Introduction: Battery Eliminator

Do you have an appliance that eats through batteries? Follow this instructable for a simple, quick and dirty trick to power it directly from an outlet! If you want to do something more intense, check out doncrush's Battery Eliminator from a recycled wall wart.

I will focus on replacing a single D battery, used in my baby's bouncy seat, but the basic technique could be applied for multiple battery appliances as well.

Step 1: Materials

Parts:

  1. Selectable DC converting wall adapter
  2. 1" wooden dowel
  3. Wood screws
  4. 1N4001 Diode (optional)
  5. Duct Tape (optional)
  6. Washers (optional)

Tools:

  1. Hand drill
  2. Hand saw
  3. Wire stripper
  4. Voltmeter

I chose a selectable adapter because it was the cheapest with a 1.5V option. If you can find an adapter that provides exactly the voltage you need, don't bother with the selectable one.

The diode is useful if you end up needing to reduce the voltage of your adapter, like I did. If you suspect your appliance may be pretty sensitive to precise voltage, (most battery powered devices are not, since batteries fluctuate in voltage during their lifetime) check out DIY Hacks and How-to's very well done instructable that uses an actual voltage regulator.

Step 2: Prepare Dowel

Cut your dowel about the length of the battery to be replaced. Pre-drill holes in the ends for screws which will mimic the terminals of your battery. It's important to pre-drill with such a short dowel to avoid splitting. Drill a hole or two through the center perpendicular to the dowel which you'll thread the wires through for strain relief.

Step 3: Prepare Adaptor

Chop off the funny barrel style connector at the end of the cord.

At this point it may be a good idea to drill a hole in the battery cover of your appliance and feed the wire through it. You may also just be able to force the cover closed even with the cord sticking out.

Now push the cord through the perpendicular holes on your dowel and strip the two wires generously.

NOTE: You may wish to purchase a switch to go between your adapter and the wall, because these adapters are notorious for eating energy even when the electronics they serve are turned off. A cheap switch like this would do the trick.

Step 4: Connect Leads

Screw two screws in the ends of the dowel, but not all the way. Wrap the stripped wires around the screws, and then tighten the rest of the way. Make sure the wires are tight and can't be pulled off.

If the wires can pull off, you might try using a washer to better trap them.

Step 5: Install and Test

Your dowel can now replace a battery! Install it in the battery slot just as you would a normal battery. If your dowel is too thin you can wrap it in duct tape for a better fit.

You may wish to check the voltage while you turn on your appliance. The power adapter I chose says it can deliver 1.5 V, but it actually was delivering 2.3 V. This isn't too surprising, since crappy adapters have a lot of internal resistance which means their voltage will vary with the current load. In fact, if you try to check the voltage without any load, you may see something crazy high. My adapter delivers 4V with no load on the 1.5V setting. This doesn't necessarily mean you will fry your appliance. As soon as you turn it on the voltage will drop to a reasonable level.

If the voltage is still too high when your appliance is running, you can follow the optional additional step.

Step 6: Reduce Voltage

In this step we add a diode in series with the battery eliminator. In addition to forcing current to travel in only one direction, diodes have a relatively current independent 0.6-1.0 V drop, which is just right for reducing that extra voltage on the power adaptor. If you need a bigger drop, you can put two diodes in series (they're $0.40 each), and if you draw more than one amp, you should put two in parallel to prevent overheating.

Just add another screw on the side of your dowel, connect the diode from the end screw to this new screw, and move the adaptor wire to the new screw.

Don't worry about direction if your adapter has a polarity knob, but otherwise diode should point from the extra screw, where positive voltage must connect, to the plus side of the battery.

Comments

author
charlesd.parker.33 made it! (author)2017-01-05

I also replace batteries in a similar way, using a barrel connector in the battery compartment lid, wired to each side of the terminals in the compartment. This way one power adapter powers many of my devices.

author
cdiaz4 made it! (author)2016-06-19

Attempting to replace the batteries on my Intex quickfill, will this wall adapter work? Also I'm a bit confused since It uses 6 C batts but the label on the item says "4.5v DC 25W".

author
dreens made it! (author)dreens2016-06-19

Hey cdiaz, cool yeah I have that pump too. Unfortunately you can't use this adaptor, you'll need to find one with either a 25W power rating or a 25/4.5=5.6A current rating.

The reason it uses six C batteries for only 4.5V is that for such a large current draw, the voltage of the batteries is significantly decreased by their internal resistance. I've read 0.1ohms for AA batteries. If it is similar for C, then with six of them and five amps, the batteries provide (1.5-0.1*5)*6=6V, not 9V. The batteries only have 1.5 volts at the very beginning of their lifetime, so this may explain the rest of the difference.

author
cdiaz4 made it! (author)cdiaz42016-06-19

Hey dreens. one last question. Will this adapter work for my pump?

author
dreens made it! (author)dreens2016-06-20

When you say "adapter", if you mean the selectable DC converting wall adapter I used, you definitely cannot use it because as you can see in the picture, it has a 0.5A current limit, and you need more than ten times as much. I don't think you'll find something that mounts in a wall adapter but delivers 25W or 5-6A. Your best bet is something like the power supply I linked you to, which will take care to mount safely but will work well otherwise.

If you mean "adapter" as in the general technique of eliminating batteries by replacing them with a wood dowel with screw contacts, yes that can still work.

author
cdiaz4 made it! (author)cdiaz42016-06-21

Sorry, yeah I meant the technique. Thanks

author
cdiaz4 made it! (author)cdiaz42016-06-19

Thanks for the reply. I'll look into the power supply you suggested.

author
dreens made it! (author)dreens2016-06-19

You might try something like this: https://power.sager.com/rs-25-5-2614691.html

Downside is that you'll have to connect a wall plug yourself and find a safe enclosure to mount it inside of, since you don't want the 120V terminals exposed when you plug it in.

author
bambuino made it! (author)2016-06-16

You plugged this into your infant's shaky chair? Really?

author
dreens made it! (author)dreens2016-06-17

Yes, absolutely! And I'm proud to say that it is still working great! In fact, a few days ago we had a power outage, and it was super easy to switch back to battery briefly. He's transitioning away from it now, but for a month or two my son sat in that thing more than half the day.

And no, I'm not worried that 1.5V will somehow set wood on fire, or that the wall wart will magically start passing 120 VAC through, or whatever else the self-proclaimed safety experts around here might cook up hahaha. This thing is safe, trustworthy, reliable, and I built it in ten minutes.

author
goldenskyhook made it! (author)2016-06-07

To the people complaining about complaining. Not everyone has even basic electronic skills, and it's kind of childish to troll somebody merely because you can do something that my grandfather taught me when I was 5. Here's what I see regarding this instructable. It demonstrates a TEMPORARY fix you could use if you don't happen to have a fresh battery laying around. Yes, it could be used more permanently on just about anything that could already use a wall wart, and no, it's not a great solution for audio.

Kudos to the creator here, for making something that does NOT require a BS in Engineering to complete. I, for one, am tired of checking out 'ables that look great, only to find out that you need an $800 3D printer, a laser cutter, or other insanely expensive equipment to complete. To me, that's a FAR cry from "DIY." I own a 3D printer, and I love it, but I don't get a dislocated shoulder from patting myself on the back about it.

We've all gotta start somewhere.

author
CelioS made it! (author)CelioS2016-06-13

Thumbs UP for your comment ! My grandfather was a genius too :-)>

author
SamM6 made it! (author)SamM62016-06-09

spot on! :)

author
HuyV7 made it! (author)HuyV72016-06-08

That's what fablabs are there for. DIY doesn't mean you have to do it at home. You can rent tools, share tools, or even just design a part and have it made professionally. It's still DIY cause you don't buy a complete product.

author
spark master made it! (author)spark master2016-06-08

thank you

author
etanercept made it! (author)etanercept2016-06-07

Thank you for asking for peace here. I just made a question and then made a comment. That's all. :)

author
dreens made it! (author)dreens2016-06-07

I'm totally going to use that line about dislocating the shoulder patting yourself on the back! Thanks :-)

author
rcochran5 made it! (author)2016-06-11

really, you could also just permanently solder in a plug reciever and plug it into the Power Converter whenever the batteries are dead... but most things (not all) have a power converter already.

author
dreens made it! (author)dreens2016-06-11

Yeah, some others have mentioned this idea also. I think that is a really good alternative. Do you know where one could find those sorts of connectors or what they are called? "barrel connectors" maybe?

author
rcochran5 made it! (author)2016-06-11

once the Diode is installed the Positive pole will only be at one end since a Diode cuts current in one direction only. if you want to reduce the voltage or amperage you should use a Resistor. That is why there are Diodes AND Resistors. Resistors cause a V drop... not Diodes. Diodes only cause a V-drop when the current is moving Against it. Not With it. What would be neat is if someone would create an inductive Pad to power old battery operated "Things" without a physical power cord. you would need a Transformer, speaker coil wire... enough for the field plate and the receiver, and a bridge rectifier to turn the Inducted AC field into DC current at the device. probably easy to scrap for a Transformer with 25-50VAC for free... then run it through a winding to generate a magnetic field and place a coil of wire on top and add winding until the voltage you are looking for is achieved, Usually about 6VDC which would be about 12VAC (pre bridge Rectified)? just a guess, but cool wooden battery anyway no doubt.

author
dreens made it! (author)dreens2016-06-11

That would indeed be cool about the charging pad! However, about diodes, you are incorrect. All semiconductor diodes, which are basically the only kind available, only begin conducting when a bias voltage of 0.6V develops. This bias voltage remains across the diode as long as it is allowing current to pass. Even Wikipedia barely mentions this fact, but look up the current-voltage curve in the data sheet of any diode and you'll find the current remains zero until the voltage crosses 0.6 volts. This is an important thing to keep in mind when designing circuits with diodes, and is described extensively in the book I learned circuit design from in college, "the art of electronics" by Horowitz and Hill. When one wishes to drop the voltage by a fixed amount regardless of current, diodes are a much better choice than resistors.

author
mmiles12 made it! (author)2016-06-07

This is far more effort than necessary. You don't have to create a battery shaped device. Simply solder the wires from the adapter to the correct terminals. This also makes the process more practical in devices which hold multiple batteries.

author
p0laris made it! (author)p0laris2016-06-07

But then you couldn't just pull it out and stick batteries back in when you want.

author
mmiles12 made it! (author)mmiles122016-06-07

Soldering is not permanent. The process of placing or removing the terminals, should you need to, takes seconds.

author
etanercept made it! (author)etanercept2016-06-07

But you need a soldering iron... :)

author
JoeG17 made it! (author)JoeG172016-06-08

Anyone heard of miniature croc clips?

author
rcochran5 made it! (author)rcochran52016-06-11

apparently not lol

author
Mark 42 made it! (author)Mark 422016-06-09

We don't have crocs in North America... we have alligators ;-)

author
mmiles12 made it! (author)mmiles122016-06-07

Perhaps we have some new visitors to instructables. The purpose of this website is to inform people how to DIY - in the most efficient manner possible. If it seems preferable to make excuses for every potential snag - such as the purchase of a $10 tool required for the instructable - then perhaps you are not quite cut out for DIY.

It's do it yourself. Not complain about not doing it yourself.

author
etanercept made it! (author)etanercept2016-06-07

Maybe you get me wrong, I meant: But you need a soldering iron each time you want to use batteries. What if you are not in a place to do that?
My comment was in response to mmiles12

author
rundmcarlson made it! (author)rundmcarlson2016-06-07

You only need to solder the wires on once. If you solder a diode in line with the power supply, just unplug the power supply and put a battery in and let the wire stick out. Hell you can even make a disconnect in the middle of the wire if you wanted so you could unplug it, then store the small length of wire inside the battery housing with the battery.

author
etanercept made it! (author)etanercept2016-06-07

Maybe you get me wrong, I meant: But you need a soldering iron each time you want to use batteries. What if you are not in a place to do that?
My comment was in response to mmiles12

author
mmiles12 made it! (author)mmiles122016-06-07

The topic isn't how to power a device in the woods. It's how to power a device without a battery. Every instructable on here requires tools. I'm not sure of the purpose of your question.

author
AlM47 made it! (author)AlM472016-06-07

soldering is somewhat permanent for those of us who don't keep a hot iron on the kitchen counter. Soldering in a little plastic toy can be problematic and it seems probable that soldering onto the battery springs will destroy their temper rendering them springless and not able to hold batteries for the rest of their born days!

author
Istarian made it! (author)Istarian2016-06-07

By that definition, nothing is permanent unless it's utterly irreversible (e.g. burning paper into ashes) What you propose is semi-permanent and requires specialized tools and a degree of care to change. The instructables is about removing the need for a battery when you have an outlet handy and the powered thing doesn't need to move.

author
Mattress67 made it! (author)Mattress672016-06-07

Excellent response!

author
dreens made it! (author)dreens2016-06-07

Soldering is not a good solution for many reasons. Its not strain resistant, so if someone trips over the cord, the solder can come undone. Also, the battery terminals are not tin coated, and their large area will make it very hard for solder to wet. Have you ever soldered wire directly to a battery terminal? Finally, as has been reiterated, not everyone has a soldering iron.

author
lmnohos made it! (author)lmnohos2016-06-07

remember the hole u said to drill thru the battery cover? if u feed the wires thru that, allowing ample wire- tie a knot in the wire so it can't be jerked out.

author
Joenavy85 made it! (author)2016-06-11

In regards to the "irregular" voltage mentioned in Step 5, this can easily be avoided by using a switching power supply (if you have one laying around at least) which is self regulated to only put out the rated voltage and current. A non-switching power supply will almost always put out a voltage higher than rated during normal operation. You can do similar mods if your equipment has it's own battery pack (which typically just holds a number of batteries) by pulling the cells out of the battery pack and using the empty shell and contacts. I've done this several times with old battery packs for my HAM Radios. Great idea and thanks for sharing.

author
AlexAndAmigos made it! (author)2016-06-11

good job and idea

author
gregdavid1 made it! (author)2016-06-08

Rather than build a custom "faux battery" end for my external DC power supplies, I find it much easier to just add coaxial power jacks to the battery powered devices I want to power. That way I can use an UNALTERED UL Labs Approved ac to dc power supply (especially when being used around a child!). I can be a bit more work, esp to do it so the new jack looks like a factory option on the appliance, but IMO its really worth it when done right.


FYI: I hate to cut factory wires on, or the factory plug off of, anything (unless the insulation is damaged & in much need of repair, of course). No matter how good I am at shrink tubing connections (or, god forbid, nasty electrical tape), my home shop efforts just ain't the same. Plus, by not altering the power supply leads, its kept from being dedicated to just one very limited use, esp. when using such a nice variable one (as used here)!


Also, instead of buying a rather pricey variable output supply (as used here), or any new supply at all, I save all my old ones from electronics gone past for future freegan-ware harvest. Fact is, I can usually find an appropriate one to use, esp, when they have RadioShack selecta-plug ends (specially made such that I can alter jack size, type & polarity on the fly). The extra selecta plug ends are also a good thing to save. Sadly, most just install the one they need at the time then toss the rest. Silly fools!.

As an in between solution, one could make a faux battery adapter that is faux battery on one end and a female coaxial power jack on the other. Then you would get the best of both worlds.

author
Scott Glorioso made it! (author)2016-06-08

Great idea! If you don't want complete DIY you can get them from these guys:

BatteryEliminatorStore.com

http://www.batteryeliminatorstore.com/index.php?id...

Looks like they have all different cell sizes too! AAA, AA,C, D, 9V etc.

author
texhoma creative design made it! (author)2016-06-08

ok...time to split instructables posting into DIYOTC or DIYPS.....thats Do it yourself on the cheap.......or Do it yourself Preppy Style....kinda like the guys who have stickers on their cars proclaiming it wasn't sponsored by Mummy and Daddy.....No offense to the guys who make their wife drive a junker and have laser cutters and 3D printers gathering dust while they talk about how much money they are going to make with it.....rock thrown....waiting for the first hound to yelp.

author
zappenfusen made it! (author)2016-06-08

Kudo's to goldenskyhook!

author
zappenfusen made it! (author)2016-06-08

Great cure for all the battery eating toys they're selling now. I've been using a Lithium cell rigged in 3/4" pvc to run all kinds of stuff with cheap boards ordered from China. I believe I got the basic idea somewhere on the site. If you've the patience you can order durn near anything from China with free shipping and only occasional bad, crushed, or worthless stuff. Never order more than you can afford to lose though and you'll never be disappointed. Only been shafted once! Great work.

zapp

author
CorySink made it! (author)2016-06-08

Man, my biggest fear about ever posting my own instructible on here is being torn to shreds in the comments. This is a cool idea. Thank you.

author
etanercept made it! (author)etanercept2016-06-08

It happens the same to me, but we should not feel that way. I think the comments section is for that, to comment. Not everyone has the time, the dedication and the will to take the nice pictures, type the instructions, even think the right order of the steps. Try and make your own instructable, this place is for that. After all, sharing knowledge or tips and tricks is one of the best ways to show our human-kindness and a way to transcend. I truly invite you to make your own. Soon I will make mine.

author
spark master made it! (author)2016-06-08

this looks nifty if you need it and do not have skills to put in a jack system which is easier to use and does not require you to remove the back door/battery compartment. If the battery compartment is water tight then if you have skills you mount the jack system inside the compartment. So when not in use it still is water tight.

Since this is external, if the unit calls for AA or worse AAA batts you can use D cells and it will go a lot lot longer. I have discussed this ad nauseam with a real true blue electrical engineer who builds prototypes and designs for a living. Why anybody uses a AAA bat for anything is crazy. AA is minimum. I made several lights using spent screw in CF lamps and Fuji film circuits. Put one on a D cell and it is fantastic. The unit does not ever draw too much and burn up, and, in a black out after Sandy I used them as marker lights. I mounted them in Peanut butter jars. They worked well and safer then candles with kids around.

This is not a bad project at all. Nice simple and as is solder free!!!! You can buy copper/brass screws and washers ,(or copper clad), to make the terminal nubies on the dowel!

keeps them sparks a flying!

author
Cayotica made it! (author)2016-06-07

the obvious error is "DC" only travels in one direction anyway, but to be fair he does say the diode is optional. The only reliable way to reduce current is to use a resistor.

author
dreens made it! (author)dreens2016-06-07

Actually diodes are great for reducing voltage! It sounds like you are aware that diodes only allow current one way, but what you are missing is that diodes also have a voltage "drop" of about 0.6 V, meaning that when current is flowing through them in the correct direction, the voltage after the diode is less than the voltage before by this value. If you don't believe me, try it out!

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Bio: Dave Reens here. Supposedly I have degrees in math, engineering, and physics from MIT, but really I just like tinkering. Special thanks to my wife ... More »
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