Charge voltage

Various, various and more various!
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Pappa
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Charge voltage

Post by Pappa » 29 Jan 2008 11:33 pm

Hi, is it normal to only have around 13.6 volts of voltage with the engine (and alternator) running? Shouldn't it be around 14.4, or is 13.6 standard for the 340?

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mac
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Post by mac » 30 Jan 2008 12:38 pm

Hi Pappa,

Assuming the alternator and regulator are both in good serviceable order :-
The measured voltage (and current) seen depends a great deal on the condition of the battery and it's state of charge and the load demanded by the consumers at the time of measurement (at the battery).

Assuming a fully charged battery with no high loading 13.6v at 800rpm + is perfectly OK. In fact factory spec calls for between 13.5-15.0v @ 13.3rps.
From my own experience 13.3-14.0 is about normal. With a 30A load the voltage should between 14.0 and 15.0v (14.7v is about right) at around 2500rpm.

On the 360 (Bosch alternator) the specs are a little tighter (5A load @ 3000rpm) at 13.7-14.1v with a cold regulator and 13.5-14.1v with a warm reg.(after driving 15mins.+).

Ignoring the figures though - if the car starts and runs OK and the battery doesn't go flat in normal use there is probably nothing wrong. As with everything in life there are huge "normal" variences - so don't get hung up on whether 13.6 is any worse than 13.8 (or whatever).

Mac.

Pappa
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Post by Pappa » 31 Jan 2008 10:59 pm

Okay. My 340 actually has a Bosch 90A alternator though, i guess it's been replaced some time in the past.

Voltage measured was with at least 50A load at 900RPM, so i guess it's OK :)

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