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Alternator Output?


plumster
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Hi folks, my battery was pan flat the other morning, fired the car up with jump leads from spare battery & pottered off to work.

45 mins journey I expected some power to have got in to the battery, however, it was still pan flat.

Jumped again & measured dc voltage at battery with car running, it was 13.6 Volts DC.

Should it be higher?

Is 13.6 enough to put some zing into the battery?

Car had been sat for about a fortnight, any ideas what could drain the battery that much, no alarm or any of that nonsense fitted.

Charged battery up on trickle over night & fired up this morning, also turned over at lunchtime.

I have another alternator but don't want to swap unless I have to, cos I'm a lazy git.

What do you think?

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the 13.6 volts does suggest that the alternator is working, however if your journey to work isn't that far and/or you had several electrical items switched on,something the puny alternator output can hardly cope with then the battery wouldn't have got enough 'juice' to charge it.

It is also possible that the battery isn't holding a charge properly, remember that if you do need a new battery Opel Manta club members (the club is affiliated to the Vauxhall-Bedford-Opel Association with its Vauxhall trade club agreement) get them at trade price at Vauxhall Dealerships, about £30 instead of £70!!!

Incidently, if you have several electrical items on the go at the same time regulary then find the alternator off a six cylinder, twelve valve Carlton/Senator, bolts striaght on with a much better bracket (you will need the wire end connectors) and is 95 amps output instead of 45amps!

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Cheers Mantaman, 45 min journey to work, sod all switched on, no fan, radio, nowt.

Luckily I have a lifetime battery warranty that I took out 25 years ago & have had at least half a dozen new batteries off the mugs.

I will just wap it in & get another, just in case.

But the current one is less than two years old & they are a 24amp HD battery from Unipart.

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45Amp was standard, exclusives got 55 Amp (well 2 X 60 watt = 120Watt / 12V = 10A drain for the additional lights in quads.

For my money old alternators are no longer worth messing with when you can get off the shelf replacements that will line up and maybe require you change a terminal ring or female spade.

55 Good Amps is a lot better that a worn 70 quite often.

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If running and you say you're getting 13.6v at battery terminals this would suggest alternator is ok.

Turn on lights,HRW and fan blower(engine running) then with your meter on volts go between the alt output(10mm nut)connection and battery positive terminal, you should be reading under 0.5 volts-the lower the better....if it's higher then there's resistance somewhere. Do the same between the alt body and battery neg terminal to check the earth circuit, same readings apply.

If this checks out ok then with engine off set your meter to amps and connect in between battery positive terminal and battery red lead....this will then tell you how many amps are being used, should be very low like 0.02 amps. If it's over say 0.1 then somethings using power.

After this get the battery tested.....or replace.

Hope this makes sense :blink:

John.

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  • 1 month later...

the 13.6 volts does suggest that the alternator is working, however if your journey to work isn't that far and/or you had several electrical items switched on,something the puny alternator output can hardly cope with then the battery wouldn't have got enough 'juice' to charge it.

It is also possible that the battery isn't holding a charge properly, remember that if you do need a new battery Opel Manta club members (the club is affiliated to the Vauxhall-Bedford-Opel Association with its Vauxhall trade club agreement) get them at trade price at Vauxhall Dealerships, about £30 instead of £70!!!

Incidently, if you have several electrical items on the go at the same time regulary then find the alternator off a six cylinder, twelve valve Carlton/Senator, bolts striaght on with a much better bracket (you will need the wire end connectors) and is 95 amps output instead of 45amps!

Mantaman,are you sure that the alternator of that motor(C30NE)is a straight bolt on?I have a CIH 2.2E motor(2200 rekord).I also have a problem with the 45A alternator and trying to find a new one.Is it a little too much 95A??Sounds like an extravagance!But if it does working,no problem.I am currently having a 65A battery by the way.

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The 3ltr alternator does fit but do need all the brackets fron the 3ltr as well

Andy

Bad news :unsure:

Thought that finding the bosch codes of that c30NE alternator and ordered it, would be fine..

Any other solution??Does anybody know a straight bolt on upgrade of a 55A or a 65A or even more?

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Monza has the bigger brackets so an 80amp will still foul. As a rule of thumb, upto and including a 70amp you should be ok to use the standard Manta brackets any bigger then the alternator body gets bigger and thats when yor get the problem

You might be able to modifiy the standard top bracket by making the slot longer but the pinch bolt will be right at the limit of travel

Cheers

Andy

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I have put a Twelve valve Carlton alternator on a Manta CIH engine but i did use the whole Carlton bracketery as well,which is of a superior design, and the wire ends off the Carlton as they have different terminals,think i might have had to use a Carlton fan belt but i would use a new one when doing this anyway.

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