Just as an aside about the battery pack, there's the problem of deep discharge to worry about. Lipo's don't like going below 2.75-3V per cell, because it permanently screws up the chemistry of the battery. Discharging below that cut off voltage will 'brick' the battery.
A lot of cell phones, pda's, Sparkfun prototyping packs, etc have protection circuits built into them to prevent deep discharge. However, most R/C packs do not have protection because the circuit would be too large and cumbersome for the high amp draw of R/C planes/boats/cars. As such most R/C electronic speed controllers have a built in detection circuit that will throttle back/off when you approach the cut off voltage.
In your case, Tek, I think you can use a audible low voltage warning board, from places like Hobby Lobby or Tower Hobbies. It will monitor pack voltage (sometimes via the balancing connector) and beep at you when you approach the cut off voltage. That'll give you a nice margin of safety.
Correct about Lipos and deep discharges.
I'm intimate with Lipos as I normally deal with 44.4V 12S Lipo systems for my Trex700 RC helicopter. In that hobby, not knowing your Lipo limits can run you costs of around $200 for new batteries, and about $400 in crash damages. not to mention putting yourself (and others) in danger.
Such as the case of a fellow flyer:
So, yeah. I do carry a little 2S lipo alarm, but it's just not practical as the audio is way too loud for this application. So, I have a non-audio version coming my way. This one uses LED bars to show voltage levels.
Another thing I use is a TIME sensitive mechanism. Meaning, I keep track of how many hours I have used a certain pack. In the last convention, my Guy Manuel helmet ran for about 2hrs straight, and I still had 60% capacity left. Needless to say, these are low amp draw systems (my GM can barely break 1 amp momentary peaks). Anything more than 2 hours is not a matter of battery issues but "fogging" the visor and sweating more than anything.
On a more serious note, I do encourage ANYONE that plans to use Lipo batteries to take note of ThreeFN's point here, and read information about Lipo batteries. These batteries can be harmful if not handled properly. Deep discharges, charging at higher "C" rating than recommended, Abuse (punctures, excess heat, shorts, etc) are all big
I do have a fancy charger as well that detects every cell while charging AND I always charge using a lipo bag. Needless to say, I always balance charge these suckers.
IMPORTANT: It is not a matter of ruining the battery pack. It is about your SAFETY! Check this video.
YouTube - ‪2S Lipo on fire‬‏
Initially I was against using lipos for the aforementioned reasons. Instead 'decided' to go with lipo external battery packs like those at batterygeeks.net. They have their own regulators so you get nice output voltages to work with (like 5V, 9V, 12V, etc) and will do all the charging and safety stuff for you. As always seems to be the case with me, I've since moved on.
Right now I'm in love with proper, regular laptop 'smart' batteries (specifically thinkpad/lenovo ones). It just about halved the part count on my master control board. All that lovely data pron you get on your laptop about remaining capacity, time to charge, remaining time estimates, etc is all calculated locally on the battery itself, then communicated to the computer. And they have all of the same safety features you'll get with the above solution. The only trick is getting access to that wonderful data pron. Luckily I stumbled across some code I can hack at to get the functionality I want.
I kinda figured more detail was being posted here vs TDC (invaded by n00bs). Great thread, tekparasite. Very helpful stuff.
Last edited by Decipher; Jul 25, 2011 at 1:57 AM.
This is how my helmet looks with a bit more gear. I'm still missing the gloves and jacket. Even though, the jacket for me will be a bit of a stretch due to Houston, Texas weather. On top of that, I've always loved the "formal" wear with those helmets.
Photo by: George Martinez
I sympathize with the heat and sweating of living in Houston. Been there for a few years but now I'm moving to... Tucson (works a pain sometimes). Living in Houston (and Tucson) is part of the reason I'm entertaining the idea of wearing a cold shirt under the 'costume' so that I should be able to wear full leathers with no problems. The trick is making it portable and innocuous.
sir this thing is beutiful could i request the arduino sketch per chance
product review. Funny thing is that they got bad reviews because they don't keep your hands warm which is excellent for this application.
Here's a link to the original manuf.
Yes. I know, they're female smarTouch gloves, so you may have issues finding bigger sizes.
Interestingly, I may have to remove the conductive smartphone touch screen 'stuff' (usually conductive fabric that connects inside to your finger) on the finger tips so that it doesn't interfere with my buttons/circuits.
Yes, the irony of that statement is not lost on me.
...after consulting with Volpin and other considerations, I opted to add 2 x 30 mm fans to my helmet. I'm still waiting for the voltage regulator, but they're in.
I had also received my 2nd bucket from Volpin to give it another stab at chroming. While talking to the owner of Coat of Chrome, he mentioned that he had a fix and if I was interested in sending the already chromed bucket back to him for re-chroming. "RE-CHROMING!!??" I asked .
He said, "yeah...." 1 week later (minus transit time), I got my helmet re-chromed with much better results.
Props to Don at Coat of Chrome as he did the re-chroming free of charge.
Last edited by tekparasite; Sep 19, 2011 at 9:41 PM.
Last edited by tekparasite; Sep 27, 2011 at 2:05 AM.
so now that a couple of you guys have finished your daft buckets with the thomas LED displays working, i wonder how long until one of you starts in on a full Guy Man LED display it seems like you folk have the concept down pat now, its only a matter of time i suppose.
everytime i look up on here, i find a new person making me feel like a chump. damn you peoples and your amazing works of art. one day, I'll join your ranks.
I love it! Excellent work!
When you gonna roll with the jacket man? haha
I had to move for work, massive work project(s) I've been scrambling on, etc etc etc and the usual excuses.
I hoping this weekend I will finally be able to get my office/workspace in order and get started on my next solder task: cheek EQ's.
Of course, the folks at Arduino had to go an release news of an ARM based arduino. Long of the short, it's like the dream platform for my main control board. It means I wouldn't/shouldn't have to have two arduinos like I do now to handle the work load. Integrating my code bases, simplifying communication, decreasing data traffic, reducing components, increasing expandability, better futureproofing, and all that wonderful stuff. Here's hoping it's kittens and rainbows.
I return you to your regularly scheduled thread.
Jeeeeze, those helmets are absolutely beautiful. You have no idea how envious I am, Guy-Man's helmet is my dream prop, and you did them both justice. Great work!
That is beautiful...
on the arduino nano, what pins did you replace with angled headers?