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HomeAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › Need help understanding Lipo cell count and redundancy Please !
02-07-2010 03:51 PM  8 years agoPost 1
tarzan_eb

rrApprentice

Central Illinois USA

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I recently read where a member had a cell fail in his lipo almost causing personal injury. I am trying to figure out if this could happen to me. These are the batteries I am currently using.


You can see 4 wafers in this battery does 2 wafers make up one 3.7v cell?
I think this is just a 2 cell pack each cell being 3.7v. @ 1250mah each = 2500
If this pack looses a cell will it only be supplying 3.7v to my electronics? I just want a battery that will still supply 7.4v if one cell fails.

Fly it ! Crash it ! Rebuild it ! Repeat as needed !! Everett

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02-07-2010 03:56 PM  8 years agoPost 2
george0079

rrElite Veteran

USA

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If you're using a single pack, and a cell fails, you will lose voltage to you RX.

A battery pack that is wired as single pack has no redundancy

Hell... I can fix that.
Uh oh..
Nope.
It's ***ked!!!
RE-KIT!!!!!

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02-07-2010 04:20 PM  8 years agoPost 3
tarzan_eb

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Central Illinois USA

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I know that. What I want to know is each wafer in this pack 3.7v
making it 4, 3.7v cells. Is the way it is put together make it a redundant battery each 2 wafers running in series making 7.4v or does it take 2 wafers to make 3.7v thus it taking all 4 to make up 7.4v

Can anybody tell by looking at this battery if it will fail if one cell fails?

What makes 1 cell one wafer or 2

Fly it ! Crash it ! Rebuild it ! Repeat as needed !! Everett

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02-07-2010 05:13 PM  8 years agoPost 4
JRjoe

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Jonesville , IN USA #1

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Looks to me like you have a 2s2p pack. 4 cells total.

2 in series = 7.4v

and then 2 of those in parallel still 7.4v

Honestly not sure what happens if 1 cell were to go. I'm sure someone will enlighten us.


JRjoe.....
Indoor plumbing??? No, we don't need that!!!

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02-07-2010 08:37 PM  8 years agoPost 5
flying4fun

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Sunny SoCal

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Well if you have a 2S2P what happens if you lose one cell is as follows: (1) If a cell shorts out (internally) than that cell being in parallel with another cell will short out that cell as well which will probably start a fire. Think of what happens when you jumper a batttey's positve to negative terminals. (2) if a cell opens up (internally) than its no problen it's just that you only have half the capacity in that parallel combination. Generally cells will short out as opposed to "opening" up.

If you want redundancy (not really a true redundancy w/o 2nd pack) go to separate pack for the electronics.

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02-08-2010 07:33 PM  8 years agoPost 6
Skybolt

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Ontario, Canada

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Hi tarzan_eb,

I have the same battery pack as you and this pack is 2 serial cell.

By convention manufacturer do no write the 1p for single cell ex: 2S1P.

In that case you would see 2S2P.

Even in a 2P configuration both cells are connected together for balancing purpose. So if one cell goes bad it may short the other one.

So for redundancy you will have to go with two battery packs with diodes or switching circuit that seperate both packs.

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