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  1. #1
    Join Date
    Aug 2009

    Question Duff Battery and Charge Warning Lamp Illumination

    Over the winter I assumed that both the domestic and engine battery banks were being charged by the AirX wind charger. I now know that the AirX only charges the domestic bank and this was the only device used over the winter, so the engine bank just sat their getting no charge at all. I also have twin alternators charging via split charge diode and a charge warning lamp for domestic and engine batteries.

    I have a 24V system and the voltage on the engine bank was 19V, so I guess they are now duff and need replacing, although they are only 3 years old.

    I started the engine for the first time after the winter on the domestic battery bank. In fact is started incredibly quickly with a very quick turn and near instantaneous ignition. The best she has ever started by far.

    The charging current as read from the BEP meter increased to about 32A and then slowly dropped back over about 2 hours to a steady 8A. However, around this time I noticed that both the charge warning lamps were glowing faintly. I stopped the engine. Later, I restarted the engine and the lamps were out.

    Would the warning lamps come on because of the duff engine starter battery having too high a resistance for example and the domestic bank being 100% charged i.e. there was no where for the charge to go?
    "'...contradictions .... are deliberate exercises in doublethink." Orwell from 1984

  2. #2
    Join Date
    Jul 2002
    Home: Kent. Boat: Chichester


    I'd recharge the starter battery with a good automatic multistage charger with an adequate output for the battery size and a reconditioning stage if possible and give it the benefit of the doubt.

    It ought to have been perfectly OK for six months with no charging if there was no load on it.

    I'd have normally thought the two warning lights were associated with the alternators rather than the batteries.

    They illuminate due to the initial alternator field excitation current from the battery passing through them.

    They go out when the alternator output reaches the battery volts.

    We've had discussions before about glowing warning lights. No sure we've identified many of the reasons satisfactorily.

    A sketch of you twin alternator twin battery and diode splitting would be interesting

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