Artemis Global Tracker - 3 Power Sources Clarifications

SPARK-X
1

The tracker can be powered from:

  • the USB-C interface

  • a LiPo battery (recharged via the USB-C interface)

  • an external solar panel or battery pack (6V maximum)

You can have the USB, LiPo and external cells connected simultaneously, it will do no harm.

If I connect the solar panel and Lipo for remote applications will the solar charge the battery and keep the system humming? I guess not due to the following additional instructions. I am not an electronics person but what is the design intent logic given the three power possibilities.

If you want to power the Global Tracker from a low current source, e.g. solar panels, the charge current can be reduced to 60mA by changing the Charge Current jumper link. The 60mA charge current is enough to offset the 9603N’s 39mA average current draw during receive, but bigger supercapacitors are needed to deliver the average current draw during a complete receive/transmit cycle. So, if you do change the charge current to 60mA, you will also need to solder additional 10 Farad supercapacitors on to the rear of the PCB using the solder pads provided.

What happens at night without solar. Would the 10 farads handle the duty cycle of receive and transmit cycle in general?

I am trying to deploy this into deep sea.

Given the current design, what is my best powering option to run the unit on solar with a backup LiPo battery?

Should I use a Solar Panel with Sunny Buddy and then feed power to the external cell power socket?

2

Hi Paul,

Sadly, the way the AGT is configured, the LiPo charger can only be powered from USB. So, no, I’m afraid solar can’t be used to charge a LiPo battery directly.

What happens at night without solar: the 10F capacitors may have enough charge in them to send one transmit after sunset. But that’s all. The design intent was for the capacitors to be big enough to provide power for a single transmit cycle and then for the solar cell and super capacitor charger to recharge them (slowly) for the next transmit.

If you want to be able to store enough charge to keep transmitting overnight then, yes, you’ll need a different solution probably, as you suggest, using a separate battery to store the charge. I haven’t tried one, but it looks like the Sunny Buddy should do the job.

Please be careful that you don’t exceed 6.0V when powering the AGT or bad things will happen.

Also, please be aware that standard LiPo batteries really don’t like the cold. Their capacity disappears dramatically below 0 Centigrade. Perversely, you can get more capacity out of the battery by drawing current to power a heater to keep the battery warm… Strange but true! Something to think about if your floater will be heading into the polar regions.

Good luck!

Best wishes,

Paul

3

Hi Paul,

Thank you for the detailed response.

Sunny Buddy with 9W Solar panel is what I have.

Noted:

Will make sure not to exceed the 6.0V when powering the AGT.

Will use a heater to keep the LiPo battery warm.

Awesome and timely support.

Thanks again,

Paul