A place for more technical discussions. Please make sure you post in the correct section on the site, this way it keeps the site tidy AND ensures you get a more relevant answer.
My other car used to eat batteries, about 18 months for a quality brand. I am told these cars are heavy on the battery and I didn't use it enough to keep the battery fully charged.
After about 6 years (several batteries) I started getting the warning light on the dash at tick over. I realised the alternator was on the way out and since the car is mid-engined you need ramps to change the alternator (not like a Jimny). The garage changed the alternator for a new one, but they were not happy with the output of the new alternator and took it off, sent it back for an exchange and fitted a second new one, which they were happy with.
They had my car for 3 days, but only charged me for fitting one alternator, so it seems you can get faulty alternators even new quality items.
Of course if your battery is very flat, that might explain the warning light coming on, especially at tick over. Does it go out with a few revs?
It could also be a connection, usually the earth, where is connects to the engine or frame are the contacts clean? Does the joint/connection get warm, that is a sign of a high resitance joint?
Sorry this is the technical bit now. There is another issue with alternators, they generate power by a coil moving through a magnetic field and in a modern alternator the magnetic field is produced by 'field coils' which are charged by the alternator/battery. To get the whole process going you have to have some residual magnetic field in the alternator and if it is a new alternator that hasn't been run it might have lost it's residual magnetic field whilst it stood on the shelf and therefore you get a weak output.
There used to be a technique called 'flashing the field coils' to put the residual magnetic field back in to the alternator, but you might have to Google this for your specific alternator to see if it is possible to do safely.
I have only ever had to do this once and that was a long while ago.
I would still try the old alternator back on if the red light keeps coming on, unless of course your battery is flat or tired?
2020 blue SZ5 (one of the last to be registered in the UK)
Ex 2011 Blue Jimny SZ4
Northumberland Jimny Blog
We use cookies to give you the best online experience. Please let us know if you agree to all of these cookies. Accepting the Cookies also accepts the Disclaimers for the website.
