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Picture of Build a battery pack using PVC pipes
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Using a 1 1/4 PVC tube, make a D-cell battery pack for 7.2 V at 17,000 millamp hours. This is a nice tubular battery pack.

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Step 1: Bill of Materials

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PVC pipe, 1 1/4" x 60cm in length
1 1/4" PVC pipe caps
1 1/4" test plugs
6 D-cell batteries
wire (~20 gauge)
battery contacts (negative ends I use for both, the spring I find has a better contact) 
urethane sealant  or another epoxy that will stick to pvc + metal + wood.. 
pvc cement 
clamps
solder iron
Drill press
scroll saw or router
2x4 wood block, 1.5"
rubber (1/8")

Step 2: Cut the pvc pipe

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Cut the PVC pipe down to 2x23 cm pieces.  Sand the inside if it has a rough edge. You should have a spare piece, which you'll use later. 

Step 3: Make a hole for the power and ground wires

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-Place the cap on the PVC tube as far as it goes on, on 1 PVC pipe. Mark a spot on the pipe right at the seam where the cap ends. 

-Drill a hole in this using a drill press. The hole should be just bigger than the thickness of your wire so that the wire can come through. 

-You can take the caps off (if you need assistance pulling it off, slide a battery in the tube and bounce it up and down so it lands on the inside of the cap a few times. This should pop the cap off).

Step 4: Wire the tubes in series

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-Place the tubes so that one hole faces up towards the ceiling, and one faces towards the far wall (ie the holes are pointing at 90 degrees from each other). 

-Hold the test plug next to the pvc tube as if it were fully in place. Mark a dot at the seam on the INSIDE of the pipes (ie the spots where they face each other). See the photo for reference. 

-Drill a hole at each dot. 

Step 5: Solder wire to 2 battery connects

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Prepare the battery connects that will go on the caps:
Solder long wire onto two of the battery connect springs. This will be the power and ground wires that extend from your battery. If you like to use different color wire, ie red + black for power and ground, do one red and one black.

Step 6: Glue on the battery connects

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-Sand the whole inside of the pvc caps.

-Bend the four corners of the square mount slightly upwards, attached to the springs from the battery connects. This will help it sit in place in the bottom of the inside of the cap.

-Glue the battery connects in the bottom of the cap by applying epoxy to the inside of the cap and to the back of the battery connect.

-Put the connect down into the bottom of the cap and press firmly. 

-Let it dry. 

Step 7: Put the caps on

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Put the two caps + battery connects that have been prepared onto the PVC pipe. 

-First, feed the wire coming off the battery connects into the holes that you cut at the seam of the cap / pipe. Feed them from inside outwards. 

-For a permanent seal,  sand the outside of the PVC pipe where the cap will touch when put on the pipe. Apply PVC cement onto both surfaces of the inside of the cap and the outside of the pipe.

-Slide the cap on firmly all the way. 

-Let it dry.

Step 8: Wire it up

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-Cut a piece of wire about 6". 

-In the holes that you cut where the test plug sits, thread it from the inside of one tube to the outside, then through the outside of the other tube extending out through the inside. 

-Solder the battery connects onto the end of one wire. 

-Adjust the length so that the connect that you just soldered comes out through the battery tube about half an inch. 

-With the tubes parallel, and the caps flush against each other, The unsoldered wire end coming out the other pipe hole, cut this at about 3 inches from where it comes out of the hole, so it sticks out of the pipe a little bit. 

-Solder on the final battery connect here.

-Now your two pipes are sort of joined as one unit.


Step 9: Prepare the batteries

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If the batteries are snug when you put them in the tubes, you might have trouble just sliding them in and out. If so, wrap a cord around the FIRST battery you will enter the tube. Wrap two cords around it using scotch tape. 

Step 10: Attach a rubber piece to the connects

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-Cut a rubber circle a bit smaller than the pipe's inner diameter. 

-Epoxy this to the battery connect. 

-Let it dry. Once finished, put batteries in the tubes. Put them in series, so that towards the red (positive) wire you insert three batteries with the nub (+) facing down, towards the pvc cap, and the opposite in the other tube. Put in the spring + rubber to touch the batteries. Put the test plugs and test the voltage of the power and ground wires that are protruding. You should see about 7.2 volts. 

NOTE: I used the flat connectors for the battery's positive side, but I found the spring ones work much better. 

Step 11: Cut a piece of wood as a stabilizer for the two torpedo like battery tubes

-On the end edge of the 2x4, Mark the center line that goes through lengthwise. Mark 3/8 inch on either side. 

-Hold the spare PVC piece flush against the edge of the 2x4, so the low point hits the edge of your 3/8" marking and comes into the corner of the wood. Trace this.

-Do the same thing on the bottom half of the edge of the 2x4. 

-Use a scroll saw or a router to cut away the round part you just traced, leaving you with an hourglass shaped piece of wood. 

-When you try to fit this flush against the pipe, if it has air space, try to sand this down with a rounded file.

Step 12: Glue your pipes flush together and caulk the holes

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-Mount your pvc pipes with the wood in place  between them, flush against one another at the cap and the pipes flush against the wood. 

-Apply epoxy sealant to each surface where the pipes are flush, adhering them together. Clamp them in place. 

-Apply caulk to the holes where the wires protrude. 

NOTE: I am using three pipes because my application is as ballast in the bottom of a boat, and I filled one with ballast. 

Let it dry.

Now you have a tubular torpedo 7.2V D-cell battery pack. 
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billbillt2 years ago
great
prini2 years ago
hi got a question have you tryed making a 12v battery pack?
DIVYA GARG2 years ago
nice
klaurson2 years ago
How about using rechargeable cells? Adding a 12V or 16V lighter socket and a USB port could make this into a useful travel pack for gear.
More complicated. K.I.S.S.
really, it's not that much greater on the difficulty scale and it's also more environmentally sound since rechargeable batteries last longer. for those who wish to go green with this project, klaurson's idea is top notch.
Yea. I would much rather use rechargeable batteries for this. Going through all this work just to house throw -way batteries seems a little much, not to mention the epic waste of good PVC pipe, LOL.
Eric Forman2 years ago
If you put this in your luggage I guarantee you'll end up missing your flight :)

If you want this to look less like bomb-like (and waterproofness is not a requirement) I'd suggest drilling large holes through the pipes, staggered at 90 degree angles, to make "windows". That way someone looking at it will see batteries inside.
I think you are thinking WAY beyond this project, which is a simple, water-proof battery pack. Check out her other aquatic posts. I love her water-snake!
Yes...I was thinking way beyond this :)

I need a 12 volt supply for a homemade field portable ham radio and this instructable is a fantastic idea! I'm going to scale this down for 10 AA NiMH batteries but I also want to avoid being molested by the TSA when they find a box full of electronics and pipes in my bags. My usage does not need to be waterproof.
I'm doing a portable ham rig myself. Here's where I'm going:

a. 1 or 2 12V 5AHr rechargeable gel cells (parallel for 2 = 10 AHr)
b. 100W 12VDC->120VAC inverter for power strip holding plugin transformers for various wall warts for peripherals.

c. RaspberryPi Linux box running WSPR and/or another ham interface.
d. Yaesu 817 ND
e. West Mountain radio/computer interface for digi modes.

Hopefully fully, back-packable with apprt. antennas.
My "monitor" is a $20 B/W 5" TV with RCA inputs and audio.
So far so good. See KB3VLW@gmail.com
You should make an 'ible about it

Pfarmkid
Still awaiting parts, but it's coming together. "ibble following completion.
Then just use clear acrylic tube instead of an opaque plastic tube. All the benefits of the original plus one can see inside it.
~Frog~2 years ago
I think the step about wood blocks can be eliminated by adding PVC connectors / as collars towards the other end ... would balance tubes ... imho .. ~Frog~
onrust2 years ago
Test plugs rule!
Denger2 years ago
Thanks for the 'structable and especially the test plug link. I have another application which will use those, and it's nice to see the variety available.
graydog1112 years ago
I am missing something......I can not find anything explaining the plugs on the ends with the V shaped wing nuts. What are they?
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Click the link in the supplies section marked "test plugs."
Thanks mslaynie.
You're welcome! I didn't know either, which is why I clicked. :D
Interplanetary drive propellers. Any noob should see that! :-)
manoj43302 years ago
That is very nice!!
I think we could make smaller battery pack using rechargable cells like ni/cd battery and use them for toys or other things !!
Nyxius2 years ago
Great job making it waterproof, but you did way too much work. Cut your tube to 1 inch longer than your stack then use pipe test plugs to both seal and create terminals. The if you are worried about the minor amount or corrosion due to exposed terminals you can put pipe caps over the plugs. That is a simple way to seal it and it is disassemblable. No messy sealants required and it should work down to about 225 feet (~100 PSI) . It'll probably work even deeper than that if you fill it with mineral oil (+ it won't be buoyant).
Cerebus3002 years ago
For instructable creators, a DIAGRAM is very helpful, especially for electrical designs, but mechanical as well. Safety is important, and there are standards for electrical wiring to help with this, as mentioned above, wiring color is one of these.

Of course if you're the only one using the device, you can do what you want, but when sharing with the public, please be aware of these concerns.

And for a perfect fit of the stabilizer/braces, just wrap sandpaper around the pipe as a sanding block!

BTW, I love doing weird stuff with PVC. I didn't know about the test plugs! Have to remember that one. Nice instructable!
jongervais2 years ago
Everyone be careful if you try this with lithium cells. If they explode you have a homemade shotgun instead. Design in pressure relief.
Just had a lithium ion back explosion last week at my office. Fun fun!
This is not a rechargeable project!
Do not do this with any battery chemistry that vents hydrogen during charging!!!
These are drug store D-cells. Chill. There's no recharge circuit!
No there isn't but that doesn't mean someone else won't think its a good idea. It's a reasonable precaution to tell people. Especially when some people might not know that batteries vent or that PVC shatters into lovely pieces of shrapnel when over-pressured.
Wazzupdoc2 years ago
I like this a lot!. It could go under a larger snake (sub-surface?). I'm working on an underwater system that is a combination bottom data collector with TV camera linked to a top water data radio buoy for remote data collection (slow scan TV TRX?). My prototype is a 4" tubular TV probe. I may switch to 6" PCB to accommodate the 12v gel-cells. Again, nice project and keep up the inspired and good engineering! KB3VLW
buster11042 years ago
Great Idea. The first thing that popped in my head is that they looked like pipe bombs in series. Maybe mark or paint them some how to designate what they are?
Or, just get over the look. This is a simple water-proof battery pack, not an air-travel luggage add-on! Think simple or think less.
noahw2 years ago
Wow, it's amazingly bomb-like.
kretzlord noahw2 years ago
i have to agree, a little too bomb-ish to be of use in public. Even so, it is a very good solution to a common problem (especially if you don't have access to a radio shack). Great job!
noahw kretzlord2 years ago
Just to clarify, my comment of "it's amazingly bomb-like" was just a silly remark. It is in fact a simple battery pack, and she is a wonderful maker with the best of intentions.
dkkim noahw2 years ago
Indeed it is very ingenious!
When I first saw it, I thought "What a great way to repair my old Petzl headlight battery pack!". Then I thought, "Not a great look for folks who need to fly a lot or cross borders or go on government installations..."
So, I think it's a valid point... Not negative about the creator or its cleverness, just a potential limitation.
Yeah, I was actually thinking about using PVC for a 12V AA pack for a time-lapse camera dolly I built for a friend but am glad I didn't. He flew to Florida for a gig with it the week after. Not worth the hassle.

The PVC flashlights I'm trying to get off my drawing board should be a little more self-explanatory...
cengel1 dkkim2 years ago
I'm sure the maker's intent is pure. Nonetheless, if I saw this in public, I would call the police immediately, and they would surely bring in the bomb robot. I work in a government building, and one day something that looks just like this (except metal) was discovered under a bush outside my window. Upon its discovery the building was evacuated and the bomb squad was called in to detonate it. Due to the disruption something like this can cause, it wouldn't surprise me if building something that just LOOKS like a bomb might be illegal.
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