I have two clock/radio television units. Both have battery backups.
I installed fresh 9 volt batteries and when power was restored last
night after a 3 hour outage, the clocks were 8-10 minutes fast. What
gives? I thought the batteries were supposed to maintain the time.
Just curious.

Hecho en Cheena, senor?

I don't know, but my guess is that quality control is suffering, all over.

Christopher A. Young
Learn more about Jesus
www.lds.org
..

"Michael" wrote in message
...
I have two clock/radio television units. Both have battery backups.
I installed fresh 9 volt batteries and when power was restored last
night after a 3 hour outage, the clocks were 8-10 minutes fast. What
gives? I thought the batteries were supposed to maintain the time.
Just curious.

On 10/30/2012 6:12 AM, Michael wrote:
I have two clock/radio television units. Both have battery backups.
I installed fresh 9 volt batteries and when power was restored last
night after a 3 hour outage, the clocks were 8-10 minutes fast. What
gives? I thought the batteries were supposed to maintain the time.
Just curious.


Normal operation uses the typically very accurate 60 Hz line frequency
as the time base.

On 10/30/2012 5:12 AM, Michael wrote:
I have two clock/radio television units. Both have battery backups.
I installed fresh 9 volt batteries and when power was restored last
night after a 3 hour outage, the clocks were 8-10 minutes fast. What
gives? I thought the batteries were supposed to maintain the time.
Just curious.

A lot of the battery back up clocks use the power line frequency for
timing. But during power outages they use a simple RC controlled
oscillator to keep the time. RC oscillators are very poor at keeping
on an exact frequency. So during power outages the clocks that use
them can drift quite a bit. The drift in your clocks isn't too
far out from what you could expect.

Of course since last year the power line frequency isn't extremely
stable. I set mine last January and the time drifted about plus
or minus 10 seconds up until Summer. Since then the clock has
gained about 30 seconds. That is because the government relaxed
their rules on how tightly power sources had to be locked to the
national frequency standard.

Bill Gill

On 10/30/2012 05:12 AM, Michael wrote:
I have two clock/radio television units. Both have battery backups.
I installed fresh 9 volt batteries and when power was restored last
night after a 3 hour outage, the clocks were 8-10 minutes fast. What
gives? I thought the batteries were supposed to maintain the time.
Just curious.


Plug-in clocks with battery backup usually seem to use a cheap RC
timebase when on battery. They're not very good at timekeeping during
power failures. Most I have are accurate on AC, fast on battery.

--
Mark Lloyd
http://notstupid.us

"If a man would follow, today, the teachings of the Old Testament, he
would be a criminal. If he would follow strictly the teachings of the
New, he would be insane." -- Robert G. Ingersoll

On Tue, 30 Oct 2012 08:17:26 -0500, Mark Lloyd
wrote:

On 10/30/2012 05:12 AM, Michael wrote:
I have two clock/radio television units. Both have battery backups.
I installed fresh 9 volt batteries and when power was restored last
night after a 3 hour outage, the clocks were 8-10 minutes fast. What
gives? I thought the batteries were supposed to maintain the time.
Just curious.


Plug-in clocks with battery backup usually seem to use a cheap RC
timebase when on battery. They're not very good at timekeeping during
power failures. Most I have are accurate on AC, fast on battery.

What others have said. In addition, fast is intentional for alarm
clocks because fast is better than slow when the goal to make sure you
get up on time.

"George" wrote in message
...
On 10/30/2012 6:12 AM, Michael wrote:
I have two clock/radio television units. Both have battery backups.
I installed fresh 9 volt batteries and when power was restored last
night after a 3 hour outage, the clocks were 8-10 minutes fast. What
gives? I thought the batteries were supposed to maintain the time.
Just curious.


Normal operation uses the typically very accurate 60 Hz line frequency as
the time base.

At on time some clocked synced with the TV vidio. Don't know what happens
with the HDTV system.

Might check with you cell phone as those do sync with the system clocks.
Another option is one of the Atomic Clocks that sync with the WWVL signal.

Michael wrote in news:3d0f106b-63b8-46af-bb3c-
:

I have two clock/radio television units. Both have battery backups.
I installed fresh 9 volt batteries and when power was restored last
night after a 3 hour outage, the clocks were 8-10 minutes fast. What
gives? I thought the batteries were supposed to maintain the time.
Just curious.


They did. Just not as accurate as what you expected.
Normally the mains frequency determens the clockrate,
but when the mains is down/out, a free running oscillater takes over.
Sort of. In some clocks.

On 10/30/2012 6:12 AM, Michael wrote:
I have two clock/radio television units. Both have battery backups.
I installed fresh 9 volt batteries and when power was restored last
night after a 3 hour outage, the clocks were 8-10 minutes fast. What
gives? I thought the batteries were supposed to maintain the time.
Just curious.

Try one of these. They keep near perfect time whether on internal
battery, generator or grid power.

http://www.amazon.com/EQUITY-40018-I.../dp/B0014KQI10

On Oct 30, 6:12*am, Michael wrote:
I have two clock/radio television units. *Both have battery backups.
I installed fresh 9 volt batteries and when power was restored last
night after a 3 hour outage, the clocks were 8-10 minutes fast. * What
gives? *I thought the batteries were supposed to maintain the time.
Just curious.

THANKS EVERYONE FOR THE ANSWERS. APPRECIATED.

On 10/30/2012 05:25 PM, diy savant wrote:
On 10/30/2012 6:12 AM, Michael wrote:
I have two clock/radio television units. Both have battery backups.
I installed fresh 9 volt batteries and when power was restored last
night after a 3 hour outage, the clocks were 8-10 minutes fast. What
gives? I thought the batteries were supposed to maintain the time.
Just curious.

Try one of these. They keep near perfect time whether on internal
battery, generator or grid power.

http://www.amazon.com/EQUITY-40018-I.../dp/B0014KQI10


It probably does keep good time, once set. However, according to the
reviews, it is NOT self-setting.

BTW, I've had a clock like that too. It even pretended to set itself. It
never did

--
Mark Lloyd
http://notstupid.us

"Father says bow your head, Like the Good Book says. I think the Good
Book is missing some pages..." [Tori Amos]

Mark Lloyd wrote:
On 10/30/2012 05:25 PM, diy savant wrote:
On 10/30/2012 6:12 AM, Michael wrote:
I have two clock/radio television units. Both have battery backups.
I installed fresh 9 volt batteries and when power was restored last
night after a 3 hour outage, the clocks were 8-10 minutes fast. What
gives? I thought the batteries were supposed to maintain the time.
Just curious.

Try one of these. They keep near perfect time whether on internal
battery, generator or grid power.

http://www.amazon.com/EQUITY-40018-I.../dp/B0014KQI10


It probably does keep good time, once set. However, according to the
reviews, it is NOT self-setting.

BTW, I've had a clock like that too. It even pretended to set itself. It never did


I have a similar clock. I don't even know if the battery is replaceable. It
was also about $20. It has so many buttons, two alarms, etc. Even works off
new saving time settings. No touch. It just sits there and works well.

My old clock was a Sony with charging battery. Having to replace a 9 volt
battery every year is costly and troublesome.

Greg

On Tue, 30 Oct 2012 03:12:43 -0700 (PDT), Michael
wrote:

I have two clock/radio television units. Both have battery backups.
I installed fresh 9 volt batteries and when power was restored last
night after a 3 hour outage, the clocks were 8-10 minutes fast. What
gives? I thought the batteries were supposed to maintain the time.
Just curious.


I've noticed the same thing, chalked it up to it not having very good
freq control when on batteries.