Hi,

JTD 115 2002 model. Was working fine when I got home Friday Evening. Sunday, nothing from the dashboard when I went to start. Voltmeter showed 0V at the battery, so I thought it had died. Changed the battery with one from another car. Started, but alternator warning light came on with messages also concerning ABS and other things, maybe a reset is needed?
I measured the voltage at tickover and saw 17V. Could that be anything other than a faulty voltage regulator? Left the car for an hour and then found only 9V left at the battery and obviously couldn't start. Looks like something is consuming power when the ignition is off.
Any thoughts?

Battery losing charge, regulator not working?

17v is way too high, should be around 14.5
Could be the Alternator is draining the battery due to an internal fault.
Charge a battery up and fit it, but disconnect the cable from the Alternator.
Leave overnight and check the voltage in the morning.

The messages concerning the abs are common once the battery runs low...so they are just a symptom and not the problem, sounds like something's draining the battery alright...could be the regulator alright.

Disconnected the wires on the alternator, battery is ok the next morning. I thought I was lucky as I have a donor car with a good alternator. But looking at how long it takes to do, I'm not sure if I want to take two alternators out instead of one so maybe I would be better off buying a new one. If I did take the alternator off the donor car, would I be able to restart and move the car with no alternator on it or would I have to put the belt back on and therefore the dud alternator too?

If you have measured 17V that is an alternator regulator failure. It may have damaged the batery and possibly other items. You may be able to swap just the regulator / brush pack, not the whole alternator depending on access. You could drive without an alternator but only for a hundred meters or so.

Robert G8RPI.