Alternator for Mercedes-Benz Unimog U-300 4.3L – 4249cc Ds 2000-2003 MAH-MG803

Q: Do I need a larger charge wire for a High Output unit?
A: The high amp unit will operate better than stock, but not to its full potential without a larger charge wire. It’s the same reason firetrucks do not use garden hoses. It is IMPARATIVE to have proper charge and ground cables.
Q: Does a High Amp unit cause any damage to my battery or my vehicles charging system?
A: As long as it is installed properly with battery in good condition, then no. A High Output unit works exactly like a factory unit and only produces what is being demanded. No alternator works continuously at full output. Higher amperage is not bad and will not hurt a battery, but high voltage will blow one up.
Q: Will aftermarket underdrive pulleys (crankshaft power pulley) have any effect on my alternator?
A: Yes, underdrive crankshaft pulleys slow all the components (power steering, a/c, and alternator) to provide more power to the rear wheels. In some cases, the charging systems will fall totally on the battery at idle and completely stop charging.
Q: Where is the best place to get a voltage reading of the alternator output?
A: You’ll get the most accurate voltage reading from the back of the alternator at the main charge post that runs directly to the battery. This must be done while the vehicle is running.
Q: Why is the pulley on a high amp alternator smaller than my stock pulley?
A: The smaller pulley advances the power curve of the alternator just slightly, which produces a little more amperage around the idle if needed.
Q: Will I need a smaller belt for my high amp unit?
A: This varies by application because not all belts and belt tensioners are in the same condition. The tensioner will always tell you if you need a new belt or not. If it’s in range, you will not. If it is out, you will. Generally, you will need a belt that is one inch shorter than stock. You should have no problem finding a replacement wherever you buy your parts. V belt applications simply re-adjust your belt tensions to 3/8” deflection.
Q: What is the difference between a one wire, self-exciting and a self-energizing regulator?
A: Nothing. They are all exactly the same. Different manufacturers use different terms for marketing. The only wire to hook up is the charge wire to the battery. This does require modification for the alternator charge light on the dash.
Q: My stock unit used a five-groove pulley, and you sent my high amp alternator with a 6 groove. Why and what can I do?
A: 5 groove overdrive pullies are not produced. Install the belt on the back groove of the pulley closest to the fan or body of the alternator. The fan is internal, and this application will work just fine.
Q: Can your alternator be run in dual or triple alternator applications?
A: Yes. When wired and mounted correctly, the alternator can run in either dual or triple applications.
Q: Will I need a new battery with a high amp alternator?
A: If your battery is in good condition, and in spec of its OEM rating, then no. Your battery should work equally well with either the OEM and a High Amp unit.