Hello there,

Anyone ever attempt this yet?

The type of laptop and battery i am talking about here is the multi terminal type that has maybe 6 terminals. The battery fits snug into a compartment in the back of the laptop so you can not get access to any terminals once the battery is installed, but the battery must be installed in order to make this measurement. It would be very hard to connect to the terminals also so the battery can be used with a clamp on ammeter or something.
I would not like to take the battery apart because if i buy a new battery i would like to be able to test it without breaking the plastic or something.
The battery is a 18 to 19v Li-ion type so there are multiple cells inside and the terminals probably break out each of the connections inside.

 

A method I use in some situatiions that might work is to get a piece of very thin double sided printed circuit board and cut it into a strip that can be pushed between the battery contact and the contact in the housing. Solder a wire to each side of the board. (When cutting it make sure that there are no shorts between the faces along the edge.)
The board that I use is only 0.2mm thick (0.008")
Les.

 

A method I use in some situatiions that might work is to get a piece of very thin double sided printed circuit board and cut it into a strip that can be pushed between the battery contact and the contact in the housing. Solder a wire to each side of the board. (When cutting it make sure that there are no shorts between the faces along the edge.)
The board that I use is only 0.2mm thick (0.008")
Les.

This is a good way of doing it.

If you can't find thin PCB then a couple strips of copper foil with thin double stick tape in between might work.

 

There are apps that can measure the battery current and also voltage, etc., But of course, that would depend on the hardware and the OS. Microsoft Research had a utility called joulemeter, which they have depracated, and say this functionality is built into visual studio. This gave just the power through.

 

Can I ask why you want to know the current? It is going to depend on what software is running on the laptop.

 

Hello,

Didnt get any alerts on this thread for some reason.

Les:
So you say we only need to connect two wires? There are 8 connectors on the battery and laptop.

Alec:
I want to know the current of the laptop itself. It's ok if it changes with application being run, there will be a max.

 

I think only two of them will be power. The other 6 could be to monitor individual cells or there could be a thermistor and also some communication with the internal battery protection circuit. It is also possible that some of them may be paralleled. I have just had a look at an old netbook. That has 9 connections. Two of them at each end a slightly larger than the other 5. I have measured the resistance between the pairs at each end and they are parallelled. The design of the connectors on this would not allow the use of the method I suggested. The only other thing I can think of at the moment would be to try to find a scrap model the same as yours and use the connectors from the battery and laptop to make a short extension lead so you can break into the power pins.

Les.

 

I think only two of them will be power. The other 6 could be to monitor individual cells or there could be a thermistor and also some communication with the internal battery protection circuit. It is also possible that some of them may be paralleled. I have just had a look at an old netbook. That has 9 connections. Two of them at each end a slightly larger than the other 5. I have measured the resistance between the pairs at each end and they are parallelled. The design of the connectors on this would not allow the use of the method I suggested. The only other thing I can think of at the moment would be to try to find a scrap model the same as yours and use the connectors from the battery and laptop to make a short extension lead so you can break into the power pins.

Les.

Hi again,

Yeah i guess that's the only way to do it, too bad, a little more work then i had hoped for.

Well, i guess i could try measuring the battery capacity itself. that would at least tell me if the battery is good.
It seemed to be running down a little faster than i thought a new battery should. I thought maybe the laptop might be drawing too much current.

 

It seemed to be running down a little faster than i thought a new battery should.

Admittedly it's a small sample, but on the two laptops I've owned (one Sony, one Lenovo), I've never been able to get the runtime that's advertised in the shiny brochure. It would be interesting to know how the manufacturers actually test runtime.

 

Admittedly it's a small sample, but on the two laptops I've owned (one Sony, one Lenovo), I've never been able to get the runtime that's advertised in the shiny brochure. It would be interesting to know how the manufacturers actually test runtime.

Hi,

They measure the actual real life run time with a precision ammeter and precision clock, then multiply it by pi (3.14159...)

 

Boot the Live version of linux and execute:
(Lie --> Live) Thanks @Alec_t

ubuntu@ubuntu:~$ upower -i `upower -e | grep 'BAT'`
native-path: /sys/devices/LNXSYSTM:00/device:00/PNP0A08:00/device:16/PNP0C0A:00/power_supply/BAT1
vendor: COMPAL
model: PA3817U-1BRS
serial: <redacted>
power supply: yes
updated: Tue Feb 13 16:29:23 2018 (22 seconds ago)
has history: yes
has statistics: yes
battery
present: yes
rechargeable: yes
state: fully-charged
energy: 26.3844 Wh
energy-empty: 0 Wh
energy-full: 26.3844 Wh
energy-full-design: 47.52 Wh
energy-rate: 0.0108 W
voltage: 12.284 V
percentage: 100%
capacity: 55.5227%
technology: lithium-ion

Capacity is the number your after. Simple.

 

Boot the lie version of linux and execute:

ubuntu@ubuntu:~$ upower -i `upower -e | grep 'BAT'`
native-path: /sys/devices/LNXSYSTM:00/device:00/PNP0A08:00/device:16/PNP0C0A:00/power_supply/BAT1
vendor: COMPAL
model: PA3817U-1BRS
serial: <redacted>
power supply: yes
updated: Tue Feb 13 16:29:23 2018 (22 seconds ago)
has history: yes
has statistics: yes
battery
present: yes
rechargeable: yes
state: fully-charged
energy: 26.3844 Wh
energy-empty: 0 Wh
energy-full: 26.3844 Wh
energy-full-design: 47.52 Wh
energy-rate: 0.0108 W
voltage: 12.284 V
percentage: 100%
capacity: 55.5227%
technology: lithium-ion

Capacity is the number your after. Simple.

Hi,

Thanks.
That's interesting. What is the "capacity' there, what does that represent?

 

This basically shows that the battery is at 55% of the designed capacity when it;s 100% charged, so the battery has degraded.

These two

energy-full: 26.3844 Wh
energy-full-design: 47.52 Wh

numbers above should be the same.

Round numbers
energy-full: 26/47 * 100 = 55.3%; Theirs, using the right numbers: 55.5227%

This "energy-rate: 0.0108 W" doesn't make any sense. it would have to be (Watt-hr)/hr; My guess is it's Watt-hours/hr
A Watt-hr is an energy unit. But, I could be way off here. Can you convert that to amps? Dunno.

 

This basically shows that the battery is at 55% of the designed capacity when it;s 100% charged, so the battery has degraded.

These two

energy-full: 26.3844 Wh
energy-full-design: 47.52 Wh

numbers above should be the same.

Round numbers
energy-full: 26/47 * 100 = 55.3%; Theirs, using the right numbers: 55.5227%

This "energy-rate: 0.0108 W" doesn't make any sense. it would have to be (Watt-hr)/hr; My guess is it's Watt-hours/hr
A Watt-hr is an energy unit. But, I could be way off here. Can you convert that to amps? Dunno.

Hi,

Well actually the degraded capacity reading would be what i would want.
Do you think this runs on all laptops?

 

Boot the lie version of linux

Ah, but will that give an honest answer?

 

Boot the lie version of linux and execute:

ubuntu@ubuntu:~$ upower -i `upower -e | grep 'BAT'`
...
state: fully-charged
energy: 26.3844 Wh
energy-empty: 0 Wh
energy-full: 26.3844 Wh
energy-full-design: 47.52 Wh
energy-rate: 0.0108 W
voltage: 12.284 V
percentage: 100%
capacity: 55.5227%
technology: lithium-ion

Only two terminals will be the power connections (probably). Some of the other terminals are for a communications link with the battery charging electronics inside the battery case. That's how the OS finds out the information above.

 

The 12.04 LTS Live CD will run from CD, later versions of Linux would require a USB stick. It's an installed app.
So, you just boot the CD and say you want to "Try linux". Linux runs from memory. The AMD64 version is 64 bit and the 386 version isn't.
There is also a comprehensive memory test available that you have boot into.

 

Only two terminals will be the power connections (probably). Some of the other terminals are for a communications link with the battery charging electronics inside the battery case. That's how the OS finds out the information above.

Hi,

So you think that maybe only two wires are used for actual running, that would make sense, so i'd only need a two wire connection to test. I guess it might be worth a try.

Now that i think about it, doesnt anyone make these connectors? Maybe not.
If i had the two connectors i could make a full link cable, and measure current in one wire.

 

Now that i think about it, doesn't anyone make these connectors? Maybe not.

maybe? https://www.rrc-ps.com/en/products/...-mc-20-battery-mating-connector/features.html

My cell phone has 4 contacts. They are +, - and a thermister.

A laptop may have an SMB bus. https://en.wikipedia.org/wiki/System_Management_Bus

 

maybe? https://www.rrc-ps.com/en/products/...-mc-20-battery-mating-connector/features.html

My cell phone has 4 contacts. They are +, - and a thermister.

A laptop may have an SMB bus. https://en.wikipedia.org/wiki/System_Management_Bus

Hi,

Hey that's pretty cool. If that was all there was to this, i could make a cable in a few minute i bet.

But i would also need the mating connector for that one shown on the link page. That could be a challenge too if i had to make my own.
I've made my own connectors in the past from raw materials, and even a 40 position rotation switch that had to fit inside a small CB radio case (try that!) but it's not easy and dont know if i want to go that far these days.