Do I need a new alternator?

[BDA]

Well, I checked the battery with a hydrometer and it checked out good. The pointer on the hydrometer got stuck on one cell so I thought it was bad and I took it to the parts store to have it checked out and replaced. It checked out good (so I knew I wasn't going to get a warranty replacement) and when I got it home and checked it again, the pointer unstuck and showed it was good.

I replaced the battery terminal clamps with brass ones. When I drove it around it looked like the ammeter was gradually drifting lower from its usual high reading but I had to put it up before it got a lot below about +15. I just took it out and it was solidly on 0. It turned out, it was just stuck (damn!) and on about a half hour drive, it reverted to it's old tricks and spent most of the time between +20 and +30 - mostly about +30. Everything seemed to work as expected - it started right up, etc. The only thing (and this isn't new by any stretch but I've been curious about it) is that there was condensation on the inside of the glass of the ammeter for some time.

Any ideas?

[jbcollier]

Extract the ammeter and join all the wires together.  When next standing near a body of water, or atop a steep cliff, hold the ammeter firmly in your right hand.  Draw that hand back whist twisting your body to move it yet further back.  Untwist your body while driving your hand forward as hard as you can.  At the point of maximum momentum, release the ammeter.  When you get home, fit a voltmeter.  Smiths make a nice one in the GT40 gauge line.

[dakazman]

 Extract the ammeter and join all the wires together.  When next standing near a body of water, or atop a steep cliff, hold the ammeter firmly in your right hand.  Draw that hand back whist twisting your body to move it yet further back.  Untwist your body while driving your hand forward as hard as you can.

Lol lol

[BDA]

I've been wanting to do that but wasn't sure it was really called for! I guess it was a good thing I had all my gauges checked over at Nisonger before I put the car together! 


I was looking into a voltmeter and was glad to find one that pretty much matches the rest of my gauges. I'll just need a half round bezel.


Thanks for your help through this, John!

[BDA]

The intermittent nature of starting continued for a time or two and then it just wouldn't start at all - no power to anything. I followed the hot wire to the ammeter and found out why. See the attached picture. The lug that connected to the spade on the right was in pretty bad shape, too. The negative battery cable clamp was corroded a bit, too. I'll be pulling the trigger on a volt meter tomorrow but does anybody have a clue what actually happened here? I suspect the water condensation may have been a symptom - or even a cause - and maybe a malfunction in the ammeter was to blame but the corrosion on the brass ground wire battery clamp is a mystery.

[E Paul]

Well, that mess is seriously not good!

[4129R]

The corrosion reminds me of battery terminals, where copper meets lead with a current passing.

The lead could be from the soldered joint, add a bit of moisture and a high current passing, and some electro-chemical reaction must be happening with possibly copper sulphate being the green colour.

I stopped learning physics and chemistry in 1969, so much like your terminals, I am a bit rusty too.

 

[BDA]

I just got off the phone with Nisonger. They have a voltmeter that is of the same style - including type face - as the rest of my gauges. Actually, I have a few different typefaces because I'm too cheap to have them re-silk screened but it's close enough to not stick out. Unfortunately, it will be a week to ten days before they can ship it to me. 

I asked the guy about my ammeter. He said that this was a potential problem with any bi-metallic gauges like ammeters and fuel gauges. He suggested it might be a good idea to check the connections occasionally.

[EuropaTC]

Going back to the ammeter, one thing that did strike me is the amount of surface rusting on the mounting screws and body (unless that's just the photograph ?).  My gauges are pretty much like new behind the dash although the car has lived outside in Yorkshire Pennine Weather for at least 10yrs while I was using it daily and of course had it's share of leaks.

As for the corrosion, it reminded me very much of what you get on a soldered joint when you don't clean off the flux afterwards, the only snag being that they are normally crimped joints there.  But even so you need some moisture to get corrosion, so I get back to dampness as being the primary culprit.  I thought you guys didn't do rain over there ?   

Brian

[BDA]

Well, it does rain here, but not nearly as much as in New Orleans where I used to live!

I neglected to mention that there was some heat. The hoods over the connectors were somewhat toasted. I expect the heat was generated by the additional resistance of the corroded connections.

I looked at the can again and there is some discoloration that appears to start behind the dash. I couldn't tell if it was very light rust or maybe discolored because of some heat. I tend to believe it was the heat. There was also enough rust on the mounting stud to require pliers to remove the thumb screw.

This whole episode is a bit disconcerting. As I mentioned earlier, I had all my gauges checked over by Nisonger before I put them in the car (here in North Carolina). The car is rarely in the rain and until the last several years, it was a garage queen most of the time. It just doesn't seem like corrosion like that was warranted and the potential consequences of that corrosion could have been severe. If I kept it outside, it would make sense to me but the guy at Nisonger didn't seem surprised at all (I wish I could have showed him my picture!). I met a guy recently who had what I thought was a clever idea. He filled the covered female connections with petroleum jelly to keep out corrosion. Maybe if the connector was old, it might be a good idea to soak it in vinegar before the jelly trick.

Last night I connected all the wires together (The only way I came up with was to put ring connectors on each big wire and I ganged the two smaller ones in a ring connector and bolted them together. Of course three don't bolt together into a compact package. Then I wrapped the whole mess in electrical tape and tied it to an existing cable. It ain't pretty. I'm open to better suggestions.). Everything started as expected. I'm just waiting for my voltmeter to arrive!

[EuropaTC]

I can't think of any better way to get the car running than what you've done. I prefer soldered joints wherever possible but if your car is like mine then the free play in those heavy cables is going to make soldering difficult and potentially messy if you slip. So I think I'd have gone the dry clamp into a ring terminal and bolt together myself for now.

Just remember to give a loud cough when the concours judges start to lean over to look underneath the dashboard at the wiring....       

(yes, I'm joking although given the cleanliness of some cars these days, maybe not.....)

[BDA]

Funny comment about concours judges! At the national Lotus meets over here, there is always a "casual concours" or "people's choice" competition. At one of the meets, they gave you an opportunity to enter a concours. I entered not realizing it was a real concours and not the casual one. Well, there isn't much that's stock on my car so when I found out it was a real concours, I withdrew my entry. Somehow my name wasn't taken off the list so when it came time for the judges to inspect my car, I explained why I withdrew (BDA, etc.). That piqued the interest of the guy organizing the concours so he came over and looked at my car. I was entered in the casual concours also and only got a third, but as a bit of consolation, when the club magazine came out, the report on the meet had a mention of my car! It mistakenly said I had a Brian Hart motor but I'll take it!

[jbcollier]

The corrosion was caused by a loose connection, material incompatibility and resulting oxidization.  Basically almost any pairing of different metals will oxidize if heated and electrically charged.

The aftermarket has a number of insulated junction blocks that will do the trick and look less improvised:

https://www.summitracing.com/int/parts/rfw-jb57/overview/

http://www.wiringproducts.com/4-gauge-power-distribution-block.html

[4129R]

The corrosion was caused by a loose connection, material incompatibility and resulting oxidization.  Basically almost any pairing of different metals will oxidize if heated and electrically charged.

I think that is what I was trying to say in my post of yesterday.

[BDA]

I don't think either of the big wire connections were loose. I replaced one of the female connectors so I'm pretty confident that neither of those were loose either. Of course, that was over fifteen years ago, so I could be mistaken or misremembered. If I still lived in New Orleans, the corrosion would make more sense to me. It's so humid there that the air is pretty much an electrolyte!


Thanks for the links to the junction blocks. Those are much nicer. I'll look into them.