Jump to content
The mkiv Supra Owners Club

Battery Woes


AlexJames
 Share

Recommended Posts

Hi Guys, a little advice needed.

 

The electrics on the Supe went a little nuts when I was driving her the other day and eventually I lost all electrics and the car died.

 

I had a look under the bonnet and found out that the clamp which holds the battery down had rattled loose and fused itself to the positive connector, there-for earthing the battery.

 

After prising it off the connector, I jump started her to get her home but it seems the alternator is not working as it only takes about 10 mins of running time for her to die.

 

Have I...

 

A) blown the fuse for the alternator

B) cooked the alternator?

or

C) Something else

 

:blink:

Link to comment
Share on other sites

Check the voltage across the battery to see if the alternators actually working. Chances are you've popped the ALT fuse. Your lucky the battery didn't go bang in your face :)

Link to comment
Share on other sites

Ok some updates...

 

So I took the fuse out, which I tell you was not easy, the plastic was as fragile as paper!! hence the 2nd picture!!

 

You can see that although the fuse is oxidized on the outside, its still well connected and not burnt.

 

Do you think i cooked the battery which is why it isnt holding charge?

 

I dont have an ammeter at the moment so I cant test the voltage when the engine is running.... any thoughts?

Picture 019.jpg

Picture 021.jpg

Link to comment
Share on other sites

Ok some updates...

 

So I took the fuse out, which I tell you was not easy, the plastic was as fragile as paper!! hence the 2nd picture!!

 

You can see that although the fuse is oxidized on the outside, its still well connected and not burnt.

 

Do you think i cooked the battery which is why it isnt holding charge?

 

I dont have an ammeter at the moment so I cant test the voltage when the engine is running.... any thoughts?

 

 

Hi Alex,

If you have enough juice to get to Halfords and back they do a free diagnostic on your battery. With the holding, start up and running power.

 

My brace came off and the car kept cutting out turns out the brace must of been lose for ages and the battery kept moving so the charge depleted over time. didnt notice until it started cutting out.

 

tightened the connectors and brace and it recharged after a few miles.

Edited by TUNERAIDER (see edit history)
Link to comment
Share on other sites

Thanks Tuneraider, thats just what happened to me!

 

So Updates:

 

Battery fully recharged. Iv taken her for a spin and re-fueled. All seems fine after a 10 min blast but thats not really enough time to run the battery down if the alternator isnt charging is it?

 

I have noticed that I have the little battery light displaying on the dash... does that mean that alt isnt working?

 

If I managed to cook the alt, why on earth didnt the fuel blow?

Link to comment
Share on other sites

Or if you don't have a voltmeter, turn on the headlights, then start the car to see if they immediately get brighter, as they normally do. Fwiw, I once ran a MkIII Supra for over an hour even with the headlights on when my alternator failed so it should last more than 10 minutes. You still need the battery to run the car, even if the alternator is ok, although the batteries are mainly as big as they are for starting/cranking amps because of the deep drain on the capacity. Supplying a high amperage or voltage is easy, just not for very long without a substantial storage medium or capacitor. The car still runs off the battery in other words and is only supplemented and recharged by the alternator/generator.

 

Your battery is probably 500-700 cold cranking amps capacity? The alternator on the other hand is 100-150 amps output and with practically zero storage capacity so anything above 100-150 amps load on the alternator circuit should blow the fuse. The reason it didn't was because you weren't loading it on it's own and the battery still provided an adequate, if somewhat shortlived buffer, from which to draw, even while shorted.

 

Have you checked the fluid levels in the battery if it has screw-in caps? May well be dry or shorted from overheating. Until you check and charge or replace the battery, I wouldn't worry about the alternator just yet.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. You might also be interested in our Guidelines, Privacy Policy and Terms of Use.