Using D-Cell battery with door lock

[tgp1994]

Hi everyone,

My front door has a Schlage touch-keypad electric lock installed in it. I've found that being able to type in a number to unlock my door is pretty handy, but this thing chews through its 4 AA batteries faster than just about any other electronic I've had. I understand that it's relatively safe to use a higher capacity battery (such as a D cell battery) as long as they have the same voltage. I happen to have a lot of D cells lying around that I don't have anything else to use for, so why not this door?

The problem is space. The battery pack slides in to the lock housing so a D cell doesn't fit. I'm fine with doing a Frankenstein modification, but does anyone have any suggestions as to how I should go about this project? For reference, it expects 6 volts DC so I was thinking of just taking out a AA battery then taping in some wire and attaching the D cell in place of the missing AA battery. The lock unit uses a snap-on like you see with 9v batteries to attach to the AA battery holder, if that also provides any opportunities.

Thanks!

 

[Tigercubrider]

A D cell is 1.5v

You could make a dummy battery pack out of wood or plastic pipe to simulate the original fittings or just solder wires to the terminals. Then drill a hole in the door and fix either a 6v rechargeable inside or run a psu to it

 

[tgp1994]

Thank you for the ideas, Tiger!

 

[big-all]

unfortunately your "D" cells may not last any longer yes larger batteries can mean larger "fuel tank"
but not always
you can get say aaa cells at 2.6ah and D cells at 0.6ah
you need to know the capacity but in general will only be shown in rechargable batteries but being 1.2v[around 1.1v-1.44v]may not have enough power to operate

 

[tgp1994]

@big-all Interesting, I didn't know you could get D cells in different capacities. I just have a bunch of non-rechargeable alkaline ones, hopefully the same capacity (and more than the AA I want to replace! )

 

[JohnD]

The Lithium batteries (often used in cameras and drones) have an incredibly long life, and slightly higher voltage than ordinary alkaline batteries. I use them in my cordless PIR/chime that watches the approach to my house. They're not rechargeable ones. You can get them, but you need a special charger.

for example
https://www.ebay.co.uk/sch/i.html?_...RS0&_nkw=lithium+energizer+batteries&_sacat=0

https://www.maplin.co.uk/search?sort=price-asc&text=lithium+batteries&productsPerPage=50&show=Page

Maplin's say "Lasts up to 7x longer than standard alkaline batteries"

 

[big-all]

@big-all Interesting, I didn't know you could get D cells in different capacities. I just have a bunch of non-rechargeable alkaline ones, hopefully the same capacity (and more than the AA I want to replace! )

look at any powertool battery they will come in say 1.3 ah up to about 6ah with perhaps 1.3/1.5/2ah/2.5/3ah cells available you then can double or tripple [in parallel] up to give you higher capacities up to 9ah
in other words go for a aa battery with more capacity rather than look for a bigger battery as it may be even worse

 

[Astra99]

Is there any possibility of using a switch-mode power supply? With 4no. AA cells, you would be looking at an output of 6V DC. As it replaces dry cells, a current of a few tens of milliamps would probably be sufficient, so more or less any 6V DC PSU would do. You might also be able to use a 5V DC power supply (USB) as well.

 

[tgp1994]

The challenge is figuring out how I would plug this power supply in, though. Keep in mind this lock is mounted to the door, and it's on the handle so it's at the point where the door swings out the most. It would probably take some tricky wiring to make it look half-way decent, but I suppose it wouldn't be impossible as a long-term solution. Right now though I'm just looking for good ways to use my D cells

 

[ericmark]

I have an old flash gun for a camera, cheap zinc cells around 6 flashes if lucky, high quality cells around 15 flashes, 2500 mAh rechargeable and the camera goes flat first. All AA cells.

I would guess it is more down to recovery, if I put the high quality cells to one side and put them back in after a week I will get some extra flashes. Never seen a no rechargeable AA cell with the capacity marked on them, last 6 times longer yes, but not 600 mAh or 3200 mAh only rechargeable seem to be marked. High capacity cells can have a short shelf life, there seems to be nothing to tell you about shelf life, however if marked pre-charged than it tends to be reasonable.

My camera also uses rechargeable cells, and these I can leave unused for months and still charged, but most of my AA cells have a max life of around 2 month.

 

[SFK]

TGP,
You are saying you wish to change
- from 4 x AA (6V) using a "snap-on connector like you see with 9v batteries"
- to 4 x D (6V) using a "snap-on connector like you see with 9v batteries"

Why not buy a 4xD cell holder and one 9V snap-on connector.
1) Wire the red wire of the D cell holder to the red wire on the snap-on connector.
2) Wire the black wire of the D cell holder to the red wire on the snap-on connector.
This will now prove 6V at the snap-on connector.

I presume this will not fit in your current lock, but will fit in a small box next to the lock on the door?

Both parts you need are here (on a UK site):
http://www.ebay.co.uk/itm/1-pcs-4-D-Size-Cells-Battery-6V-Clip-Holder-Case-Box-with-Lead-Wire-/390845007901?hash=item5b002d881d:g:ygUAAOxyP4dTeYys
https://www.ebay.co.uk/sch/i.html?_...X9V+connector.TRS0&_nkw=9V+connector&_sacat=0

and on the US site:
https://www.ebay.com/sch/i.html?_fr...0&_nkw=BATTERY+HOLDER+FOR+4+x+D-CELL&_sacat=0
https://www.ebay.com/sch/i.html?_fr...X9v+connector.TRS0&_nkw=9v+connector&_sacat=0
SFK

 

[tgp1994]

Thanks SFK, that sounds like a good solution!

 

[Doggit]

We tend to see batteries as all the same, but they're not. Some batteries are designed to last long, and have a low disharge rate, whilst others can handle a high discharge rate for a longer period. This guide will give you a few pointers, but in the end, rechargable may be the best option.