William_H
Well-known member
To explain precisely an alternator when first running will feed full current to the field coils which then produces an output voltage feeding in to the batteries which is dependent on alternator speed, the current taken by the batteries and internal resistance of the alternator. The regulator (on dumb alternator regulator) will then limit the field current until output voltage comes down to set voltage. (around 14v plus or minus) If the current taken by the batteries and or the alternator is not running fast enough then the regulator will supply max current to the field coils and the output voltage will be less than regulated voltage.
I appreciate the value of a smart regulator. However it does seem that desired regulated voltage of a charger has increased over the years. In my early days I believe 13.75 was a good regulated charge voltage. Now it seems this has crept up to 14.4. Battery chemistry has not really changed so much. So while 14.4 will ensure a max charge rate for a low battery, will it result in over charge for a very long engine run? At least Graham should check on the temperature and fluid level (if possible) of the batteries while being charged at high current. Yes if current does not reduce after a while then a battery has something wrong with it. (usually showing up as a low voltage when at rest) Typically like a shorted cell giving a 10v battery so gross over charge.
We note that he has a rated 120 amp alternator which probably means it is capable of more current if the batteries will take it. All very good but then also capable of overcharge.
My gut feeling is that if he can reduce charge voltage from 14.4 down then he should do so. Unless he is expecting to recharge batteries with a short engine run when 14.4 would be good. ol'will
I appreciate the value of a smart regulator. However it does seem that desired regulated voltage of a charger has increased over the years. In my early days I believe 13.75 was a good regulated charge voltage. Now it seems this has crept up to 14.4. Battery chemistry has not really changed so much. So while 14.4 will ensure a max charge rate for a low battery, will it result in over charge for a very long engine run? At least Graham should check on the temperature and fluid level (if possible) of the batteries while being charged at high current. Yes if current does not reduce after a while then a battery has something wrong with it. (usually showing up as a low voltage when at rest) Typically like a shorted cell giving a 10v battery so gross over charge.
We note that he has a rated 120 amp alternator which probably means it is capable of more current if the batteries will take it. All very good but then also capable of overcharge.
My gut feeling is that if he can reduce charge voltage from 14.4 down then he should do so. Unless he is expecting to recharge batteries with a short engine run when 14.4 would be good. ol'will
