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User avatar
By -Cog-
#234201
I am attempting to use the OpenLog device with a 3.7V primary lithium cell connected to the JST port, but the device will not start up properly. The red and blue LEDs flash once, and that's it -- no recording, and no further LED action. Pressing the reset button has no effect. The battery is a SAFT Li-SOCl2 cell. The OpenLog works fine with other power sources, such as alkaline, NiMH, and LiPo batteries and even a DC power supply. Is there something about the Li-SOCl2 chemistry that is incompatible with the OpenLog?

Any help would be greatly appreciated!
User avatar
By PaulZC
#234203
Hi Cog,

It sounds like you are trying to draw more current than the battery can deliver - or perhaps that you have the polarity connected the wrong way?

Some of the Saft Lithium-chemistry batteries can only deliver very low currents. Can you tell us the exact Saft part number?

Best wishes,
Paul
User avatar
By -Cog-
#234213
It's the Saft LS 14500: https://www.saftbatteries.com/products- ... ls-lsh-lsp
Sorry, I should've noted the voltage as 3.6, but I measured 3.68V off the cell.

Endurance tests with a LiPo battery showed an average draw of about 15 mA, which seems (?) to be ok.

Oh, and I checked the polarity -- no issues in that regard with the Saft cell or the others I tested with.
User avatar
By PaulZC
#234219
Hi Cog,

It is probably the rush of current when the microSD card powers up that is causing the issue. That battery can only deliver 50mA continuous (recommended), 250mA pulse. The microSD card power-up could push the current higher than that. If you remove the microSD card does the OpenLog power up normally and stay on? If so, you have your answer.

You could try the LSH 14. It's a C-cell so larger and heavier but can deliver way more current. I've used LSH cells for balloon instrumentation in the past. They work well, even when really cold.

Best wishes,
Paul
User avatar
By -Cog-
#234228
Great call, Paul! The microSD card start-up current does seem to be the culprit. I really appreciate your help in troubleshooting this! Oh, and thanks too for the battery suggestion!

Best regards,
Cog
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