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'[EE] car short-circuit'
2006\01\22@195850 by Pedro Drummond

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My friend's Renault Clio has a 45Ah battery. After not being used for "some"
days, the car won't start. Something around 8 to 12 days, she guesses. Now I
have one question, phrased two ways:

1) Turning off everything I can in the car, how much current should I expect
to measure being drained from the battery? On a healthy system I figure it
should be about 20mA, some mA for the internal clock, some for the radio
memory, some for an idle on-board computer.

OR

2) How low is too low for a 45Ah car battery? When will autonomous ignition
become impossible? Is it half of its capacity enough?


TIA,

Pedro

2006\01\22@201246 by David VanHorn

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>
> My friend's Renault Clio has a 45Ah battery. After not being used for
> "some"
> days, the car won't start. Something around 8 to 12 days, she guesses. Now
> I
> have one question, phrased two ways:


Car batteries really don't work in amp-hours terms. Providing a steady
current for a long time is not something they are really designed to do.
Their spec is in "cold cranking amps" which reflects what they are designed
to do.

I have a bit of a frustration myself down that line.  I work from home, so
it's not that unusual for me to not drive for 3-4 days. I've had my battery
go flat in less than 24 hours, and other times a week later it's fine.. Been
replaced a few times, each time it's been just about dead (won't take a
charge)
Nothing seems to be a problem.. I have added some ham radios, but nothing
that draws more than a few mA when off.

Maybe it's just me, but I think that they truly don't make 'em like they
used to.

2006\01\22@211632 by Richard Prosser

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My daughters car battery was going flat in under 2 week consistantly
when not used. I checked the leakage (clock/radio etc.) and is came to
about 70mA which did seem a bit high.

On disconnecting the battery, the car will now start OK every 2 weeks
without a problem. (With the battery temporarily reconnected).

70mA x 2 weeks = 23Ahrs so for an old battery that was probably only
30Ahrs to start with it seems about right.

I have my suspicions about the radio installation - I think that's
where the current is going. It looks like someone got the wires around
the wrong way for the main supply & battery backup.

Once I get the oil leak fixed I'll have a look at the radio!

We gat at least 3 "classes" of battery here - 6month, 1 year and 3
year warrantee versions. Prices roughly $NZ60, $NZ90, $NZ120 for the
same size.

One trick that can extend the life of a "semi sealed" battery is to
make sure it is topped up. Low maintenence is not No maintenence &
I've had 6 - 12 months extra use out of a failed battery by just
topping the water up.

Richard P


On 23/01/06, David VanHorn <spam_OUTdvanhornTakeThisOuTspammicrobrix.com> wrote:
{Quote hidden}

> -

2006\01\22@211723 by Bob Blick

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On 22 Jan 2006 at 22:50, Pedro Drummond wrote:
> My friend's Renault Clio has a 45Ah battery. After not being used for "some"
> days, the car won't start. Something around 8 to 12 days, she guesses. Now I
> have one question, phrased two ways:
>
> 1) Turning off everything I can in the car, how much current should I expect
> to measure being drained from the battery? On a healthy system I figure it
> should be about 20mA, some mA for the internal clock, some for the radio
> memory, some for an idle on-board computer.

Factory equipment should draw less than 10mA, more like 5mA. Add-ons can draw much more,
depending on what they are. Car stereos and alarms can be quite sloppy. Also if the car stereo is wired
with the switched power lead getting power all the time, you need look no further. The output stages are
not switched by the power switch in today's stereos.

> 2) How low is too low for a 45Ah car battery? When will autonomous ignition
> become impossible? Is it half of its capacity enough?

Above freezing, the car should start with the battery half-charged. As the battery ages, the total capacity
decreases, so at 4 years, the 45 Ah battery is now only 22.5Ah, more or less. So in freezing weather, 4
years is the typical life of a car battery.

However, I have 8 years on my car battery and it still starts fine, and a friend has a 1990 Toyota truck with
the original battery (California climate). I almost believe him, too :)

Obviously, your mileage may vary.

Cheerful regards,

Bob

2006\01\22@213500 by Chen Xiao Fan

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> From: .....piclist-bouncesKILLspamspam@spam@mit.edu
> [piclist-bouncesspamKILLspammit.edu] On Behalf Of Bob Blick
>
> However, I have 8 years on my car battery and it still starts
> fine, and a friend has a 1990 Toyota truck with
> the original battery (California climate). I almost believe
> him, too :)

The road condition in California is much better than other
parts of US or other parts of the world. ;-) So the life
of the car battery is also better and they can live longer. ;-)

>From my limit experience with cars (I do not know how to drive
and can not afford a car here in Singapore anyway), a 10-year
old car in CA has similar conditions as a 5-year old car in NY.

Regards,
Xiaofan

2006\01\22@214655 by David VanHorn

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>
>
> >From my limit experience with cars (I do not know how to drive
> and can not afford a car here in Singapore anyway), a 10-year
> old car in CA has similar conditions as a 5-year old car in NY.


General motors has a plant here in Muncie Indiana.
They also make tanks for the US army.

Why won't they test them here in Muncie?
The roads are too damned rough.

I used to drive down from wisconsin a lot, usually on the chicago tollway
which is famous for always being under construction.  Even including that, I
hit more bangs and bumps in the last 10 miles into muncie, than in the whole
rest of the trip.

Occasionally, when we wear the train crossings down to where they only leave
bruises, they go out and "fix" them.  We have a LOT of train crossings.

2006\01\23@071955 by olin piclist

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Chen Xiao Fan wrote:
> The road condition in California is much better than other
> parts of US or other parts of the world. ;-)

You've just hit one of my pet peeves.  California is a big place.  Some
people seem to forget the other 90% of the state when the referring to warm
and dry area as "California".  California has more different climates than
many countries.  Regions like the northern coast, the coastal range, the
Cascades area, the central valley, the Sierras, the desert east of the
Sierras, the Mojave desert, the San Francisco Bay area, all have different
climates with some very different.


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2006\01\23@105555 by David VanHorn

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>
>
> You've just hit one of my pet peeves.  California is a big place.  Some
> people seem to forget the other 90% of the state when the referring to
> warm
> and dry area as "California".


California consists of LA,  SF, and some "other"..  At least in the
political spectrum.

2006\01\23@124002 by Hector Martin

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Richard Prosser wrote:
> One trick that can extend the life of a "semi sealed" battery is to
> make sure it is topped up. Low maintenence is not No maintenence &
> I've had 6 - 12 months extra use out of a failed battery by just
> topping the water up.
>

A few weeks ago a friend's car wouldn't start. Battery at 7V-ish IIRC.
It was a "no maintenance" battery, supposedly. Not sealed, of course. I
topped it off, drove for a while, and it's been working fine since, at
normal levels. It's had some years of use by now, but I think it should
at least last another year or so.


--
Hector Martin (.....hectorKILLspamspam.....marcansoft.com)
Public Key: http://www.marcansoft.com/hector.asc

2006\01\23@144505 by Danny Sauer

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Olin wrote regarding 'Re: [EE] car short-circuit' on Mon, Jan 23 at 06:23:
> You've just hit one of my pet peeves.  California is a big place.  Some
> people seem to forget the other 90% of the state when the referring to warm
> and dry area as "California".

Much like there's a lot more to IL than Chicago, even though anything
south of Joliet (which borders Chiagoland on the South) is considered
"downstate" by the news facilities in and around Chicago...

So, if I'm gonna be considered "downstate" when I'm less than 1/3 of
the way south in IL (it's just us farmers and other rubes down here),
it's only fair that the part of CA above the bend be considered
"Downstate Oregon".  There aren't any mountains or vineyards in CA.

--Danny

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