Lets talk about batteries

TCP Socket Keepalive

Phil Vella October 28, 2023

TCP Socket Keepalive Astra Telematics IoT devices, like many others, communicate with the host server using TCP sockets. Once the socket has been opened, the

Roaming SIMs and Automatic Network Selection

Phil Vella July 12, 2023

Roaming SIMs and Automatic Network Selection Open roaming SIMs are widely used today in IoT and telematics applications, for good reasons. Coverage is extended by

Phil Vella April 22, 2023

Lets talk about batteries Astra Telematics devices are powered-on by inserting the SIM, and should not be left for long periods with SIM inserted without

Lets talk about batteries

Astra Telematics devices are powered-on by inserting the SIM, and should not be left for long periods with SIM inserted without external power, to avoid deep discharge of the battery.

However, this aspect still regularly gets overlooked and we see a lot of devices returned for RMA repair with SIM inserted, and battery damaged by deep discharge. Possibly these devices have been stored for months with the SIM inserted, and that’s long enough to cause permanent damage to the battery. Our devices automatically shutdown when the battery gets to 3.4V, but there is still some battery drain in sleep mode and hence it wont take too long until the battery goes into deep discharge.

We reviewed this issue and decided to try and mitigate this problem by 2 changes:

Our batteries have deep discharge protection built in, and this was previosly set at 2.7V, this was a default for our battery supplier. We have asked them to increase the protection threshold to 3.3V to prevent (at least slow down) the deep discharge of the battery. Our devices cannot operate below 3.4V battery, so we lose nothing by cutting off the battery at 3.3V. This is now implemented and in production.
We have the low battery shutdown at 3.4V by default in all our devices, but from 7.0.60 we have enabled an automatic shutdown when external power is disconnected, after a short delay. The device will still operate almost as usual, it will wake on ignition, movement or reporting timers. Our devices can operate for weeks in this mode (depending on events, wakes and configuration), and hence it buys a little more time until the device goes into low-battery shutdown.

These 2 changes should give us more time to tolerate leaving devices with the SIM inserted and no power, before battery damage occurs. However, we still recommend that devices should not be left with the SIM inserted and no power for more than a week or two, usually this is necessary only during shipping. In cases where SIMs are installed before shipping devices, we recommend the use of “Despatch Mode”, using the command $DIAG,111. Despatch Mode puts the device into sleep mode to limit battery drain in transit, until the device is connected to power, when it wakes and operates as usual.