Battery not getting a charge sos please

deano75 · Mar 25, 2014

Hi guys , please can anyone help. 1994 defender 90 , 300 tdi.

1st of all battery light on dash started to light up, some times bright and sometimes faint and sometimes not at all.
Battery then went flat so off it went to local garage, who replaced fan belt , tensioner and water pump (which was making a lot of noise). I then broke down with no electric power and had to get towed home.
I then bought new battery which made no difference it just went flat after a short time.
I have tested the wire at back of alternator which read 6 volts.
So I have just fitted a brand new 100 amp alternator and still no charge going to battery, I have retested the wire at back of alternator and it now reads 12 volts when ticking over.
Dash board battery warning light is now lit up bright constantly.
Any advice would be welcome, I have came to the conclusion that the problem lies between alternator and battery ,,

Oscar Romeo · Mar 25, 2014

This is very easy fix, take it back to the garage who fitted all the parts and whom presumably charged you accordingly and ask them why after bring in a vehicle with a obvious charging fault they didn't sort it!

Tell them you broke down with no electrical power! Why should you pay for their mis diagnosis?

Lee

matt101 · Mar 25, 2014

Hi
I would connect a voltmeter to the battery, first with the car not running and you should be getting 12v or around that figure. Then start the car and then check the battery and you should be getting around 13-14v if the battery is charging. This will just confirm if you are getting charge or not at the battery (sounds like you aren't)
As you have fitted a new alternator the problem does sound like a wiring fault, think the next thing to do is trace all the wiring back from the alternator and check for any damage or anywhere where the wire could have been rubbed through/ trapped etc

Oscar Romeo · Mar 25, 2014

Standard lead acid battery is 2.2 vaults per cell when fully charged you have 6 cells, 12 volts on standard lead acid is flat.

A battery needs at least 13.6 volts to reach the gaseous phase of the charging cycle and start charging most alternators put out 14volts or above, remember your alternator is the vehicles power source not the battery.

Take it back

deano75 · Mar 27, 2014

Hi guys ,, thanks a lot for your prompt response as usual, great forum.
However it turns out that I am complete dumpling and wired up the new altanator the wrong way, my mechanic mate now has it sorted,
Thanks again
]Deano

trax · Mar 27, 2014

Oscar Romeo said:
Standard lead acid battery is 2.2 vaults per cell when fully charged you have 6 cells, 12 volts on standard lead acid is flat.

A battery needs at least 13.6 volts to reach the gaseous phase of the charging cycle and start charging most alternators put out 14volts or above, remember your alternator is the vehicles power source not the battery.

Take it back

think i've seen you say this a few times.

it's 2.1 volts per cell, which is why anything around 12.6 is considered good.

trax · Mar 27, 2014

deano75 said:
Hi guys ,, thanks a lot for your prompt response as usual, great forum.
However it turns out that I am complete dumpling and wired up the new altanator the wrong way, my mechanic mate now has it sorted,
Thanks again
]Deano

glad you fixed it.

they are right though, the first garage should have fixed the alt right away, not mucking about changing other parts. 300tdis are well known for squealing the belt due to the tensioners.

i would never use the garage ever again, as they are either useless or are robbing you.

Oscar Romeo · Mar 27, 2014

trax said:
think i've seen you say this a few times.

it's 2.1 volts per cell, which is why anything around 12.6 is considered good.

I was not only told this when started which was too long ago to remember, but also on battery/charging manufacture courses i ve attended over the years.

I totally agree with your statement 12.6 is considered good and i think .1 or .2 on a volt meter could also be put down to temperature, the reason i posted is because there is only a matter of at best less than 1volt between charged and flat and "around 12volts" isn't good enough to know what state a battery is in.

Best regards
Lee

trax · Mar 27, 2014

Oscar Romeo said:
I was not only told this when started which was too long ago to remember, but also on battery/charging manufacture courses i ve attended over the years.

I totally agree with your statement 12.6 is considered good and i think .1 or .2 on a volt meter could also be put down to temperature, the reason i posted is because there is only a matter of at best less than 1volt between charged and flat and "around 12volts" isn't good enough to know what state a battery is in.

Best regards
Lee

afaik, it's 2.2v per cell fully charged and float charged. however, resting charge drops closer to 2.1volt, which is why you never see rested 12v bats over 13v.

but i am not a sparky, i just pick stuff up over the years.

yeah 1v is a massive difference

Oscar Romeo · Mar 27, 2014

deano75 said:
Hi guys ,, thanks a lot for your prompt response as usual, great forum.
However it turns out that I am complete dumpling and wired up the new altanator the wrong way, my mechanic mate now has it sorted,
Thanks again
]Deano

Thats very brave to come on here and admit that Deano, we've ALL made mistakes it takes backbone to stand up and admit it

I think these forums are often a place where folks try and get one over on each other.
most of my colleagues look down on these forums and theres even forums that are invite only to people in the trade and most dont know they even exist but i personally think that is not a good way to live life, i have weekly dealings with Main agents (mostly Merc) and some of these guys are no better than anyone else but they sure know how to charge.

My personal philosophy is if worth doing, its worth doing right if that means
doing it yourself so be it.

I am made up you got it sorted and if your a bit wiser for the experience that can only be a good result.

deano75 · Mar 29, 2014

Thanks again guys,
I have always had bad luck with mechanics, they never do the job properly.
I am not terrible with the easier jobs so I give them a go. Every day is a school day.
Once again fantastic forum

Ta till next time lol

Battery not getting a charge sos please

deano75

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Oscar Romeo

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matt101

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deano75

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trax

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