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Author Topic: A compact battery charger for motion detectors  (Read 12655 times)

BoyntonStu

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A compact battery charger for motion detectors
« on: August 06, 2010, 06:49:07 AM »

This plug in charger for 3.6 Volt Li ion batteries has no cord and can serve as a base mount for a motion detector like the MS16a.

http://cgi.ebay.com/Universal-Travel-Cell-Phone-PDA-Camera-Battery-Charger-/180533341014?pt=PDA_Accessories

Instead of a Wally Mart charger with a cord, this would be an all in one compact charger mount.

What do you think?
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Brian H

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Re: A compact battery charger for motion detectors
« Reply #1 on: August 06, 2010, 06:58:39 AM »

Mounting a motion sensor on the face of the charger. Could make its RF sending range very short. As the motion sensors antenna is on the PCB.

Also some of those universal charges have been known to kill X10 communications with noise.
http://jvde.us/x10/x10_cellet_noise.htm
http://jvde.us/x10_troubleshooting.htm
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BoyntonStu

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Re: A compact battery charger for motion detectors
« Reply #2 on: August 06, 2010, 08:19:59 AM »

Mounting a motion sensor on the face of the charger. Could make its RF sending range very short. As the motion sensors antenna is on the PCB.

Also some of those universal charges have been known to kill X10 communications with noise.
http://jvde.us/x10/x10_cellet_noise.htm
http://jvde.us/x10_troubleshooting.htm

Good find, thanks.

Brian,

You are a very good Devil's advocate and you make me think, this is great!

A try it and see approach, with and without an 18" passive reflector would be a cheap first step.

Assume that it fails due to noise, etc.

OK  We want 24/7 performance.

We do not want to reset our MS16a' every few months.

One possible solution.

Use 4 rechargeable AAA batteries, 2 in the sensor and 2 outside in a battery holder wired in parallel.

http://cgi.ebay.com/Battery-case-box-holder-2-x-AAA-size-cells-3V-1006-/280532205420?pt=LH_DefaultDomain_0

The AAA battery charger is located elsewhere.

On even months replace the outside batteries, odd months, inside batteries.  (remove battery cover screw)

Power is always on.
« Last Edit: August 06, 2010, 08:28:35 AM by BoyntonStu »
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nybuck

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Re: A compact battery charger for motion detectors
« Reply #3 on: August 06, 2010, 10:57:08 AM »

One possible solution.

Use 4 rechargeable AAA batteries, 2 in the sensor and 2 outside in a battery holder wired in parallel.


Wouldn't that make the batteries charge each other - Like the old expression, "water seeks its own level" - In other words, the 2 batteries inside are down to 2 volts, the ones outside are a fresh 2.4 volts - The electricity flows and makes the 2 pairs equal, or 2.2 volts all around.  Then, when the voltage drops below the "threshhold", the motion sensor loses the codes  B:(

I think the batteries, if mounted in parallel, would act like a charger for each other unless you had the proper diodes to block the current from the other pair.  Like a diode on each positive leg (1 from each pair) so that the current didn't flow into the other pair.  That might work.   ;D
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BoyntonStu

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Re: A compact battery charger for motion detectors
« Reply #4 on: August 06, 2010, 11:32:00 AM »

One possible solution.

Use 4 rechargeable AAA batteries, 2 in the sensor and 2 outside in a battery holder wired in parallel.


Wouldn't that make the batteries charge each other - Like the old expression, "water seeks its own level" - In other words, the 2 batteries inside are down to 2 volts, the ones outside are a fresh 2.4 volts - The electricity flows and makes the 2 pairs equal, or 2.2 volts all around.  Then, when the voltage drops below the "threshhold", the motion sensor loses the codes  B:(

I think the batteries, if mounted in parallel, would act like a charger for each other unless you had the proper diodes to block the current from the other pair.  Like a diode on each positive leg (1 from each pair) so that the current didn't flow into the other pair.  That might work.   ;D

Not quite, if you have one set of batteries drawn down to 2V instead of 3V, they would do as you indicate.

Do AAA batteries last only 1 month?  No, they are still fairly up there.

Assume 2.9 V.

Adding fresh 3.0 V batteries would make the combination 2.95V which is perfect!

If that is not perfect enough and you really want to go crazy

Keep 4 AAA batteries charged for each MS16a.

Change 2 and then change the other 2 that were in parallel.

No loss in power. 

And finally:  Bring a 3 Volt source with you with alligator clips.

Clip on the 3 Volts, remove and replace the batteries.

Remove clips.

Simple, tiny, cheap, and cosmetically exactly as original!

No loss in power.


« Last Edit: August 06, 2010, 01:17:42 PM by BoyntonStu »
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dave w

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Re: A compact battery charger for motion detectors
« Reply #5 on: August 06, 2010, 02:58:44 PM »

Not quite, if you have one set of batteries drawn down to 2V instead of 3V, they would do as you indicate.

Not sure I understand your answer, but if wired in parallel, both sets of batteries will have the same terminal voltage. They will be drawn down togeather. Running two sets will just last twice as long as one set.

So you would want to change both sets at the same time, and changing only two batteries at a time will prevent MS16 memory loss.

Earlier I committed to wiring a one farad cap across MS batteries to see if one could change batteries with out losing programming. I just oredeed parts from All Electronics and forgot to get a cap.    :'

Sigh....brain juice all dried up.
« Last Edit: August 06, 2010, 08:54:56 PM by dave w »
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Brian H

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Re: A compact battery charger for motion detectors
« Reply #6 on: August 06, 2010, 03:29:25 PM »

dave w. Thank you for confirming I am not the only one with drying brain juice.  ???

I would also think that all the batteries in parallel would try and equalize their terminal voltage.

Thread on batteries and motion sensors.
http://forums.x10.com/index.php?PHPSESSID=2m6argm59a4mtk4f7cp89lbdu1&topic=19670.0
« Last Edit: August 06, 2010, 03:40:31 PM by Brian H »
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nybuck

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Re: A compact battery charger for motion detectors
« Reply #7 on: August 06, 2010, 06:52:27 PM »

OK, so I got a few of you to agree....

And I thought that NiCad's were 1.2v, not 1.5 volts...

Any takers?
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BoyntonStu

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Re: A compact battery charger for motion detectors
« Reply #8 on: August 06, 2010, 07:24:31 PM »

OK, so I got a few of you to agree....

And I thought that NiCad's were 1.2v, not 1.5 volts...

Any takers?


The question is:

How does a MS16a detector operate on 2.4 volts compared to 3.0 volts?

Anyone know?
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nybuck

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Re: A compact battery charger for motion detectors
« Reply #9 on: August 06, 2010, 07:39:16 PM »

What about using an old cell phone Lithium Ion battery?

 - Those things last for ever.
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BoyntonStu

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Re: A compact battery charger for motion detectors
« Reply #10 on: August 06, 2010, 08:45:49 PM »

What about using an old cell phone Lithium Ion battery?

 - Those things last for ever.

Fresh cell phone batts are OK, but D cells would last even longer.

However, keeping the shape original, and changing batteries every few months or so without memory loss is simple enough.
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