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Alternative power source for power-tool enhancement design project? Answered


Hi this is my first post here :-)

I'm a Design student in London currently researching power-tools.

I've made this really crude prototype of a system that looks at enhancing the vibration of a power-drill by vibrating the user as they pull the trigger on the power-drill.

It consists of a 12v 55AH car battery running through a 300watt 12v to 230v inverter which in turn powers a cheap 135watt 230volt orbital sander. It's all mounted to a British Army paratrooper clansman radio pack frame and has a very crude wooden arm with a temp on/off toggle switch mounted inside a vitamin c bottle :-) and tapped with gaffa tape, very much bricolage....

I used what I had to hand and what was cheap, i know it's not safe (yet) but i'd like some opinions on alternative smaller and lighter power sources?

I know I could just use cordless sanders but there expensive and i need multiple units 2-3 and as this is only a small part of what I'm doing so cost is an issue.

I'm considering looking at cheap 12v battery packs from cordless drills but don't fancy using lithium and blowing myself up?

All suggestions and opinions appreciated!

Thanks

James

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frollard
frollard

9 years ago

I'm confused. How does a vibrating backpack adjust the drilling experience?

If the vibrations aren't equal and opposite to any oscillations from the drill, then they are just....MORE...oscillations which would cause...MORE...vibration based injury, not less.

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Jack A Lopez
Jack A Lopez

Answer 9 years ago

I'm pretty sure that this is intended for masochists, and I am guessing the attendant pain and injury are its intended features.

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le_bricoleur
le_bricoleur

Answer 9 years ago

I was going to get a deep cycle battery but to be honest i've had an array of different things running off this battery for over 30minutes without draining and charging it takes 2-5minutes to take to full charge again. It's purpose is more of a prop in a film than an object I need to run for hours. I just wanted to reduce the weight and size really.

I guess it is akin to masochism in a way, although it's not painful at all, the picture is misleading, it's more of a massage than anything and everyone that has had a go laughs when they use it which was my intention.

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Jack A Lopez
Jack A Lopez

Answer 9 years ago

Well, I dunno. Maybe it is good like it is. I mean in simple terms the charge you take out of the battery, in ampere*hours, is the current being drawn multiplied by the time you have it running. If you need to draw 10A for 1/2 an hour, then that is 5A*hour, or about 10% of your battery, and 10% is not really deep. I think a "deep cycle" is more like 50% or more of the battery's rated capacity.

But maybe you already knew this, and I'm not really telling you anything new.

The idea of using a battery pack for a cordless drill is not a bad idea, for the purpose of finding a battery that weights less.  I am guessing the tricky part for doing that would be picking a drill battery with a voltage that is in the acceptable range for your inverter.  I mean the inverter is intended to be used with a 12 V (nominal) lead-acid battery, but it ?might? also work with a drill battery with an open circuit voltage of 14.4V.  Also it will be necessary to find a drill battery beefy to supply the current (some number of amperes) the inverter wants for those loads.

Sorry for the vagueness.  The only thing close to this idea that have tried involved using an 18V lithium ion battery that was intended as an external laptop battery, to power an inverter, to power a 14 W compact fluorescent light bulb.   I put the battery and the inverter in a backpack, and then walked around outside at night, lighting my way with the CFL.  The inverter I was using used to be a cheap Chinese-made UPS (uninterruptable power supply), and I think it had be to that inverter.  I tried others, but they did not like the 18V input voltage, and shut themselves off, or basically refused to run at that voltage.  I am guessing the cheap UPS inverter did not have any over-voltage sensing, and that's why it worked.

Anyway,  I guess what I am saying is that a lighter battery for your thing is likely possible, but I don't have any specific suggestions as to what this lighter battery would be, or the cheapest way to obtain it.

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le_bricoleur
le_bricoleur

Answer 9 years ago

It's not intended to be functional in a legitimate sense. But I like the point your making.

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Jack A Lopez
Jack A Lopez

9 years ago

I like the use of a car battery, because it's heavy, and this certain to add to the agony and discomfort of using such a "tool". 

However I am going to going to humbly suggest using a lead acid battery intended to be deep cycled, rather than a starting battery, because the deep-cycle battery will work better with this kind of load, i.e. a for a moderate load that must be sustained over several hours.  In contrast, starting a car is a very heavy load, but just for a few seconds.

However breaking the battery, so that it becomes a useless lead brick that cannot be recharged, would certainly be aggravating!  So if you think that could add to the overall burden, and unpleasantness,  of this "experience", then I say do it!