NEw car battery require charge.?

NEw car battery require charge.?

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Discussion

gaz1234

Original Poster:

5,233 posts

167 months

Thursday 22nd January 2015
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Or do they come fully charged?
Thanks

McSam

6,731 posts

123 months

Thursday 22nd January 2015
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All modern sealed car batteries come charged, typically 90% or more. Totally discharging them is extremely detrimental.

Faust66

1,601 posts

113 months

Thursday 22nd January 2015
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They usually have a decent charge when you buy 'em, but I always like to take a reading with a multi-meter and put the new battery on charge for as long as necessary.

Replaced the battery in my girlfriend's V70 last autumn. Seem to recall it was holding 12.8 volts after we picked it up from ECP but after I put the new unit on charge for a few hours the new battery was showing 13.3 volts...

Always better to top up/charge the battery when it's off the car IMO.

McSam

6,731 posts

123 months

Thursday 22nd January 2015
quotequote all
Don't confused terminal voltage with state of charge. Lead-acid batteries have an initial voltage drop as soon as they're at anything less than fully charged, but then settle to a pretty steady level as they discharge further.

The typical car battery might show 13.5V or higher when it's freshly charged, but 90% charge will be more like 12.6-12.8V. It then steadily drops towards 11.5V or so, only falling off sharply from there when below ~10% charge.

That's not to say it's not worth topping it up before fitting if you can, though smile

gaz1234

Original Poster:

5,233 posts

167 months

Sunday 25th January 2015
quotequote all
So replaced it turned it over twice and locked unlocked it twice no problem.
Day later struggled to start.
So I guess it should have been charged..

Oh asked what's in a battery and how does it work... Who knows

TooMany2cvs

29,008 posts

74 months

Sunday 25th January 2015
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gaz1234 said:
So replaced it turned it over twice and locked unlocked it twice no problem.
Did you actually start the car and use it?

gaz1234 said:
Day later struggled to start.
Have you checked to see if there's something draining the battery?

spaximus

3,631 posts

201 months

Sunday 25th January 2015
quotequote all
All depends on the type of battery construction. An old type lead plate acid battery will always lose a bit of charge whilst standing. And typically when you fit it on a car it will start it easily, but once the small build up of sulphur on the plates drops off as the alternator starts to top it up, it will then be fully charged and will recharge discharge well.

Other batteries, like gel, or glass matt should be charged fully when fitted. Usually they are now tested before they are sold to ensure they are tip top.

9 times out of ten, when people say they are having an issue with a new battery, there is an underlying problem with the charging system on the car.

Claudia Skies

1,098 posts

64 months

Sunday 25th January 2015
quotequote all
For the benefit of those who are unaware, when a car battery is first made it does not need to be charged.

The "chemical energy" of the battery is already contained in the acid which is added to the cells. So the battery is at full energy, or "fully charged", as soon as cells are filled. However, car batteries will gradually lose charge if left standing.

So, you might ask, if my battery goes flat why can't I just chuck out the old acid, fill with fresh acid and Bob's your uncle?! The answer is, you can, and it will work. However, the "plates" inside the battery suffer wear and tear over time due to the ion exchange process which makes a battery work. Further, the plates of a flattened battery are likely to have suffered from a process called sulphation.

Car batteries really do wear out, especially if they aren't kept fully charged all the time. They're not like a phone battery which is happy to be flattened and then recharged over and over again. This process will rapidly kill a car battery.