Ping: VanguardLH and Mike: Battery life

My wife's Asus laptop is approaching 4 years old. Almost from
Day 1, its battery has been stored in the refrigerator under the
40-40 Rule (40% charge stored at 40°).

Are you saying that this battery is probably dead, that it won't
warm up and recharge?

TIA for your thoughts.

Kirk Bubul wrote:
My wife's Asus laptop is approaching 4 years old. Almost from
Day 1, its battery has been stored in the refrigerator under the
40-40 Rule (40% charge stored at 40°).

Are you saying that this battery is probably dead, that it won't
warm up and recharge?

TIA for your thoughts.

Should have stored it at 60% charge.
Should have verified charge yearly, or depending
on self-leak rate, sooner than that.

You can't leave a battery in the refrigerator for
four years straight, without some kind of maintenance.

If the battery terminal voltage is below the minimum
value acceptable to the charger circuit, it will refuse
to charge it. The battery becomes dangerous, if
charges after the changes caused by deep discharge,
which is why the charger will not allow bringing a
laptop battery up from "zero".

That's why the fridge storage thing, you have
a yearly maintenance, to help keep the thing
at 60%.

Ref:

http://batteryuniversity.com/learn/a..._ion_batteries

"Do not recharge lithium-ion if a cell has stayed at
or below 1.5V for more than a week. Copper shunts may
have formed inside the cells that can lead to a partial
or total electrical short. If recharged, the cells might
become unstable, causing excessive heat or showing other
anomalies."

That is why a charger may refuse to recharge a battery.
The battery self-discharged too low, and now the
recharger won't touch it, for safety reasons. While
there are techniques for forcing a charge in it,
who knows what will happen later.

The battery needs to be kept between the two extremes.
A defective charging circuit, that leaves a too-high
terminal charging voltage when finished, shortens the
life. And discharging too low, then the charger won't
touch it. Your job, is yearly maintenance, and keeping
it between the two extremes.

The 40% rule in the above article, refers to how the
manufacturer ships the unit with the monitor chip "sleeping",
until the first charge takes it above the initial minimum.

You can store at any percentage you want, but a little
less than 100% is less stressful for the battery. And putting
it away with a relatively low charge on it, increases the
odds of coming back to the fridge, and it's dropped
too low. You could develop an "adaptive maintenance"
procedure, like monitor the self-discharge rate, and based
on that, adjust the frequency of recharge cycles. That would
help you avoid the too-low voltage problem.

Paul

Kirk Bubul wrote:

My wife's Asus laptop is approaching 4 years old. Almost from
Day 1, its battery has been stored in the refrigerator under the
40-40 Rule (40% charge stored at 40°).

Are you saying that this battery is probably dead, that it won't
warm up and recharge?

As Paul mentioned, how do you know it was always at the 40% charge
level? All batteries "leak". All batteries are chemical so state will
change regardless of temperature. Charging changes state so there
exists chemical stress that becomes relaxed over time.

Take the battery out of the fridge. Let it get to room temperature.
Put it in the computer, boot, and check its charge level. If it's been
chilled in the fridge for 4 years, yep, you'll probably need a new
battery. The old one will probably take a charge but not have much
capacity so it'll drain much faster. It's also slowly discharged over
that 4 years so you've been storing at much less than 40% charge and has
probably been under 3% for a long time.

http://www.ehow.com/way_6190526_prop...batteries.html

The cold storage (within storage temperature range specified for the
unit) is recommended to extend the life of a battery by slowing the
discharge rate so you have to recharge it less often. As previously
mentioned, rechargeable batteries have a maximum lifespan whose measure
includes the number of recharge cycles. Recharging less often means a
longer lifespan (well, longer before recharging results in less
capacity). Not charging to 100% reduces the chemical stress of a full
charge (at which discharge is greater than at a lower charge).

As the article mentions, "You should recharge the battery to 40 percent
every two or three months." Have you been checking charge state every
few months? That you put it in the fridge at 40% charge does not mean
it will stay at that state. Cold slows discharge. It does not stop it.

As mentioned, start out with a reminder to check the battery charge
level every 3 months. You can guage based on the actual charge level at
that time if you need to modify the reminder interval. Even cold the
battery will still need maintenance. Paul mentioned monitoring the
voltage of the battery to guage its charge state except voltage doesn't
indicate capacity. For example, a PSU might show good voltage levels
under no-load but drop drastically or incur severe ripple under load.
I'd say to measure uptime when the battery is new (after the first
couple recharges) to note how long you can use the battery from a full
charge down to, say, 5% (your power scheme might have a cutoff level,
too). Track that time. Don't use the computer but just let it drain
while otherwise idle. For yearly maintenance (your 2nd reminder other
than the 1st to check voltage every few months), take the battery out of
the fridge, let it warm to room temperature, charge to 100%, and track
the time to discharge to the same 5% level, then recharge to 40% and
store again. You'll be able to guage the reduction in capacity as the
battery ages by how much less time the computer can remain powered.

Paul gave a BatteryUniversity article on charging lithium batteries.
Here's one on storing them:

http://batteryuniversity.com/index.p...tore_batteries

No matter what you do to preserve the battery, it will wane over time
regarding its capacity which will also affects the voltage it can
produce under load. From experience, I've found lithium batteries for
laptops usually go bad enough to be noticed by casual users after about
3 years: it won't charge or uptime is too short after a charge. If
you're watching uptime, you'll probably notice it decreases after around
2 years but perhaps not enough to yet consider replacing it. Depends on
whether you demand as much uptime with an old battery as you got when it
was new, and whether you're willing to carry around a spare battery to
increase uptime.

To address your specific inquiry, the above article states "Primary
alkaline and lithium batteries can be stored for up to 10 years with
minimal capacity loss." That's assuming you do the maintenance the
interval of which you'll have to guage every few months based on voltage
which will dictate when you need to charge back to 40%. If you've done
nothing but stick the battery (inside a sealed bag to eliminate
moisture) in the fridge and left there unattended, you'll be lucky to
achieve 50% recoverable capacity but much less for uptime. It will
probably still have some usable uptime but whether it is enough for you
is your decision.

Take it out now, let it warm up, and measure the voltage. You won't be
able to get the individual cell voltage since the batteries are in
series and those series can be in parallel, plus not all packs are
grouped in 3 in series and those in parallel but can have some other
arrangement to produce different voltages. The case should tell you
what is the full charge voltage. Alas, cells don't age (deteriorate) at
the same rate so there could just one cell that is bad. Unless you're
willing to dismantle the case and do some soldering, you have to replace
the entire pack.

On Friday, November 15, 2013 4:13:59 AM UTC-6, Kirk Bubul wrote:
My wife's Asus laptop is approaching 4 years old. Almost from

Day 1, its battery has been stored in the refrigerator under the

40-40 Rule (40% charge stored at 40°).



Are you saying that this battery is probably dead, that it won't

warm up and recharge?



TIA for your thoughts.

I have an HP 6730b with the original LiIon battery.

It has always been kept attached to the laptop.

It is still going strong.

I think your storage in the frig has shortened it's life.

Doing so has introduced moisture into the battery.

Andy

On Sat, 16 Nov 2013 23:05:18 -0800 (PST), Andy
wrote:

On Friday, November 15, 2013 4:13:59 AM UTC-6, Kirk Bubul wrote:
My wife's Asus laptop is approaching 4 years old. Almost from

Day 1, its battery has been stored in the refrigerator under the

40-40 Rule (40% charge stored at 40°).



Are you saying that this battery is probably dead, that it won't

warm up and recharge?



TIA for your thoughts.

I have an HP 6730b with the original LiIon battery.

It has always been kept attached to the laptop.

It is still going strong.

I think your storage in the frig has shortened it's life.

Doing so has introduced moisture into the battery.

Andy

The battery was put into a baggie with as much air removed as I
could without using a suck-and-seal device. Then *that*
battery-and-baggie was place inside a second baggie in an effort
to eliminate condensation.

(Aside: when the battery was new I think I recall that I looked
up the price of a replacement for my Asus K50ij laptop, and it
was about $180. In the past day or two, the only batteries I
found for this laptop are in the $30 range. Have battery prices
come down that much?)