I'll start with a simple question, then give a little background.
Would the voltmeter on the engine panel always show the charging voltage (approx 14v or whatever) regardless of the condition of the battery (even a fully charged one)?
From my brief smattering of flight training, I did retain the habit of scanning the engine instruments immediately on startup (Oil pressure, charge, RPM ad later temp). I seem to recall that the volt meter always came up to that nice >12v charging region that gave me the warm and fuzzies that the alternator was "putting out" and i happily keeping the batteries charged.
Recently, Judith sprang for a new house battery (starting batt was always in good shape). Bless her heart! anyway, I've noticed that the meter now likes to hang around 10v and will stay there regardless of RPM at least until the temp hes been up for a considerable time. It will eventually show the usual charging voltage "eventually", however, I have a strong feeling that this voltage should always be up to par, and that its the charging CURRENT that varies as a result of the sensed battery charge.
Thoughts?
Thanks!
OK then, this *is* an alternator question
Moderator: Jim Walsh
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Warren S
- Posts: 254
- Joined: Jul 27th, '06, 21:22
- Location: s/v Morveren
Cape Dory 270 Hull #5
Washington, NC
OK then, this *is* an alternator question
"Being hove to in a long gale is the most boring way of being terrified I know." -Donald Hamilton
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Andy Denmark
- Posts: 630
- Joined: Feb 5th, '05, 11:38
More details needed
Warren,
What kind of battery did you replace and what kind do you have there now (the new one) -- flooded, AGM, gel cell? They all charge at different rates, voltages and acceptance curves.
Like cold fusion and AGW, it's all a WAG until the facts are known.
Could be that your alternator has an intermittent problem (diodes?) that cause the voltage to fluctuate.
Just some thoughts ...........
________
Montana Medical Marijuana Dispensary
What kind of battery did you replace and what kind do you have there now (the new one) -- flooded, AGM, gel cell? They all charge at different rates, voltages and acceptance curves.
Like cold fusion and AGW, it's all a WAG until the facts are known.
Could be that your alternator has an intermittent problem (diodes?) that cause the voltage to fluctuate.
Just some thoughts ...........
________
Montana Medical Marijuana Dispensary
Last edited by Andy Denmark on Mar 16th, '11, 07:05, edited 1 time in total.
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Oswego John
- Posts: 3535
- Joined: Feb 5th, '05, 20:42
- Location: '66 Typhoon "Grace", Hull # 42, Schooner "Ontario", CD 85D Hull #1
Re: OK then, this *is* an alternator question
[quote="Warren S"]I'll start with a simple question, then give a little background.
Would the voltmeter on the engine panel always show the charging voltage (approx 14v or whatever) regardless of the condition of the battery (even a fully charged one)? [unquote]
O J - Answer
If the voltmeter was working properly, I'd say yes. The voltmeter reads the battery positive to ground. The +B terminal of the alternator is common to the battery pos. terminal. The voltage of the output of the alternator, as well as the voltage of the battery anode should be identical and show on the voltmeter as equal.
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[Quote Warren]
Recently, Judith sprang for a new house battery. I've noticed that the meter now likes to hang around 10v and will stay there regardless of RPM at least until the temp has been up for a considerable time. It will eventually show the usual charging voltage "eventually", however[unquote]
O J - Ans.
I don't know why temperature should have an effect on the voltmeter reading. I would think that the volt reading would be instantaneous. I would double check the voltmeter for malfunction.
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[QuoteWarren] I have a strong feeling that this voltage should always be up to par, and that its the charging CURRENT that varies as a result of the sensed battery charge.
Thoughts? [unquote]
O J - Ans
I feel that you are correct.
Since you are familiar with reading control panels, I feel that you also are aware of the following. There are some who confuse the function and readings of the voltmeter with those of the ammeter.
Some people think that the voltage regulator alters the voltage from the alternator to the battery. Not so. It raises or lowers the voltage across the field coils, which in turn raises or lowers the AMPS output of the alternator to the battery.
With a fully charged battery, if high amps were continually pumped into the battery, it would soon be fried, over sulphated, maybe boil over, go kaput.
When a fully charged battery is subjected to a large, prolonged electrical demand, the available amps that are stored in it start to diminish. As the amount of available amps lowers, so does the voltage. Because of the cable between the battery +anode and the alternator +B terminal, the voltage regulator senses the voltage drop and lowers its internal resistance to the field coils. As the resistance to the field coils lowers, the actual coils, themselves, being a fixed resistance, more volts are allowed across the field coils resulting in a higher amperage output to the battery. As higher amps are pumped back into the battery, the battery's voltage returns to normal. This raise in battery voltage is recognized by the voltage regulator, which gradually cuts back the flow of amps to the battery.
Happy New Year.
O J
Would the voltmeter on the engine panel always show the charging voltage (approx 14v or whatever) regardless of the condition of the battery (even a fully charged one)? [unquote]
O J - Answer
If the voltmeter was working properly, I'd say yes. The voltmeter reads the battery positive to ground. The +B terminal of the alternator is common to the battery pos. terminal. The voltage of the output of the alternator, as well as the voltage of the battery anode should be identical and show on the voltmeter as equal.
**************************************************
[Quote Warren]
Recently, Judith sprang for a new house battery. I've noticed that the meter now likes to hang around 10v and will stay there regardless of RPM at least until the temp has been up for a considerable time. It will eventually show the usual charging voltage "eventually", however[unquote]
O J - Ans.
I don't know why temperature should have an effect on the voltmeter reading. I would think that the volt reading would be instantaneous. I would double check the voltmeter for malfunction.
****************************************************
[QuoteWarren] I have a strong feeling that this voltage should always be up to par, and that its the charging CURRENT that varies as a result of the sensed battery charge.
Thoughts? [unquote]
O J - Ans
I feel that you are correct.
Since you are familiar with reading control panels, I feel that you also are aware of the following. There are some who confuse the function and readings of the voltmeter with those of the ammeter.
Some people think that the voltage regulator alters the voltage from the alternator to the battery. Not so. It raises or lowers the voltage across the field coils, which in turn raises or lowers the AMPS output of the alternator to the battery.
With a fully charged battery, if high amps were continually pumped into the battery, it would soon be fried, over sulphated, maybe boil over, go kaput.
When a fully charged battery is subjected to a large, prolonged electrical demand, the available amps that are stored in it start to diminish. As the amount of available amps lowers, so does the voltage. Because of the cable between the battery +anode and the alternator +B terminal, the voltage regulator senses the voltage drop and lowers its internal resistance to the field coils. As the resistance to the field coils lowers, the actual coils, themselves, being a fixed resistance, more volts are allowed across the field coils resulting in a higher amperage output to the battery. As higher amps are pumped back into the battery, the battery's voltage returns to normal. This raise in battery voltage is recognized by the voltage regulator, which gradually cuts back the flow of amps to the battery.
Happy New Year.
O J