Battery is at 0% and running

[murka]

Hello!

I was searching the web looking for any battery app that could possibly measure a battery that windows reports to be at 0%. Only way would be to guess the batteries capacity and compare it to the sum of every discharge rate multiplied by the refresh rate in seconds. This should give the remaining charge.
The problem is quite long actually and I'd like to get some of you guys up to speed who aren't(Seeing as your sticky advises people to buy a new battery).

Namely, windows 7 started using the "capacity remaining" on batteries as the full charge capacity but this posed problems because some older laptops didn't have any usable value there or that for some people the value suddenly started decreasing after using windows 7. Employees at Microsoft stated that it couldn't write the remaining capacity and wear values but not everyone thinks it's true. Now a lot of users get the "Consider replacing your battery" message quite early.

While a lot of people do claim that batteries do indeed last 2-3 years, i have never seen a laptop battery have 5min capacity even after 5 or 10years. I actually have a toshiba satellite from 1996 that has a battery capacity of 30min and some others from late 90's and early 00's with an hour in them so luck has it that I'm no stranger to laptops. To confirm that my battery actually had more juice in it than what windows reported(and any other os as the value is written to the batteries eeprom), i set the critical level to 0% and my laptop ran for 3hrs before i shut it down as the battery reached 9.9V, but I'm unsure how low i could safely let it go. Charging it back up and checking the charging rate i calculated that i had used 30Whr of it's 48Whr. I'm sure it does have even more but i don't feel safe trying as the battery could lock up due to too low voltage and I'd hate to spend 70€ on a new one. Also i don't know if the 48Whr means that it's safe to go there on a new battery or that it will physically contain such capacity yet draining it all would mean bricking it.

So still as of now there is no word from Microsoft and the only workaround is to set the battery critical level to 0% which will disable all hibernation/shutdown and let it keep running on the battery.

[Chris]

I'm not entirely certain what your question is.

Over time ALL chemical batteries lose the ability to a hold a charge. I have personally seen several laptop batteries that are incapable of holding a charge. The typical useful lifespan of a battery is less than three years. Even if it works, it probably only holds < 20% of what it did when it was new, so what used to be a 5 hour battery is now less than 1. A 3 hour battery down to about 40 minutes.

That is, unfortunately, the nature of the beast. Some batteries wear out slower and some faster. I had a secondary battery that only lasted two years because one of the cells died and the whole battery stopped charging.

[murka]

tl;dr version: My battery and actually most of the batteries out there with a reported wear of ~80% actually have a wear of 10-20%, just that some way or somehow this gets wrongly written on the battery eeprom and a lot of people waste money buying a new battery while their current one could be used.

Long version better explained: I'm going to write write a battery meter for myself as currently i have no way of telling how much battery i have left, just some estimation based on previous runs. It's not safe to let a cell run below 3V but i can only read the voltage for the whole battery pack and that while the laptop is drawing current from it meaning this reading will be smaller than the rest voltage.

My question would be regarding the actual wear on batteries. I'd like to know what the usual real-world wear on lithium batteries over time is and under which conditions. The lab results of auto degradation and such tells nothing of real world applications. My estimate is that batteries lose about 4-10% a year when used on a regular basis, but this can indeed vary and the most important factor is heat. So share your opinions and experience here.

[Chris]

It definitely depends on the battery on how it's used. Frequent discharges below 30% will degrade the battery significantly faster than recharging before hitting 100%. Also, keeping the battery constantly charged at 100% is bad as there's, basically, a sort of high pressure built up in the battery.

Prior to Windows 7, not many applications queried the battery's detailed status, so many companies didn't put a lot of effort into making sure their batteries reported good and valid data, as long as the percent remaining and discharge rates were accurate (more or less). That's why people with some laptops (ASUS, for example) were getting the "Please replace your battery" warning from Win7. It was the battery's fault for reporting bad data.

BatteryBar checks the same data. You could use BatteryBar to dump a log file of you using your battery. It includes a lot of detail like rate and voltage that you can graph.

[murka]

Well i'll share some info on my research. First i wanted to use charging rate to determine battery capacity but while it's almost accurate enough for discharge(if the remaining capacity is correct, tho at this point i doubt anything the acpi is telling me) the charging rate is clearly wrong. This makes discharging, charging to middle and discharging a nightmare as at this point there is no way to tell how much the battery has left. It might be possible to estimate via voltage and discharge rate, but requires gathering a lot of statistics.


Picture taken after windows showed 0%(my program used design cap as 100%).
Ran down to 36% when i let it recharge again. Voltage was 9.9V at that point.