Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: LeftAngle on Saturday,September 18, 2021, 01:16:24 AM
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The original voltage regulator on my car doesn’t give me the warm fuzzies. I need to hook up my temperature and oil gauges and like the original alternator, technology has come up with simpler ways to do things (the 1 wire alternator and voltmeter were a godsend). I searched the internet and talked with Ray and was unable to find a simple power in/power out 12 to 10 volt regulator. Instead, I’ll wire two 12 to 5 volt regulators in series and wire the instruments that way. The only 12/5v plastic housed regulators I could find that are small enough to stuff under the dash are 3 watts.
I think 3 watts should be enough but could use some feedback before I invest in a couple of electrical widgets.
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The instrument voltage regulator only powers the fuel gauge and also the temperature gauge. The oil pressure gauge is mechanical on the TC/S and wired direct on the S1/2. The regulators come in two types: takes 12v to 15v and makes it 10v; or, provides a steady pulse of ignition power. Both work. Test what you have. If it works, why reinvent the wheel?
They are available new from the usual British parts suppliers. I find if they work out of the box, they continue working just fine.
On this forum and others, there are plans to make your own 10v regulator. I don't get the point of doing so but the option is there.
I find modern alternators simpler to diagnose -- it either works or it doesn't -- and more powerful but they all still fail. The quality rebuilt one I got lasted barely 8K. Had a bent rotor shaft (!) and couldn't be rebuilt. The first two replacements were duds out of the box (!!). So modern is mostly just newer and not much else.
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Thank you JB. The two issues I have are: 1. At the time I rewired there were no S2 harnesses available so I modified a kit one. The stock wiring diagram bears no relation to my “one wire at a time” hookup. And 2. The stock regulator is case grounded and (with my wiring) shorts easily if I mess with any wires in the bundle near it. It’s wrapped in tape now and very close to the + and - posts I have mounted under the dash because I don’t trust frame grounding points. :) A plastic cased regulator(s) would be a better fit for me. I’m more interested in hearing about the 3 amp limit.
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The original regulators work fine. Mine did for over 100K miles but....
They create a lot of electrical noise so your radio or cell phone may have problems (this is why there is a factory retrofit kit with a hand full of capacitors to try to reduce the noise).
They have loose tolerances and stability so the fuel and temp gauges have different reading depending on the cabin temperature.
They are fairly large.
But they are the factory part, if that is important go for it. Other wise do a search on this site, there are several schematics of modern solid state replacements that do not have those problems and (I think) there is a commercial solid state replacement.
It was easy for me to make one with parts from Digit-Key. It nicely fits in the space next to the temperature gauge.
Ron