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MG Midget and Sprite Technical - 1500 Alternator

Well we've had an overcharging issue, which involved me sticking a used mini alternator on which solved the problem, although I did have to modify the original adjusting strap. Now this morning we had extremely slow cranking, after jump-starting and checking adjustment of the belt it was showing 13.6 idling or being held at revs. So I suspect its time for a brand new alternator.

Any recommendations? Local motor factors or MG place?

Also I think its going to be wise to get another starter, just cant decide to get an exchange in town, MG place or try out a high torque!

D Tetley

If you had overcharging, cured by fitting the Mini alternator, it is more than feasible that your battery has been damaged.

Check the electrolyte levels inside it to see whether the cells are damaged by drying out.

The level in most modern batteries should be between 5 and 10 mm above the "plates" in each cell

The electrolyte should be like clear water, not looking grey or greasy or full of suspended bubbles or particles. All these are good indicators of damaged cells as is not seeing any liquid inside.

As for buying a new alternator if needed. Your local motor spares shop is likely to cost less than an MGist but his stuff may be "reconned" at some local back street reconditioner's. But having said that I have had excellent stuff from many of those guys in the past.


Have the battery properly recharged before you buy anything, then test the alternator and battery.

13.6v or above is a perfectly ordinary charging voltage for an alternator although 13.8v or more is preferred
Bill

Like Bill I think 13.6 volts would indicate that the alternator is charging. A better way to check this is to measure the voltage across the battery with the engine stopped and ignition on, it should then drop down from 13.6 to about 12 .7 after a couple of minutes. If it stays at 13.6 volts then you meter is crap.

If your alternator is working and does as described above then I think the battery is about buggered. I have one exactly the same on my midget at the moment, even after a good overnight charge with my high capacity charger it still only turns the engine over a few times before failing.
Robert (Bob) Midget Turbo

I replaced the battery last night for a heavy duty type, It span over nice and quickly after fitting.

This morning it was VERY slow cranking and wouldnt go. Ive had the battery on charge this afternoon and with it fully charge its now not turning the starter. Ive tried another earth from the battery. The solinoid is clicking and the motors getting power....

Think its time to take the motor out!
D Tetley

Tried powering the starter directly from the battery and it wouldn’t turn. Tried again, turned extremely slowly for a second and came to a stop. Ordering a motor now.
D Tetley

Nice work mate, well done
Robert (Bob) Midget Turbo

This thread was discussed between 01/02/2009 and 03/02/2009

MG Midget and Sprite Technical index

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