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Can I ask for some advice from you fine gentlemen?

The battery on my 745 furs up quite quickly. I haven't as yet applied anything like Vaseline but I will do. However the interesting this is this;

I was in the habit of removing the +ve terminal from the battery when not using the car as it was always this one that furred up badly. To save time with the spanner I fitted a quick-release isolator as per the picture. Because of the different sizes of the two poles on the battery, it was necessary to fit it onto the -ve terminal but this was OK and it works fine.

However, I now find that its the -ve terminal that furs up quite ferociously.

Why would this be? The car is 6 volt +ve earth.

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Those "green knob" ones are kinda junk, and not really rated for 6v applications. Look for a Cole Hersee battery disconnect/switch. They are pricier, but will last a life time.

Those things are entirely unsuitable (read as CRAP) for a 6-volt system, and at best only marginally OK for 12-volt. Regardless of whatever other problems you might have at the battery posts (acid fumes leaking from poor seal at the top?), you'd be much better served to get one of the high-amperage capacity rotary switches like the Cole-Hersee.

colehersee.com/home/products/r/index.htm

Ok, but why would the voltage make any difference at all?

I was actually quite happy with the isolator. I looked at the rotary key-type ones but I didn't want to start drilling the car to mount the switch. The one I fitted is discreet and easily removable. Its not actually the green knob one anyway which is renowned for being poor quality - its the same style but a better brand.

The isolator wasn't really the point of the question - it was the corrosion but I think you answered that - I must have disturbed the seal on the battery when fitting the switch and capilliary action is drawing the acid up to the top.

I'll clean it off and apply a new seal - silicone probably

Cheers

As always, BigKev and OD speak the unvarnished truth.
And some wet batteries simply leak more at the terminals than others, even battery to battery, same brand/model.
Just another reason most vintage/Classic owners in my circle have been supremely happy with the Optima six-volt battery since the 1990s.
I installed, as in previous collector cars, a brass, marine-grade master disconnect switch in my '47 Super,which was available at my local auto parts emporium. NAPA or any quality store should carry or be able to order it. Just make certain the switch you use is rated for more amps than your starter pulls.

I mounted it in the firewall, beneath the dash, keeping
my 00 gauge battery cable as short as possible. A great convenience and peace of mind, and of course, it prevents the Packard clock from draining the battery during the long periods between runs in rare, rare windows in our hellish traffic to keep the car fettled.

kts68 asks: Ok, but why would the voltage make any difference at all?

It's not the voltage per se, it's the associated amperage (current). If a 12-volt starter draws 200 amps under load, an equivalently designed 6-volt starter would require twice the amount of amperage and the area in the cheap little switch is inadequate to passing that amount of current for more than the very briefest of moments. And many 6-volt starters, especially on heavier engines, can draw 600 or more amps at lock-load.

As to sealing your battery terminal/case junction, I don't believe silicone will take 20% sulfuric acid for very long. Old time battery makers used tar and that's what I've used the very few times I had occasion to do it and it works perfectly. Leakage of acid fumes at the terminals on lead/acid batteries is pretty much a thing of the distant past, unless the terminals have been pushed, shoved, or otherwise mistreated.

Dear kts:

The corrosion build up on the terminals means that you have a battery condition problem and/or a parasitic drain problem as well. It is possible that there is a carbon track taking place in the battery box even when one of your terminals are disconnected.

To test, clean the battery case thoroughly and disconnect both terminals. Make sure there is no high carbon rubber and what not contacting the battery case. Bring the battery to a full state of charge (out of the car) and test test with a hydrometer. Leave everything off and recheck the state of charge over the period your cables would take to become fouled.

From there it's either the battery or the car causing your problem.

Hope this helps.

KTS, the gents above wisely get to the gist of your problem. But the last wet battery i had, an extra large 3EH in my case, for which i had to slightly bend the battery tray lips out to accept, did maddeningly seep at one of the terminals, despite my electrical system being in fine shape. That, and preferring the Optima's mere 18-lb. weight against the 56-lb. extra HD wet battery, and my friends reporting satisfactory starting using lone six-volt Optimas in their large-engined survivors, clinched it for me. Being in England, you get the concept behind Bentley Continentals,
Railtons and the like. Weight is the enemy in any fine road car, and your 745 be grandfather of us all.

BTW, i can now use all the empty space on my battery tray as a place to rest tools, drop light whilst fussing in the engine bay, but this added benefit moot given the location of your 745's battery.

Quote:

Guess who has one of those switches on his '51! I have been experiencing a starting problem which is that if the engine doesn't start on the first of second try, the battery acts like it has a low charge. I've assumed that I need to replace the battery. However now I'm wondering if it's the switch. What are the symptoms caused the the "green knobbed wonders"?

My '51 came to me Negative Ground and I haven't yet switched it over.

What are the symptoms caused the the "green knobbed wonders"?

Exactly the same symptoms as with undersize battery cables, slow cranking with corresponding weak spark, and hard starting. Feel the "green wonder" while trying unsuccessfully to start, I'll bet it gets pretty warm from failure to be able to pass adequate current. I've even seen the green knob begin to melt on occasion,