Advice on rechargeable/standard batteries for locks and blinds

[simonmason]

There are a couple of posts on this topic but not recently so I thought I would start a new one now that rechargeable lithiums are readily available.

I have four Schlage z-wave locks and a lot of Somfy blinds that are all powered by AA batteries. I have been playing around with different batteries - so far I have settled on standard alkaline AAs for the locks and Lithium AAs on the blinds.

Schlage doesn't recommend Lithium as they produce "undesirable results". As far as I can tell this means that the lock will go from working correctly with a reasonable battery level to not responding and completely dead within a day. The key is figuring out what that drop-off point is.

I am trying some rechargeable lithium batteries in one of the locks:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

They are down 10% in 2 weeks. The lock is barely used. So this doesn't look promising.

I also tried these batteries in one of my somfy blinds. The blind goes up and down once a day and the batteries ran out in a matter of weeks.

It could be this particular brand of rechargeable batteries is just no good.

What have others had success with?

[Gadgetman!]

Rechargeable Lithium tech tends to have a high 'self discharge' rate.
Low discharge for Lithium just means 'won't drain completely before you manage to install them'...

I would suggest using Alkalines in the locks for just that reason.

I have blinds, too, with the cheap 433MHz remotes. But they run on 12V. Just need to figure out how to not make it look completely arsed up.

[TC1]

Your expectations dictate what type of battery technology you should be using. Once you choose a battery technology you need to throw away your preconceptions of how they should work. Let's use lithium batteries as an example, they do not have the same smooth/linear discharge rate as alkaline batteries, hence they will stay at a certain level for a long time and then suddenly drop-off to a very low level one day, using the current measuring methods built-into battery powered devices.

Just off the top of my head:

High-quality alkaline
Pros: Long lasting production use, predictable discharge rate, longest storage-charge shelf-life (I think some Duracells are guaranteed for 5 to 10 years).
Cons: One time use, continuous cost to replace, ends up in the garbage sooner than rechargeable.
Comments: In my Schlage locks I find these can last 6 - 12 months, dependent on temperature exposure and usage.

Non-rechargeable quality Lithium batteries
Pros: Probably longest lasting production use (many battery powered sensors use Lithium coin-cells and last 1 to 2 years), good storage-charge shelf-life
Cons: Non-linear/unpredictable discharge rate, One time use, continuous cost to replace, ends up in the garbage sooner than rechargeable.
Comments: All my Zigbee and some Zwave sensors use these.

Nickel–metal hydride (NiMH) rechargeable batteries
Pros: Currently dominates the marketplace, meaning lower initial-cost and easy availability; various mAH sizes (larger storage capacity available); don't end up in the garbage right away, predictable discharge rate.
Cons: Bad self-discharge (shelf-life) you'll need to have these sitting in a charger to use right away, average production use time (you'll end up changing them out constantly).
Comments: I used to use these everywhere

Low self-discharge nickel–metal hydride (NiMH) rechargeable batteries (Sanyo Eneloops)
Pros: Superior storage-charge shelf-life compared to regular rechargeable, don't end up in the garbage right away, predictable discharge rate.
Cons: Higher initial cost than regular rechargeable
Comments: I now use these everywhere where battery swapping is easy, in my locks I get about 3 to 4 months of use before swapping them with a freshly charged set. I personally like keeping as much stuff out of the garbage stream as possible.

Rechargeable Lithium batteries
Pros: Good production use time, don't end up in the garbage right away.
Cons: Higher initial cost than regular rechargeable, Non-linear/unpredictable discharge rate.
Comments: My only experience with these are my power tools, I will get around to buying a sett of AAs batteries to evaluate

Hope this helps, of course YMMV

[123qweasd]

+1 on Sanyo Eneloops
and I would add the MH-C9000 charger.

[TC1]

Just as an FYI, I use an old LaCrosse BC-900 charger which has all kinds of programmable parameters, including refresh mode (continuous discharge/charge cycles) to help older batteries regain near their full storage capacity.