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The battery technology is Li Ion, 59 watt-hours (3.8 amp-hours) at 14.8 volts, by Sony. A 27 watt-hour battery is also available (half capacity, half weight, half price) but I recommend against it; a friend with this battery finds that it allows much too short a run time. Also see below about capacity losses.
Nominal run time for the 59 watt-hour battery (when new) is about 3 hours, which I regularly achieve easily despite less than radical power conservation: I had SpeedStep engaged, the kernel made BIOS idle calls, the display was on low brightness, and the disc used autonomous adaptive power conservation, but nothing beyond that. Suspend to RAM, in one test 15.5 hours used 6% of charge, for a total life of 260 hours (almost 11 days). But see below about estimates of the charge level. You can load 2 batteries (displacing the CDROM) which doubles the run time.
Dell says (see link below): The 8-cell battery should last about 2 hours
and the 4-cell should last about 1 hour if you use a single application with
regular portable settings. With all of the factors listed above causing the
maximum power drain, it is possible for the 8-cell battery to last less than an
hour and the 4-cell to last less than 30 minutes. This does not indicate that
the battery is going bad.
There is no memory effect in Li Ion batteries; partial cycles aren't bad for
it. Estimated self-discharge rate: 6% in 5 weeks, or possibly less. Nominal
battery life is 500 full charge/discharge cycles or 2000 ``partial'' cycles.
However, the battery degrades just with the passage of time, and you should
expect it to last about 2 years. Quoting Dell's What is the battery life of my Dell Portable
Computer
, A battery's average life expectancy is 1 year. After this
time, it is normal to experience a decrease in battery life.
A battery that I have had for two years (in an Inspiron 3800), but mostly used on external power, turns out to hold about 40% of the charge it should. After an additional 6 months, during which the battery was never in a machine, its capacity went down to no more than 22%.
The power controller periodically ``tops up'' the battery, and I can't tell if that behavior damages it, or if the capacity loss comes merely from the passage of time while charged. I'm doing an experiment: I unplug AC power whenever I suspend the computer, to minimize the ``topping up'' behavior. In two years we'll see if the effect was beneficial.
After about 9 months (2002-10-01), the battery now holds about 75% of the original charge. Judging from the number of actual charge-discharge cycles, I would expect at most 2% loss. The rate of loss of capacity, per calendar time, is not significantly less than on the Inspiron 3800 battery despite probably a 2:1 reduction in ``topping up'' time. I'm changing the experiment, leaving the battery completely out of the machine whenever AC power is applied or when actually charging, so it will almost never be ``topped up''.
The BIOS and the ``smart'' battery chip are none too bright about estimating how much charge is in the battery and how long the battery will last. The rated charge seems to be fixed, not updated from experience as the battery wears out. The remaining run time is updated based on experience, but only on those infrequent occasions that you fully discharge the battery, which likely are not representative of your normal use. In particular, on the Inspiron 3800 (I don't know if the 4100 does this), if you have two batteries loaded and you discharge them after 5 or 6 hours, then each of them thinks it can run your machine for 5 or 6 hours all by itself. It is particularly annoying when you think you have 20% or half an hour left, but the battery level suddenly declines like a leaky balloon, and you're lucky if you have enough charge to get the machine home in suspend-to-RAM state.
I and other users on the net have noticed that the APM BIOS underestimates the battery charge level when the machine is on AC power. A fully charged battery is said to be 95% full. But when the charger is removed, the BIOS reports it as 100% full. Strange but true: after a month or so including several episodes in which the battery was almost completely discharged, this phenomenon has gone away and the fully charged battery is said to be 100% full. Occasionally it decides it's 101% full (reported as -1 by the BIOS). That will go away if you unplug AC power for a few minutes.
The AC power converter works on 100v to 240v AC; interchangeable cords can be purchased for non-USA plugs. It can charge the battery in about an hour with the computer off, or 2 hours with it running. I also got the optional 12v DC power converter, which plugs into a car's cigarette lighter. It also has a cable for airplane power connectors, for planes so equipped. I have found this device to be worth the expense given my pattern of computer usage. I have seen a solar panel about 30 cm x 120 cm costing about US$100 which goes with this power converter and is advertised as putting out enough power to run a laptop computer (in full sunlight).
This is generic information about Sony LiIon batteries from their catalog. As with all such documents, be alert to updated versions (this one is dated June 2001) and changes in web addresses.
Characteristics: LiIon batteries have three technology variants: hard carbon (the oldest), graphite, and polymer (the newest). The discharge characteristics of the Inspiron battery are not consistent with hard carbon, and I think Dell would say if they used a polymer battery, so I conclude that it probably has a graphite anode. The cathode is lithium cobalt oxide.
| Quantity | Polymer | Graphite | Hard Carbon |
|---|---|---|---|
| Volts per cell at 50% | 3.75 V | 3.75 V | 3.75 V |
| Voltage change, 25% - 75% | 0.25 V | 0.20 V | 0.55 V |
| Series resistance* | 0.06 V | 0.09 V | 0.08 V |
| Recommended charge time | 1 hr | 2 hr | 1.5 hr |
| Capacity loss
after 500 full cycles | 19% | 16% | 13% |
Series resistance: the voltage drop occurring when you draw a current that would discharge the battery in 2 hours.
Charging behavior: The recommended charging schedule is current limited so as to fill the battery in a specified time (see table) or more. When the battery is 80% full it will reach a voltage of 4.20±0.05 V, at which point it should be voltage limited, the current declining exponentially. It will reach 99% of full charge within one more hour. There is no indication in the catalog that holding the battery at 4.20 V has any deleterious effect, but overcharging or reverse charging is clearly not good for it. The battery must not be discharged below 3.0 V per cell; in the Inspiron battery this is sufficient to prevent reverse charging any cell.
Transport regulations: LiIon batteries containing no more than 1.5 gram per cell and 8 grams per battery of lithium can be treated as ``non-dangerous goods'' under the United Nations Recommendations on the Transport of Dangerous Goods, Special Provision 188. ICAO Special Provision A45 replicates the U.N. Recommendation, IATA follows ICAO in this, and US DOT regs are based on the U.N. Recommendation. The amount of lithium is 0.3 grams per amp-hour per cell. The Inspiron battery has two parallel strings of 4 cells, and 3.8 amp-hours, so 4.56 grams of lithium.
Safety precautions: (See the catalog for the complete list.)
I inserted a battery in the media bay (right side) and couldn't get it out. This is unit ``B'' from the list below.
| Batteries, LiIon 3600 mA-H @ 14.8v (53.28 Watt-hrs, 1.91e5 joules) | ||
| Part number 0001691P rev. A02 | Referred to on labels as P/N 1691P | |
| Unit ``A'' (from Insp 3800) | DS/N 12798-045-625M | |
| Unit ``B'' | DS/N 12796-045-62SU | |
| Battery, LiIon 3800 mA-H @ 14.8v (56.24 W-Hr, 2.02e5 joules) | ||
| Sony LIP8084DLP DP/N 07H508 rev A00 | Referred to on labels as P/N 75UYF | |
| Unit ``C'' (from Insp 4100) | DS/N JP-07H508-48330-1BA-0PWC | |
Considerable force causes the battery to pivot around the right side where the power connector is. It feels like the connector has jammed. Opening the bottom door and shoving on the battery doesn't help. Neither I nor the hardware tech at work could get it out. It isn't physical compatibility; the label on unit ``C'' says ``replace with 75UYF or 1691P or various others''. All Dell Latitude and Inspiron laptops take the same physical shape of LiIon battery, but the newer batteries have a higher capacity.
Service call attempt 1: "I put the battery in and it won't come out." "Is this a second battery that you bought with the system?" "Well, um, er, no..." "If the battery were under warranty we'd replace it, but as it is, you're on your own."
Attempt 2: "I put the battery in and the power connector won't let go of it." "Well, there's a special battery for that side." "No, on Inspirons and Latitudes the same battery form factor is used." "Um, yeah." "That power connector really likes the battery." "Hmm. OK, we'll send someone out. Here's the transaction number..." The technician removed all the B, K and P screws from the bottom cover except the ones around the fan. There was enough flexibility that he could lift the battery vertically off the power connector. It turned out that the power connector was not at fault. The battery had swollen on that side, and there was a projection just high enough to snag on something. So the Inspiron 4100 is not to blame on this event. Advice to users: know what your battery is supposed to look like, and inspect it periodically (monthly?) for evidence of swelling.
A credit card or screwdriver stuck along the side of the battery would have probably gotten it loose (like ``loiding'' a door lock, or an old-fashioned shoehorn), if I had not been fixated on the power connector as the culprit.
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