[Healeys] Electrical - general questions BT7
michael.salter at gmail.com
Thu Feb 19 22:47:56 MST 2015
I'm sure that you are correct Richard but my numbers are just based on the results of many such tests.
I have found that the thin brass crimped cable terminations that were used on the original cables perform very poorly, so much so that they get warm after a few seconds of starter cranking even when in good condition.
Also, by my count, there are 4 connections on the supply side and 4 more on the ground side plus the solenoid and the master switch (which usually has fairly considerable resistance), many more than current vehicles.
I have also found that the original starters are serious current hogs compared to more modern reduction gear units...I've seen over 400 amps stalled and not a lot less when slowly turning a very cold engine.
Granted the tests I suggested won't really show the true voltage that the starter is seeing but hopefully they will point John in the right direction.
Hardly surprising that your typically Healey cranks fairly slowly even when things are in good condition.
From: "Richard Ewald" <richard.ewald at gmail.com>
Sent: 20/02/2015 5:56 p.m.
To: "Michael Salter" <michaelsalter at gmail.com>
Cc: "John Spaur" <jmsdarch at sbcglobal.net>; "healeys at autox.team.net" <healeys at autox.team.net>
Subject: Re: [Healeys] Electrical - general questions BT7
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.
Sent from my iPhone
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