Lester Lugnut
New member
Every Asian vehicle I've owned going back to the early 80s has had a cold start open circuit voltage(OCV) reading upwards of 14.20V with engine idling at first startup of the day. Most of the time it's in the 14.25V range. Toyota, Honda; Isuzu, you name it.
For those who may not understand what I just said, you pop the hood on a cold engine(sitting overnight) - start vehicle - set VOM(voltage ohm meter) on the DC 20 scale - put red probe on + battery terminal - put black probe on the - battery terminal and observe reading on VOM screen. You can do the same on an engine that's not running to obtain idle OCV.
This provides an indication of how healthy your alternator is at first startup. As the engine heats up, this reading will drop. Heat will create resistance in an electrical circuit. Some will jump in and say an OCV test is meaningless and I would agree if you are talking about measuring a batteries cranking strength. A load test answers that question, but an OCV test on a cold idling engine says a lot about general alternator health.
On my 2014 4Runner SR5 2WD I see alternator part # 27060-31180 installed. Research on this forum shows this to be a 100A alternator.
Start the 4Runner up first thing in the morning cold and I see an OCV reading of 13.91V.
A member here named rigtec put together the following thread while doing an alt. upgrade. In his opening post I see he too received a reading that pretty much matches what I'm seeing. 13.91V
http://www.toyota-4runner.org/5th-gen-t4rs/172070-4runner-alternator-upgrade-gen-5-a.html
A small flashlight and mirror will help bring up the alt. part #. OEM 130A alts are part # 27060-31190 on the 2014 4Runner .
Curious as to what voltage readings others may be seeing on their 2014s with the 100A alternator. rigtec's 4Runner was equipped with an OEM130A alt. before upgrade and he was seeing the same as me, so alt amp rating may not be relevant.
Thanks for your time.
For those who may not understand what I just said, you pop the hood on a cold engine(sitting overnight) - start vehicle - set VOM(voltage ohm meter) on the DC 20 scale - put red probe on + battery terminal - put black probe on the - battery terminal and observe reading on VOM screen. You can do the same on an engine that's not running to obtain idle OCV.
This provides an indication of how healthy your alternator is at first startup. As the engine heats up, this reading will drop. Heat will create resistance in an electrical circuit. Some will jump in and say an OCV test is meaningless and I would agree if you are talking about measuring a batteries cranking strength. A load test answers that question, but an OCV test on a cold idling engine says a lot about general alternator health.
On my 2014 4Runner SR5 2WD I see alternator part # 27060-31180 installed. Research on this forum shows this to be a 100A alternator.
Start the 4Runner up first thing in the morning cold and I see an OCV reading of 13.91V.
A member here named rigtec put together the following thread while doing an alt. upgrade. In his opening post I see he too received a reading that pretty much matches what I'm seeing. 13.91V
http://www.toyota-4runner.org/5th-gen-t4rs/172070-4runner-alternator-upgrade-gen-5-a.html
A small flashlight and mirror will help bring up the alt. part #. OEM 130A alts are part # 27060-31190 on the 2014 4Runner .
Curious as to what voltage readings others may be seeing on their 2014s with the 100A alternator. rigtec's 4Runner was equipped with an OEM130A alt. before upgrade and he was seeing the same as me, so alt amp rating may not be relevant.
Thanks for your time.
