nevins Posted October 5, 2013 Share Posted October 5, 2013 Right guys here's one for you. Had one fail on an auto .and as a quick fix till a repair was done a manual one was fitted. Car didn't seem right then a few days later the same warning lights came up and it was not charging. Fitted the recon old one just now and all is fine now. My question is are they the same as the manual one has caused my alternator fuse to melt which is 120 amp the same as the alternator. I have been told the manuals are 150 amp which would explain. A lot but when looking for a new one everyone was saying that they are the same across the mkiv supra. Quote Link to comment Share on other sites More sharing options...
Dave Posted October 6, 2013 Share Posted October 6, 2013 hi nevins got an alternator issue on mine too ,did you have it refurbed if so how much did it cost ?? http://www.mkivsupra.net/vbb/showthread.php?297449-alternator-problems-n-a-93-auto Quote Link to comment Share on other sites More sharing options...
Guest aspire Posted October 6, 2013 Share Posted October 6, 2013 i cant see why the auto and manual would be different. if you go from auto to manual via conversion you wouldnt swap alternators Quote Link to comment Share on other sites More sharing options...
nevins Posted October 6, 2013 Author Share Posted October 6, 2013 Hi Dave. Mine cost £95 simply due to the fact that oil leaked inside and had burnt it out completely. The bearing inside had also worn through the shaft only thing left of the oringinal was the outer cage. Aspire. Only thong I can put it down to is that the ratings are for the systems. The manual is rated at 150 amp and auto is 120 amp. The fuse was not rated to the manual rampage so started to burn the wiring out the fuse was cooked. Quote Link to comment Share on other sites More sharing options...
mattdavies Posted October 6, 2013 Share Posted October 6, 2013 Does the car have after market pulleys ? As a smaller alternator or larger crank can over spin the alternator Quote Link to comment Share on other sites More sharing options...
nevins Posted October 6, 2013 Author Share Posted October 6, 2013 Completely stock. Quote Link to comment Share on other sites More sharing options...
Guest Roger NE Posted October 6, 2013 Share Posted October 6, 2013 The Amperage rating of an Alternator is the MAXIMUM current it is capable of delivering Just because it is rated at 120 Amps DOESN'T mean it will be pushing that much current out ! It will only be sending as much current as you are drawing from it To be honest I find it hard to believe that even if you turned on EVERYTHING on the car at the same time - Headlamps, Heated Rear Window, Wipers, Washers, Stereo etc etc - you'd still be lucky to be drawing more than about 60 Amps So if you are burning out wiring (and blowing up Alternators), you have a short circuit in your wiring somewhere ! Quote Link to comment Share on other sites More sharing options...
listy Posted October 6, 2013 Share Posted October 6, 2013 i cant see why the auto and manual would be different. if you go from auto to manual via conversion you wouldnt swap alternators If the Auto is 120amp and the manual is 150amp, then there wouldn't be a problem, as you are dropping the ampage, not increasing it, therefore there is no requirement to change it. If you go manual to auto, you are using a higher amped alternator, so increasing the ampage, meaning more ampage through a smaller 120 amp fuse, hence maybe the need to change the alternator? No one ever goes manual to auto though, so I guess it's a bit of a grey area. Maybe the 150amp alternator put too much through the fuse, being 120amp? Quote Link to comment Share on other sites More sharing options...
Guest Roger NE Posted October 6, 2013 Share Posted October 6, 2013 (edited) Maybe the 150amp alternator put too much through the fuse, being 120amp?You clearly don't understand basic physics! A 150 Amp Alternator will not put 150 Amps through anything UNLESS you draw that much current !! (which would take some doing, as I explained in my last post) And quite honestly, there is no reason why you need a different rating Alternator on a Turbo, N/A, Manual or Automatic transmission Car . . . it's just what Toyota happened to fit to each model, but there is no logic to why, as there's no reason why you would ever need to draw more current from it, depending on your engine or transmission ! And in fact, most cars only have 70 or 80 Amp Alternators . . . there is no logical reason why a Supra needs a bigger one ! (it's just less likely to fail) If you want an analogy, think of having a 10 gallon petrol tank . . . you can put UP TO 10 gallons in it . . . . just because you put a 15 gallon tank on your car instead will not make it use any more fuel (nor make it go any faster!) . . . . equally you can just put 5 gallons in EITHER tank without any problems - it's just the MAXIMUM it is capable of holding. Edited October 6, 2013 by Roger NE (see edit history) Quote Link to comment Share on other sites More sharing options...
listy Posted October 6, 2013 Share Posted October 6, 2013 There is no need for the derogatory comment at the start of your post. If you noticed, I put that sentence as a question, not as a statement. It was an idea, not a factual answer. If you want to make comments like that, I'd be wary of doing it to a Mod, you won't like the results if it happens again. I understand that the maximum draw is 150amps, and that it doesn't need to use the maximum ampage. My point was, if it had peaked to over 120amps for some reason, could it have blown the fuse? It is a possibility, maybe not the most likely, but possible. I do not understand why some people feel the need to make others out to be idiots. Especially when they don't know people from Adam, imo it only makes that person look more foolish themselves. Quote Link to comment Share on other sites More sharing options...
LOGIE Posted October 6, 2013 Share Posted October 6, 2013 I always thought manuals were 90 amp and autos were 100 amp... regardless of engine. ToyoDIY backs this up. Quote Link to comment Share on other sites More sharing options...
nevins Posted October 6, 2013 Author Share Posted October 6, 2013 Well I'm going by what it says on the unit. And the fact that a 120 amp fuse has melted goes to show that a 150 amp alternator has over powered it has it not hence it being melted. Quote Link to comment Share on other sites More sharing options...
Guest Roger NE Posted October 7, 2013 Share Posted October 7, 2013 (edited) I'm sorry, I have not meant to cause offence to anyone, but I just find it frustrating that people don't seem to read an explanation when someone bothers to post one. Let me try another analogy . . . . A chair that is strong enough to withstand a 30 stone person DOESN'T mean it will put a 30 stone load on your floor . . . . it just means it won't break if a 30 stone person sits in it. If a 10 stone person sits in it, the load will be 10 stone, if a 20 stone person sits in it, it will be 20 stone, etc etc In the same way, a 120 amp Alternator is CAPABLE of supplying 120 Amps (in theory), but if you are only drawing 10 amps, it will just supply 10 amps, if you're drawing 20 amps, it will supply 20 amps, etc etc So blowing the 120 Amp fuse is NOT because of the rating of the Alternator The only way I can imagine you would possibly draw enough current to blow a 120 Amp fuse is if you have a bad short circuit in your wiring . . . even then, it would have to be on a really thick wire (like the one to the Starter Motor) to be low enough resistance to draw that much current. I always thought manuals were 90 amp and autos were 100 amp... regardless of engine That may be true . . . but as I posted earlier, there is no logical reason for a higher rating Alternator on a car with an automatic transmission. Edited October 7, 2013 by Roger NE (see edit history) Quote Link to comment Share on other sites More sharing options...
fastnfurious Posted December 29, 2013 Share Posted December 29, 2013 great explanation Roger! now i've much better understanding of amp rating on alternator as i'm in the midst of getting mine replaced and hope the following (found on eBay) will work... not sure if there's a different between LHD and RHD alternator for our RHD Supra TT auto? http://www.ebay.com/itm/100-NEW-TOYOTA-SUPRA-TURBO-ALTERNATOR-AUTOMATIC-100Amp-/290225957723?pt=Motors_Car_Truck_Parts_Accessories&hash=item4392d0ab5b&vxp=mtr Quote Link to comment Share on other sites More sharing options...
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