How to construct a battery pack?
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taoster

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Anyone made a portable battery pack that they are happy with and would like to share what how/what they did?

my main problem are:

1. casing.. the ones for the job all need screws to close and open. i want to fit 3 9V battery.

2. how to connect the battery pack to the amp
my porta corda has a power socket... the battery pack is wired or has a male power plug sticking out. ideally it can be hidden when not in use..

3. on/off switch?
 
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JMT

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1) Have you tried an Altoids tin? Not sure if it will fit 3 x 9v though.

2) You would have to run a wire from the pack to the Porta, I have not seen any plugs that you can attached directly to the pack enclosure.

3) Well, you can just put a SPST switch on one of the leads.
 
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tangent

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You can fit 3x9V into an Altoids type mint tin. They rattle around a bit, so what I do is add a metal 9V battery clip from Radio Shack to the side of the box, which holds one battery against the others so they all stay put.

The main problem is setting up the cabling so that you don't overstrain them as you change batteries. I would recommend using Radio Shack's heavy duty 9V battery straps, cutting the leads precisely, fastening it all together with solder and heatshrink, and covering the main cable out of the box with nylon flex tubing. You need the flex tubing because during the battery change, you need to move the cable back and forth through the hole in the case, so it needs the armoring. Flex tubing is very tough stuff.

The result is quite serviceable and reasonably durable. I've built a few of these.

A useful variation you might consider is one for 2x9V. In that variant, I put battery clips on both short sides of the case, then make the cabling into a T shape which comes out the front edge. This version is more secure, and the cabling will probably last longer.
 
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taoster

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thanks tangent, thanks JMT

the altoid mint box looks to be a good fit and with the ideal flip box, thanks for the heads-up.

ill need to experiment with it a little more and think how to cord it for my needs.. but that's a good start. :)


mint anyone?
 
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taoster

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Casing, Socket and 3-step switch so far.

Ive decided to give the altoid mint tin a try for my battery pack. Ideally i would of liked it a little wider. There's 3 batteries inside and its VERY cramped with the 9V battery caps + socket + switch. I was initially contemplating using two 9V battery holders but after testing out the Porta Corda with 2 vs 3 batteries i thought the more excessive 3 battery is alot more fun. thus opting for the 3 battery with battery caps.

Ive added a power socket and a 3-step switch to the battery pack. Power socket because my porta corda uses it too and the cord is thus replaceable and can be lengthened or shortened. The 3-step switch hasthe off, 2 9V in series and 3 9V in series positions, quite the luxury.


Finally, I dont know how you guys cut a straight line into the tin but i had major, MAJOR difficulties. by the time a hole was made available for the sockets, it looked as if the tin has been through a few wars and been sat on by a large elephant. the only way to hide it all was the black tape you see in the picture. you DIY guys do great works.. its only when one try will one realise how difficult it is. hats off to all you elite builders.

tangent,
one more question.. how do i go about heatshrinking the terminals.. is there something i can buy? what do i use to shrink it? fan? an old soldering iron?
 
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tangent

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Quote:

I dont know how you guys cut a straight line into the tin


You don't. You cut a crooked-as-hell gash into the tin, then file or Dremel it straight.

Quote:

how do i go about heatshrinking the terminals


You can get the shrink tubing lots of places. There are many different sizes and types available, ranging from cheap PVC stuff to nice polyolefin tubing with heat-activated adhesive on the inner surface. The latter is great for cabling work, since it will cling to nylon braid, but plain PVC will tend to slide a bit.

The right tool for shrinking the tubing is a heat gun, but if you're careful you can use a cigarette lighter. You just have to be careful to walk the fine line between not-hot-enough-to-shrink-tubing and setting-tubing-on-fire.
 
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Quote:

The right tool for shrinking the tubing is a heat gun,...


You don't need to get the expensive dedicated heatshrink heat gun. I use a cheapo($20) paint stipping heat gun by Black and Decker. I haven't tried it, but maybe a hair dryer might work, as well.
 
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Quote:

Originally posted by puppyslugg
I haven't tried it, but maybe a hair dryer might work, as well.


It works perfectly, just make sure you have all the tubing in place because the heat isn't very directed.
 
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taoster

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thanks! will give it a go.
 
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Quote:

Originally posted by taoster

Finally, I dont know how you guys cut a straight line into the tin but i had major, MAJOR difficulties. by the time a hole was made available for the sockets, it looked as if the tin has been through a few wars and been sat on by a large elephant. the only way to hide it all was the black tape you see in the picture. you DIY guys do great works.. its only when one try will one realise how difficult it is. hats off to all you elite builders.


You can try using a dremel to do the job. If that's not possible, clamp the metal surface with a piece of wood as backing. Then drill a hole through (the wood will prevent the metal from denting or buckling).
Slide a jewellers saw blade through and saw your way through.
OR:
Repeat the drilling process and use cutter pliers to cut the small pieces of metal.

File to finish.
 
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taoster

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well, its all done. thanks for the tip with the heatshrink. The hair dryer worked great and the porta corda running off the portable battery pack is sounding better than ever..

until the next project(meta42!), signing out, thank you all for the ideas and help. much grados(sic).
 
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