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MG Midget and Sprite Technical - Overcharging

I thought I'd check and see what the voltage across the battery was today! Im glad I did now.

When running at 2000rpm (A guess as its hard to open the throttle and hold the multimeter on) it's showing 18v! (13v when stopped)

Whats the process to trace the problem? Its a 1500 on a alternator.
D Tetley

Assuming your meter is accurate and it sounds like it is then you have found the problem. The alternator is junk. It is actually the voltage regulator on the alternator, some can be replaced but very often it need a recon alternator. You can check with you local auto electical suppliersw if they carry the regulators or if you need an exchange unit. This kind of charging will soon cause the alternator to fail completely or severely damage the battery.
Bob (Robert) Midget Turbo

Bob is correct--the alternator needs replacing NOW. I had a similar problem, the alternator began to put out just over 18 volts, and did not happen to put a volt meter on it while it was happening. Found out when the battery fried due to over charging. When I installed the new battery, I checked the system voltage as I always do when changing out components in the charging system.

The alternator going to excessive voltage has only happened to me once in over 40 years. More commonly, the alternator quits charging and you wind up running on the battery instead of the alternator. An illuminated volt meter might make an excellent upgrade for our cars.

Les
Les Bengtson

thanks Les and Bob, Spent ages tonight in the bloody cold, but i happened to have one off a mini which happened to fit with a "custom" bracket. Back to 14v at about 2000rpm so all is well.

This midget has it in for me im sure!
D Tetley

The Midget doesnt have it in for you

it is simply making sure you fix what you need to before you take it to France

or Italy

Or Germany

Or anywhere else for next year's holidays

Especially helpful that it knew you had a spare alternator handy...
Bill

This thread was discussed between 23/11/2008 and 24/11/2008

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.