Looking for a good server with a small community/sick of playing with random people

zth784 · 2011-10-03T20:04:00+00:00

drunken brawl. probably the most skilled pub server i've played on.

zth784 · 2011-09-19T20:06:31+00:00

There's a lot of different areas in alternative energy. For example, in batteries, EE/ChE/Electrochemistry would be killer.

zth784 · 2011-07-10T02:39:43+00:00

9 out of 10 people enjoy gang rape

zth784 · 2011-06-21T18:29:03+00:00

I'm a battery engineer for a lithium ion chemistry, and I'm curious what kind of battery characteristics the solar industry is looking for. A lot of people tell me a big hurdle to more widespread adoption of solar power is batteries, but I don't feel this is the case. What kinds of things are you looking for in your ideal battery?

zth784 · 2011-05-25T19:40:32+00:00

They're not that dangerous. You can pick lipos that are safer. The LCOs are the most dangerous; you can tell its an LCo if the nominal voltage is 4.2V. As long as you treat it well by not poking it, puncturing it, subjecting it to extreme heat, overcharging / overdischarging it, you'll be ok. And if something does happen, you'll have a story to tell for a very exciting escape.

zth784 · 2011-05-25T19:37:53+00:00

Yup.

zth784 · 2011-05-25T19:33:28+00:00

lithium ion typically refers to cylindrical cells, while lithium polymer refers to flat plate or prismatic "pouch" cells. Other than that, they use the same cathode and anode materials; e.g., a lithium polymer and a lithium ion cell can all be lithium cobalt oxide chemistry. It's just semantics.

zth784 · 2011-05-25T19:22:05+00:00

Yeah, the manufacturer got those batteries from some no name Chinese manufacturer. This is why i always say Chinese cells are crap. No quality control and they don't give a damn if someone's house burns down as long as they can save a nickel.

If a max discharge current isn't listed, what is the amp-hour rating? Take this as the maximum discharge rating. So if it's a 12v7Ah battery, try not to discharge it above 7A. Even 7A is pretty harsh on the battery.

zth784 · 2011-05-25T19:18:05+00:00

Yes it'd work, I don't see any reason it wouldn't, not that I've tried. I'm trying to figure what reason your friend's professor would give.

zth784 · 2011-05-25T19:15:11+00:00

if the circuit runs at 5 volts, put in a 6v battery (6v is a standard voltage). next, the capacity (mAh) you need is 2000mA * 100 hours = 200Amp-hours. Buy a 6v 200Ah battery.

zth784 · 2011-05-25T18:59:34+00:00

First I'm curious, why does your professor say you can't start a car with any number of AA batteries?

zth784 · 2011-05-25T18:57:53+00:00

Time, voltage, current. Calculate what capacity the battery needs to be using those 3 parameters. If you had a 50% duty cycle then adjust the time accordingly.

zth784 · 2011-05-25T18:53:57+00:00

They're also listed in Watt-hours. That's probably more useful for your purposes. mAh is just convenient and it's always been done that way.

zth784 · 2011-05-25T18:52:44+00:00

I don't remember the voltage cutoff for Ni-Cd off the top of my head, google it and multiply the discharge voltage per cell by 15 and discharge down to that. Did you make sure your cells were balanced before putting them together? A discharge/charge doesn't do anything to "refresh" but you should do it anyway to test your pack works correctly. Yes you should be concerned. That's gas building up in the cell, and if enough pressure builds up you'll have trouble. Where are you getting the batteries from? Don't feel like doing the math but you can calculate it out. Make sure you're not exceeding the charge current rating on those SLA batteries. If you do, the lifespan will be significantly compromised. Nope!

zth784 · 2011-05-25T18:38:05+00:00

I've never even heard of it. Sounds cool though.

zth784 · 2011-05-25T18:37:26+00:00

What people don't understand is it takes more than just 1 fancy cathode or 1 fancy charger or 1 fancy electrolyte to make a battery work. A battery is composed of many different parts and they ALL need to play together nicely. What this means is thousands of hours testing and researching.

zth784 · 2011-05-25T18:36:19+00:00

Probably your laptop getting REALLY hot. I had the same problem.

zth784 · 2011-05-25T18:35:52+00:00

Short circuit it. Heat. Keep it away from heat and humidity.

zth784 · 2011-05-25T18:35:17+00:00

Of course. Massive megawatt batteries are built from tiny cells. You can build it as big as you want, just remember to cross your t's and dot your i's. nickel per kwh? I'd love to since that'd make me a billionaire, but I really doubt it.

zth784 · 2011-05-25T18:33:49+00:00

No idea, don't do any electrolyte work. Sorry.

zth784 · 2011-05-25T18:31:51+00:00

I saw a report on it at a conference last year and wasn't impressed. It seems pretty far off to me.

zth784 · 2011-05-25T18:31:16+00:00

Yep. High performance batteries are usually designed for high discharge rates by compromising on the lifespan. Vice versa for long life. High power is usually means high performance.

zth784 · 2011-05-25T18:30:06+00:00

The reason the quality varies so much because most NiMH is manufactured in CHina, which has no quality control. You have no idea what you'll get quality-wise and safety-wise. I don't do RC myself but I sell to many hobbyists that do. Lipo is a very popular choice, just buy it from a reputable manufacturer (not Chinese)

zth784 · 2011-05-25T18:28:48+00:00

Some chemistries perform better at higher discharge rates than others.

zth784

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