Battery with Reverse Polarity

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Re: Battery with Reverse Polarity

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Re: Battery with Reverse Polarity

Postby Mark » October 16th, 2017, 6:13 pm

I'd make sure all the light switch levers are in the proper positions
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Re: Battery with Reverse Polarity

Postby m3a1 » October 16th, 2017, 7:45 pm

Ok. I'll report back with my findings.
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Re: Battery with Reverse Polarity

Postby m3a1 » November 1st, 2017, 7:27 am

So, in tracking down whatever was sucking the life out of my batteries I decided to remove and replace my starter switch since it wasn't working quite as well as I would have liked. The plunger was getting hard to depress but only occasionally and, as it turns out, it was very slow to return to its neutral position so it made sense to put a new one in and get it over with.

My truck is equipped with a ROPS which didn't make the job especially miserable but the ROPS was something of a hindrance on this job, particularly when it came to putting everything back together. So this post is going to be about the starter switch and some of the little hiccups that you might encounter, particularly if you are using a 'new" switch.

The bolts that secure the switch housing to the floor pan are 7/16". BEFORE removing these I would suggest loosening the two small screws at the top of the starter switch housing. They secure what is a cap of sorts (with sides), to the starter switch housing.

Ok, back to removing the starter switch housing - There are two bolts at the bottom and two at the top, and all bolts go through slotted holes in the starter switch housing and into captive nuts at the floor pan, making this a one-man job unless your captive nuts are no longer "captive". There is really no need to remove the top bolts entirely. Just loosen the top ones, remove the bottom ones and the entire switch housing comes down and away.

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Note the cable coming in from the left. Two cables joint the lead on the left side of the starter switch which is easy to remember as the cap of the starter switch housing has a short side on the left to accommodate it.

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Now is also a good time to mention that the two top bolts, like the two lower bolts, all have a washer and a lock washer. With the starter switch housing removed, these washers have a natural tendency to lay flat on the floorboard which makes getting the starter switch housing back up and underneath the top ones a bit difficult. I just put a tiny bit of grease on them just before reassembly to make them sticky and to hold them up off the floorboard. If you have normal sized hands it is possible to reach up there and get those bolts in place but the presence of the top two leads does make that difficult.

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The nuts that secure the leads to the terminals are 9/16". The nuts that anchor the terminals to the old starter switch are quite a bit thinner than the ones on the new switch. I will swap them onto the new switch in order to maximize the amount of terminal I have to work with. This will allow me to shorten the length of the terminals because, as you will soon see, they are quite a bit longer on the new switch.

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Take note that the cap or cover has a non-conductive coating on it and the short side is oriented to the left (driver's side). Remove the leads from the terminals and the switch and housing come away entirely.

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Two large screws secure the switch to the housing from the inside. There are captive nuts on the outside of the housing.

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There is a generous amount of space between the terminals of the original switch and the housing. If you have a 'new' starter switch, you may find that the terminals on it are just a bit longer than the original.

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This switch was made on the quality control guy's day off and this securement tab didn't quite make it. It's not a fatal flaw, however. I'm going to leave it just as it is.

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Longer terminals mean less space. In this case, I can't even get a nut on it. I might also add that the collars at the screw holes in the new switch are quite proud (tall), more so than the original. As an afterthought, I might have been ahead to remove them altogether because, once installed, the mounting screws would serve to hold everything together and with the tabs, there really is no chance of the two halves separating anyway.

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Here we see that the terminals on the new switch are clearly longer than the original.

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So, I put a regular steel nut on the terminal, cut away several turns and then removed the nut and in doing so, trued up the threads. A bit of careful hand-filing and the ends of the terminals were as good as new.

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Here, I have opened up the original switch, looking for evidence of a circumstance in which the switch is not returning to fully open, or for a carbon trail that might conduct electricity, or for debris that might conduct electricity.

Along with bending back the tabs, I also had to drill out the collars at the screw holes to separate the halves. Again, there is really no need to worry about that. They are unnecessary because when the switch is installed, the screws that hold it to the housing will serve to hold halves together at the screw holes.

As you can see, I did not find evidence of a power drain at the switch but I did find evidence that the switch wasn't opening promptly which is something that was very evident even before I took it apart. That is probably why we see evidence of arcing between the contacts of the switch. I will see what I can do to make the plunger move less sluggishly, then clean the contacts, reassemble it and put this switch back on the shelf for use later.

Image

I am happy to say that while I was looking for what was draining my batteries (and didn't find it here), I did get a new switch installed, which was something I had been putting off.
Last edited by m3a1 on November 2nd, 2017, 11:27 am, edited 4 times in total.
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Re: Battery with Reverse Polarity

Postby m3a1 » November 1st, 2017, 7:31 am

Later in the day, I came home and found what was draining my batteries! Drove up to the house in my Yukon and the MUTT's brake lights were on! Whaaat the ****? This turned out to be a very simple matter.

Now, I normally leave my light switch set with the service lights in the 'ON' position because, frankly, I have a tendency to forget to turn it on. As it turns out, you can have the master switch off and still have functional brake lights if the service lights are switched on. But, how is this possible without touching the brake pedal?

Well, the brake light switch has a helical spring inside it and because of that spring, the switch always wants to be 'ON'. When the brake pedal returns to its neutral position, it actually pulls on the connecting rod (which joins with the armature of the switch) pulling the switch to the OFF position.

So, when you depress the brake pedal, this allows the spring inside the switch to bring it ON and conduct power to the brake lights -or- if the connecting rod is out of adjustment and as a result of that, too long (such as mine was) it can also allow the brake light switch to come on. So, I have to tighten the nut on the connecting rod and I'll be good to go. There it is...problem found and we're back in business.

These trucks can be a very humbling experience!

Cheers,
TJ
Last edited by m3a1 on November 2nd, 2017, 11:29 am, edited 1 time in total.
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Re: Battery with Reverse Polarity

Postby Auzziemutt » November 1st, 2017, 6:36 pm

Rick whats the septic system got to do with it . Are you saying your battery has got the $#!T$
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Re: Battery with Reverse Polarity

Postby rickf » November 1st, 2017, 7:35 pm

Auzziemutt wrote:Rick whats the septic system got to do with it . Are you saying your battery has got the $#!T$

I went back to see what I was talking about and I have no clue, something TJ and I had going on back and forth.
1964 M151A1
1984 M1008
1967 M416
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12/1952 M100- Departed
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Re: Battery with Reverse Polarity

Postby Fil Bonica » November 1st, 2017, 9:31 pm

To your original problem,
Put an ammeter in the main battery lead to see if there is any draw.
Had two different cases where there was leakage through the light switch in the stop light position.
For the most part they are bullet proof but they do fail.
The other was a funky stop light switch .
Both cases were fixed by replacing the part.
Hope that this helps.

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Re: Battery with Reverse Polarity

Postby m3a1 » November 2nd, 2017, 10:10 am

Well, I'm 99% sure I nailed it....quite by accident, by the way. I came back home after running an errand. Mutt was nose-in to the driveway where it's always kept (We've had two cars totaled while parked at the curb in front of the house and I would never receive adequate compensation for the MUTT if it got hit.)

Anyway, I noticed the brake lights were on...juuuuuuuust barely and I really only caught it because I was squarely behind the truck. A few degrees off, I might not have noticed it. Anyway, adjustment of the brake light switch is apparently VERY critical and mine was just on the cusp of allowing the switch to say on when the pedal was in the neutral position. I'm also betting that this very reason is the culprit for a lot of drained batteries on other people's trucks.

Anyway, I don't spend a lot of time looking at the back end of my MUTT, owing to the way I park it. That was quite clearly the drain I was looking for.

So, there are two solutions.
One - Commit to the idea of leaving the service lights OFF and remember to switch them ON every time I drive.
Two - Find a better nylon lock nut for that brake light switch adjustment.

I'm going with solution number two because I can't tell you the number of times I went out without having the service lights on. :oops:
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Re: Battery with Reverse Polarity

Postby rickf » November 2nd, 2017, 10:13 am

Or do what someone else did and go with the A1 hydraulic light switch.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
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Re: Battery with Reverse Polarity

Postby m3a1 » November 2nd, 2017, 11:06 am

Nah. I see no reason to re-engineer things. This is just one of those issues that we all need to become aware of. It's like those darned bolts on the M38 king pin bearing caps. It's just a design that presents a huge trap for the unwary, but once you know about it, all is well. While I don't enjoy having to go out and throw endless amounts of money at these vehicles and deal with problems every day, I do like learning about them through use and ownership.

Here's a short anecdote that illustrates the value of it - My police partner and I restored a DUKW for a local museum and made it ready to swim. We used all the parts procured by the museum and (rather foolishly, it turns out) installed a NOS brake booster. Well, I went to the event early and when the DUKW got delivered by the National Guard, it wouldn't run unless the choke was fully engaged. Well, the museum people were giving me that jaded look... like the quality of my work was the root cause of the problem.

After much trial and error and gnashing of teeth I finally concluded that the diaphragm in the NOS booster had ruptured and the engine was drawing air into the intake through the booster. So, I disconnected the rather large vacuum line to the booster at a compression fitting, cut a small dime-sized disc out of a soda can and put it into the fitting and cranked everything back down, effectively blocking the leak. This was a pure field repair as there were no other parts to be had and I'm proud to say that it worked like a champ.

Fast forward to several years later. We were attending another event and I was keeping late hours. I went to their museum at about 1AM to use the facilities which took me through the motor pool and I found four gear heads having fits with an M3 half track....one that wouldn't run unless the choke was fully engaged. :wink: I wandered over to see what the hubbub was about because wrenches were actually being thrown and I was hearing some oaths that I had never actually heard before (they must have been Navy men). Well, I had them up and running in the time it took to fashion another disc from a soda can and install it.

So there's the proof of the benefit of working through difficulties such as this. Experience!....and it's good to be able to pass it along because these vehicles are going to be around long after we're gone.

In short, learning this stuff, proof testing it by applying and passing it along it is really what its all about.

Cheers,
TJ
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Re: Battery with Reverse Polarity

Postby rickf » November 2nd, 2017, 1:29 pm

And did you teach them the proper Army way to throw a wrench? :lol:
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AN/TSQ-114A Trailblazer- Gone
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Re: Battery with Reverse Polarity

Postby 64 M151 » November 4th, 2017, 10:17 pm

Battery drain could be cause by one battery is not up to snuff and the good battery is trying equalize it. The most common situation is one will replace the bad battery with a new battery which will cause the new battery trying compensate the old battery and end up with the same results. One must replace both batteries with the same type, size, group, lot number / DOM. Do not mix match because one will run into the same problem down the road. Also battery drain can come from the Voltage Regulator. Its a Shunt that is not operating correctly. Reverse polarity comes from the batteries by either shorting out or connecting charger leads on the wrong poles. You might have a wire bleeding through when everything is off.

later Joe
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Re: Battery with Reverse Polarity

Postby rickf » November 5th, 2017, 8:50 am

Joe, that battery scenario only pertains to parallel connection of batteries. It doesn't work quite the same on series connections. With series connections and mismatched batteries the problems shows up in the charging. With one low battery the total voltage is low but one battery is at peak voltage so the regulator is putting out full charge and the one good battery is overcharging.
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AN/TSQ-114A Trailblazer- Gone
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Re: Battery with Reverse Polarity

Postby 64 M151 » November 7th, 2017, 10:15 pm

rickf wrote:Joe, that battery scenario only pertains to parallel connection of batteries. It doesn't work quite the same on series connections. With series connections and mismatched batteries the problems show up in the charging. With one low battery the total voltage is low but one battery is at peak voltage so the regulator is putting out full charge and the one good battery is overcharging.

Very true but I can't remember everything.

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Re: Battery with Reverse Polarity

Postby m3a1 » November 12th, 2017, 9:59 am

Well, let's put this to bed.

First, I had a battery go dead and go into reverse polarity but only by 1 or 2 volts.

The drain on the battery was caused by the brake lights staying on because the brake pedal wasn't returning to the full neutral position and (2) it is my habit to keep the service light switch on.

Yes, I had mis-matched batteries hooked up in series and yes, both were used batteries from other applications and despite all the warnings about mismatched batteries, they worked fine for quite a long time and most likely would have continued to work fine.

I replaced the dead battery with a match to the one remaining "original" battery and at this point I had not yet fully determined what the drain was.

Before I could get the power drain problem resolved, the "original" battery then died and went into negative polarity (again, only by 1 or 2 volts) which, I suppose, is just what happens under the circumstances of having one battery go dead when hooked up in series.

So I replaced THAT battery with a perfect match to the other "new" battery and lucked into finding the power drain which I have resolved and now all is well.

Cheers,
TJ
Last edited by m3a1 on November 12th, 2017, 10:53 pm, edited 1 time in total.
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