emich

The alternator won't charge under certain load conditions. Had the
alternator and battery check OK. When the battery is not fully charged and it reads
around 12.3 vdc using a voltmeter across the battery terminals. Leaving the voltmeter
across the battery terminals and the car is started the voltmeter reads around 14.3 vdc
for about 10 seconds. Then the voltage starts to drop down to around 12.3 vdc with the
car running. If the head lights are turned on the voltmeter will then go up to around 14.3
vdc. If driving with the lights on the battery will start to fully charge up. If the car is
driven with the lights off the battery will slowly go dead after several days of starting.
Any advise?

ezone

It's probably normal.
Study up on how Hondas ELD controlled charging system works. It's been in use for something like 3 decades or more.
The current version uses some different hardware, but the principles and theory are still the same.



EDIT
If you aren't driving it, repeated starts may run the battery down.


And if the battery is original to the car, it's likely due for replacement.

emich

The original batteries of my previous Hondas lasted 7 and 8 years.

Colin42

battery quality isn't what it used to be, i usually see 5 years if the battery was well taken care of, maybe 3 years if it was abused

ezone

Batteries have always been hit or miss. Some last, others don't.
I occasionally see batteries in brand new cars that need replaced before the car is sold.