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LiIon, LiPo, NiCd & NiMh General General Battery Support


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Old 05-20-2010, 12:18 PM   #61
halley
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Originally Posted by carlocivicsi View Post
can anyone tell me the basics of parallel and series.

im new at this and i would love to save money not buying new batteries if i can mix them together. for example i bough a new trex 500 esp and i have 6 3s 11.1v 2200 mah and the trex requires 6s 22.2v and at least 2200mha. so what can i do with this batteries?? thanks.
In series, aS + bS = (a+b)S

You can wire two identical 3S batteries in series to make one 6S battery. They should each have the same capacity (2200mAh each), and the total capacity of the new 6S battery is the same (it doesn't get bigger). Ideally, they should have the same internal characteristics and age, like C-rating and how many times they've been charged. If not, the weaker cells will drag down the performance.

Wiring in series is easy: the negative of one battery is wired directly to the positive of the other. The remaining two poles are your new discharge to the machine. (This is why you usually stack AA cells in one column, or they sit side-by-side in opposite directions.)

In parallel, aS * aS = aS2P

You can wire two identical 3S batteries in parallel to make a larger 3S battery. Your new battery would have the same flight power as the individual 3S batteries, but it would be heavier and would have, in this example, 4400mAh total discharge capacity. Again, a weaker cell can ruin the whole performance and stress the stronger cells.

Wiring in parallel is easy: both negative poles on your batteries are merged into a single negative pole for the machine, and also both positive poles on your batteries are merged into a single positive pole for the machine.
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Old 05-20-2010, 12:21 PM   #62
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thanks SPOK. you have no idea how much i needed your answer. thanks a lot man.


you da man.
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Old 05-20-2010, 12:30 PM   #63
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another quick question. if i series the 2 3s 11.1v 2200 mah together i get the point that would make it a 6s. my question is:::: IT MAKES IT A 22.2V RIGHT???? i know it might be a dumb question but im new at this parallel and series thing.

thanks.
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Old 05-20-2010, 12:36 PM   #64
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thanks SPOK. you have no idea how much i needed your answer. thanks a lot man.
No problem. Halley also made a good point about the importance of starting with well matched packs.

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Originally Posted by carlocivicsi View Post
another quick question. if i series the 2 3s 11.1v 2200 mah together i get the point that would make it a 6s. my question is:::: IT MAKES IT A 22.2V RIGHT???? i know it might be a dumb question but im new at this parallel and series thing.

thanks.
Not a dumb question. Yes, the voltage is additive when you add cells in series. What you have in front of you are two packs that each have 3 cells already mounted in series. Each cell is 3.7V. That gives you a 3S 11.1V pack. When you add two of those packs together in series you'll have 6 cells in series. That'll give you a 6S 22.2V pack.
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Old 05-20-2010, 12:56 PM   #65
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halley and spok thanks alot.
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Old 07-08-2010, 05:25 AM   #66
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dont know if this has been posted but for any one wanting to know more and i mean WAY more you can check out these MIT couses on it
here are the frist lectures from 2 of them
if you can stick with it youll know just about all you ever wanted to know lol
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Old 07-08-2010, 06:42 PM   #67
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HI! I decided to delete my post. Have a great day.

Last edited by cvdiver; 07-08-2010 at 06:45 PM.. Reason: has been previously posted
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Old 07-08-2010, 11:16 PM   #68
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HI! I decided to delete my post. Have a great day.
I thought it was a perfectly good post that helped to clarify an issue that sometimes confuses folks. The stuff you're studying in dynamics now is exactly what lets us build a wind powered vehicle that goes directly downwind, faster than the wind (but I'd still give even odds that your dynamics professor would claim it's impossible).
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Old 07-16-2010, 06:39 PM   #69
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I thought it was a perfectly good post that helped to clarify an issue that sometimes confuses folks. The stuff you're studying in dynamics now is exactly what lets us build a wind powered vehicle that goes directly downwind, faster than the wind (but I'd still give even odds that your dynamics professor would claim it's impossible).
I was worried I was being a bit preachy. Oh well. On your example, there would seem to be lots of things to consider there. Assuming the area of the sail collected enough wind to overcome (substantially) the frictional force opposing the forward motion and the force on the forward portion of the vehicle itself from it having to move through the air (Drag, i think). I wonder what he would actually say?
Geez, the more I think about the problem the more variable that I come up with, crap! This is going to keep me up all night.........
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Old 07-16-2010, 06:41 PM   #70
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Originally Posted by Elios000 View Post
dont know if this has been posted but for any one wanting to know more and i mean WAY more you can check out these MIT couses on it
here are the frist lectures from 2 of them
http://www.youtube.com/watch?v=3omwHv3Cmog
http://www.youtube.com/watch?v=AfQxyVuLeCs
if you can stick with it youll know just about all you ever wanted to know lol
I love this guy's lectures. He helped me through Physics. I just wish that I could actually have been in one of his classes. He's really awesome.
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Old 07-16-2010, 07:26 PM   #71
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Originally Posted by cvdiver View Post
Assuming the area of the sail collected enough wind to overcome (substantially) the frictional force opposing the forward motion and the force on the forward portion of the vehicle itself from it having to move through the air (Drag, i think). I wonder what he would actually say?
Geez, the more I think about the problem the more variable that I come up with, crap! This is going to keep me up all night.........
I don't want to takeover this thread, but you can see all about it in its own thread: http://www.helifreak.com/showthread.php?t=24303&page=25
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Old 08-06-2010, 05:07 PM   #72
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The Volt would be the height difference between the water level in the tank and the end of the hose. A bigger tank would not increase the pressure (Volt)
Actually the higher you fill the tank with water the more pressure at the bottom of the tank. Think of it like the deep end of a pool. The farther down you swim the higher the pressure and therefore the more your ears start to ache. This is because of the weight of the water above you. It works the same in the tank. If you have 20 feet of water in the tank above the opening you will have more pressure at the bottom then if you only had 10 feet.
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Old 08-09-2011, 05:39 PM   #73
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Great article. I also had electrical course work in HS, then 2 AAS degrees in computer sciences and a BS in computer science and some master degree course work as well. I am by no means an expert but that pdf is a very good easy to read document. Well done.
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Old 12-09-2012, 04:27 AM   #74
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The problem with using water "pressure" and water "flow" to explain potential (voltage) and current (amps) is that many people who don't understand electricity don't understand water either.


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