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I've noticed that the dash clock flickers slightly and also the front sidelights (ebay white LED's). Suspecting that the alternator might be faulty I checked the battery with my multimeter:
12.2 v when not running, rising to 14.4 when running with headlights on and revving the engine to 2000 rpm. The reading when not running is too low but does the latter indicate that the alternator is ok?
Thanks
Last edited by Nick_Cat; 17 October 2022 at 01:42 PM.
Please explain to me how the regulator knows: -
1) how to regulated 14.8V
2) how to regulate at 14.1V
Some background information.
I think 14.8V will boil a sealed lead acid battery.
Our 2000, 2.5 the float on our Subaru's battery Yuasa battery
has sunk almost out of sight.
Yuasa tell me I can't get the top off to top it up.
My certificated meter showed 12.5V across the posts before starting
14.8V immediately after starting with the engine ticking over..
Around 26 Amp along the battery cable after say 10 mins.
After a run, the meter showed 14V with the engine ticking over.
Could 14.8V be a correct charge voltage for a flattish, suspect
battery on start-up please?
Please explain to me how the regulator knows: -
1) how to regulated 14.8V
2) how to regulate at 14.1V
The alternator monitors the battery's output load and adjusts accordingly both voltage and current. (known as a smart charger)
Some background information.
I think 14.8V will boil a sealed lead acid battery.
Only if the alternator current output is not regulated correctly.
Our 2000, 2.5 the float on our Subaru's battery Yuasa battery
has sunk almost out of sight.
Yuasa tell me I can't get the top off to top it up.
Will be a sealed for life battery.
When you say "the float on our Subaru's Yuasa battery has sunk almost out of sight".
Are you refering to the green/black telltale? green for good; black for recharge?
My certificated meter showed 12.5V across the posts before starting
14.8V immediately after starting with the engine ticking over..
Around 26 Amp along the battery cable after say 10 mins.
After a run, the meter showed 14V with the engine ticking over.
:
A reading of 12.5v is about 90% charged depending upon temperature at the time and if the battery has lost it surface charge from previous charging.
It's CCA reading would tell you it's condition and whether it is suffering from sulphation.
To charge a 6 cell 12v battery you need to supply a voltage greater than 12v usually somewhere starting between 2.35v/cell (14.1v) and 2.45v/cell (14.7v) depending upon the charging method and the battery's temperature. https://www.power-sonic.com/blog/how...-acid-battery/
The more crucial question is what is the battery's capacity/condition when charged or it's CCA (cold cranking amps) value.
The typical Yuasa battery for a Subaru is the Silver YBX5005 12v 65Ah with a CCA of 580A when new and fully charged.
So in answer to
Could 14.8V be a correct charge voltage for a flattish, suspect
battery on start-up please?
My answer would be yes and to get yourself something like a Ctek battery charger and conditioner.
The alternator monitors the battery's output load and adjusts accordingly both voltage and current. (known as a smart charger)
Only if the alternator current output is not regulated correctly.
Will be a sealed for life battery.
When you say "the float on our Subaru's Yuasa battery has sunk almost out of sight".
Are you refering to the green/black telltale? green for good; black for recharge?
A reading of 12.5v is about 90% charged depending upon temperature at the time and if the battery has lost it surface charge from previous charging.
It's CCA reading would tell you it's condition and whether it is suffering from sulphation.
To charge a 6 cell 12v battery you need to supply a voltage greater than 12v usually somewhere starting between 2.35v/cell (14.1v) and 2.45v/cell (14.7v) depending upon the charging method and the battery's temperature. https://www.power-sonic.com/blog/how...-acid-battery/
The more crucial question is what is the battery's capacity/condition when charged or it's CCA (cold cranking amps) value.
The typical Yuasa battery for a Subaru is the Silver YBX5005 12v 65Ah with a CCA of 580A when new and fully charged.
So in answer to
My answer would be yes and to get yourself something like a Ctek battery charger and conditioner.
I have an MXS 5.0 Don.
And an external connector.
But I have to admit to being too dumb
to disconnect before I drive off
The alternator in question is a simple 3 wire one.
Are there Smart 3 wire alternators please?
I have an MXS 5.0 Don.
And an external connector.
But I have to admit to being too dumb
to disconnect before I drive off
The alternator in question is a simple 3 wire one.
Are there Smart 3 wire alternators please?
What is it you are trying to say???
You have to switch off and disconnect the Ctek before driving off, why would you leave it attached??
What alternator /car model are we talking about??
What is it you are trying to say???
You have to switch off and disconnect the Ctek before driving off, why would you leave it attached?? Stupidity Don.
What alternator /car model are we talking about??
I've noticed that the dash clock flickers slightly and also the front sidelights (ebay white LED's). Suspecting that the alternator might be faulty I checked the battery with my multimeter:
12.2 v when not running, rising to 14.4 when running with headlights on and revving the engine to 2000 rpm. The reading when not running is too low but does the latter indicate that the alternator is ok?
Thanks
Have you got a clamp ammeter Nick?
How many volts at tick over with headlights on.
How many volts at your battery in the morning
before you start please?
How long since you last replaced & then tighten
your fan belt please?
17 October 2022, 12:19 PM
Alternator voltage
