AlexJames Posted May 23, 2011 Share Posted May 23, 2011 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 Quote Link to comment Share on other sites More sharing options...
AlexJames Posted May 23, 2011 Author Share Posted May 23, 2011 (bump) Quote Link to comment Share on other sites More sharing options...
David P Posted May 23, 2011 Share Posted May 23, 2011 If it turns out that you have cooked the battery, I have an 18 months old Halfords which will be coming out of mine in a couple of days to make room for the HHO system. Quote Link to comment Share on other sites More sharing options...
Guest ugp Posted May 23, 2011 Share Posted May 23, 2011 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 Quote Link to comment Share on other sites More sharing options...
snake Posted May 23, 2011 Share Posted May 23, 2011 just buy a tester and see if any current is charging the battery /check the fuses first Quote Link to comment Share on other sites More sharing options...
David P Posted May 23, 2011 Share Posted May 23, 2011 The (150amp?) main fuse is at the bottom of the fuse box fastened with a 13mm nut, the only 13 on a Supra. Quote Link to comment Share on other sites More sharing options...
AlexJames Posted May 23, 2011 Author Share Posted May 23, 2011 Brill, thats some good help right there Quote Link to comment Share on other sites More sharing options...
AlexJames Posted May 24, 2011 Author Share Posted May 24, 2011 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? Quote Link to comment Share on other sites More sharing options...
TUNERAIDER Posted May 24, 2011 Share Posted May 24, 2011 (edited) 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 May 24, 2011 by TUNERAIDER (see edit history) Quote Link to comment Share on other sites More sharing options...
AlexJames Posted May 27, 2011 Author Share Posted May 27, 2011 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? Quote Link to comment Share on other sites More sharing options...
tomgeer Posted May 27, 2011 Share Posted May 27, 2011 Sounds like the alternator if you still have a battery warning light, if the big fuse is okay and the battery is okay, I would imagine thats your next port of call. Quote Link to comment Share on other sites More sharing options...
AlexJames Posted May 27, 2011 Author Share Posted May 27, 2011 Yeah, thats what im worried about. How long do you think it would take to drain a battery thats not being charged? Quote Link to comment Share on other sites More sharing options...
AlexJames Posted May 27, 2011 Author Share Posted May 27, 2011 Yeah, got her running then took the battery terminal off and she dies... am I right in thinking that that means the alt isnt charging? Quote Link to comment Share on other sites More sharing options...
Jellybean Posted May 27, 2011 Share Posted May 27, 2011 Yeah, got her running then took the battery terminal off and she dies... am I right in thinking that that means the alt isnt charging? The only way to test if the altenator is doing its job is to test the voltage across the battery when running Quote Link to comment Share on other sites More sharing options...
Morpheus Posted May 28, 2011 Share Posted May 28, 2011 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. Quote Link to comment Share on other sites More sharing options...
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