charging circuit fault

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Mon 9 Nov 2020 11:47
charging circuit fault - toolapcblack

please help no charging voltage getting to battery, 13.84v at the alternator where can i look next in the circuit for the fault?

where is the regulator housed

many thanks

Jeff

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Mon 9 Nov 2020 12:42
charging circuit fault - toolapcblack

i get 12.6 at the battery when engine is running(so not charging), i get 13.84v measured at the alternator when car is running(obviously not getting through to battery when idling).

car off i also measured earth at alternator is ok and there is continuity from red on alternator to red on battery + all fuses ok

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Mon 9 Nov 2020 12:50
charging circuit fault - elekie&a/c doctor
Looks like you have a volt drop on the alternator charging circuit. High resistance on the power or earth lines (or both) . What is the voltage between the earth terminal of the battery and alternator body ? . Engine running. Are the battery terminals getting hot? What car is this and what age?

Edited by elekie&a/c doctor on 09/11/2020 at 13:06

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Mon 9 Nov 2020 13:13
charging circuit fault - toolapcblack

battery earth to alternator body is 0v (same engine off as running) meter buzzes continuity

terminals not getting hot, made a schoolboy error doh when measuring alternator voltage earlier still had jump leads on from other vehicle so was reading 13.84 actually is 12.16 coming out of alt

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Mon 9 Nov 2020 13:17
charging circuit fault - toolapcblack

its a ford focus 04 1.8 zetec

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Mon 9 Nov 2020 13:26
charging circuit fault - elekie&a/c doctor
If I recall ,the alternator power lead spurs onto the starter cable , down the back of the engine .could be a problem here. You could run a suitable cable from the alternator output direct to the battery to see if this improves the voltage .
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Mon 9 Nov 2020 15:20
charging circuit fault - edlithgow

battery earth to alternator body is 0v (same engine off as running) meter buzzes continuity

terminals not getting hot, made a schoolboy error doh when measuring alternator voltage earlier still had jump leads on from other vehicle so was reading 13.84 actually is 12.16 coming out of alt

IF you mean that, and I/m understanding you correctly, then voltage at the battery (12.6 above) is slightly higher than voltage at the alternator, so the voltage drop is the other way, and your alternator is doing nothing.

Edited by edlithgow on 09/11/2020 at 15:25

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Mon 9 Nov 2020 13:46
charging circuit fault - Railroad.

Check for voltage drop between battery positive and the alternator B+ terminal. Connect your multimeter red lead to battery +, black lead to alternator B+. Start engine and read the voltage display. With all electrical loads switched on the voltage reading must not be greater than 0.5V. If it is then you have a poor connection between these two points. Do the same check on the earth side.

The voltage regulator is internal within the alternator.

Edited by Railroad. on 09/11/2020 at 13:47

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