[Roadsters] battery not charging

[Graeme Suckling]

On 22/06/2011 10:36 AM, Tim wrote:
> First off: I am an electrickery novice. Big time.
>
> This is a new condition this spring: 70 1600 w/ gm alternator upgrade
> done three or four years ago. Alt is putting out over 12 volts at 600
> rpm idle; more at higher rpm. Battery is over 12 volts once charged with
> battery charger. But car won't start if battery does not have most of a
> fresh charge from the charger. Amp meter will go into the negative if I
> turn on the head lights but never goes into the positive any more.
>
> Is this my regulator going (gone) bad? How do I test it?
>
> Thanks
>
> Tim
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>
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>
If you see the battery terminal voltage increase with revs. to ~13.8 - 
14.2 then the alternator and Voltage Regulator may be OK.
If the battery still lacks power to crank the engine then I would 
suspect the battery as faulty.
Can you swap for a different battery to verify.
If the engine is not running [i.e. not charging] turning on the 
headlights will cause the ammeter to go negative [i.e. discharge from 
battery]
If the engine is running, when turning on the headlights you should see 
a momentary dip of the ammeter needle to zero from +, then the needle 
should recover to the + side to indicate charging.

-- 
Regards,
Graeme Suckling
1965 SP310 Datsun Sports
1971 P510 Datsun 1600
1972 PL510 Datsun 1600 LHD
1973 HS30 Datsun 240Z
1984 B120 Datsun 1200 utility
1993 ECR33 Skyline GTS25t
http://tinyurl.com/6n5aza
Adelaide
South Australia.