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Yes, but it may have different connectors and power. May not fit if your 307 has the 1.6 diesel engine.
All car alternators produce AC which is then converted internally to DC and voltage is regulated not to exceed 14.4 volts to avoid blowing bulbs, ecu's etc.
 

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Further thought, why not overhaul the current alternator, if you are lucky it probably only needs new brushes obtainable on ebay and Youtube shows you how to replace them. I'm assuming it is the earlier clutchless alternator
 

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Discussion Starter #4
It's off my 307 2.0 hdi. Need car running asap as it's my family car. Used to know a guy who did it but think his shut up shop due to age. Has the dreadful freewheel pulley

Jerry
 

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Freewheel pulleys are not dreadful they are designed to take the load off the engine when the battery is full and the electric draw is low the result of this is less strain on the alternator and better MPG ok its only going to be a tiny amount but every little helps :)
 

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Got this from another website, I live and learn!
1) Alternator with roller clutch built into pulley:

This is to de-couple the alternators rotational inertia from that of the crankshaft. Because the alternator is typically geared approx 3x faster than the crank, it's rotating inertia is also refferenced to the crank via this ratio. The "clutch" is a simple PASSIVE "roller bearing clutch" (google it). This means that when the crank shaft accelerates the alternator rotor is accelerated with it, but when the crank decellerates, the alternator can "freewheel" along on its own. This massively reduces the belt load and hence wear (important now cars have LONG service intervals and the FEAD (Front End Auxilary Drive) system is heavily loaded (high elec loading and A/C load etc)

This de-coupling of the alternator is important for two scenarios where the crankshaft undergoes rapid deceleration:

a) Upshifts, especially with DSG transmission etc: On a road car with wide gear ratios, the crankshaft is required to slow by several thousand rpm in as little as 100ms these days!

b) High BMEP with low cylinder count: As power and torque output increases from lower cylinder capacity and lower cylinder count, the crankshaft torsional vibration increases massively. in effect, everytime a cylinder fires the crank accelerates, and then slows again up the next compression. This kind of torsional activity can exceed 50krpm/s at high low low rpm, and would put the FEAD under huge loads, as it will be reacted into the alternators rotational inertia


2) Alternator with "smart charge" capability
Entirely seperate to the roller clutch for belt life maximisiation detailed above. The Battery management system uses a "colomb counting" strategy to determing the State Of Charge (SOC) of the lead acid battery, and only commands the alternator to charge it when is drops below a certain SOC (depending on a load of parameters, such as temp, vehicle speed/load etc etc). Because a claw pole alternator is in-efficient at light load (low output currents) it is more efficient to use the batteries charge storage capacity to buffer the alternators output as / when necessary. Further, this load can be used to move the engine operating point to a higher efficiency one (high BSFC point), and this brings significant benifits over a low average road load cycle like the EUDC emissions/fuel economy test cycle.
This smart charging requires no mechanical changes to the system, the alternator rotor is still turning all the time (at approx 3x engine rpm) but the system only energises the field windings in the rotor when required. Conventional "dumb" alternators simple have a regulator that targets a constant output voltage (voltage control mode), usually 14.7v. However, smart alternators are controlled in the current domain, and (usually) the engine ecu will command an output current, that is practically independant of output voltage, but is driven by battery SOC (modelled in the ecu control system)
 
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