Lotus Elan

Possible to run with battery reversed?

PostPost by: dogmotor » Mon Apr 08, 2013 11:48 am

Hi,

Elan S2 back from the shop. The car runs, but a bit rough at lower rpms but tach and speedo are dead. The cables are not connected as I remember them (red is now to neg. on battery)!

Is it possible they reversed the battery? Would the car run in this condition? The car still has the generator, btw. (Yes, I feel really stupid asking this...)

Thanks much,

Mark
dogmotor
New-tral
 
Posts: 7
Joined: 31 May 2009

PostPost by: billwill » Mon Apr 08, 2013 1:16 pm

Yes cars with dynamos (not alternators) can be run with the battery reversed but that is normally part of a deliberate action to convert to Negative earth.

The process normally requires reversing connections on the rev counter and brief-touch-connecting the field coil of the dynamo briefly a few times to reverse the remnant magnetism.

You may need to do that now to get it back to negative earth.

Perhaps they looked at an original manual and did not realise that your car had been converted to negative earth (they were all ? originally positive earth.)

~~~~
If they have done this wrong, it may have ruined the circuit in the rev counter. If so I think they should pay for getting it mended, they should have asked you!

However the speedometer is just mechanical and should not have been affected.

Is it an Elan or is it a Plus 2 ? ... Oh I see you said it is an S2.
Bill Williams

36/6725 S3 Coupe OGU108E Yellow over Black.
billwill
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 4717
Joined: 19 Apr 2008
Location: London UK

PostPost by: billwill » Mon Apr 08, 2013 11:01 pm

Though I did my own conversion to negative earth long ago, I remembered reading how to do it. Anyway I did a bit of a search and found this PDF file which includes a description.

http://www.google.com/url?sa=t&rct=j&q= ... 3ExN7pKCeg

It seems to cover it OK.

I had forgotten about the electric windows, so if they now go the 'wrong' way you know for sure that your car had been converted to negative earth by someone who remembered to reverse the window motor wires.
Bill Williams

36/6725 S3 Coupe OGU108E Yellow over Black.
billwill
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 4717
Joined: 19 Apr 2008
Location: London UK

PostPost by: EdHolly » Mon Apr 08, 2013 11:08 pm

I once reversed the polarity in a 3.8 E type - the only thing needed was to change the coil wires over and to reverse the polarity of the generator by making it run as an electric motor with the wires connected the other way round for a few seconds.

Only thing was the gene sat around for quite a while before I started the motor and the amp meter when it started went full scale discharge. It must have reverted back to its old ways over the elapsed time. I managed to disconnect the battery before anything untoward happened, but wonder if in your case now whether it might have damaged the generator.
EdHolly
First Gear
First Gear
 
Posts: 31
Joined: 22 Apr 2012

PostPost by: dogmotor » Mon Apr 08, 2013 11:27 pm

Thanks for all the replies. I'm tempted to just try the battery the way it was before, but need to call the mechanic. I'll report back but won't be able to look at it until the weekend.

Thanks again,

Mark
dogmotor
New-tral
 
Posts: 7
Joined: 31 May 2009

PostPost by: AHM » Tue Apr 09, 2013 2:56 am

Smoke and lots of it!

Did the car run before you took it in?

Why would your mechanic take the battery out and turn it around?.
AHM
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1493
Joined: 19 Apr 2004

PostPost by: Quart Meg Miles » Wed Apr 10, 2013 4:08 pm

Mark,

I would pull the power lead off the tach before running the car again. It sounds like you already had a negative earth conversion but you need to ask your mechanic what he did, and why. If he did change the polarity he must have known he was doing it to get the generator to work, assuming that it is; I have a non-standard ammeter but you'll have to use battery volt rise to work out if it's charging.

As already mentioned, battery won't affect the speedo so he has work to do.

Bill,

I didn't know you could upgrade a S2 to electric windows. :lol:
Meg

26/4088 1965 S1½ Old and scruffy but in perfect working order; the car too.
________________Put your money where your mouse is, click on "Support LotusElan.net" below.
User avatar
Quart Meg Miles
Fourth Gear
Fourth Gear
 
Posts: 982
Joined: 03 Oct 2012
Location: Barnham, W Sussex, UK

PostPost by: billwill » Wed Apr 10, 2013 5:16 pm

>I didn't know you could upgrade a S2 to electric windows.

I have to admit I don't know much about the specifics of Elans before the S3. 8)


Anyway for S3s you get a bit of a rude shock if you convert to negative earth and forget about the windows. They then go up when you meant down and down when you meant up.

{its because they have permanent magnet motors, unlike the dynamo and starter motor which have electric fields}
Bill Williams

36/6725 S3 Coupe OGU108E Yellow over Black.
billwill
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 4717
Joined: 19 Apr 2008
Location: London UK

Total Online:

Users browsing this forum: No registered users and 11 guests