.  Modern batteries seem to die suddenly.  You may keep it going for a short while, but if it's damaged, it's probably dead.  The only way to really tell is to get a garage to do a battery discharge test.

I replaced the first dead battery in my car at 5 years old.
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Steve440

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Re: Charging a flat battery by driving
« Reply #2 on: 24 March 2013, 07:05:55 PM »
Put a voltmeter across the terminals.

A good battery will show about 12.5v and a poor but usable battery will be about 11.5v. Anything less and its dead.

If your battery charger does not think it needs to charge it its probably about 12.5v but after a decent run it could be OK but could loose it after a cold night.

A cold start in the morning with the weather we are having at the moments will be a good indication of how good or bad it is.

Steve
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dw

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Re: Charging a flat battery by driving
« Reply #3 on: 24 March 2013, 07:24:40 PM »
Thanks for the comments
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TomPaine

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Re: Charging a flat battery by driving
« Reply #4 on: 24 March 2013, 09:40:17 PM »
D'you know how old it is? As sgould says, modern batteries tend to just go. I replace mine every five years in order to avert the moment generally between five and seven years when it'll just die without any warning.
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dw

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Re: Charging a flat battery by driving
« Reply #5 on: 24 March 2013, 10:59:41 PM »
The battery is about 4 to 5 years old - it was replaced under warranty so I do not have any documentation - given what has been said - I am getting a new one fitted tomorrow.
One less thing to worry about for the next few years.

Thankss 
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TomPaine

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Re: Charging a flat battery by driving
« Reply #6 on: 25 March 2013, 10:31:50 AM »
Good move.
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CitTone

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Re: Charging a flat battery by driving
« Reply #7 on: 25 March 2013, 01:26:17 PM »
Quote from: sgould on 24 March 2013, 06:13:34 PM
I replaced the first dead battery in my car at 5 years old.

An engineering child prodigy! How did you manage to reach over the wing??
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TomPaine

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Re: Charging a flat battery by driving
« Reply #8 on: 25 March 2013, 06:18:54 PM »
Quote from: CitTone on 25 March 2013, 01:26:17 PM
Quote from: sgould on 24 March 2013, 06:13:34 PM
I replaced the first dead battery in my car at 5 years old.

An engineering child prodigy! How did you manage to reach over the wing??

sgould is pretty resourceful. I wouldn't have put it past him. ;D
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sgould

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Re: Charging a flat battery by driving
« Reply #9 on: 25 March 2013, 06:40:37 PM »
Ah!   :)

Not cars at 5.  I was cooking then.  Something I've gone back to since I retired.

My father was a trained mechanic, due to RAF war service.  He bought me a Morris 8 as my first car. When it broke down on day one, he rescued me.  Next day I came home to find my car in pieces on the garage floor.  He has dismantled it.  I was told "I'm not spending my evenings chasing you around. Time you learnt to fix it yourself". :)
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Bruce

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Re: Charging a flat battery by driving
« Reply #10 on: 25 March 2013, 08:08:57 PM »
Quote from: Steve440 on 24 March 2013, 07:05:55 PM
Put a voltmeter across the terminals.

A good battery will show about 12.5v and a poor but usable battery will be about 11.5v. Anything less and its dead.

If your battery charger does not think it needs to charge it its probably about 12.5v but after a decent run it could be OK but could loose it after a cold night.

A cold start in the morning with the weather we are having at the moments will be a good indication of how good or bad it is.

Steve

Exactly what happened to mine before I changed it at the weekend. Seemed to lose charge overnight if it was cold - wasn't so much of a problem if it was that bit warmer. Voltage was away down & after morning after morning of charging it up with the charger - replaced it & hey presto! So far, so good. My last battery was a GM one from the dealer - replaced in June 2008. Went for Bosch this time - there's a separate thread if you want some info.

Bruce
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steventon95

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Re: Charging a flat battery by driving
« Reply #11 on: 25 March 2013, 08:21:04 PM »
When you think about it, batteries are quite a cheap service item. Twenty quid a year is pretty insignificant in the overall scheme of things ...  8)
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Steve440

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Re: Charging a flat battery by driving
« Reply #12 on: 25 March 2013, 08:39:54 PM »
Quote from: steventon95 on 25 March 2013, 08:21:04 PM
When you think about it, batteries are quite a cheap service item. Twenty quid a year is pretty insignificant in the overall scheme of things ...  8)

For cars they might be, I have just had to get one for my Motorbike. £75 and its a 1/5 of the size of a car battery.  :o

Steve
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MikeIOW

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Re: Charging a flat battery by driving
« Reply #13 on: 25 March 2013, 10:46:07 PM »
We have owned a Nissan Figaro for over 10 years......we have an Oxford Battery optimiser try to keep it ticking over (it is very much a sunny day car!)....but even so, we have had 2 batteries die on us.   
Now I guess other cars aren't so bad and get better charged & used, but yup, probably 5 years is fair enough these days for a battery!

cheers
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