Datsun Roadster Forum-311s.org

Good info. I don't do external VR. I don't know squat about them and intend to keep it that way. Changed mine to a Nissan IR alternator. Easy to replace, inexpensive and easy to buy. With a low car easy to change to. You may need to do a JT setup.

Thank JT. I understand what the alt/vr combo is trying to do. And I believe this system works by cutting field voltage to get less output from the alt as it senses the battery's/system needs. Yes, I think the problem is that I need the past, the old vr was constantly charging at 17 (and 30amps on the ammeter) and was definitely cooking the battery, like it wasn't sensing the battery status. So this is the third new battery and third attempted vr. In the past I have been running the high beams and sometime the blower fan all the time to bring that down, getting the ammeter in the 10a range, but it still cooked it. So this is a new battery again (love that three year exchange warranty!).

So I'm hoping the new vr is the answer. I've been through the harness and the wires seem correct except to check wires at the vr plug. Odd that the new vr does not engage the alt at all, and the old ones engage the alt constantly. You can hear it engage and watch the VOM when I switch the plug from the new one to the old one. I'm leaving the battery on charger overnight, so should be full when I start working on it. So I thought the new one may be working correctly, not putting out much charge as not much needed, but it's not adding any at all, even directly after a start. Soooooo