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algernon23

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Dell Latitude battery is not fully recharging

Hello,
I have a Dell Latitude D830 that is less than 2 years old. I almost always use it plugged into AC power through a port replicator. At one point, I found that the original battery was completely discharged and would not accept a charge. I replaced this battery with a Rayovac replacement. Initiallly, the replacement battery showed 100% charged in power meter. I fully discharged and recharged per recommendations. The maximum recharge, according to the power meter, was then 95% or so. Subsequently, the battery continued to recharge to a lower and lower percentage. Power meter always indicates "Charging" even after turning the machine on after being off overnight. Again, I am on AC power at all times. Currently, Power Meter shows only 54% power remaining. It appears that the laptop is somehow reducing total battery capacitiy over time. I also suspect that this is how the first battery was ruined.

How can I isolate the cause of this problem and hopefully rectify it? Is there any diagnostic tool that would be helpful? Thanks iin advance for any help.
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lamaslany
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What type of battery is it?
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algernon23

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Hi,

My current battery is a Rayovac COM10005, which is a replacement for the original Dell DF192 that shipped with the laptop.

The original battery died prematurely and the replacement seems to be heading in the same directlion as the total charge keeps decreasing. I suspect a problem not directly due to the battery itself.
I believe that Li-ion batteries actually suffer increased degredation if there are constantly charged (as it would be if it was sitting in a dock).  


If after just a single deep cycle the maximum charge held decreased by 5% I would suspect a dodgy battery.  Have you contacted Rayovac?
Actually, I should mention that this is the second Rayovac battery that has exhibited the same behavior. This is after the orginal Dell battery died completely. My experience with my previous Dell (Inspiron) was that the battery would remain at 100% charge at all times. I used the same docking arrangement with the previous laptop. So, the current system is displaying very different behavior under identical conditions across multiple batteries.

Is there any circuitry in the laptop itself that could have this degrading effect on multiple batteries?

Thanks.
Most batteries do utilise some form of monitoring.  Indeed it is recommended that after several dozen cycles a deep cycle is performed to 'reset' the electronic monitor.  Whether this is in the battery or the laptop I could not say I am afraid.
Thanks for the information.

The problem I'm having with understanding this is that I'm never discharging the battery, I'm only running the laptop in the dock. My previous laptop maintained a 100% charge under the same conditions. So, I'm leaning towards a laptop problem as the cause, just don't know how to begin isolating this.
Some laptops have in BIOS a "calibration" function for the battery; if present, try to run this.

In this case, I think it is the metering circuitry that is, either by design or in error, counting down the battery capacity with no actual relation to the cell condition at all. If the circuitry could be "reset", you'd probably have a 100% battery again. Life expectancy of Li-ion cells are several hundred cycles over several years. Leaving them in constant full charge is sometimes said to be a cause for shortened life, but we're still talking years, not months. The real killer is heat. Modern charging circuits are fairly well designed and don't kill batteries, normally. Your system may have faulty circuits for charging and/or metering the battery. You might try running the system on battery only and let it run down till shutoff and then re-charge, see if there's a difference in purported capacity.

One other possibility is that the power brick (the actual AC-to-DC adapter block) is faulty and can't keep proper voltage or something like that; have you tried another brick?
/RID
Hi RID,
Good questions/suggestions. I have not tried switching the brick, but I do have one at work and one at home, so if one is bad probably the other is still good, is there a way to measure these?

The possibility of a faulty circuit feels the most likely to me based on what I have observed. I have tried discharging fully and then recharging and what I find is that it only seems to recharge to the previous maximum, which keeps going lower and lower over time (I will try this again to confirm).

Are we looking at a motherboard replacement if the charging circuitry is bad? Any way you can think of to prove this or rule it out?

Thanks for your assistance with this.
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rid
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Thanks for your help.