Relationship between voltage and remaining charge

[Mr Happy]

The question often comes up about how to estimate the remaining charge in a battery from measurements of its voltage. I stumbled across an interesting document from Maxim that explores this topic in some detail. I thought I'd post the link here for reference as I found it valuable: Inaccuracies of Estimating Remaining Cell Capacity with Voltage Measurements Alone (Maxim)

 

[SilverFox]

Hello Mr Happy,

If we narrow the view down to a temperature range of 10 - 30 C and a capacity range of 20 - 80%, it seems to clean things up a lot.

Tom

 

[abvidledUK]

1.20v seems to be the turning point for vastly reduced remaining capacity for 4/3A single cell nimh charged to 1.40v at most temps, with 1.15v being absolute minimum for any usable capacity.

Presumably this cell size chosen for direct comparison with 4/3A li-ion cell.

Dimension (D x H): 18mm (0.71") x 67mm (2.64") approx

 

[Bullzeyebill]

1.20v seems to be the turning point for vastly reduced remaining capacity for 4/3A single cell nimh charged to 1.40v at most temps, with 1.15v being absolute minimum for any usable capacity.

Presumably this cell size chosen for direct comparison with 4/3A li-ion cell.

Dimension (D x H): 18mm (0.71") x 67mm (2.64") approx

And this is depending on discharge rate, I would think.

Bill

 

[VidPro]

temperature, load, age, condition, and the original style of battery too.
hurts my head.

i have some of them extreeme High-discharge li-ions (rc type) and the Graph installed in my brain, was wrong for THOSE by a mile.
but now i am familliar with them, i wont get fooled again.

i think the best you can do , is to know what THAT battery acts like, under those conditions.
Good "meters" on electronic devices and flashlights would be a miltiteered Led redout with at least 10 steps
then you just know about how it acts, and see the (sorta) analog readout of how many lights are lit

And whats with the huge MATH on the resistance stuff, cant everything be simple?
read the voltage, put a load on, see the load voltage, assume ABOUT its condition, and go on. or Pay $300 for a machine to do 2 calulations and show you the results (that will change tomorrow
life should be easier than this.

 

[abvidledUK]

I really don't see why people don't just buy a battery tester that tests under load, after all the simpler ones are not that expensive.

You don't really need all bells and whistles for most uses.