series 1 advice needed

[el shano]

New to this forum - hopefully someone knows the answer to these 2 questions - I have a 1951 series 1 with no battery - any advice on an appropriate battery would be welcome - also the polarity has been changed and I don't know how this will affect the starter motor - has anyone gone through this?

[isuzurover]

An N70 is the battery you want.

It would have been positive earth from the factory, but this is fairly easy to change, if it hasn't been done already.

[JDNSW]

As Isuzurover says, an N70. Originally it would have been positive earth system, but changing to negative earth is trivial - the only thing required is to reverse the connections to the ammeter and polarise the generator by momentarily connecting it direct to the battery positive. (Easiest way to do this is to take the cover off the voltage regulator and momentarily close the cutout points by hand.)

The easy way to tell whether it has been changed is to connect the battery, putting the earth lead on the positive (but not if an alternator has been fitted - see below). Before attempting to start, switch on the lights and check that the ammeter shows discharge. If it shows charge, the polarity has been swapped and you should swap the battery connections before attempting to start.

If you get the polarity wrong, nothing will be damaged, least of all the starter, but the generator will not work, and running it like this for a long time without polarising the generator may damage the regulator. However, if there is a radio fitted, this probably will be damaged by incorrect polarity - if a post-1970 radio is fitted, it is almost certainly negative earth. And if an alternator is fitted, it is certainly negative earth and will be destroyed if the battery is connected positive earth!

John

[101RRS]

When I bought my original series 1 it was connected as negative earth - it started and ran OK. However after I had the car for a while I realised the ammeter was working odd. I connected the battery the other way around so it was positive earth and it still started and ran Ok but the ammeter now worked.

So to start an original series 1 with a generator, it doesn't seem to matter how the battery is connected - and no the engine does not try to turn backwards when the battery is connected the wrong way around.

Garry

[Rangier Rover]

All my series 1s are now - earth. Starter is fine. Have a bedford starter in one of them though. Other than dyno and Amp meter you might look at the coil They can get hot

[JDNSW]

All my series 1s are now - earth. Starter is fine. Have a bedford starter in one of them though. Other than dyno and Amp meter you might look at the coil They can get hot

Coil heating will not result from changing the polarity. However, strictly speaking, coils are polarised, and the connections should be reversed (if they were right in the first place!)- this is because the polarity of the initial voltage rise of the spark is determined by this, and the spark is easier to initiate when the centre electrode of the spark plug is negative, as electrons are more easily stripped from there since it is hotter than the outer electrode. In practice, the effect is not usually noticeable unless the spark was pretty marginal in the first place, not usually a problem with these relatively low compression engines. Coils are usually marked with + and - but may be marked with switch and distributor, leaving you to guess what battery polarity they were designed for.

John