Electrical System Failure

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Electrical System Failure

Postby CertifiedCarNut » Fri Oct 09, 2015 12:26 pm

Help!

Sent: Thu Oct 08, 2015 9:19 pm
From: CertifiedCarNut
To: Charlie Tolman I meant to send this as a pm, but I don't think it was sent. I have had problems with sending personal messages here. If anyone else has suggestions I would appreciate hearing from you. This problem has really got me bummed out.
Hi Charlie, I'm Russ Mullaly from Easton, MD, the guy looking for the hubcap lever and the guy who was having problems with Moss brake shoes. I have a 62 Midget I have had for 51 years. Today I was trying to get the rest of the air out of the brakes and adjust them while I was at it. I went to drive the car back in the garage and the starter locked up like these cars do. I put it in 4th and got out and pushed it to unlock it. Getting back in to restart, there was nothing! No starter and I noticed nothing else electrical was working. I got out and put a wrench on the starter shaft and it was free. The instrument panel worked with the key on but the horn barely sounded and no lights. When I'm not using the car it is always on the battery tender . The battery was still fully charged when I checked it.
I suspected the starter switch might be the problem somehow,and I had a spare since I had this happen before. I replaced the switch which was not the problem. So I checked the starter cables which are all fairly new and they were clean and not corroded. I pulled the battery cables which were about the same age as the starter cables. I cleaned them and the posts, and the screw for the ground into the firewall and the threads in the firewall. I checked the small ground wire that goes to the negative battery clamp. It is not a great connection since I modified it to fit the small wire that comes off the clamp, but it works because the instruments come on when the ends are held together and go off when the ends are disconnected. That setup has worked for years, but I will make a better connection for it.
I did look at the ground strap, which is also fairly new and I tightened the bolts. There's grease and oil on it, so I would guess it is okay, but I will jack the car up and get a better look at it tomorrow. I have had the car 51 years and have all kinds of experiences, but this is a new one. I am completely baffled at this point. It sure seems like something is not grounded properly. There was no warning that anything was going on, the car started properly when I took it out to test the brakes. and the car behaved completely normally.
I wanted to ask you for help with this, because you have lots of knowledge with these cars. My 2 long time friends I had on the forums, Frank Clarici and Biff Jones, sadly have passed away and I used to depend on them to fill in the stuff that after 51 years I need to learn about. I am always finding new tips to help me. I would greatly appreciate any tips or suggestions to get though this crisis. I have hit the wall, I don't know where to go next to figure this one out. Thanks, Russ Btw, why is that brown ground wire that goes to the neg. battery clamp there? I don't think I have ever known or asked about.
Russ Mullaly
1962 MG Midget GAN1L1440
Russ Mullaly
1962 MG Midget GAN1L1440
CertifiedCarNut
Pit Crew
 
Posts: 28
Joined: Sat Sep 22, 2007 2:06 pm
Location: Easton, Maryland (Eastern Shore)

Re: Electrical System Failure

Postby CertifiedCarNut » Fri Oct 09, 2015 4:55 pm

Update: I removed the ground strap and it is still new and shiny. I cleaned it and made sure all mating surfaces were metal to metal. I made a proper connection of the brown wire to the connection on the neg. terminal of the battery. It is not a ground wire, I should have known better, ground is black. I did continuity tests (about as far as my multitester knowledge goes) on the starter switch/solenoid (new), the battery cables, and the cable that connects to the starter(all cables fairly new). All had good continuity. The battery is good, I determined that yesterday, and I put it back on the battery tender.
I repeated the car in 4th gear procedure twice again, and put a wrench on the post on the starter and it turns free. Still no sounds of anything going on with the starter when you try to start the car, and the instrument panel has some power, the horn is very faint, the fuel gauge works, no lights come on, the blower on the heater turns slowly. It has that feeling that something somewhere is not grounded right and full power is not going to components. The fuses are good, btw, indicating maybe no short circuit. That is where I am now, at the proverbial roadblock. I am very discouraged that I can't figure this one out after all the years of owning this car.
Russ Mullaly
1962 MG Midget GAN1L1440
CertifiedCarNut
Pit Crew
 
Posts: 28
Joined: Sat Sep 22, 2007 2:06 pm
Location: Easton, Maryland (Eastern Shore)

Re: Electrical System Failure

Postby Charlie Tolman » Sat Oct 10, 2015 1:41 am

Russ,

My Inbox was full of older messages, so your message was placed on hold.
In the past, I would receive an e-mail message when there was a new PM, but this mode has not been in service for some time. I do not always log-in when visiting the SS forum.

1. Batteries can fail. Try "jumping" the battery with a second battery and jumper cables.

2. I do not know where the battery ground cable is connected on your car. On my '63, I ran this cable to one of the bolts that held the transmission to the engine block. I also had a
cable running from one of the mounting bolts for the clutch slave cylinder to the chassis, under the car.

3. Run an electrical cable from the electrical post on the starter motor directly to the "hot" terminal on the battery. Do not damage the threads on the motor post. You can use a jumper cable for this test.

4. With your multimeter, choose the lowest DC voltage scale. Place the positive (red?) probe directly on the center of the positive (large) battery post, and place the negative (black?) probe on the end of the battery cable that is on the post. Have an assistant turn on the headlights, or engage the starter motor with the starting switch, and observe the reading on the voltmeter.
If everything is working well, the meter should read 0.2 volt, (200 mv) or less. If it reads significantly higher, then there is an electrical connection problem between the battery post and the battery cable.
Repeat the test on the negative battery post, with the probe wires reversed.
Repeat the test at the ground connection to the chassis and/or the engine block.

When the starter motor is "engaged", it might draw 100 to 200 amps from the battery. If there is some resistance in a connection, from a cable to its battery post, for example, then there will be a significant voltage drop across this connection. Even if there is a resistance of only 0.1 ohm at a connection, with a current flow of 100 amps, this will generate a voltage drop of 10 volts at the connection. Only 2 volts would be applied to the starter motor.

Charlie T.
Charlie Tolman
Judson Supercharged
 
Posts: 1198
Joined: Wed Mar 01, 2006 10:36 am
Location: Minnesota

Re: Electrical System Failure

Postby CertifiedCarNut » Sat Oct 10, 2015 8:51 pm

Hi Charlie, Thank you so much for your help! The problem WAS the battery. I had assumed it was okay since it is always hooked up to the Battery Tender, which indicates if there is anything wrong with the battery. I did check the battery after the problem started and it was still fully charged, so I eliminated it first. After reading your information today, I jumped the MG's battery with my Toyota pickup and everything worked!!
The battery turned out to be older than I thought - 11 years old. I can't understand why it didn't indicate a problem. The day the problem occured it started strong and it stayed charged after. Something must have shorted in the battery. Maybe the starter lockup was the last straw for the battery. I got a new one this afternoon and problem solved. Life is good again. I printed out your troubleshooting in case something else in the starting circuit causes a problem. Many thanks again, Russ
Russ Mullaly
1962 MG Midget GAN1L1440
CertifiedCarNut
Pit Crew
 
Posts: 28
Joined: Sat Sep 22, 2007 2:06 pm
Location: Easton, Maryland (Eastern Shore)

Re: Electrical System Failure

Postby Charlie Tolman » Sun Oct 11, 2015 12:55 am

Russ,

You are welcome.

Battery life can usually be measured by the magnitude of the charging voltage from the generator or alternator. If the voltage is 12.5 to 13.0 volts, battery life is quite long.
If it is 13.5 volts and higher, battery life is usually short.

You were fortunate to have a battery that lasted for eleven years. Batteries will usually fail in the summer, due to the heat. Batteries will lose capacity in the winter, due to the cold weather, and might not have enough charge to start the engine.

Charlie T.
Charlie Tolman
Judson Supercharged
 
Posts: 1198
Joined: Wed Mar 01, 2006 10:36 am
Location: Minnesota


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