Solved

Four 'AA' batteries and a deadbolt, how to hard wire

Posted on 2014-02-16
29
614 Views
Last Modified: 2014-02-21
I know this is a long shot, but I figure if there's a Religion category, i should be able to ask a question about AA batteries too

I have little to no electrical background but i will explain the situation

I have a powered door lock on the side door of my house.  I'm sick of replacing the batteries almost weekly, so i'd like to see how i can replace them with an ac to dc adapter

I have seen the first 20 google search results, but i have an issue not covered by those links.

With the four AA batteries in the internal battery box in the lock, positioned in series

when i measure the battery box +/- it reads 5.98 volts dc, and the lock works perfectly.

when i move the battery box to the other end of a 20 foot copper wire run, the voltage is still the same and the lock still works perfectly

when i connect an ac to dc adapter to the 20 foot wire instead of the battery box, the lock exhibits these symptoms:

with a DC6V  2.0A ac to dc adapter:  it barely budges, the bolt doesn't move, but the lock is powered

with a DC6V 0.200A ac to dc adapter:  it moves a little bit more but not enough to unlock it (have to put in the unlock code 7-8 times to move the bolt the 5 inches)

the dc adapters test at 6.28 volts DC output

so the question is what specifically can i do to get non-battery power to this lock?
0
Comment
Question by:FocIS
  • 8
  • 8
  • 5
  • +3
29 Comments
 
LVL 90

Expert Comment

by:John Hurst
Comment Utility
with a DC6V  2.0A ac to dc adapter:  it barely budges, the bolt doesn't move

with a DC6V 0.200A ac to dc adapter:  it moves a little bit more but not enough to unlock it


Are you sure about the above? You are say a 6V DC source A with 10 times the current capacity of 6V DC source B cannot move the bolt, but the much smaller supply can move the bolt. This makes no sense on the surface of it.

A good AA battery can supply about 6 amps when new for a short period. So what you need here is a 10 AMP 6V DC Supply. A decent electronics supply house can get you one of these. Make sure it is filtered and regulated to produce good DC and no noise.

The little adapters you used may not be filtered or regulated in any way causing what you see.
0
 
LVL 2

Author Comment

by:FocIS
Comment Utility
i know it didnt make sense to me either, the more amps should have moved it more but it was the opposite.  probably bad construction of the adapters

i have no way to measure amps (i have like 4 volt meters, maybe i can but not sure how) all i can say for sure it the dc output was 6.28 - but these are small no-name generic ones from overseas

can you point me in the direction of what to specifically buy?  seems like a 6v 10a is hard to come by (radioshack/ebay/google)
0
 
LVL 47

Expert Comment

by:dbrunton
Comment Utility
Suggestions

Try another 6 Volt 2 Amp power supply in case the first one was faulty.  A good one may have sufficient power to do it and you may not need a 6 Volt 10 Amp one.
0
 
LVL 90

Expert Comment

by:John Hurst
Comment Utility
The pick of 10 amps was just a number. I just went to my recycle box and fished out 4 AA cells. One of them gave me 5 Amps.

I don't think 2 Amps of unregulated DC will do the trick.

Depending on what the store can offer you, a 6A or greater supply should work.
0
 
LVL 2

Author Comment

by:FocIS
Comment Utility
Any harm in going higher amps?  If one random AA gives 5, should i get 20 amps?

I'll head up to the local shack monday and see what they have - unless there's something specific i can find online
0
 
LVL 90

Accepted Solution

by:
John Hurst earned 300 total points
Comment Utility
There is no harm in going higher, because current is drawn, not pushed.

I have a 14V regulated DC supply good for 3 Amps continuous and 4 Amps surge. So something like that in 6V with 4 or 5 Amps continuous, 5 or 6 Amps surge will likely do the trick. More will not hurt.

The common little adapters are not regulated or filtered and have little surge capacity. That is why they do not work in this application.

Batteries are good for surge currents like moving a bolt once. They rest up for the next surge. That is what you want to replicate in a DC power supply.
0
 
LVL 91

Expert Comment

by:nobus
Comment Utility
it can be, if you hook up a large 6v capacitor to it's output, that the 2A adapter does work (with the discharge of the capacitor)
but is John said, you best buy an adapter with a higher rating, like 5-6 A

**ps.  hooking the capacitor is always a good idea for filtering the output
0
 
LVL 2

Author Comment

by:FocIS
Comment Utility
This sounds like the best thing - can you help me find for sale a 6v, 6 or more A, regulated/filtered supply?
0
 
LVL 90

Expert Comment

by:John Hurst
Comment Utility
6 volt supplies are not all that common. 12 Volt is much more common. The 14 volt supply I have here is made by Pyramid, so you can look up that manufacturer to see if they have 6 volt supplies.

Another manufacturer is Acopian and they do have 6 volt supplies: 3, 4, 5 and 6 amp. Look down the list for Mini with screw terminals and look at the product information.

http://www.acopian.com/power-supply-voltages/6-volt-power-supplies.htm

Also, look at your deadbolt specifications. It well may work with 12 Volts. and if so, 12 Volt supplies are much easier to find.
0
 
LVL 2

Author Comment

by:FocIS
Comment Utility
Oh wow I didn't realize we were talking about power supplies that are $200-$400, that might be a little over the top for this project.  

If something like that is required, maybe i'm better off doing something where rechargeable batteries are used, but in a way where they're connected AND charging at the same time? Is that possible?
0
 
LVL 90

Expert Comment

by:John Hurst
Comment Utility
That is why I suggested seeing if your deadbolt will take a 12V input. I got my 12 (14) Volt Pyramid for $35 or $40 and it would do what you want if the deadbolt will accept 12 V.

Failing that, rechargeable batteries are a good option, although you will probably need to recharge weekly.

Check the input voltage on the deadbolt. It may allow a range of 6 -12 volts.
0
 
LVL 2

Author Comment

by:FocIS
Comment Utility
Hmm i'll see what i can find out from the  manufacturer - remember it was only designed for 4 batteries there's not actually a dc jack :)  

it doesn't look too complex of a board, i'll post some pictures tonight

this was something our local big box home improvement store had on the shelf a few years back, but no longer available.  the internal board has some identifying marks, i'll see what i can find for voltage tolerance.
0
 
LVL 90

Expert Comment

by:John Hurst
Comment Utility
After some reflection, you might be better to consider a new, more modern deadbolt that has a better supply arrangement.

My guess is the manufacturer of the existing deadbolt knew about the surge requirement to move the bolt, and elected batteries to keep the sales price low.
0
 
LVL 91

Expert Comment

by:nobus
Comment Utility
another option is building a PS yourself
you need an AC transformer 110 or 220 V primary, and about 4.5 Secundary, capable of delivering on the secondary side your 5 Amps
then connect a rectifier diode (or bridge), and a filter capacitor and you're good to go
here an example; you can leave the chip out, it is only for stabilizing the voltage
ps
0
Threat Intelligence Starter Resources

Integrating threat intelligence can be challenging, and not all companies are ready. These resources can help you build awareness and prepare for defense.

 
LVL 47

Expert Comment

by:dbrunton
Comment Utility
Another possibility is a remote battery.  For example http://www.amazon.com/volt-4-5-Rechargeable-Battery-Electronics/dp/B002QGVW3K
0
 
LVL 44

Expert Comment

by:Darr247
Comment Utility
Did you try rechargeable AA cells?
e.g. Five 1.2 volt NiMH AA cells in series would give you 6 volts nominal at 2 to 2.7 amps...
in a holder like http://www.tme.eu/en/details/bh-351d/batteries-holders/comf/ (~90 cents US)... NiMH cells can typically get 25-30 charges before they need to be reformed with 'break-in' cycle on a charger like the Maha Powerex MH-C9000.
0
 
LVL 32

Assisted Solution

by:_
_ earned 200 total points
Comment Utility
Just as something else to think about:

Rechargeable batteries only put out 1.2v, instead of 1.5v. And while they seem to work as a replacement, that is only 4.8v.
So, you might see if you can get a power supply from an old computer, and use the 5v line.
Free if you have one around. Maybe $10 at a flea market, or "Mom-N-Pop" repair shop.

If you need more you can use the 12v and 5v lines (instead of a ground), to get about 7v.

If the deadbolt will handle 12v straight, you're "gold".


edit:
missed Darr's post about rechargeables being 1.2v
   : /
0
 
LVL 2

Author Comment

by:FocIS
Comment Utility
Great suggestions here guys - after a little research i've found that this is the Kwikset PowerBolt 907 - haven't found electrical tolerances yet but i'm considering just feeding it 12v to see what happens

nobus - your comment sounds amazing but it's way outside my ability as i only actually understand about 30% of that :)

dbrunton - that looks real interesting, a 6v 4.5a rechargeable battery i can hide in the basement... any way to keep it constantly recharging while being able to power the lock at the same time?

coral47 - interesting way to use one of the 30 old computer power supplies... so if i connect the 12v to one lead (+) and the 5v to the other lead (-) the device would receive around 7v?  

i've considered rechargeable batteries, but only as far as if i can keep them constantly recharging... the goal isn't necessarily to reduce the cost of buying batteries, as much as it's having to open the lock and replace them, and getting locked out when they're too drained to open the bolt.
0
 
LVL 90

Expert Comment

by:John Hurst
Comment Utility
I looked up information on the Kwikset. The technical information says not to use rechargeable batteries. That will be because of the lower voltage. Both the 907 model and the 1000 model use 4 AA cells.

However if 4.8 volts is too little, it may well accept more than 6. Worth considering.
0
 
LVL 47

Expert Comment

by:dbrunton
Comment Utility
>>  any way to keep it constantly recharging while being able to power the lock at the same time?

Your 6 Volt 0.2 Amp power supply.  The grunt is done by the battery.  The power supply just keeps it topped up.  And it may not need to be on all the time.
0
 
LVL 32

Expert Comment

by:_
Comment Utility
>> ...so if i connect the 12v to one lead (+) and the 5v to the other lead (-) the device would receive around 7v?

If my memory hasn't gone completely wanky.
I remember seeing that one few years back (for a case mod), where he did that to lower the rpms of a noisy fan.

I think the 12v was positive and the 5v was negative.
Maybe it was the 3.3v.  You might want to check this with a voltmeter, first...   : /

Also, if you have an old AT psu (with the actual AC switch), it might work better. You wouldn't have to "jump" the green/black wires for it to run.
0
 
LVL 44

Expert Comment

by:Darr247
Comment Utility
Actually, they should both be positive (or both negative) for a 7V potential.
If one is positive and the other negative, the result would be 17V.
0
 
LVL 32

Expert Comment

by:_
Comment Utility
>> ...they should both be positive (or both negative)...

Might be. Unfortunately I don't have that mag anymore.
Man's Best Friend almost woke up dead, after tearing up several boxes I had stored my collection in, to make space for the new ones.     : (
0
 
LVL 2

Author Comment

by:FocIS
Comment Utility
alright so i just gave it some options (work, die, or something else)

i found a power supply for an external hard drive (regular molex plug) and gave it the 5V side (1.5A) and it makes the typical 1 second tone meaning "hey i have power and i'm ready"

in this way, the "lock" button throws the bolt strongly (as strong as new batteries) all the way.  the unlock function retracts the bolt halfway, but i suspect it might be because it's below freezing.  hitting the code to unlock again, retracts the bolt the rest of the way

then i said, "more power" and gave it the 12v 1.5A.  The one second tone was significantly higher pitched then instead of stopping it just kept going.  then after a few more seconds the tone stopped in a "winding down" sort of falling-off instead of abrupt.  the lock didnt function at all in this mode

luckily going back to the 5v wire (5.15v dc) returned it to normal

so - assuming it needs a little oil or warmth, i think that's the fix.  weird that 6.2v 2a didnt do it, but 5.15v 1.5a does.

or maybe it's the power adapter too - the 6v was a standard block type... but this 5/12 volt one has it's own rectangular block like a laptop charger would have
0
 
LVL 44

Expert Comment

by:Darr247
Comment Utility
If they're lightweight (like, a couple/few ounces) they're switching power supplies that draw power only when called for by the output; if the 'wall wart' is heavy, it's a transformer that draws the label input wattage all the time, whether any power is being called for by the output or not (with the wasted power shed by emitting heat). Same for the separate 'brick' supplies... the older heavy ones draw the rated input all the time, while the lighter ones draw full power only when the output needs it (otherwise it draws just enough to light the LED that shows mains power is connected).
You can check that with devices like Kill-a-Watt usage meters.
0
 
LVL 2

Author Comment

by:FocIS
Comment Utility
Nice info Darr - this one is light as a feather compared to other ones i've seen, added bonus there

i think i have a working solution, although not fully understood the difference between 6v and 5v, but it works

i had a lot of great comments here, will split points as fairly as i can

thanks to everyone who offered help here
0
 
LVL 32

Expert Comment

by:_
Comment Utility
Nice experimenting.  Thanks for the interesting Q.      : )
0
 
LVL 90

Expert Comment

by:John Hurst
Comment Utility
@FocIS - Thanks and I was happy to help.
0
 
LVL 32

Expert Comment

by:_
Comment Utility
Thank you much.    : )
0

Featured Post

Find Ransomware Secrets With All-Source Analysis

Ransomware has become a major concern for organizations; its prevalence has grown due to past successes achieved by threat actors. While each ransomware variant is different, we’ve seen some common tactics and trends used among the authors of the malware.

Join & Write a Comment

I've been asked to discuss some of the UX activities that I'm using with my team. Here I will share some details about how we approach UX projects.
Great sound, comfort and fit, excellent build quality, versatility, compatibility. These are just some of the many reasons for choosing a headset from Sennheiser.
Notifications on Experts Exchange help you keep track of your activity and updates in one place. Watch this video to learn how to use them on the site to quickly access the content that matters to you.
Articles on a wide range of technology and professional topics are available on Experts Exchange. These resources are written by members, for members, and can be written about any topic you feel passionate about. Learn how to best write an article t…

762 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

12 Experts available now in Live!

Get 1:1 Help Now