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MG MGB Technical - It's the Battery. Dummy!!

Just a quick update to a problem I've had with my MGB.
Went out to fire up my "B" the other day and after a few second of cranking the lights and everything just went dead. I put my charger on the battery and it seemed to take a charge just fine. When I tried to start the car the battery would load down to 2VDC. I figured the starter must be shorting and loading everything down. Pulled the starter and had it checked. It was just fine. Put it back in and still no good. Just for grins I jumped it off another battery and it cranked right up.

The moral of the story is always check the battey first. In my defense the battery was less than a year old. I just didn't think it could be bad. Th good thing is that it gave me a chance to fix some potential wiring problems.
Rick Bartell

Good opportunity to add an experience I just had. 77B, bought last year with marginal battery that was always just good enough. Also noticed that the fuel gage never made it to "full" reading. Recent episodes with fuel pump(s) caused the battery to hit bottom and not come back. Replaced it with a new one, and noticed when I filled the gas tank that the gage now read a healthy "Full". Coincidence? I don't think so. Something to consider before you go off tinkering with your fuel gages.
FWIW,
Mark
Mark Rotsky

Further to the first story:
The exact same symptoms can be produced with a perfectly good battery simply having dirty terminals. I too have removed (and even disassembled)a starter when only the battery terminals needed cleaning. The jump from another battery can even fool you because it will bypass the dirty terminals.
Kelvin Palmer

Yes those batteries are down and out of the way and it is a trouble to check them out. IT should be regular part of service, especially for you folks in the east and north.
Geoff Kimler
Geoff Kimler

Battery terminal corrosion is only half of the problem. Have you ever removed the battery cable to ground? Unbolt that FROM THE BODY! Thoroughly clean mounting area and cable end. Or just replace entire cable. Should make a difference. I think this connection to the body is too often overlooked. Worked wonders on my B.
Good luck!
Tom

Colder weather is coming so everybody should be giving their batteries a careful going over. For those who don't know yet, the 12 Volt battery is a Group 26. Interstate Batteries makes very good ones. Be sure to get the version without the mounting flange on the bottom or it'll hang up part way down in the battery well when you try to put it in. As Tom pointed out, clean those battery ground cable ends and the mounting point on the body. The battery won't charge for beans if its not properly grounded.
Steve S.

Just been through a similar excercise with my factory V8. Two days after an 80 mile run and with no prior warning went to start it and just got chattering. Measured the voltage on the battery *posts* and that was way down. Question was, why? Not charging? The warning light has been functioning as normal. Or do I have a drain? Charged up over night and next day there was still only just enough charge to start. At least that allowed me to confirm that the alt was charging OK, the battery post voltage was still low, and there were no abnormal drains. Charged it again then left it disconnected for a day, and it was flat again - pretty conclusive. The battery was less than two years old with a three-year guarantee so back it went. The first thing I notice is that the new battery (Lucas!) cranks noticeably faster than I ever remember the previous battery doing, and the turn flasher is noticeably faster with lights, fans and brakes on.

PaulH.
Paul Hunt

I put in a group 26 battery, but couldn't find a flangeless one, so i simply took my tenon saw a wacked the flanges off- about two minutes work.
Ken R
Ken Rich

This thread was discussed between 01/10/2001 and 03/10/2001

MG MGB Technical index

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