Mondial electrical problems: load/alternator/battery mismatch?

Discussion in 'Technical Q&A' started by snj5, Jan 1, 2006.

  1. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    San Antonio
    Full Name:
    Russ Turner
    As most know, the Mondial has had a reputation of having weird electrical things. And, as has been documented, often time the weird behaviors start mysteriously, and then many are mysteriously cured by a new battery or fresh charge, even with a working charge system.
    Here is the history of Mondial alternators and batteries:

    M8: Bosch 65A alternator and 66 Ah battery
    QV: Bosch 80A alternator and 66 Ah battery
    3.2: Bosch 85A alternator and 66 Ah battery
    t: Delco 105A alternator and 66-70 Ah battery (same as 348)

    reference example:
    911 3.2: 92A alternator and 66Ah battery
    911 3.4: 115A alternator and 72 Ah battery

    So, what I think may be happening is a circuit load/battery/alternator mismatch. The electrical load is NOT that different between Mondials (or a 911, I'd guess), and notice they kept going up every year while the real 'requirement' was about the same; Also, the drive train was engineered for the 2 seat 308/328 as well, with a bit lesser load potential: Especially if a more powerful battery and/or stereo amplifier is installed, it may accentuate the condition.

    Ergo, I think a basic solution to some of the Mondials weird electrical behavior may be solved by going to a bigger alternator and/or battery to better meet load requirements.

    Would a Delco Remy 30SI series work? It has an output at 6000 rpm of 90/105 amps and at 1600 rpm of 44/53 amps. It has a max rpm range of 10K rpm continuous, and is a brushless (long life/reliability) one wire hook-up, and will take rotation either way. I'm brand new at this, so all advice welcome.

    So, anyone have advice or a suggested a higher output replacement alternator and how to wire it up? I know the alternator is easy to get to through the starboard rear wheelwell.

    Many thanks, and happy new year to all!
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  3. CliffBeer

    CliffBeer Formula 3

    Apr 3, 2005
    Seattle, Washington
    Full Name:
    Russ, IMHO the Mondial's frequent electrical problems stem more from certain overloaded circuits rather than an undersized alternator or battery. Specifically, I've seen melted fuse boxes and melted wiring as a result of hack electrics related to aftermarket stereos/amps, alarms, old car phones, etc. Also, I also believe the older Mondials have electrical gremlins because of the inevitable corrosion in the fuse box riveted connections. Certainly, a strong battery and alternator with a healthy voltage level might help reduce the severity of this problem, however, the underlying problem isn't the alt/batt. Just my opinion
  4. dakharris

    dakharris Two Time F1 World Champ

    Jun 7, 2001
    Sleepy Hollow
    Full Name:
    Cavaliere Senzatesta
    What he said. I have experimented with a bigger battery. It makes the clock flash 0:00 every time you switch on.

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