Another symptom of low battery voltage?

Another symptom of low battery voltage?

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bcr5784

Original Poster:

7,182 posts

152 months

Thursday 6th April 2023
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I went out in the car this morning and it was very reluctant to select reverse. Subsequently it has been very reluctant to select either drive or reverse, though after doing so the car drives perfectly normally. Naturally I was beginning to get worried that I would be stranded and feared the worst.

However thinking about it when I got home, it was quite likely that the battery was low on charge. I have been on holiday for 3 weeks and subsequently only gone on short journeys - often with the wipers on or on full demist.

Sure enough the battery was registering below 11 volts - though, thankfully, the charging circuit seems to be working as the voltage comes up when you rev the engine. Battery now on charge. Possibly the battery is on it's last legs - I'll hopefully know more in a few hours.

Anyone else had a similar issue?

Panamax

5,077 posts

41 months

Thursday 6th April 2023
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Below 11v is almost certainly a knackered battery. 11v is only 20% charged - on a good day!

Once you've charged it you need to let the battery stand overnight (or at least let it settle for several hours) and measure the voltage with a good quality voltmeter. Anything under 12.4v you need a new battery.

A "perfect" battery should show 12.7v.

neil-g8km6

198 posts

30 months

Thursday 6th April 2023
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If you are measuring the voltage across the battery with the engine running it should be reading 14+v, no matter the engine rpm or your alternator is duff.

bcr5784

Original Poster:

7,182 posts

152 months

Thursday 6th April 2023
quotequote all
Panamax said:
Below 11v is almost certainly a knackered battery. 11v is only 20% charged - on a good day!

Once you've charged it you need to let the battery stand overnight (or at least let it settle for several hours) and measure the voltage with a good quality voltmeter. Anything under 12.4v you need a new battery.

A "perfect" battery should show 12.7v.
Thanks for your input -Ctek is still charging (and seems quite happy) I'll try "recond" mode if the voltage is still lowish after taking it off charge. I have to say that I find it disappointing that batteries can die in less than 5 years( which others seem to have found), given the "sophisticated" charging regimes on modern cars.

neil-g8km6

198 posts

30 months

Friday 7th April 2023
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Both my alternator and battery died after just 4 years, 2018 P.E.

a110au

292 posts

58 months

Friday 7th April 2023
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neil-g8km6 said:
If you are measuring the voltage across the battery with the engine running it should be reading 14+v, no matter the engine rpm or your alternator is duff.
no because on the alpine the alternator cuts in and out and the voltage cycles from 12.4 to 14.5 constantly.

guys just get the bluetooth monitor I linked to in my lifepo4 thread then never wonder again about state of charge of whether you need to trickle charge or drive it or whatever.

as to why these batteries are dying its because the cars run the fans after stopping and use a lot of power if you come back to the car to open/shut the door so are often run low accidentally, and the battery is possibly also slowly cooked where it is located, in urban traffic, in summer.

Edited by a110au on Friday 7th April 02:04

neil-g8km6

198 posts

30 months

Friday 7th April 2023
quotequote all
"o because on the alpine the alternator cuts in and out and the voltage cycles from 12.4 to 14.5 constantly."
Thanks for sharing, an intelligent alternator, good to know. Upgraded to lithium on my motorhome leisure battery and what a difference + the ability to monitor the ins and outs is very helpful😃.

a110au

292 posts

58 months

Friday 7th April 2023
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yeah but you can buy the monitoring gadget and attach it to anything it defaults to lead acid anyway.

bcr5784

Original Poster:

7,182 posts

152 months

Sunday 9th April 2023
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Curiouser and curiouser. Charged the battery and now holding 12.5v. No change!

The odd thing is that the problem seems to be related to how hard you press the brake pedal when selecting Drive or Reverse. Press it hard and the car is reluctant to select the gear, press it gently and gear selection is fine every time.

CliveJ7

65 posts

70 months

Sunday 9th April 2023
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Interesting that the gear selection is affected by the pressure applied to the brake pedal...

Have you tried disabling the stop/start before selecting the gear and see if it's any better then?

Just thinking that if the battery isn't up to scratch then the stop/start won't work. Also, the stop/start is affected by the pressure applied to the brake pedal.
So, these things may be connected and it could just be all down to the battery...


bcr5784

Original Poster:

7,182 posts

152 months

Tuesday 11th April 2023
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It has now fixed itself and is working fine! Another software glitch? Who knows.

Martyn P

167 posts

83 months

Friday 14th April 2023
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I had a faulty battery replaced at under two years.

However, after replacement, I definitely felt that gear changes in automatic improved - faster changes and slightly earlier.
At first I thought it was just my imagination but a bad battery cell might just be enough to limit power to the gear shift?

You definitely might want to consider swapping out to a new battery, for a £100 quid not worth worrying about?