Alternator regulator problem?

14.4V output, 0.1V drop between alternator and battery? Sounds like a very desirable situation to me /forums/images/graemlins/smile.gif

How accurate is your multimeter anyway?
 
Has your question been misinterpreted?

Are you asking if readings in the region 14.2, 14.3, 14.4 are too high?

They are OK but maybe you would not want them any higher except from an alternator with a fancy regulator that boosted the output, before dropping back to normal.

(you'd expect the highest reading at the alternator terminals and the lowest at the battery by a small margin but you cannot be certain that the multimeter and the battery monitor will agree exactly)

The discrepancy between the battery terminals and the alternator might indicate a poor connection somewhere but depending upon how you measured them some of that may be due to the monitor shunt.

What was the charging current when you made took the readings?
 
0.1V shows there might or might not be a current . Try measuring between the battery terminal and the alternator terminal
 
Just as a matter of interest the regulator on my son's car died and the system voltage rose to 18volts blowing lamps fuses and demolished the wiper system. (It shorted the intermittent function electronics so that wiper started operating uncontrollably until the teeth on the gear box failed. All that within a few minutes of failure.

A failled reglator you really know about. good luck olewill
 
That's interesting. Immediately after getting the car going again after replacing the head gasket (see other post) I discovered that the battery wasn't charging. I took out the regulator / brush unit and, sure enough, one of the brushes was worn down past the limit. So I pumped up the bike tyres and cycled to the local auto electrician for a new one (I'd forgotten just how cold your hands get cycling in winter). That seemed to do the trick, but a couple of days later, driving at night, I noticed that the lights were pulsing rapidly (3 or 4 times / second). Very odd. The following day I checked the battery voltage and it was high, around 15V, rising to 16V with high revs.

Next day at the auto electrician's: "I think there's something funny with this new regulator I bought." "Can't be, it's a genuine Bosch." "Well have a look at this, then" "Fine healthy charge." "No it's not, it's boiling the battery! And what about the pulsing?" "Ah, your slip rings must be knackered." "But the pulse rate is independent of engine speed!" "Ah, well, dunno..." "How about we try another regulator?" "But it's a genuine Bosch..." "I know, but how about humouring me?"

Ten minutes later, steady 14V on the battery and no pulsing. "Well I'll test this one on the bench, never had a faulty one yet..."
 
The point of my question was not to do with voltage drops, but the fact that more than 14v was showing with a regulator rated at 14V. I have a boost charger, which takes the charge up to 14.8V when required, but in float mode it should be at 14V. Will the extra 0.2V do any damage? I am in the Med and often have to motor 8/10 hours a day when the wind fails.
 
I repeat my answer. These voltages are perfectly normal. Relax. any lower and you would not be getting full charge.
 
[ QUOTE ]
Just as a matter of interest the regulator on my son's car died and the system voltage rose to 18volts blowing lamps fuses and demolished the wiper system. (It shorted the intermittent function electronics so that wiper started operating uncontrollably until the teeth on the gear box failed. All that within a few minutes of failure.

A failled reglator you really know about. good luck olewill

[/ QUOTE ]

Surely depends how they fail - can be high or even zero ?
 
Surely depends how they fail - can be high or even zero ?
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Generally the failure will allow unregulated (high) current to pass. It is possible to fail to no current but unlikely.
 
[ QUOTE ]
The point of my question was not to do with voltage drops

[/ QUOTE ] I thought not! [ QUOTE ]
Will the extra 0.2V do any damage?

[/ QUOTE ] I think it will be Ok but keep an eye on things, at least the battery electrolyte level. Like you I'd be happier if it was just a touch lower but so long as you are not forever topping-up the battery you'll be OK. I'd act though if the volts went much higher.

Boatmike is quite adamant, so you know who to blame if things go tits up.
 
As boatmike and VicS have said, the voltage won't be a problem. Many people don't realise that most modern alternators are regulated at a higher voltage than 14.0v anyway - often at 14.4v or 14.5v - and these don't cause battery problems in automotive applications.
 
Yes Boatmike is adamant! There have been many threads on this subject here and you don't need to take my word or it, just Google "Alternator Charging Rates" and you will get authoritative information from many authors.
Automotive alternators can be set to deliver anything from 13.8 to 14.5volts for automotive use. However even this voltage won't get a battery to 100% charge capacity which is why we use smart regulators to boost the voltage to circa 14.8 volts when charging deep cycle batteries on a boat (dependant on type).

Heres an excerpt from Adverc's website.

Alternator Theory and Voltage Regulation.

All alternators are very similar in design and construction, providing rectified AC for 12 volt and 24 volt systems. The voltage regulator is a simple , robust, low cost device designed essentially for the motor car, where the demands on the battery are minimal. Engine starting is the basic function of the battery, after which the alternator supplies all the essential equipment on the vehicle.

The role of the regulator is essentially to 'clamp' the alternator output voltage at approximately 14.2 volts ±0.4 volts in order to protect electrical equipment. Conventional regulators perform this function well and, because voltage losses are usually very small on motor cars, it is extremely unlikely that sophisticated battery management systems will find their way into average-sized family saloons.

Also, because the alternator voltage-regulator provides little or no compensation for changes in ambient temperature, car batteries tend to be overcharged in the summer and undercharged in the winter causing premature battery failure, usually during a cold spell. However, the cost of battery replacement is not prohibitive.

In the case of the following:

Marine craft with long cable lengths, considerable electrical equipment and reduced engine running time;
Executive cars with engine management-systems, telephone and on-board computers;
Large commercial vehicles with electric tail-lifts, cab-heaters, telephones or radios;
Fire Engines, Ambulances and Social Services Vehicles, Mobile Library Vehicles;
the requirements are totally different and the demands on the battery system substantial. The same type of voltage regulator is employed and this is inadequate for the circumstances.

I rest my case (adamantly!)
 
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