Status lights on USB LiIon/LiPoly charger indicate test mode?

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Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by mangocats »

I'm trying to make sense of the status lights on my USB LiIon/LiPoly charger - v1.2 Product ID: 259

My general setup is: a 12V 2A wall wart feeding a 12-5V DC-DC converter which is outputting a pretty solid 5.132V - that 5.132V into the +/- DC IN on the 259 PCB. BATT goes to a pid353 6600mAh 3.7V 3 cell LiIon pack, and load goes to a Raspberry Pi Pico W. Both the Therm and Prog surface mount resistors were removed, Prog replaced with a 1KOhm thru-hole part, and Therm replaced with a 10K 3950 NTC (pid372) with the encapsulated end inserted in the LiIon pack.

When the 5.132V input is present, the red PWR led is on (and BRIGHT!!!), and generally both the amber and green LEDS are also always lit, which would seem to indicate System Test mode from the flowchart on the data sheet p13, and described on p17 as a mode you can reach by driving the Therm input close to VDD with no battery present - which doesn't make a whole lot of sense to me because when I disconnect the 12V input, all the lights on the 259 go out and the Pico continues to run, for days, on battery power which is coming to it through the 259 board, from the battery.

Anyway, this was just a curious question until I forgot and left the 12V source unplugged for too many days and the battery presumably ran down - hopefully a bit protected from over-discharge by the 73833/259? In any event... the Pico still runs well from USB power, everything looks normal programming and running it with Thonny over USB (with the power input line from the 259 disconnected) connects to WiFi etc, but... when I try to run an onboard main.py of the same program with the Pico W powered by the 259 load output, even with the 12V->5.132V input to the 259 present (and all lights lit), the Pico powers up and runs it's attempt to connect to WiFi, but fails to connect and just re-cycles trying to connect over and over (~25 second cycle) - or, occasionally it indicates that it has connected (via a pair of LEDs that both go out when connection is successful), but... I still can't reach it over WiFi.

Unlike before, now when I disconnect the 12V input to the system the Pico dies (no power from battery), but it powers right up when the 12V is restored. Power in to the Pico from the 259 is currently reading about 3.1V most of the time, though occasionally I will reset the Pico and instead of coming up like it usually does it will hang, the green light on the 259 will go out, and power input to the Pico will read around 1.61V and falling slowly, but another reset of the Pico will bring it back to the 3.1V state... The amber light only state seems like a nice encouraging "battery charging" state according to the 73833 flowchart, but... it's not a happy place for the Pico.

One additional setup detail: there is a pid4712 battery monitor inline between the battery and the charger board, I was hoping to work on getting it talking to the Pico this afternoon so I would have better battery state info, but that software is still in development and not making much progress with this distraction....

Any ideas what I should look at next to attempt to get the battery to charge back up?
Last edited by mangocats on Sun Sep 25, 2022 3:46 pm, edited 1 time in total.

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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by adafruit_support_bill »

The over-discharge protection is a function of the battery protection circuit - not the charger. Some of these require that you fully disconnect the battery from the circuit in order to reset the protection circuit after it trips. Try disconnecting and re-connecting the battery and see if it starts charging.

As for the test-mode indication, please post some photos showing all your soldering and connections to the board.

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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by mangocats »

Thanks,

After about 90 minutes of being plugged in again I'm now getting a solid amber light only, which decodes as one of the charging states.
adafruit_support_bill wrote: Sun Sep 25, 2022 3:45 pm As for the test-mode indication, please post some photos showing all your soldering and connections to the board.
Yeah, not so easy at the present time as the whole thing is assembled into a project box, I have attached a reasonably clear view of the front of the board, you can see solder in the holes of the PROG resistor, but not so much the front side of the thermocouple wire - it is much more reassuring from the back side, but I'd rather not pull that board from its mounting at the moment.
73833.jpg
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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by adafruit_support_bill »

Based on the symptoms, I'd suspect a marginal connection on the RTD. The RTD connects between the charge controller THERM pin and GND. If there were a bad connection there, the THERM pin could float HIGH and put the charger into test mode.

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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by mangocats »

Voltage to the Pico continues to climb, at 3.3V now, and the WiFi is connecting and talking again... and the green light is back - so indicating test mode again. Pico stayed powered through a removal of external power, so the battery seems to have taken at least some charge.

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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by adafruit_support_bill »

If you gently tug on the RTD wires, do you see any change in the lights?

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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by mangocats »

Here's a shot of the back:
259back.jpg
259back.jpg (726.83 KiB) Viewed 95 times
sorry for the blur, my phone this go around didn't come with a macro mode on the camera.

The green light status doesn't change when manipulating the thermistor wires, they're securely attached so I'm assuming that they got some solder flow around the multi-strand holding it to the pad.

When I disconnected the power to take the back-side photo, then reconnected, I'm back in amber-only charging mode now, and it seems that WiFi connection was possible when in test mode, but not in charging mode, at least at this level of battery charge; which I guess might be expected with 1A feeding into a 6600mAh battery. Wondering if some capacitance on the power to the Pico might help the situation...

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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by adafruit_support_bill »

The green light status doesn't change when manipulating the thermistor wires
The next time it goes into test mode, measure the resistance across the RTD leads. There is an outside chance that the RTD itself has a bad internal connection. If that checks out OK, then I'd have to assume that the problem is in the charge controller.
it seems that WiFi connection was possible when in test mode, but not in charging mode, at least at this level of battery charge
Test mode will be putting out a steady 4.2v @ 1A. The output in Charge mode will depend on what phase of the charge cycle it is in. Not a good idea to leave it in Test mode with the battery connected for very long - since Test mode is essentially the same as the Fast Charge phase of the charge cycle.

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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by mangocats »

O.K. - these were some interesting? observations:

Pressing the button that grounds RUN on the Pico caused the green light to light, together with the amber, Pico reset but didn't connect to WiFi this time.

Assuming it has something to do with load, tried disconnecting the load out from the 259 board, in that state it now shows green, no amber. Voltage on the unloaded load output reads 4.209 steady (just a multimeter, Fluke 117)

Reconnecting load, essentially just to the pid987 amplifier which currently has floating inputs, solid amber light and green flashing rapidly on the 259 charger. Voltage on load output bouncing rapidly from 3.99 to 4.07.

Reconnecting the Pico in combination with the amp, I initially get a green & amber, Pico apparently boots, turns on 2 leds, then after a second or two it goes "off script" from it's normal sequence - one Pico driven LED goes out and the other stays on (not a normal behavior for the main.py that is onboard), and simultaneously with this the 259 switches to amber only. Voltage on the load output is 1.609, probably why the Pico isn't running as expected.

Remove Pico as a load, back to amber and green flash state on the 259. Disconnect all loads, back to solid green no amber on the 259.

Don't know how helpful this is, but here's a sort of project box overview - it wasn't made to be an instructable:
projectbox.jpg
projectbox.jpg (397.92 KiB) Viewed 93 times
The whole BOM in the box is:
* 12V->5V DC-DC converter https://www.amazon.com/dp/B07YV25LDX
* pid259 battery charger
* pid4712 battery monitor
* pid353 6600mAh 3.7V 3 cell LiIon pack
* Raspberry Pi Pico W
* pid987 amplifier
* pid3487 lighted button - serves to ground RUN pin on Pico when pressed, and the LED shows software status.

When it's working, the Pico serves a webpage that controls output of tones from a couple of GPIO to the amplifier. It is intended to live in the yard, drawing power intermittently from some 12V landscape lighting power that's available in the location, but running on battery most of the time.

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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by mangocats »

adafruit_support_bill wrote: Sun Sep 25, 2022 6:48 pm Test mode will be putting out a steady 4.2v @ 1A.
Thanks for that (and all your help!), I hadn't gotten that far in the datasheet yet.

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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by adafruit_support_bill »

Pressing the button that grounds RUN on the Pico caused the green light to light, together with the amber
Did you measure the resistance across the RTD leads when it is in Test mode?

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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by mangocats »

adafruit_support_bill wrote: Sun Sep 25, 2022 7:27 pm
Pressing the button that grounds RUN on the Pico caused the green light to light, together with the amber
Did you measure the resistance across the RTD leads when it is in Test mode?
Next time I have it out I'll measure it, but the switching in and out of test mode seems much more correlated with changes in load on the 259 output than any physical manipulation of the thermistor.

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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by adafruit_support_bill »

A broken or intermittent RTD junction could cause the THERM input to float. In that state, just about any fluctuation in the circuit could cause the measured voltage to change.

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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by mangocats »

Well, when I went to bed the amber light was on, green off, and the Pico website was responsive - everything seemed normal/hopeful for a recharge overnight.

This morning the lights were the same but the Pico's website was non responsive. Removal of 12v input power was instant off for everything, so apparently no battery charging was accomplished, even with amber light only status - presumably all night.

Reconnecting 12v in puts me back to amber+green, Pico running but not connecting to WiFi. 12v disconnect: all cold again. I guess my next step is to try another battery, get the battery monitor software working and hopefully figure out some kind of safe self shutdown for when power is unavailable for an extended period (for example the up coming hurricane...)

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Re: Status lights on USB LiIon/LiPoly charger indicate test mode?

Post by adafruit_support_bill »

This morning the lights were the same but the Pico's website was non responsive. Removal of 12v input power was instant off for everything, so apparently no battery charging was accomplished, even with amber light only status - presumably all night.
If the system did fall into Test mode overnight, it might have overcharged the battery. With luck, the protection circuit in the battery would have shut it down before any damage was done.
Reconnecting 12v in puts me back to amber+green
And the resistance across the RTD when in that state is . . . ?

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