SparkFun Forums

[Bearrito]

Hey folks. Been some years since I've even touched a soldering iron so I'm more than a little rusty when it comes to figuring out how to get the bits and pieces together.

With the holidays coming up I've decided to make a friend of mine a hoodie with two gimmicks. Button in pocket one will turn on the heating elements to keep her toasty. Button in pocket two will turn on the electroluminescent wire piping along the zipper and actual hood to make her feel awesome.

Would like to run the whole deal off a lipo battery or two, then have a charging cable snake out of one of the sleeves so she can top off the battery and run it off her laptop.

So, not the most complex of ideas out there, but I'm having trouble getting my head back to the point where I figure this out without getting very confused.

In my head, I'd have a "power pack" of one or two of these. Running from those to a on/off button that controls either function. Have a usb cord in the sleeve so it can be charged while she sits with her laptop or at her desk.

I was hoping one of ya'll could help me pointed in the right direction. I'm thinking I can get the two batteries in series to give her the most time between charges. But I'm confused on if I can get an inverter in the mix for the EL wire without having another little brick to hide in the hoodie.

Basically, is my idea workable or should I just scrap the EL wire and stick with a little toasty garment?

[Mee_n_Mac]

What wattage is needed to makes things toasty ? That will determine your battery requirements. What's your thinking re: heating elements ? The EL wire will draw nothing, relative to the heating elements.

[UNTEngineer]

What Mee n Mac said....but it isnt likely that you can power a heater with a small LiPo, especially if you are trying to get a decent amount of warmth on a cold day. Think bigger: maybe a laptop battery would do the job....unless you split the work on many batteries to make for a less bulky power pack.

[Bearrito]

Sorry, forgot to mention I was just going to heat up strips of carbon fiber "tape" for the heating portion. My understanding was they only need a couple of volts to put out a decent amount of warmth. It isn't so much a heater in the traditional sense, just something to turn on to offset a bit of the chill

[UNTEngineer]

Thankfully, you're not the first person to think of this. Take a look at this build.

http://www.advrider.com/forums/showthre ... 32&page=12

And heres the heating wire they talk about:

http://www.dipmicro.com/store/WIRE-K30BLK

[Mee_n_Mac]

Sorry, forgot to mention I was just going to heat up strips of carbon fiber "tape" for the heating portion. My understanding was they only need a couple of volts to put out a decent amount of warmth. It isn't so much a heater in the traditional sense, just something to turn on to offset a bit of the chill

Links if you have them.

Heat, as we perceive it, is power and electrical power is volts x amps. So to get moderate heat at low voltage means high current. Current levels your batteries may not support, or if they do, not for long. I grok "taking the chill off" so your concept may work but sizing the batts to even a low power element is step #1.

[lyndon]

You can find heating tape easily enough, but it's meant for large power sources, e.g., a motorcycle alternator, not a battery you can carry in your hand. I think the EL hoodie is a cool idea, but for heating, you're probably better off with a Hot Hands packet.

Then again, LiPo batteries do have pretty high energy density.

[Bearrito]

Tape here. Or any other supplier really. I just remember this stuff from a friend who used it to repair his RC planes when they crashed. Course he was slathering it with epoxy.

The batteries are just whatever I can get to work. I'd like to keep it running off something about the size of a mobile. But like I said, I couldn't even begin to guess at the actual power requirements. I just was looking for lipo cells here cause I've bought a few odds and ends here over the years and so far the company has been just dandy to deal with.

Glad I talked to ya'll before I just up and bought all the stuff, seems like the heater idea is gonna have to be shelved unless I can convince her to walk around with a cell the size you'd see on old lanterns.

[UNTEngineer]

Unless shes a student with a backpack, or a biker (or cyclist), theres not much space in a jacket to place a power back with the weight of a brick...

While LiPos are great for a myriad of projects they dont have the power density you need. However, before you give up, go and take a look at super capacitors. The latest product from Fluxmob provides a backup phone charger that fits in the palm of your hand. Maybe that might provide the energy density? Just throwing the idea out there.