Comment by 45ure | Hacker News Reader

Comment by 45ure | Hacker News Reader

I read this CVE with some interest, to see if it provides a solution to a frustrating problem, involving a Latitude 5300 (2-in-1). The problem: once the device is fully charged and subsequently shutdown, it rapidly drains the battery to around 80% within a few hours ─ at which point it retains the remaining charge. The problem is less pronounced, when it is put into sleep mode.

I have been through numerous suggestions and permutations; 'hard' shutdown by holding the power button for varying durations, BIOS updates, OS updates (W10 latest build/version/updates/drivers), manufacturer specific driver updates, fresh rebuilds, tweaking power,wake,idle,throttle settings for CPU, network adapters (via BIOS and OS), date/time anomalies, turning off Modern/Connected-Standby, Registry hacks etc. Furthermore, I have contemplated using Wireshark and other tools to diagnose the problem, but that would require a significant chunk of my time troubleshooting a device, which I expect to work, out of the box. I resent the fact, that no explanation or a solution is forthcoming from Dell, which is a matter of concern.

The post below describes my conundrum, fairly accurately.

https://www.dell.com/community/Latitude/Latitude-7400-batter...

I’m not sure if this helps, but if the battery is charged to 100% and then stored for a long period of time, it will not last long at all. 2 years, tops.

As an engineering approximation that we use in the industry, each 5% undercharged may very well double the cycle life of your battery. 80% is usually the good point of compromise for most consumer electronics.

My XPS has options for smart battery charging/storage so you might try playing around with the optional battery optimisation apps to see if one of those charging modes is enabled. Chances are it might be “fake charging to 100” but intentionally limiting to 80 based on your usage pattern.

Thank you for engaging, and for your suggestions. I have owned the machine from new, for a little more than a year. It was manufactured approximately 4 months prior to the date, it came into my possession. The laptop was displaying the problem described, from the outset.

I am in full agreement with your assessment on ageing devices exhibiting the Bathtub Curve, and also your suggestion on undercharging. However, the battery on this device has less than 15 cycles in total. Furthermore, when in Sleep mode, it only loses 2-3% daily from its designed capacity -- which is an acceptable range.

Hence, the reason for my curiosity to determine the precipitous drop in charge, when the machine is in a complete shutdown state. You are correct, there are a lot of features in the latest BIOS for management i.e. CPU, power, network, battery etc. I have disabled most of them or opted for the best possible option, where appropriate.

The point about the battery is moot, as I am more concerned about an undocumented feature which might be causing the high drain. There are more reports of Dell laptops exhibiting this unsolvable behaviour, than any other manufacturers combined ─ which usually relate to Modern Standby and/or Intel Management Engine(IME).

Hi, I am not talking about your device ageing. I am talking about the protections put in place by Dell to prolong the life of your product. Dell are especially innovative in this space.

For example, in my opinion, you're seeing the effect of "Dell Smart Charging", which is a by-design feature of the Dell Power Manager [1].

Your profile may be set to 'Adaptive', and it may automatically use the 'Primarily AC' behavior. Here is an excerpt from that behavior: 'Extends battery life by lowering the charge threshold, so that the battery never charges to 100 percent capacity. Recommended for users who primarily operate the system while plugged into an external power source'.

My experience with Dell Power Manager is that this is done transparently to the user, for example the user may see '100%', but at the battery firmware level it knows that it is only charged to '80%'. I think that you're just noticing the smoke and mirrors and getting concerned when there's probably nothing at all to be concerned about. There is a numeric filter between your real and fake battery levels, and yes, at times you're going to see inconsistencies when rebooting your product. And there will especially be differences between sleep and cold-start. But if Dell had implemented it differently, on the flipside plenty of people would send their laptops back for 'not charging to full'.

My recommendation here might be to reset your BIOS settings to factory default and see if the settings in the Dell Power Manager can resolve what you are experiencing instead (i.e. from Windows DPM disable Advanced Charge and use the Standard setting instead of the Adaptive setting, fully charge and discharge your product, then leave attached to an adapter for 4+ hours).

[1]: https://dl.dell.com/topicspdf/power-manager_users-guide_en-u...

Source: electric vehicle battery engineer.

>Your profile may be set to 'Adaptive', and it may automatically use the 'Primarily AC' behavior.

Initially, it was set to Adaptive by default in the BIOS. During the process of fault-finding -- changed it to 'Standard' hoping that the firmware will relinquish control and give it back to the OS, allowing it to over-ride any settings. I have toggled settings for power management where you can choose the mode of charging, to prolong battery life i.e. constant power or restricted to certain levels, schedules etc., without any joy.

I have reset the BIOS a couple of times, but will try all your suggested solutions from scratch, including installing the Dell Power Manager ─ something I have not tried before ─ to see where it leads. Thanks for your continued patience. I will let you know what happens, regardless of the outcome.

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