[Healeys] Electrical - general questions BT7

Richard Ewald richard.ewald at gmail.com
Thu Feb 19 21:56:05 MST 2015

First off battery voltages: a wet cell battery produces 2.12V/cell when fully charged.  
So a fully charged 12V is 2.12 X 6= 12.72V. Anything above 12.6V is accepted as fully charged
Anything above 12.72 is surface charge that has to be removed for testing by letting the battery sit or turning on the headlights for about a minute. 
So: 12.6 fully charged
12.4. 3/4 charge
12.25. 1/2 charge
12.0 1/4 charge
Michael, your numbers for voltage drops is too high by a factor of at least 2 if not more. 
Auto industry standard for a starter cable voltage drop is 0.2V +0.1V for each connection or solenoid, so you get a standard spec of .2+.1+.1+.1=0.5V not 2.0V. Now the Healey has a long + cable so I might accept a drop of a little more than 0.5V but for sure I would be doing a repair on 2V. On the ground side I would expect about0.3V not 1V like you said. 

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