Battery Type Detection using Resistance

Thread Starter

mishra87

Joined Jan 17, 2016
947
Hello all,

I wanted to detect the battery type. there is fixed resistance is connected in the battery so i wanted to read the resistance value.
Two 18V battery is connected in series and resistance is connected at negative (-) terminal of battery per below image.

There is buck converter which convert 36V to 3.3V and micro controller supply is 3V3.

For lower battery V2, i can easily read the resistance value using divider R3 and R3 since microcontoller GND is same V2 GND.
For upper battery V1, it is hard to read the voltage using microcontoller since voltage microcontoller pin is VR1+18V.

Could any one suggest any solution to read the distance R1 value?

Note R1 and R2 are resistance connected with battery.

1634831453946.png
 

Thread Starter

mishra87

Joined Jan 17, 2016
947
Hi ,

Just to update in above thread if let say,
R1=R2 =10K (fixed) that means battery is manufacture X
R1=R2 =10K (fixed) that means battery is manufacture Y
So idea here to sense resistance R1 and R2 value to identify manufacturer

Thanks again !
 

LowQCab

Joined Nov 6, 2012
1,308
Batteries do not have Resistors.

The "Internal-Resistance" of the Batteries
changes with the Charge-Level, and Temperature, of the Batteries.

You can not reliably identify a Battery-Manufacturer by measuring Resistance.

In Your Circuit, You should put the Batteries in parallel, not series,
this will give longer service between charging, and increase efficiency.
.
.
.
 

Thread Starter

mishra87

Joined Jan 17, 2016
947
Batteries do not have Resistors.

The "Internal-Resistance" of the Batteries
changes with the Charge-Level, and Temperature, of the Batteries.

You can not reliably identify a Battery-Manufacturer by measuring Resistance.

In Your Circuit, You should put the Batteries in parallel, not series,
this will give longer service between charging, and increase efficiency.
.
.
.
Thanks for your reply !

For your information, now a days in battery pack 4 terminals comes out.
BAT+
BAT-
NTC
Fixed value Resistor for battery identification (as shown above)

If it single cell resistance value easily can be found by giving external supply with voltage divider. In this case we have 18V+18V two cell in series so hard to measure using microcontroller.
 

Irving

Joined Jan 30, 2016
2,308
Batteries do not have Resistors.
True, but some laptop packs do have 'ID pins' that use resistances, or other techniques, to ident a particular capacity or version...

However I have never come across it being a way of identifying manufacturer. I wonder if the TS is actually measuring internal thermistors for temperature sensing?
 

Irving

Joined Jan 30, 2016
2,308
@mishra87 our posts crossed... so you are indeed measuring thermistors. That's not guaranteed to be manufacturer specific. Most will use a nominal 10k @ 25degC NTC device but the actual values will vary slightly depending on various factors.
 

Thread Starter

mishra87

Joined Jan 17, 2016
947
True, but some laptop packs do have 'ID pins' that use resistances, or other techniques, to ident a particular capacity or version...

However I have never come across it being a way of identifying manufacturer. I wonder if the TS is actually measuring internal thermistors for temperature sensing?
True, but some laptop packs do have 'ID pins' that use resistances, or other techniques, to ident a particular capacity or version...
Yes, you are correct this is to identify the same using resistance.
Post #1, R1 and R2 are those resistance we are talking about.
Now question here how do we measure R1 value.

Thanks !
 

Irving

Joined Jan 30, 2016
2,308
There a
Post #1, R1 and R2 are those resistance we are talking about.
Now question here how do we measure R1 value.
No, I'm pretty sure you're seeing the internal temperature sensing thermistors. Do you have examples of the actual battery packs? Idents are usually zero ohm links or low values such as 100 or 500 ohms, never 10k

As to reading the upper thermistor, there are various techniques, much the same as reading the upper cell/battery voltage, Normally the battery management system would handle the offset as part of its ability to read the upper voltage. But there would normally be a link to the junction between both batteries so you can get to both ends of R1 in your original post. If not it becomes quite difficult.
 

Thread Starter

mishra87

Joined Jan 17, 2016
947
There a

No, I'm pretty sure you're seeing the internal temperature sensing thermistors. Do you have examples of the actual battery packs? Idents are usually zero ohm links or low values such as 100 or 500 ohms, never 10k

As to reading the upper thermistor, there are various techniques, much the same as reading the upper cell/battery voltage, Normally the battery management system would handle the offset as part of its ability to read the upper voltage. But there would normally be a link to the junction between both batteries so you can get to both ends of R1 in your original post. If not it becomes quite difficult.
Thanks for showing your interest !
Below is the battery circuit.
Now as explained above , two battery is connected in series.

Let say i want to measure the value of NTC or R2 of upper cell,
How will i do that ?
1634843885285.png
 
Top