My name is Helena Parewyck and I am working on developing a USB operated/rechargeable battery heated saddle pad for riders to use on their horse.
I have bought wire that can be used for heating and currently am trying to find ways to attach it to my foam pad saddle (1inch thick), best ways to heat it so it is warm enough (not sure a phone battery would give enough warmth).
Also I want to learn how to solder and how to get this working.
Any suggestions? Or willing to help me out on this project?
hi, Helena
if you are looking for help with soldering up your physical prototype, come on down on Tuesday open night from 7 to 10 PM. the soldering station will be open for you to use. we usually have a few members around on tuesday night that can give you some pointers to get you started soldering and well as design considerations
You’re definitely going to want to look at power supply here. I think you should base around the newly popular heated jackets that Milwaukee makes. You’re task is even a bit harder because a jacket is by design made to insulate and keep even a small amount of heat inside. You have the advantage that a horse can carry more weight than a human. But do expect to have you mount a large battery or two to make it work. The heated jackets use tool batteries to run them.
Heating in general is a big power draw, but is very easy to calculate. Do you have any details on the wire you’ve chosen? You should be able to measure out how much you need, and from that, how much power it will draw at a chosen voltage.
I’m the one you spoke to at VHS yesterday. You mentioned you bought some nichrome wire from lees electronics. If you know exactly which wire you bought, maybe someone here can run some calculations about the voltage and current required.
Here’s a thread on that topic:
I noticed that Lee’s also sells this device:
It takes 5volts (perfect for using a USB battery pack) and draws 600mA. That means a 1800mAh battery pack would power it for 3 hours.
I purchased a 12v rechargeable battery pack and am a bit confused on how to put it all together… I will come by tonight to see how I can get my heated saddle pad working
I would second the concern about avoiding overheating. I did a quick search and found this breakdown of how electric blankets work. Interesting. You certainly don’t have to build this controller, it might be possible to buy one. If you haven’t done this already it’s definitely worth googling to see what other people have made with similar components to the ones you have.
How did it go?
I checked out a heated vest that would be similar technology, and it was running on 3200 mAh at 7.4 volts. By the shape of the battery compartment, I’d say it was two 18650 Lithium batteries in series.
I’m actually surprised such a small pack would power the vest, but that is a data point to have.
Do you happen to know the battery capacity or power draw of any other similar devices?
Hello! I managed to get the NiChrome wire and the 12v battery pack to connect to each other and it heats up but I am afraid it is not warm enough. I am not sure about the battery capacity or power draw of any other devices. Any suggestions that I can do to get the wire to be warmer by using a 12v battery?
Can you draw a diagram of how you’ve hooked it up?
I suspect that you’re using one long string of NiChrome that will end up having a pretty large resistance and therefore not dissipate a whole lot of power.
Here are a couple resources that describe the problem:
I don’t know what your tech comfort levels are, but don’t panic! For this purpose, “power” described in the above articles are “heat”, and your length of wire is the resistor.
The gist of it is that if you cut your wire in half, and connect them in parallel, you will get 4 times the amount of heat. 4 times less battery life, too, but that’s the price you pay.
If there was another metre of wire put in parallel, that would work best. Cutting the existing one in half would work, too, but the smaller length of wire might not be desirable.
I have just made a heated jacket using lipo batteries and these great pads from sparkfun i found! it works great but way to hot at full 12 volts. I made 555 PWM circuit to control the voltage and heat. per 12v 1500mah pack i get 1.5 hours of heat. ill post some pics of the system and links for parts.
i would also ditch that NiMH battery. Way to heavy for the output you get.
I used the 1500mah batteries from Nokia cell phones. There are 100s still left at the hack space for projects.
Pics coming soon.
lipos are perfectly safe if the correct safety features are added. That was already discussed in the posts above. Yes fuses! Also those Nokia batteries all have built in protection, that is a huge plus.
Interesting! I can’t think of why not… bu you’d have to make sure not to overdraw it. And you’d have to make sure you’re actually providing >12 volts, but putting a controller on the system is a great idea. Not sure how batteries love having pulses drawn from them their whole life, but I think it’s fine. Good find @wander
