Goals:

• power a Schlage Camelot Z-Wave lock (BE469) that normally uses a 4xAA battery pack (6V) on an AC adapter
• battery backup using 18650 batteries (see parts below)
  • trickle charge 18650 when AC adapter is being used

Parts hopefully to be used (reduce/REUSE/recycle):

• 6x 18650 Li-Ion batteries (obviously don't have to use all of them)
• AC power supply (12V) at various amperages (1A/2A/3A) -- I also have a 6Vpower supply, but it's only rated at 200mA, and I think the lock needs at least 300mA to operate the bolt
• DC/DC step-down voltage regulator (12V->5V [adjustable])

I found this project description:

https://www.allaboutcircuits.com/projects/battery-backup-power-supplies/​

which seems to meet what I need.

If I want to use 2x18650 in series (2S), should I worry about modifying the linked circuit if I will use the step-down regulator at 6V?

Seems like a basic question, but I'm concerned about how to trickle charge the 2S 18650 as a battery back-up while powering the lock.

 

Goals:

• power a Schlage Camelot Z-Wave lock (BE469) that normally uses a 4xAA battery pack (6V) on an AC adapter
• battery backup using 18650 batteries (see parts below)
  • trickle charge 18650 when AC adapter is being used

Parts hopefully to be used (reduce/REUSE/recycle):

• 6x 18650 Li-Ion batteries (obviously don't have to use all of them)
• AC power supply (12V) at various amperages (1A/2A/3A) -- I also have a 6Vpower supply, but it's only rated at 200mA, and I think the lock needs at least 300mA to operate the bolt
• DC/DC step-down voltage regulator (12V->5V [adjustable])

I found this project description:

https://www.allaboutcircuits.com/projects/battery-backup-power-supplies/​

which seems to meet what I need.

If I want to use 2x18650 in series (2S), should I worry about modifying the linked circuit if I will use the step-down regulator at 6V?

Seems like a basic question, but I'm concerned about how to trickle charge the 2S 18650 as a battery back-up while powering the lock.

Try the TP4056 charger and then your dc-dc converter. I’m working on a similar project. Here’s the link to the data sheet for the TP4056 let me know if this helps. https://dlnmh9ip6v2uc.cloudfront.net/datasheets/Prototyping/TP4056.pdf

 

Interesting. I may need to buy a DC-DC booster (step-up) instead of the buck (step-down) converter if I'm going to wire the 18650 in parallel (they are about 4.15V at maximum charge) because the Schlage needs ~6V:

https://www.addicore.com/TP4056-Charger-and-Protection-Module-p/ad310.htm

 

You can wire the 18650 batteries in series. Then you can produce the max volt output 7.4volts.