By Jess Hartley
p-j-hartley@worldnet.att.net

From The LoON Tribune
Lotus Owners of the North

I recently had a problem with the alternator on my Europa TC. The symptom was the warning light was on, but dim. The ammeter showed that little if any charging was going on. At least the two indicators were consistent. Intermittently, the ammeter would register that the battery was charging. I had never had a problem starting the car.

I started trouble-shooting by disconnecting the battery and charging it up. The battery appeared to take a charge OK: the no-load voltage was 12.6 volts.

For Lead-acid batteries the open-circuit voltage is an indication of the state of charge.

Voltage	%Charge @80F
12.6-12.72	100%
12.45	75%
12.3	50%
12.15	24%

I hooked the battery back up and started the car. Checking the voltage at the battery with the alternator running showed 12.6-12.7 with the engine reved up. Just a bit more than the battery alone and not enough to supply the car and fully charge the battery. It was time to replace the alternator.

The Europa had a US Motorola alternator that the dreaded previous owner must have put in. I knew that Motorola itself hadn't been in the alternator business for a long time. I tried looking through the stock of a very friendly parts store without any luck of finding one that was easy to fit. The parts store referred me to a place around the corner that supplied them with rebuilt alternators.

I went to the rebuilder and he told me that the Motorola alternator operation had changed hands. I think he said Prestolite had it now, but I am not sure. Parts for the Motorola units are readily available and they are popular in industrial and marine applications. It was not cheap at $160 US, but it was a bolt up replacement. He did include a new voltage regulator that attached to the back of the alternator. Not integral like the newer Delcos, but a better package than the remote voltage regulator that I had. The rated current was 55 amps just like the old one. There are probably bigger ones that would fit.

The plot thickens. Last summer, I had the alternator bracket break. I called around and no one had anything like a bracket in stock or even knew that one existed. I looked through the Lotus Ltd. Europa Tech Manual and found an article describing a broken bracket just like mine. George Hovsepian said that his Europa TC didn't have the bracket. The alternator bolted directly to the bellhousing. George said that he thought that a Saturn alternator could fit without the bracket shown with a little filing to fit. So it appears that Lotus used a number of alternators some that used brackets and some that didn't.

The drawing is the one that I gave to the machine shop to have the new one made up last summer. I had them do it in 7075 aluminum, because they had a chunk of it and Carrol Smith (Machine To Win) said it is strong and easy to machine. The original bracket had cracked in the middle where Lotus had a sharp inside corner. The new bracket has filets on the inside corners and I rounded the outside corners and polished all the holes smooth to minimize stress risers. Tim Engel suggested that 7075 isn't as corrosion resistant, so I borrowed some Alumiprep from him and painted the bracket.

Note that in the original bracket, both the one on my car and the drawing in the Europa Tech Manual show the lower bolt hole as off center. The way that it goes in, it doesn't really need to be off center. Centering the hole puts a little more meat around it. There was cracking around the hole on my cast original. The front corner I cut off with a hacksaw after I could see what was necessary for clearance. Be sure to file and sand the cut edge to a smooth surface.

When you install the bracket with the alternator, don't tighten the lower bolt. Just let it pivot. If you tighten the bolt, you are asking for the bracket to break just where mine did. Be sure that you have a good Nyloc nut so that it doesn't come off.

If I had it to do all at once, I would have a new mounting bracket made and replace the alternator with a Delco. The cost of another bracket and the added hassle made the exact replacement more attractive.

There is some info on alternator conversion on the Internet at http://www.vtr.org/maintain/maintain.html