Card Voltage Accuracy & LiPo Battery Thresholds/LiPo Fuel Gauge

Troubleshooting
1

Hi,

My LiPo voltage thresholds are set at the default, confirmed after querying the thresholds from the in-browser terminal:

“usb:4.6;high:4.0;normal:3.5;low:3.2;dead:0”

My voutbound parameters on periodic mode are:

“voutbound”: “usb:30;high:60;normal:90;low:120;dead:0”

I am using a 3.7V 10000mAh 1160100 Lipo Battery, connected to the LIPO JST port on the Notecarrier-F v1.0.

My confusion lies in that the card was still performing outbound syncs hourly (high) whereas the reported voltages in the event JSON bodies were less than 4V (should be normal and uploading every 1.5 hours between 3.5 - 4.0 V - right?).

Below is a screenshot of my Ubidots graph widget showing the voltage levels over time. I drew a red line at the date that I observed the card switched from uploading hourly to every 1.5 hours. Before the red line it was still performing outbound updates hourly.

Ubidots graph widget showing the voltage levels over time
Ubidots graph widget showing the voltage levels over time1690×567 60.5 KB

Are these reported voltages that I am routing to Ubidots accurate? Am I wrong in using this as a LiPo battery fuel gauge?

Apologies if I am missing something trivial.

1 Like
2

Hi @tsuzenski,

At first glance, I don’t see anything wrong with what you are trying to do. Can I first ask which version of the Notecard firmware you are using? I’ll follow up with some folks internally to see if I am also missing something :slight_smile:.

Thanks,
Rob

3

@tsuzenski - can you please issue a card.voltage request and let me know what the response is from the Notecard? Thanks!

4

Hi Rob,

Notecard firmware version is 5.1.1.16026.

Sure thing - Can I issue a card.voltage request OTA? I’ve only done it before via Blues’s in-browser terminal.

5

Ah, no, sorry I didn’t realize this was already deployed! We are definitely scratching our heads as this functionality has been part of the Notecard firmware for some time now. If there is a chance to recover the Notecard and issue the request locally, that would be ideal but I completely understand if that isn’t feasible.

Rob

6

Hi,

Oh - I actually do have the device in my possession – sorry for the confusion. I have been trying not to plug it into USB to see how long the battery will last until it dies without charging, but I think plugging it in for just a minute won’t affect this result much.

Here is the response from the request locally:

> {"req":"card.voltage","mode":"?"}
{
 "usb": true,
 "mode": "usb:4.6;high:4.0;normal:3.5;low:3.2;dead:0",
 "value": 4.688748469169242
}
7

You’re right - with it plugged into USB you won’t get the voltage level from the battery! I don’t suppose you happen to have the FTDI debug cable on-hand? It’s a really convenient way to send requests to the Notecard without also powering it.

8

I do not have one of these, but it sounds convenient! Definitely something I’ll look into.

9

I think you can look at the Notecard in the Notehub on the Summary tab and it will show you the last 20 or 30 voltage readings. Anyway that is how I checked the battery voltage on my devices.

Karl

10

Hi Karl,

Yes, it does. I think these should be the same voltage readings I am uploading to Ubidots so the graphs should show the same thing.

I’m still confused about the thresholds though, and why it was still uploading hourly (about a month or so ago) despite the voltages being under 4V.

11

Sorry, but I can’t help you on the thresholds. We don’t use the threshold feature and keep the Notecard in minimum mode to reduce power except when manually syncing after our hourly reading.

Karl