Save the batteries and the landfills

Thread Starter

Eleon430

Joined Apr 6, 2021
2
Every Xmas my wife lights up an Xmas village with about 90 batteries. I want to replace the 30-40 decors battery compartments with a power supply the decors require 2, 3, or 4 batteries. What is best recommendation to stop wasting so many batteries?
 

MaxHeadRoom

Joined Jul 18, 2013
23,338
Are they different voltages, or all the same?
What total current are you looking at?
Have you checked out emergency lighting lead-acid batteries, re-chargeable!

.
 

Tonyr1084

Joined Sep 24, 2015
6,051
Every Xmas my wife lights up an Xmas village with about 90 batteries. I want to replace the 30-40 decors battery compartments with a power supply the decors require 2, 3, or 4 batteries. What is best recommendation to stop wasting so many batteries?
Assuming EVERY device being powered uses four AA batteries - that's over 22 devices. That's a lot of wiring. Are you up to the task? If the bulk of devices run on two AA batteries each - that's 45 devices.

Assuming the double A batteries last the whole season, AA batteries, depending on manufacturer can deliver -
  • AA batteries. A typical alkaline or NiMH battery in the standard “AA” size has about 2000 to 3000 mAh (or 2 to 3 Ah). With a cell voltage of 1.2 V to 1.5V, this corresponds to 2 to 4 Wh per cell.
Assuming each device is lit for 4 hours a night, every night, for three weeks (21 days) an average 2500mAh supply should deliver (2.5Ah ÷ (21 days X 4 hours) = approximately 30mA draw. Assume you have 45 devices; that's 13.5 [edit] 1.35 amps total [end edit]. That's not a small power supply.

While it's applaudable you want to end tossing batteries into the landfill - the power supply is going to be - um - not small. And given that you mentioned three different battery quantities - that's going to be three different power supplies. I'm predicting a whole lot of work. And one mistake can cost the power supply unless you put a fuse in line. And at that - it's not a small fuse either. It all depends on the exact number of devices and the exact voltages each use before we can begin to make a suggestion. Just understand - that's a whole lot of work. Doable. Plug-in type is best. AND different styles of plugs to avoid throwing a 6V supply on a 3V device. Oops. Knowing some of my family members as I do - it's a guarantee that someone would plug the wrong power supply into the device. And if you get individual supplies - that's 23 to 45 supplies you'll need. Where are you going to plug in all those supplies?
 
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MisterBill2

Joined Jan 23, 2018
8,983
The voltages required are 3 volts, 4.5 volts, and six volts. to replace strings of 2,3, or 4 series batteries. So a single 5 volt power supply of adequate capacity can be rigged to power them all. The six volt items will be getting 5 volts, which is close enough for that kind of devices. For the other devices needing lower voltages the simple scheme will be to use series diodes to drop the5 volts to the lower voltages. One series power diode will drop the 5 volts down to about 4.3 volts, close enough for the 3 battery devices, Then an additional 2 more diodes in series will drop that down to a bit less than 3 volts, OK for the 2 battery items. The current rating for the diodes should be about the same as the current rating of the 5 volt supply that you use.
This setup will not be the most efficient one possible, but it will work well and not need much math to make it work.
This arrangement will be mich simpler than the suggestion in post #5, and quite a bit cheaper. You will need a regulated 5 volt supply, and quite probably several fuses, one for each voltage. Just be sure to avoid short circuits and shock hazards and allow adequate cooling ventillation forthe power supply.
 
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Audioguru again

Joined Oct 21, 2019
3,293
I use many Ni-MH and Li-PO rechargeable batteries. I use some alkaline batteries. My city picks up and recycles batteries left in a bag on top of my garbage can.
 

BobTPH

Joined Jun 5, 2013
3,469
Oh come on, admit it. The real reason you want to do this is so you can turn them all on and off with one switch.

Bob
 

Yaakov

Joined Jan 27, 2019
3,316
Every Xmas my wife lights up an Xmas village with about 90 batteries. I want to replace the 30-40 decors battery compartments with a power supply the decors require 2, 3, or 4 batteries. What is best recommendation to stop wasting so many batteries?
Is this outdoors?
 

MisterBill2

Joined Jan 23, 2018
8,983
You need 3 volt, 6 volt and 9 volt power supplies. Then you need to figure out how to connect them to the controllers and that includes whether to bus the power around the house (room) or have clusters.
DC, WHY a nine volt supply??? and why in the world 3 different supplies when the voltage dropping scheme will work so very well. Power diode voltage drops are close enough for this sort of application, and surplus regulated 5 volt supplies are rather cheap, especially if they are used, (RUE, removed from used equipment.) hy work so hard at making a project complicated and expensive???
 

DickCappels

Joined Aug 21, 2008
7,533
Whoops! If these were lead-acid the above numbers would be correct.

But they are probably carbon-zinc or a more modern reaplacement, so the voltages would be 3 volts, 4.5 volts, and 6 volts. Sorry about the mistake.
 

MisterBill2

Joined Jan 23, 2018
8,983
Whoops! If these were lead-acid the above numbers would be correct.

But they are probably carbon-zinc or a more modern reaplacement, so the voltages would be 3 volts, 4.5 volts, and 6 volts. Sorry about the mistake.
If they were Lead/acid battery types, which I have actually seen, they would be rechargable. They would also be rather costly, over $5 for a single "D" size cell. Then came the NiCad batteries, both cheaper and lighter.
And evidently you did not understand using the power diodes to drop the voltage. It is not the most efficient, but it is simple and it works and it is very reliable, if adequate diodes are used.
 

Thread Starter

Eleon430

Joined Apr 6, 2021
2
Excellent responses and you all understood my ask. Btw, one switch on/off would be a nice extra :). Also, i am ready for a lot of wiring with all the decors spread across 8’ x 6’ village. It has taken years to build the scene, what’s a few days of wiring for the wife (clears throat). I will research the power diodes since that sounds very doable. In case you find that 8x6 a bit out of the norm, I attached a pic of last year‘s village.
please add any other suggestions on the wiring if you have them. Good for thinking this through..
thanks
 

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MrChips

Joined Oct 2, 2009
23,849
Make a complete list of every light or string of lights showing the voltage and current required.
If you do not have these numbers then get a DMM and make measurements.
Once we have this information we should be able to suggest a solution. The hope is that there should be one power supply that powers the entire village unless the voltage and power requirements indicate otherwise.
 

Tonyr1084

Joined Sep 24, 2015
6,051
Took a 5V power supply and attempted to limit its voltage to 3.6V using diodes. The device I wanted to power worked for a short while, but soon failed. I haven't done a post-mortem on it.
 
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