Battery overcharging (Ford Focus)
Harry Truman
-- thinking that was the problem -- then the Alternator, because, as
it turned out, it wasn't charging.
Yesterday, we took the battery and alt. to have them checked because
the battery was overcharging. (a fifty mile one-way drive, BTW, so it
is a bit diffucult to just drive down the street and have this stuff
checked) He isn't satisfied that the kid who checked the alt. knew
what he was doing ( ! ) but the kid said the alt. was OK, so we came
back with a new battery. Now IT is overcharging at 15 volts. Is the
real culprit the alternator/regulator? (I have a feeling it is, but
are there any other possible causes of such a problem: like I noted,
idt is a longgggg drive into town.)
Thanks // HarryTruman
HLS
What is it really? 14.4 ???
You need to have the data, accurate data, to look at these things.
If there is an overcharge, where do you think the problem is most
likely coming from???
m6onz5a
Put a voltmeter on the battery while the motor is running. Set it to
DC volts and see what it's charging at. If it is overcharging the
alternater is your problem since it has an internal regulator.
One other thing you can check is your ground cables to make sure they
are nice & tight. I know on motorbikes if the ground isn't good I get
an overcharge and I blow bulbs.. Not sure if it applies to
automobiles but it can't hurt to check.
hubcit
vary slightly depending on the type of battery, but 15 volts sounds
good. What is wrong is it boiling the water out of the battery or?
Mike Romain
I will second checking and cleaning all the main battery cable
connections! Don't forget the cables have two ends. A dirty connection
sure can make a volt gauge read high on my vehicles, so can a polished
up fan belt.
When the fan belt gets polished up, it will no longer grab the
alternator pulley under load which again makes my volt gauge get really
swingy and stay too high. I test for that by taking a cold off engine
and seeing if I can hand slip the alternator pulley. If I can and the
belt is properly tight, it have become polished up and needs replacing.
The alternator takes a few HP to spin up under load and if it will hand
slip it will load slip too.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
'New' frame in the works for '08. Some Canadian Bush Trip and Build
Photos: http://mikeromainjeeptrips.shutterfly.com
KG
An additional note
A normal lead acid auto battery should charge a 14.2 volts and read 12.8 volts after surface charge
os gone 1-3 hours. Heat is what does the dammage in most cases of over charging. As a rule of
thumb if the temputare is above 85f, it should not be charged at more than 14.2 - 14.3 volts, if
temputare is 32F, 14.2 - 14.5, at no time should the battery be charged at more than 14.5 volts, it
will warp the plates quickly and the battery will never recover.
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> When the fan belt gets polished up, it will no longer grab the
> alternator pulley under load which again makes my volt gauge get really
> swingy and stay too high. >
LOL. When a fan belt slips, it over charges!!! LOL That's a good one
Mike!
HLS
"hubcit" <box...@sasktel.net> wrote in message
news:38f48a09-eb94-4933...@v38g2000yqb.googlegroups.com...
> 15 volts sounds about right. i think the voltage requirement might
> vary slightly depending on the type of battery, but 15 volts sounds
> good. What is wrong is it boiling the water out of the battery or?
That is a question I asked way back in the thread.. How does he know
it is overcharging? No response.
Steve
> 15 volts sounds about right. i think the voltage requirement might
> vary slightly depending on the type of battery, but 15 volts sounds
> good.
No, its not right. 15.0 volts sustained for an extended period is too
high. The charging threshold for a lead-acid battery is around 13.8 to
14.4 volts depending on temperature. Holding one at 15 volts for an
extended period will just boil the electrolyte.
But trusting the dash gauge is also a mistake- the voltage should be
measured with a quality voltmeter at the battery terminals. Tenths of a
volt are very important in this case.
Mike Romain
It slips under the original starter load, then when it finally grabs a
bit, the volt gauge shows high as it tries to charge the battery back
up. It is still slipping so the amps aren't transferring well so the
volt gauge stays high.
Same for a bad connection, it makes the volt gauge go high, but be
really swingy under load.
When mine is reading high, cleaning the battery connections and/or
fixing the fan belt gets it back more rock solid near 14.2V.
Mike
Mike Walsh
When voltage regulators were adjustable I would set them for about 13.5 volts when hot to 14 volts when cold. That is high enough to charge a battery in good condition and will never overcharge. It has been a long time since I have seen a voltage regulator that is adjustable, and the specs for some alternators call for voltage as high as 15 volts. It is unfortunate that an alternator and voltage regulator operating within specs will overcharge a battery.
--
Mike Walsh
HLS
"Steve" <n...@spam.thanks> wrote in message
news:r56dnbm2nZiZ1aTU...@texas.net...
I fully agree with you, Steve.. He posted "15 volts" but that does not give
me any confidence that it is really 15.00 volts. Could be anything
Steve W.
The quick way to see what it is actually doing is to toss a meter on the
battery and a scan tool as well. The scan tool will tell you what
voltage the computer is seeing and the meter on the battery will give
you that voltage. In many vehicles 15 volts on the dash could be OK,
When you look at the voltage drop due to the circuit resistance the
battery may only be charging at 14 volts or so.
Also keep in mind that on most newer vehicles the computer is
controlling the charge rate, regardless of the internal regulator. It
varies the voltage on the sense line to the regulator to compensate for
the load and temperature the vehicle is in.
--
Steve W.
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man of machines
man of machines
Steve
significan over-voltage for a number of years now. It plays hell with
light bulb life, too.