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Old 12th June 2010, 20:17   #1
kollamraja's Avatar
Join Date: Jun 2010
Location: Kollam, Kerala.
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Default Travails caused by a fault in my Sumoís alternator.

The alternator problem that Iím writing about refers to my Sumo. Iím a newbie at Team-BHP but my Sumo has appeared here almost a year ago. http://www.team-bhp.com/forum/modifi...nde-victa.html (1996 Sumo to 'Grande' Victa)

Iím not much of a techie and depend almost entirely on the opinion of the mechanic or technician attending to any fault. The reason for this longish post is the hope that my experience will help someone else in a similar predicament solve their problem sooner.

Simply put, the problem was intermittent dull glowing of the ignition light while driving and steady discharge of the battery when vehicle is parked.

Almost 4 months back, I started noticing that at times, it appeared as though my Sumoís engine was just a little sluggish at cold start in the morning. Then I realized this sluggishness was felt only when cold starting after the vehicle had come back from a night run. I also noticed the red glow of the ignition light while driving one night. This glow would disappear after some time and may not appear again for a few days.

I decided the problem cannot be ignored any longer. Since then, over a period of 3 months, I have taken the Sumo repeatedly to a local ĎAuto electric shopí and to 2 different TASSs.

Each time they would do something (explained to me as only cleaning, tightening, servicing) and claim to have fixed the problem. None could pin point any serious fault. Around this time I got delivery of the Nano and the Sumo remained unused for long periods. I found the battery dead when I tried starting it after a gap of 2-3 weeks. Got the battery recharged and used the vehicle for a day. Next time I tried starting it 3 days later, the battery was dead again.

The TASS where I took it declared that 3 cells in the battery were too weak so it is impossible to hold any charge. The alternator too needed servicing. Later they called to say that the alternator did not have any major problems and only the carbon brushes needed to be re-positioned correctly. They even gave me a Ďzeroí bill for the service.

The battery was only 8 months old, so I confronted the battery dealer. He found the battery to be in perfect condition and successfully re-charged it. He blamed the alternator.

I finally landed at the local service center of Lucas-TVS and the friendly people there successfully unraveled the mystery. Turns out, the alternator was the culprit. It wasnít delivering enough voltage to charge the battery and there was also a diode complaint that was actually discharging the battery continuously.

They replaced the diode assembly, AVR, 2 bearings and the oil seal. As you can see in the pics below, they proved that the alternator after servicing was at its healthy best using their testing rigs.

Did it really have to take 4 months and umpteen trips to the workshop to get a fault like this diagonised? And how could that TASS fault the battery and give a clean chit to the alternator? Ideal nominee for the this-can-happen-only-to-me program.

One half of the Alternator testing rig is seen in the pic below.
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And this is the other half.
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In the foreground is the diode assembly. Out of the three diodes, the middle one had blown, causing the battery discharge. This faulty diode also damaged the AVR seen in the background.
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Two bearings and the oil seal (right extreme) that were replaced.
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The alternator after servicing, showing an output between 14-15 volts.
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With an applied load of 30 amps, the alternator output is still between 13-14 volts which I am told is quite satisfactory.
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