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Alternator output

28689 Views 39 Replies 15 Participants Last post by  orton
Has anyone measured the actual output of the alternator voltage? I want to look at the possibility of using the alternator to provide a partial bulk charge to a lithium battery. Volts must stay below 14.5V.



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Mine shows 14.7 at times on the built in voltmeter accessed through the OBDII port via the Torque app.
Well now I am more confused. I went out and checked using Torque and found there are 2 Volts listed, Control Module and OBD2. Highest on CM was 14.3V but highest on OBD2 is 14.9V.

Does anyone have any idea why they are so different? I wish Torque displayed battery voltage but that option is greyed out. I may need to put a recording meter on the battery and drive around.

Are the CCP terminal a valid way to check battery voltage? They are much easier to get to than the battery.
I figure the highest one is closest to actual alternator voltage- the CM one probably has some wiring losses.
BTW the voltage varies according to intake air temperature also, the PCM controls it- colder= higher voltage.
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Budsky said:
BTW the voltage varies according to intake air temperature also, the PCM controls it- colder= higher voltage.
A minor correction; it is not inlet air temperature. There is a battery temperature sensor on the positive terminal of the battery. This signal goes to the PCM and as you say the lower the temp the higher the charge voltage with the range being about 14.4 to 15.5.

Well- that isn't want the Ford WorkShop Manual on DVD says- section 414-00 "The PCM uses a signal from the IAT sensor to adjust the charging voltage according to the battery temperature"
Maybe they made an error and meant a sensor on the battery- does seems odd they'd adjust voltage based on outside air temp when the batteries are INSIDE;)
There is a battery temperature sensor on the positive terminal of the battery.
Are you sure it is a temp sensor? The WSM shows only a hall effect current sensor on the battery positive...and that is only on gas engines- the diesel does not have it.

Maybe Ford changed this for 2016 forward..my WSM is for 2015 since that is what I own.
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