My '73 1800ES is not charging the battery. I have replaced the voltage regulator with another identical voltage regulator from a '71 142E. I have also tried putting the alternator from my '72 142E. Still no luck, the car still does not charge the battery. However, it does run just fine, I charge the battery every night, and it runs fine all day. However at night, or after a long time driving I have a hard time starting the car. The amp light is always on bright red. Where do I go from here? What should I be looking for?

You got several choices. One might be the fuse that serves the amp light.
It also serves the turn signals on most oldtimers so you could check to make
sure they are working OK.

It could be that either both regulators or both alternators are nonfunctional
or there could be some kinda wiring problem.

Current from the amp light furnishes initial excitation for the alternator
so it needs to be in the circuit and powered.

Be sure that all your grounds are connected and clean.
--
George Downs, Bartlesville, Oklahoma, Central US

Could I take a line from the B+ out let directly to the battery? the alternator checked to be working. I disconnected fuse to amp light, light went out, turnsignals and tach went out. Lead from D+ outlet test well on contiuity at voltage regulator. I really don't understand how to fix this. no on seems to be able to help. please this is my daily driver. i have to put the battery on a charger every night and limit my driving. otherwise its stuck on the side of the road till i can get a jump.

I guess my next guess is that you have 2 bad regulators....

Right now I am in somewhat the same situation with the yellow peril
but since it is not going anywhere till it gets a good fuel pump,
that is the number one concern.

If worse comes to worst you might bite the bullet and go see your
local equivalent of "Bud's Automotive Electric".
--
George Downs, Bartlesville, Oklahoma, Central US

the voltage regulator worked in the car it came out of. I really don't want to take my car to a shop. i did that once when I first got it (Swedish Automotive) and the shop charged me $600 and never fixed the problem that i was experiencing (not with the charging system). can i run a line directly from the B+ outlet on the back of the alternator to the battery? I really need this thing to work, it is my only car right now.

I haven't ever had an 1800ES, closest is the 145E I am working on now.
Should be pretty similar though.

I don't recognize the term "B+". Most of the alternators I have had were
SEV/Motorola so that might be why. The one in the Yellow Peril is Bosch
and I have an Echlin VR32 regulator on it. It has 2 connections and clear
marking on the lid saying DO NOT GROUND EITHER TERMINAL!! One is marked
Field, has a green wire that goes to the spade terminal on the back of the
Alternator (the brushes) and the other is marked IGN. It's got a red wire
that goes to a smaller screw post terminal on the back of the alternator
(Not the big heavy output terminal). Another wire hooks to this terminal
which disappears into a jacket with the output wire and (I'm pretty sure)
goes to the amp light.

The VR-32 has a jumper on each side inside the box and an adjustment.
I suspect someone either grounded one of the terminals or pushed down
on the regulator relay at the wrong time because one of the jumpers had
burned in two. I replaced it with about 4 strands of fine copper wire
soldered in, and it works OK now. I did have to adjust the adjusting
screw (which controls relay spring tension) to get it to put out 14 volts.
If you have a similar regulator (brand immaterial) you may also have this
problem. If so you will get no charging till you fix it.

Philosophy: Anyone who charges you $600 for working on an old car and
does NOT fix the problem is NOT your friend. You need to find the old guy
who fixes starters and generators in your area and has a bunch of them
lying around his shop among motor-driven testers, meters, etc (NOT computerized)
and get him to help you if you can't get this worked out yourself.
Don't go to somebody who specializes in foreign cars with shiny paint jobs.

The Bible says "Where no oxen are, the stable is clean." In other words, if
there is productive work going on, there will probably be some mess.
--
George Downs, Bartlesville, Oklahoma, Central US