"Homemade" Emergency Battery Adaptors/spacers - or What to Do With a Battery That Won't Fit?




About: So what ideas would you like to try?

The household need for several types & sizes of batteries on short notice drove me during frequent storms and power outages here in Texas to finally find materials in and around the house to convert ANY available batteries to existing equipment such as flashlights , Radios and other equipment.

Perhaps every boat, car and camper needs a set of retail adapters for emergencies. Commercial adaptors look like regular batteries but heavy plastic and hard to service.

Disposable alkaline batteries, lithiums and recharables like Nickle Metal Hydride or Lithium Polymer can be obtained most anywhere now...In widely varying sizes and all sizes between!

Exotic chargers, PCB temp control and voltage controlled chargers are not addressed here...

Please be careful, recharge OUTDOORS on a hard fireproof surface and clear from all combustables. Cover or contain especially LiPO cells. Use over temp and voltage/current monitored re-chargers for THAT cell type and pack size with voltage and current + temprature regulation.

Ok on to the various battery sizes & dimisions!


Step 1: Battery Sizes Charts (length & Widths for Fitting Adaptors)

"Table of modern battery sizes" (c) GFDL by Wikipedia editors, http://en.wikipedia.org/wiki/Battery_sizes#Table_of_modern_battery_sizes Retrieved March 16, 2008,

Use spacers or adapters and retail converters...these should be within .5mm of actual sizes for snug fit.

Use springs, spacers or magnets for slight adjustments 1-5mm.


Step 2: Now We Know Lenghts...how to Make 'Easy' Diameter Changes

Diameter modifications are easy, tape cells together then wrap cheap adhesive foam sheets (.49c) from Hobby or Crafts store around smaller batteries till diameter in chart is reached.

See 4x 'C' cells for a 3x D batteries pack below..

3xAA for D cells can be made from household materials.

hum...4xC a little long for the light below...

NOW onto more mods for lengths...

Step 3: Exact Size Is Everything ! Mods for Length and "slugs/springs"


1) Layout the original old "dead" cells you have at home

2)Adjust wrapped (width modded) replacement cells for required appliance voltage and lengths. Use Tape or re-size with household paper/foam etc.

NOTE:Alkaline cells are 1.5V and NiMH rechargables 1.2v ea. avg.

3)Please be aware Lithium cells are 3v and some LiPo packs are 3.7v...adjust accordingly! if using 1.5v alkalines.

4)Modify legths from chart. Measure and use nuts, springs or even remove original springs or spacers from flashlight/radio bases & use higher voltages for brighter (rated) bulbs. Most devices tolerate slightly higher voltages as battery packs voltage rated are not "under load" so internal resistance will limit voltages.

NOTE: Some battery sizes are EXACT matches for lengths:
Use 2x 1/2D for full D cell
4xC for 3xD cells....etc...
3xAA or 4xAA packs for multi D cell (parallel)
Bulbs are rated for number of CELLS and not voltage so note the recommended ratings

TIP: Specialized Series and Parallel adapters can get voltages above 12-15v for devices originally sized for 3-4 "D" cells by using multiple 1.2v NiMH or high power 3.7v LiPO battery chemistry as direct replacements for AA/C & D cells.

5) Keep sizes on hand or in car/boat. Specialized adaptors for Lantern sized, D, C and CR123 cells can often be made from cheaper but smaller AA cells!

Tip: Pry open 9v cells and find 6-9 AAA or 'button' dry cells!
These vary by maker but are useful in a pinch for watches, toys or other devices when only a 9v is avail but require AA/AAA or coin type batteries!

Step 4: Summary: DIY Spacers & Slugs (adjustable Battery Spacers From Junk in a Pinch!)

Long term you can buy Commercial fixed sized adapters that are avail, AA for C or AA for D cells. My easier fix is to wrap in foam and used spacers from 'around' the house!

Old Button cells(dead), older smaller cells N sized or L sized, hardware like a 5/16 Bolts and hex nuts can be "filled" with solder.

Plastic 'tubes' or teflon tape will insulate from walls or other cells for width.

Springs and adjustments to original devices can be used to accomidate most batteries ...see below...


Step 5: 9v Specials...

9v cells can use taped or custom AA 'packs' in 9v configs just "plugged" into a 9v connector from radio shack.

Or pry off the top from a used 9v, use the AAA cells inside and the collector to wire to a 9v device, use the AA or AAA cells to make a new "pack" for 3, 6 or 9v cell combos.

Step 6: Finish

Stick your new spacers, slugs, plugs or adaptors into your toolbox, car or boat...so they are there when you NEED them...

in a pinch...use the old AA or AAA cels EVERYWHERE! just tape, sizes and set lengths & widths from the charts!




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    18 Discussions


    10 years ago on Step 6

    There are 3 things needed to fit a beterry if there is enough space: 1. aluminium foil 2. some kind of paper 3. tape


    11 years ago on Introduction

    I have found these sold at Wally world and big lots. I have 3 of them in a 3 D cell mag-lite with an led bulb. The flash light is really light. Also if any one has not noticed when you buy a NiMH D cell it is just a 2500mah AA cell in a D package.


    11 years ago on Introduction

    I've actually hacked this at home putting C-cells in a D-cell flashlight by using the bottoms of empty 35mm film containers. Put a hole in the bottom of each container and wrap a bit of thin cardboard outside for a nice jiggle-free fit.


    11 years ago on Introduction

    yeah, I build custom spacers. AA to C and D size converters in serial 5v to 12v and parallel in 4.5 to 6v for use in Mag flashlights converted from Icandecent to LED or Hitwire MR16 and Welsh-Allen bulbs... see pics E

    C:\Documents and Settings\gillisgi\My Documents\My Pictures\IMG_0028.JPGC:\Documents and Settings\gillisgi\My Documents\My Pictures\IMG_0017.JPG
    2 replies

    I think you should reword the title of your instructable to better describe what you just said above. That makes more sense to me. I think what camp is trying to say is that your instructions don't have very much follow-through. It takes a lot of detective work to figure out what it is you are trying to convey. This is a cool concept though! Show those flashlight companies you'll use whatever batteries you want!

    Mr. Chicken

    11 years ago on Introduction

    I have to agree with camp6ell and hananiel, this is rather poorly put together and chaotic. While there is a good concept behind this, it doesn't flow as well as it could. Perhaps a step by step for each size/conversion. Also, I use rechargeable batteries and always have extras that are charged and ready to go. Much easier I think.


    11 years ago on Introduction

    this is a good concept and subject for instructible, but it just doesn't seem very clear/organized to me... sorry, you probably don't find this comment "constructive," but it kind of seems all over the place/it's not clear what you're doing in each step. it would be easier to understand if each of your steps dealt with how to adapt one size of battery to another, instead of whatever it is you did. sorry.


    11 years ago on Introduction

    yeah, so true. That's why we use LiIon 3.7v with 'balanced' rechargers and temp control monitors. For the 1.2-1.5v cells I never use the alkaline as pictured but use NiMH and again use a quality recharger. Most people would never recognize the 14500 or the button top LiIon & NiMH generic industry cells (attached) so I 'swapped' some for panasonic, walgreens and rayovac batteries from my old "dead" drawer of lonely batteries! lol Ed

    C:\Documents and Settings\gillisgi\My Documents\My Pictures\Adobe\Digital Camera Photos\2007-07-03-1243-16\HPIM0130.JPG

    11 years ago on Introduction

    Instead of the metal spring, consider the plastic coil binding springs. You can usually get a few from Kinko's just for asking, if you're in there on other business. They're not conductive, and they weigh practically nothing, but the larger size looks like it should upsize AAs to Cs pretty easily.

    1 reply

    Reply 11 years ago on Introduction

    The coiled plastic thingy's on the binders and presentation folders etc...? i guess they do have lots of sizes to accomidate more pages...hum...I got some at work. I'll go try. E