Introduction: AA to D Cell Adapter

Picture of AA to D Cell Adapter

An easy-to-build adapter that allows you to use AA batteries (especially rechargeables!) in place of D cell batteries in many devices.

Step 1: Cut a Piece of Dowel, Drill It Out Most of the Way

Picture of Cut a Piece of Dowel, Drill It Out Most of the Way

Drilled out a piece of 1 1/4 inch dowell to about 1/3 of an inch from the bottom, to make the dowel + AA battery the same heigh as the D cell. 1/2 inch drill bit is just a bit small. I think a 5/8's would work best with a drill press. Without a press, a 9/16's would probably be best.

Step 2: Pound Tee Nut on Bottom, Install Screw.

Picture of Pound Tee Nut on Bottom, Install Screw.

The "inspired" part. Drill about a 1/4 inch hole through the bottom. Pound the Tee Nut in place. Screw the short round head slotted machine screw in from the inside and adjust it to make the AA height 'just right'.

Step 3: Use Them!

Picture of Use Them!

Here's two of the adapters in our Roomba's "virtual wall" that requires two D batteries. We can now use AA rechargeable batteries and save $$$.

A drill press and a little sandpaper and these would have turned out much more professional looking. But they are functional as is, if a bit raw. You can make 8 of these for less than $7, no shipping.

Although such battery adapters are available on the internet, I was not able to find any locally.

Comments

hmowery (author)2009-11-06

There is a little more involved than just the voltage and current capacity of the battery, you also need to look at the voltage vs time curve of the battery. As it turns out, an alkaline battery does start off at 1.5 V as opposed to the 1.25 of the NiMh battery, giving a brighter light however after a fairly short run time the voltage drops quickly and continues on a steady decline over the life of the battery. The result is a brighter light for the first few minutes followed by a steadly decreasing light.  On the other hand, a NiMh starts at 1.25 V but holds almost that voltage throughout it's charge cylce until the end where it drops off quickly. So instead of the bright start and slow decline of the alkaline battery the NiMh starts off a little dimmer but stay the same brightness over a longer period. Each has their advantages and disadvantages. The big disadvantage of the NiMh in lighting is it tends to drop off quickly giving you no warning you are about to be in the dark but at the same time keeps you constantly lit over a longer period. 

itsmescotty (author)2009-09-06

17 moths late.
Battery background: Just because it's big doesn't mean it's more powerful. Check the side of the battery for x.x volts and xxxxx mAH.
Rechargeable cells are typically 1.2 volts where alkaline batteries are 1.5. putting a 1.2 v battery in circuit lowers the voltage and raises the current which uses up the battery faster and runs the motor at a lower speed or less light from a bulb. Putting a larger battery (mAh capacity) into a circuit provides more current and will allow a current dependent motor to run at a higher speed.
So: rechargeables replacing alkaline in the same device = lower speed, less light. Inversly, alkalines replacing rechargeables = run faster, more light. Mixing rechargeables and alkaline degrades performance.aqnd discharges the alkalines.

drummonkey92 (author)2008-04-03

i bought a set of these in a pound store a while ago, they're plastic n the set goes from AAA to AA and AA to C etc... this means you can also use a AAA for a D. one thing to remember though is that these batteries wont last very long (the manufacturers suggest larger batteries for a reason) all in all, a great instructable!!

acctually companies that sell in places like target and wallmart just stuff cells equal to AA's in there rechargeable batteries thats why all energizer AA, C, and D cells are all 2500mAh maybe some one should cut a rechargeable energizer D cell open and see

Vater Araignee (author)2008-04-08

I am no expert but...
When I was a kid we had these electrical cars called stomper trucks, they ran on AA . One day I had this great idea "I'll wire a C onto it and it will run longer"
small 1.5v replaced by bigger 1.5v = longer run time, right?
It did run a bit longer but it also ran faster, so I have to ask doesn't this adapter have the potential to under power a device?

dermbrian (author)Vater Araignee2008-04-09

I'm guessing the answer could be yes, at least in a device that needs high current such a toy motor. There's a reason why they always had us building electromagnets with 20 penny nails and the biggest batteries around. But if you have a device that works with a AA in place of a D, and you don't mind replacing the battery a lot more often, this works. Since I have a lot of rechargeable NiMH AA batteries, this makes powering such items a LOT cheaper going forward.

Vater Araignee (author)dermbrian2008-04-10

*breaks out a dowel and starts drilling*

Derin (author)Vater Araignee2008-06-20

you broke it off my chair rite *bang*

ow

Scott_Tx (author)2008-04-04

A good way to use AA rechargables too. With a drill press you might be able to make a 2xAA or 3xAA to D converter also. Making the tops connect would be the tricky part.

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