TalentCell YS1203000 "State of charge" monitor - take two!

[jimrh]

As discussed, I have decided to fork the original “TalentCell YS1203000 “State of charge” monitor” topic into several parts as it was becoming unwieldy.

The original thread can be found here:

TalentCell YS1203000 "State of charge" monitor

I have decided to break out the discussion of the TalentCell “state-of-charge” indicator from the rest of the battery discussions. Summary: Though the TalentCell battery appears to be a Thing of Beauty, the state-of-charge indication is more like a Thing of Gagh! Due to @cyclicalobsessive and @KeithW’s exhaustive research on the battery’s runtime and voltage cut-off limits, I was able to make some significant progress today. First of all: A fully charged YS1203000, fresh off the charger r…

[jimrh]

Update:

Ref:  The original message with approximate values for the state-of-charge indicator lights.

TalentCell YS1203000 "State of charge" monitor

Update. I’m guessing that the original divider network was scaled for NiMH batteries since it was scaled to trip each LED at 11.8, 10.8, 9.8 and 9.1v. If we assume a certain amount of linear space after 9.1 volts, then it smells strongly of NiMH. Or, they divided up the space between 12.0 and 8.2 (or so) and chopped it up into equal segments, not considering that there is a sharp knee beginning at about 10 volts. I have re-calculated the values and we can get very near our ideal scaling if we…

Today, I have officially wrapped this up.

Today, I:

1. Re-measured the state-of-charge indicator trip points with the more accurate metering on the new bench supply.

2. Measured the un-modified trip points on batteries 2 and 3.

3. Made the component changes on the last two batteries.

4. Measured the now modified trip points on batteries 2 and 3.
    

Results:
(Rather than try to make a table, here’s a picture from my notes.)

You will notice that all the modified trip points are right around 11.5, 11.0, 10.5, and 10.0 volts which should be appropriate for the Li-Ion battery chemistry.
 

Here is a sectional view of the TalentCell battery state-of-charge indicator.

All tht needs to be done is to replace the three highlighted resistors, (1k&,ohm;) with 510Ω resistors to recalibrate the battery’s meter for Lithium-ion battery cells.

What say ye?

P.S.
@mitch.kremm @cleoqc
Can you folks communicate this modification to TalentCell for inclusion in subsequent Li-ion battery packs?

P.P.S.

Just in case you’re interested:

Here’s what happens when you let the “magic smoke” out of an electrolytic capacitor.

It turns out that electrolytic capacitors have “magic fur” instead of “magic smoke” inside them.

It’s a good thing I have spares!

[cyclicalobsessive]

@jimrh

You will notice that all the modified trip points are right around 11.5, 11.0, 10.5, and 10.0 volts which should be appropriate for the Li-Ion battery chemistry.

Is this the behavior goal?

11.5v will go off about 1 hr ~90% capacity left
11v will extinguish at about 3 hrs 65% capacity left
10.5 at 6 hrs 30% capacity left
10.0 at 8 hrs 6% capacity left. (15-30min)
9.5 dies

[jimrh]

@cyclicalobsessive

@jimrh

You will notice that all the modified trip points are right around 11.5, 11.0, 10.5, and 10.0 volts which should be appropriate for the Li-Ion battery chemistry.

Is this the behavior goal?

If you go back to the original thread, (the relevant posting is marked), you will note that you set your drop-dead at 9.75v, and the voltage steps were the ones agreed upon.

Giving the user 15-30 minutes to get out of what he’s doing and shut down seems like enough time.  Though, IMHO, I would design the last LED to go red, warning the user that death is imminent.

[cyclicalobsessive]

@jimrh

I would design the last LED to go red, warning the user that death is imminent.

Or play a submarine dive klaxon

[jimrh]

@cyclicalobsessive

Or play a submarine dive klaxon

We want to warn 'em, not give 'em a heart attack!

P.S.
“Battle Stations” is a better sound if you want to scare the poor sod outta his socks.