Cylindrical Cell Recommendation Needed

Hardware (and firmware) Dash
1

Hi, Team Hologram and Everyone,

I’m looking for a recommendation for a cylindrical cell to use as a backup battery. The Hologram-supplied PK Cell pouch cell works great, but I’d ultimately prefer a cylindrical cell due to it’s sturdy package (vs. a pouch cell).

I’ve now tested a few PCB-protected 10440 and 18650 cells, but I’ve come up against an interesting issue: When used as a backup cell, the cells perform fine and shut off at the claimed lower-limit voltage. Unfortunately, they “latch” there, so that returning 5V USB power does not allow charging resumption / Dash function without first disconnecting and then reconnecting the battery to the circuit. That means that auto-reboot when USB power is restored is not possible. Conversely, the PK Cell does not exhibit this behavior: When it shuts off at low voltage, subsequent resumption of USB power brings the board and charging back online.

I recall that back in the “Dazzling Duke” days, there was talk of a Konekt making a protected 18650 cell available.

Possible commercial application being considered here, so I’d like to move to cylindrical from the easily-mishandled pouches. Any recommendations are much appreciated!

Michael

2

The pouch cells provided by Hologram have a cut-off voltage of 3.0v and the 10440’s and 18650’s with protection have a cut-off at 2.5v. Is the charging circuit designed to work with specific battery parameters? If so are they available? Thanks!

3

Bumpity-bump!

Any thoughts?

Bueller? Bueller? :slight_smile:

4

Still looking for any recommendations for cylindrical cells and/or specific battery parameters for Dash charging circuit. Thanks !

5

L6924U
Here’s the datasheet for the battery charger on the Dash. It’s designed for use with single-cell Li-Ion/Poly batteries. You can take a further look for other parameters for operating characteristics to find batteries that would be suitable for use. Hope that helps.

6

Hi Ryan,

Thanks ! The documentation notes that some of parameters are programmable. Is it possible to reprogram the charger?

7

@tonym63

Unfortunately the charger is not under software control. The programmable parameters referred to are by hardware only, via capacitor and resistor value selection.

8

Got it…Thanks Erik!

9

Very good to know, Erik - thank you!