Is the Voltage Level Too High

I have a 1991 Miata and a one year old Westco Battery.

The Alternator has been replaced and everything appears to works fine,
however, I checked for the Battery Voltage and it seems high.

(1) Voltage at Battery Treminals with MOTOR NOT Running is: 13.18
Volts.

(2) Voltage at Battery Treminals with MOTOR Running is: 14.58 Volts.

I called Westco Tech and they claim that 14.6 Volts, while engine is
running, represents the High and is Acceptable.


I thought I'd ask Miata Group to see if there is any other opinion/
experience.

Also, if its too high, is there a way to adjuct the Voltage, from
Alternator, DOWN?

Pat wrote:
> I have a 1991 Miata and a one year old Westco Battery.
>
> The Alternator has been replaced and everything appears to works fine,
> however, I checked for the Battery Voltage and it seems high.
>
> (1) Voltage at Battery Treminals with MOTOR NOT Running is: 13.18
> Volts.
>
> (2) Voltage at Battery Treminals with MOTOR Running is: 14.58 Volts.
>
> I called Westco Tech and they claim that 14.6 Volts, while engine is
> running, represents the High and is Acceptable.
>
>
> I thought I'd ask Miata Group to see if there is any other opinion/
> experience.
>
> Also, if its too high, is there a way to adjuct the Voltage, from
> Alternator, DOWN?

The theoretical magic value is 13.8, but things like cold temperature will
push that upward. 14.5 is on the high side, but not to worry about in my
opinion. I had a van years ago that always ran over 15 volts. I replaced
light bulbs unusually often, and I had to keep an eye on the battery water,
but aside from that it wasn't a problem.

To my knowledge, the voltage is not adjustable, but I could be wrong.

--
Dale Beckett

On Mar 4, 7:41*pm, Dale Beckett > wrote:
> Pat wrote:
> > I have a 1991 Miata and a one year old Westco Battery.
>
> > The Alternator has been replaced and everything appears to works fine,
> > however, I checked for the Battery Voltage and it seems high.
>
> > (1) Voltage at Battery Treminals with MOTOR NOT Running is: 13.18
> > Volts.
>
> > (2) Voltage at Battery Treminals with MOTOR Running is: 14.58 Volts.
>
> > I called Westco Tech and they claim that 14.6 Volts, while engine is
> > running, represents the High and is Acceptable.
>
> > I thought I'd ask Miata Group to see if there is any other opinion/
> > experience.
>
> > Also, if its too high, is there a way to adjuct the Voltage, from
> > Alternator, DOWN?
>
> The theoretical magic value is 13.8, but things like cold temperature will
> push that upward. *14.5 is on the high side, but not to worry about in my
> opinion. *I had a van years ago that always ran over 15 volts. *I replaced
> light bulbs unusually often, and I had to keep an eye on the battery water,
> but aside from that it wasn't a problem.
>
> To my knowledge, the voltage is not adjustable, but I could be wrong.
>
> --
> Dale Beckett- Hide quoted text -
>
> - Show quoted text -

Its extremely cold. Getting down to single digits in the evening. The
Westco is a Gel battery and adding water is not an option.

In article
>,
Pat > wrote:

> I have a 1991 Miata and a one year old Westco Battery.
>
> The Alternator has been replaced and everything appears to works fine,
> however, I checked for the Battery Voltage and it seems high.
>
> (1) Voltage at Battery Treminals with MOTOR NOT Running is: 13.18
> Volts.
>
> (2) Voltage at Battery Treminals with MOTOR Running is: 14.58 Volts.

Both of those readings sound real good. Theoretical max for a fully
charged "12 volt" battery is 2.25 volts per cell, or 13.5 volts total,
and a "12 volt" alternator in good working order is almost always set to
push its matching battery's theoretical max "plus half a cell" - Which
would make your 14.58 volt reading just the slightest bit on the low
side of "perfect".

Adjusting the output voltage on an alternator is at least theoretically
possible. In the old days of mechanical voltage regulation, it was a
simple matter of turning a screw or bending a tab on an external
regulator module. These days, voltage regulation is almost always done
inside the alternator by varying the current on the stator coils via a
built-in semiconductor, so while it's not impossible, it usually isn't
particularly practical.

--
Don Bruder - - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... <http://www.sonic.net/~dakidd> for more info

Pat > wrote:

> I called Westco Tech and they claim that 14.6 Volts, while engine
> is running, represents the High and is Acceptable.

It depends on the vehicle. Years back GM used to set output voltage to
around 13.? (memory fails, sorry.), Ford to around 14.8V and Mopar in
between the two. Since regulators are no longer adjustable it's
difficult to find specs now but I doubt there's been any changes.

I wouldn't worry, it's reasonable.


--
XS11E, Killing all posts from Google Groups
The Usenet Improvement Project:
http://improve-usenet.org

There are all sorts of "funnies" when you get into what the charge voltage
limit should be for an automotive lead acid battery.
First, all automotive batteries are not created equal. As a result, the
ideal charge voltage limit is a few tenths of a volt different between
different batteries.

Next, more specific to the Miata-- When the battery is a fair distance from
the regulator and alternator,
there is some drop due to resistance in the battery cables that allows the
charge voltage limit to be increased slightly.

Finally, smaller batteries need to charged to a higher level than a larger
battery, so that more of the batteries capacity is available.

The there are "AGM" batteries that can be charged to a slightly higher
voltage than the old lead acid battery, if the charge current is lowed to
about 2 Amps.

There is more than you 'd ever want to know about batteries on the internet.

14-14.6 seems to be the most common charge voltage limit these days. At one
time, GM called for about 13.8.

"XS11E" > wrote in message
. ..
> Pat > wrote:
>
>> I called Westco Tech and they claim that 14.6 Volts, while engine
>> is running, represents the High and is Acceptable.
>
> It depends on the vehicle. Years back GM used to set output voltage to
> around 13.? (memory fails, sorry.), Ford to around 14.8V and Mopar in
> between the two. Since regulators are no longer adjustable it's
> difficult to find specs now but I doubt there's been any changes.
>
> I wouldn't worry, it's reasonable.
>
>
> --
> XS11E, Killing all posts from Google Groups
> The Usenet Improvement Project:
> http://improve-usenet.org