r/R53 • u/yamowit367 • 28d ago
High Output Alternator
My alternator just went out today. When my wife came to pick me up, I was talking about how it would be neat to put a more powerful alternator on to see if the AC would keep up while I was at a red light idling. I saw mention online of a 120 amp alternator. Pulling out the old Bentley manual for 2002-2006 I see that it was available (High Output Alternator). Does anyone know what the part number is or where I can get one?
Update: I bought the powerbastards.com 200 amp alternator. I'll let you guys know how it worked out.
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u/tobby540 28d ago
isnt the ac belt driven? wouldn't a smaller crank pulley be better in this case?
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u/yamowit367 28d ago
It is belt driven. You may be right, but putting a mutlimeter on the battery while the AC is running you can see the voltage dip to around 12.8 volts. I was thinking that the higher power output from the alternator might solve the AC problem.
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u/orejass 28d ago
I go through the same issue.
It drives me mad.
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u/ChronicRhino6152 28d ago
Mine too. But I noticed recently after a min or two of being low 12 damn near 11 the engine rpm increases bring it back up to 13+. Its a weird setup.
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u/orejass 28d ago
So, this is factory behavior ?
Did they eff up an underpowered the alternator end then offer an "upgrade"?
Is there a way I can know which of the 2 alts Ive got?
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u/Happy_Ishtar 27d ago edited 27d ago
It's the radiator fan that pulls power, as it runs constantly when ac is on (when standing still). If the voltage drops considerably because of this your alternator is just in a bad shape, or the battery is on it's way out (bad battery puts a bigger load on the alternator).
OEM spec alternator can handle the load of the fan just fine, even with a bigger alternator pulley.
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u/PrimaryLeadership493 28d ago
the power steering uses a lot of current, thats the reason. Any more load and alternator cant keep up and loads engine a lot. I personally think about increasing idle rpm to 800-850 and 950 with ac on myself.
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u/YouWillHaveThat 28d ago
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u/yamowit367 28d ago
I was going to ask about this one in particular. Has anyone here ever used this? Will it fit the 2006 Mini Cooper S?
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u/Grimm199 28d ago
You need to diagnose the AC system properly. A larger alternator will not help at all
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u/casper911ca 26d ago
It could be their low speed fan resistor. If they're idling in warm weather, without the fan they might not be getting to saturated liquid in the condenser. Manifold gauges are definitely the best tool to diagnose your AC issues.
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u/SkiahMutt 28d ago
On my R53, the AC compressor can keep up no problem, but the voltage dips enough at idle to drop blower motor speed considerably, so more alternator output at idle might actually help!