Battery Terminal Post Sizes

[svenedin]

As many of you will know, I am restoring the engine bay (and in fact the whole front) of my car.

As I put things back in the engine bay some things are just a bit too tired and worn out and I have either repaired and restored them or replaced them. One such item is the earth lead and terminal from battery terminal to the side of the battery box. In my case, this lead connects to the POSITIVE battery terminal as my car is positive earth.

I bought a new battery earth lead with pre-fitted terminal connector from ESM. It would not fit over the battery positive terminal post. The post is too big, connector too small.

I queried this with ESM parts department and I received what I think is a nonsense reply but I would like to confirm this. The response is in quotes below:

"Some modern battery’s have different size terminals, these cables are setup as per the originals so are not always compatible.
You’re welcome to return it, but I don’t have any other sizes I’m afraid."

Now, my old earth lead with pre-fitted terminal DOES fit and it is clearly made for the larger positive battery terminal.

What's going on here and are ESM just trying to sell an earth lead that is only for NEGATIVE earth cars?

Stephen

[Andmurph]

Hi Steven, I’ve been busy looking through my photos but can’t find what I’m looking for.
Both the Morris Minor pickup and MGMidget had replacement batteries in the last couple of years. The replacement battery on each is NAPA branded and the terminal posts have a removable collar so that they can be used with earlier cables.
The pickup is negative earth and I had to remove the collar from the post for the earth cable to fit.
The battery on the Midget replaced a Lucas battery and both cables there fit over the outer collar.
It appears there are different sized posts on at least some modern batteries. Auto Electrical Supplies list battery lead clamps at 10mm 12mm and 16mm

https://www.autoelectricsupplies.co.uk/ ... screw-type

[geoberni]

I have found that sometimes responses from ESM stand up to the same low standard as a 'Saturday Boy' working in Halfords, or similar store.
Complete garbage.

"Some modern battery’s have different size terminals, these cables are setup as per the originals so are not always compatible.
You’re welcome to return it, but I don’t have any other sizes I’m afraid."

I wouldn't believe that for a moment. If they are 'set up as per original' then the clamp should clearly fit the Pos Terminal.
I don't know when the terminals adopted different sizes, it was certainly many decades ago. I've not found out when it happened, despite considerable internet searching.

I'm suspicious of the ESM, item as it's shown with N/P on the casting of the clamp.....
https://www.morrisminorspares.com/elect ... le-p829853

The same 'dual purpose' earth strap can be found on ebay: https://www.ebay.co.uk/itm/295618428445

It does rather make a mockery of the international standards requiring different size terminal posts to try and prevent cross connection....

Getting a genuine Pos Earth 'Strap', as opposed to an insulated cable with a Pos Clamp fitted, can get expensive. Moss want £30. I've seen them $50 or more online.
A definite mark up just to get one 'Pos Earth'....
Personally I'd just cut the end off a regular one and fit the correct end fitting. A far lot cheaper.

[geoberni]

Hi Steven, I’ve been busy looking through my photos but can’t find what I’m looking for.
Both the Morris Minor pickup and MGMidget had replacement batteries in the last couple of years. The replacement battery on each is NAPA branded and the terminal posts have a removable collar so that they can be used with earlier cables.
The pickup is negative earth and I had to remove the collar from the post for the earth cable to fit.
The battery on the Midget replaced a Lucas battery and both cables there fit over the outer collar.
It appears there are different sized posts on at least some modern batteries. Auto Electrical Supplies list battery lead clamps at 10mm 12mm and 16mm

https://www.autoelectricsupplies.co.uk/ ... screw-type

They are quoting different cable entry, i.e. fitting the clamp onto different cable diameters...

But yes, there are different battery post sizes, actually 3 different 'standards' (excluding the Japanese Pencil post) which tend to have global geographic areas of preference, although DIN & EN are basically the same with a slight height difference.

JIS are on older/historic Japanese vehicles...

Battery posts.JPG (93.3 KiB) Viewed 8443 times

[panky]

The posts on every battery I've bought over the last few years for my eclectic collection of cars (the last one for my traveller) have been different sizes. When I converted to negative earth a few years back I needed to purchase new terminals, as the old ones were past their best, they were indeed different sizes.

[svenedin]

Hmm. This is more complicated than I thought!

So how do we know which type of terminals a battery will have when we buy one????

Stephen

[geoberni]

Hmm. This is more complicated than I thought!

So how do we know which type of terminals a battery will have when we buy one????

Stephen

I've just done a quick check of the battery numbers I put on my list of suitable batteries, viewtopic.php?p=684798#p684798
and they all come up as Type A/Standard Automotive.
For example, a 005R suitable for a Pos Earth.
https://www.bmstechnologies.co.uk/produ ... code-005r/
https://www.powerland.co.uk/products/mf ... -480a-005r

I then looked at some other battery manufacturer websites and found that searching the Exide Group...
https://www.exidegroup.com/eu/en/battery-finder, they all seemed to be the EN tapers.
Sure enough, when I looked specifically for an Exide branded 005R, it has the EN Taper...
https://batterygroup.co.uk/batteries-by ... -390a-005r

So yes it's complicated, most batteries in the UK, from my research today, seem to be Type A, but not all....
Check the specs provided by seller, if not listed, cross check elsewhere.

[svenedin]

Many thanks. It seems that my battery (which is a few years old and ironically fitted by ESM when they were doing some work on the car) must have the DIN or EN 19.5mm diameter positive terminals and so the new earth cable connector is too small as presumably "universal" (pos or neg) only for SAE terminal posts......So in fact, what the ESM parts department said is accurate!

It's just as well I am not trying to fit the Lucas "helmet" type terminals as I don't even know what sizes those are. I do have two sets of those......somewhere. My car had those terminals a long time ago and they would never stay tight. No end of starting problems.

Incidentally, has anybody ever seen a car with a lower battery clamping bar as well as the top one? My battery box has all the holes for a lower clamping bar but it didn't have one during my tenure and I assume it never had one as only used on earlier cars.

https://www.moss-europe.co.uk/en-gb/bat ... 16--02--01

Stephen

[myoldjalopy]

I suppose there aren't many of these around now, but if I need a new battery I always go to a little independent battery place with my car and they have the correct battery and terminals which is swapped over there and then. I had no idea it could get so complicated!

[svenedin]

I suppose there aren't many of these around now, but if I need a new battery I always go to a little independent battery place with my car and they have the correct battery and terminals which is swapped over there and then. I had no idea it could get so complicated!

Neither did I !!!! At least I know now.

Stephen

[les]

I hadn’t realised this issue either, when ever I’ve needed a battery I just match the amp/hr and buy one !

[oliver90owner]

The positive terminal of this type has always been larger than that on the negative side. It (hopefully) prevented interfering amateurs from mis-connecting the battery. Batteries with bolted terminals need the fitter to actually check/look at the + and - embossed on the battery case.

[svenedin]

Yes but we see from the diagram that Berni posted that:

Type A SAE/JIS Pos 17.5mm Neg 15.9mm

Whereas

Type A1 and A2 DIN/EN Pos 19.5mm Neg 17.9mm

So in my case it appears I have a battery with DIN/EN terminal posts and I have been supplied an earth lead that fits SAE/JIS terminals so it won't fit the positive terminal of my battery. I did try to open up the connector a bit but it still won't fit.

Stephen

[geoberni]

I've yet to find a retailer selling clamps that don't just describe their product as 'suitable for round posts'....

As to your other question about clamp bars, there would be no need for both to be fitted.
However, there were quite a few over the lifespan of the Minor.
Compare the LCV Parts illustration, which covers the entire production run from introduction mid SII (May 53), with that for the Minor 1000 car version (1956 to 71)

LCV battery clamp.JPG (64.7 KiB) Viewed 7389 times

S3-5 Battery clamp.JPG (61.22 KiB) Viewed 7389 times

Incidentally, the change on the cars from items 4 & 5 to items 4A & 5A is annotated as 'change point not available'... so even during production, they didn't know when it changed...

[svenedin]

The plot thickens.

Looked at my currently installed battery Yuasa YBX1038.

A rather piddly little battery at 35 Ah but it has never been an issue for me in terms of power reserve. I had not realised that this is not a sealed battery and therefore I should check and top up as necessary (which I will do right now). It's been so many years that I have only had sealed batteries. I haven't checked or topped it up in 3 years or more......Anyway, according to Yuasa's own data sheet this battery has a so-called "British Leyland" type case and has DIN terminals so the positive terminal is 19.5mm and my old earth connector fits it. Conclusion: the ESM supplied cable with terminal is incorrect for a positive earth car IF the battery posts are DIN or EN (A1 or A2). It will only fit the positive of SAE type A terminals.

Stephen

[svenedin]

Did the battery need a top-up? It certainly did.

Thank you one and all. A most interesting discussion that has saved me a lot of hassle and possibly getting stranded with a dried out battery!

Incidentally, I often see people asking about batteries on the FB MMOC page. I direct them to Berni's excellent list. Invariably people will say "get the biggest one that will fit" (meaning the most Amp hours). Clearly this is not necessary and remember my car is dynamo and it is used at night and in Winter. I do admit though that I don't have any extra electrical equipment: no radio, no heated screens, no GPS. I do have halogen headlights BUT they actually use a little bit less power than the original sealed beam headlights that my car had from new (1969).

Stephen

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