Fun, Learning, Friendship and Mutual Respect START  HERE


Unregistered
Go Back   HeliFreak > R/C Batteries and Charging Support > LiIon, LiPo, NiCd & NiMh General


LiIon, LiPo, NiCd & NiMh General General Battery Support


Reply
 
LinkBack Thread Tools Display Modes
Old 07-22-2008, 09:27 AM   #41 (permalink)
Registered Users
 
My HF Map location
Join Date: Jun 2007
Default

Quote:
Originally Posted by geoavia View Post
Just realised that, the problem I belive will arise is: If I manage and charge 6s packs half by half, than I will get two charged and balaced 3s packs connected in series in one brick, but this can not guarantee that any cells from different halves will be in balanced voltage range.

So probably this is not a wery good idea of chargind 6s cells half by half, even if charger and pack allows it. Huh, think, time to look at larger chargers...
Does it? An integrated balancer will terminate the charge when all cells are 4.2v +/- 0.01v or so.
daijoubu is offline        Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 07-22-2008, 09:43 AM   #42 (permalink)
Registered Users
 
My HF Map location
Join Date: Jun 2007
Default

Quote:
Originally Posted by geoavia View Post
Thanks for precautionary words I know about lipo safety, and won't do anything that potentially may cause damage. that's why I'm asking.
You're welcome, not everyone reading this thread knows though. I met a guy at the field on Saturday who started telling me how he cut his lipos open and was testing them out. He wanted to open a pack, cut it up and re-assemble it as a smaller lipo to fit in different planes. The only thought in my head was "Oh my god, get away from me! Put your batteries back in your case and keep them away from my car and helis!"
daijoubu is offline        Reply With Quote Quick reply to this message
Old 09-26-2008, 04:13 AM   #43 (permalink)
Registered Users
 

Join Date: Jun 2008
Default

Yawn, ho hum.

Never realised how boring electricity and electronics was.

I just want to plug n fly

Glad I never studied to become an electrician. I'd have fallen asleep in class every day.
minskie is offline        Reply With Quote Quick reply to this message
Old 01-24-2009, 03:00 PM   #44 (permalink)
Registered Users
 
Posts: 353
 

Join Date: Jul 2008
Default

Quote:
Originally Posted by daijoubu View Post
You're welcome, not everyone reading this thread knows though. I met a guy at the field on Saturday who started telling me how he cut his lipos open and was testing them out. He wanted to open a pack, cut it up and re-assemble it as a smaller lipo to fit in different planes. The only thought in my head was "Oh my god, get away from me! Put your batteries back in your case and keep them away from my car and helis!"
Hmm, I've taken two packs that had bad cells, cut them apart, and used three good cells to make a 3S pack from them. They were identical packs... Nothing wrong with that... I've also cut the tops open to resolder the balance plug wires back on when they break off. In fact, I'm considering taking 4 3S packs and making 3 4S packs out of them...
__________________
odam2k is offline        Reply With Quote Quick reply to this message
Old 02-04-2009, 03:16 AM   #45 (permalink)
Registered Users
 
Posts: 4,545
 

Join Date: Jun 2008
Default

Quote:
Originally Posted by odam2k View Post
Hmm, I've taken two packs that had bad cells, cut them apart, and used three good cells to make a 3S pack from them. They were identical packs... Nothing wrong with that... I've also cut the tops open to resolder the balance plug wires back on when they break off. In fact, I'm considering taking 4 3S packs and making 3 4S packs out of them...
I think a clarification of "cut it apart" is in order.Ive also modified quite a few LiPo packs.They are all packaged a bit differently.Generally the seperate LiPo cells are encapsulated in their own airtight shrinkwrap type membrane with the leads both on one end.Airtight being the key part of this package.Multiple cells are stuck to each other usually with some kind of double sided tape,adhesive,etc.Then a piece of pcb(printed circuit board) the size profile of the end of the pack is positioned on one end for a solid place to connect leads and provide strain relief to lead ribbons LiPo cells use.Then once everything is in place the entire assembly is shrink wrapped again further protecting the cells and connections.Some dont have an outer shrink wrap and have like a fiber tape wrapped around them.So Id say "cut it apart" is better defined as "cut apart outer wrapping".Any and or all of the secondary package(outside shrink wrap or tape) can be removed to expose the cells and connections.Two main precautions are to never puncture the membrane,case,plastic wrap on an individual cell and to excercise higher than usual care not to short the leads together once they are unsoldered.If the cell membrane/case is puntured an oxygen is allowed to get inside its done and there is the very real chance it may spontaneously combust.Maybe in a few minutes maybe hours tomorrow who knows?Punctured LiPo cells very very bad.The leads on them are mostly all a flat ribbon type lead and are many times plenty long enough to easily come together when loose.Even if they just barely touch there will likely be enough current to make them spot weld themselves together in a short and get very hot and possibly start a fire or on fire or at best ruin the cell or cells in a matter of seconds.Toughest part I found is serperating the cells themselves without stretching or poking a hole in the cell.Most seem to use something like servo tape.I found that a credit card kind of sharpened works good.Gentle pressure and work the card in the gap slow steady pressure.I ruined a few using a knife too.Obviously this is something that requires more care than making Ni-Cd packs but with a bit of extra care and attention can be done quite safely.Be aware.Be prepared for eventualities.It is what it is.
aerocal is offline        Reply With Quote Quick reply to this message
Old 02-04-2009, 09:05 AM   #46 (permalink)
Registered Users
 
Posts: 353
 

Join Date: Jul 2008
Default

Exactly... yes, good definition of "cutting apart" - seperating the single cells... he he

I find the cheap packs don't have the pcb on the top, and the balance plug wires easily come off the tabs. I've started folding the balance plug wire over the top of the pack and taping it there now, its shorter, but there is no strain on the solder joints any more... I have a bad habit of picking them up by the wires
__________________
odam2k is offline        Reply With Quote Quick reply to this message
Old 04-22-2009, 01:05 PM   #47 (permalink)
Registered Users
 

Join Date: Feb 2009
Default

Quote:
Originally Posted by HFG View Post
One thing that is really wrong is your discription of a watts "...Watt is a unit of work done over time".

''Watts'' just tells you how many amps and volts a particular device needs in order to function, i haven't heard anything about time when working with the term ''watts''.

''Watts'' is just the correlation between Amps and volts, VxA=watts
__________________
Zoom 400 (R.I.P)Bell 47g micro coax (R.I.P)Blade CX2 (R.I.P, lost at sea!)Shuttle Z, Reincarnated !HB1,MCX,TREX 250,MSR,MCPX,Raptor V2,Nano qx
Tom.C is offline        Reply With Quote Quick reply to this message
Old 04-22-2009, 01:16 PM   #48 (permalink)
The Capi
 
Posts: 25,182
 
My HF Map location
Join Date: Oct 2006
Default

I am somewhat familiar with electronic theory.
__________________
Spreading capibara awareness since 2006
DominicD is offline        Reply With Quote Quick reply to this message
Old 04-22-2009, 01:38 PM   #49 (permalink)
Registered Users
 
Posts: 569
 
My HF Map location
Join Date: May 2008
Default

Quote:
Originally Posted by alex_p_kiel View Post
Volts in the electromotive force in a current or how fast it is moving. Amps is the electric potential or ammount of power. Watts is is volts x amps. Ohms is electrical resistance. From my own calculations, a "C" is about 2 or 2.1 amps. A miliamp is one-thousandth (0.001) of an amp. I don't know if I am forgetting anything.
Quote:
Originally Posted by Tom.C View Post
''Watts'' just tells you how many amps and volts a particular device needs in order to function, i haven't heard anything about time when working with the term ''watts''.

''Watts'' is just the correlation between Amps and volts, VxA=watts





"From my own calculations, a "C" is about 2 or 2.1 amps"

__________________
MCX,MSR, CX2 Extreme,
CP Pro, Blade 400, T-Rex 250, T-Rex 500 ESP
T-Rex 600 ESP

All on DX6i
ENDO1 is offline        Reply With Quote Quick reply to this message
Old 04-30-2009, 11:50 AM   #50 (permalink)
Registered Users
 

Join Date: Sep 2006
Default

nm
rcboosted is offline        Reply With Quote Quick reply to this message
Old 08-26-2009, 08:52 PM   #51 (permalink)
Registered Users
 

Join Date: Jul 2009
Default

Im kinda confused on how they calculated the 5 minutes to kill the battery at 1000 mah and 12C. Anyone wanna help explain that with maybe at 2200 mah at 25C.
LowOreo is offline        Reply With Quote Quick reply to this message
Old 08-26-2009, 09:28 PM   #52 (permalink)
Registered Users
 
Posts: 5,849
 
My HF Map location
Join Date: Sep 2005
Default

Quote:
Originally Posted by LowOreo View Post
Im kinda confused on how they calculated the 5 minutes to kill the battery at 1000 mah and 12C. Anyone wanna help explain that with maybe at 2200 mah at 25C.
Sure, I'll take a crack. The battery capacity is 1000 mah (that's 1000 milliamps for 1 hour - at its rated voltage). If you think of it as a jug of water, the capacity is how much water is in the jug.

12C refers to the rate the water can flow out of the jug. 1C is sort of short-hand for "1 capacity" which is sort of shorthand for "1 capacity in one hour. But keep in mind, this is a RATE of flow. So 12C would be 12 times that rate. This would suggest you could dump 12 times the battery's capacity in one hour. But of course the battery doesn't *have* 12 times its capacity. It only has 1 times its capacity (by definition). But 12C is still 12 times the *rate* of 1C. What this means is that you'll dump the entire battery's capacity in 1/12th of an hour - or 5 minutes.

So let's look at your case of a 2200 mAh battery at 25C. To know how fast you can dump the entire contents, it doesn't matter the capacity of the battery. Just the "C" rating alone will tell you that. If it's a 25C battery, you can dump the entire battery in 1/25th of an hour - or about 2.4 minutes. Since you can dump 2200 milliamps for one whole hour, you would dump 25 times that current (or rate) over the 2.4 minutes. So you'd be putting out 55,000 milliamps (or 55 amps).
__________________
Nothing is ever as good or as bad as it seems.
spork is offline        Reply With Quote Quick reply to this message
Old 08-26-2009, 10:33 PM   #53 (permalink)
Registered Users
 
Posts: 2,781
 
My HF Map location
Join Date: Jan 2008
Default

I like the "jug" analogy, thanks for that.
__________________
- Chris
TJinTech heli...info...news...such
Helis: TRex 450 Pro - Protos - TRex 550e
Stuff: Spektrum DX7 - iCharger 208B - Hyperion G3
TJinGuy is offline        Reply With Quote Quick reply to this message
Old 08-31-2009, 09:56 AM   #54 (permalink)
Registered Users
 

Join Date: Jul 2009
Default

ah gotcha. thats what i thought but just wasn't sure. i appreciate the help.
LowOreo is offline        Reply With Quote Quick reply to this message
Old 04-25-2010, 11:08 AM   #55 (permalink)
Registered Users
 
Posts: 737
 

Join Date: Jan 2010
Default analogy analysis

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.
freewheel510 is offline        Reply With Quote Quick reply to this message
Old 05-06-2010, 01:03 PM   #56 (permalink)
Registered Users
 

Join Date: Jul 2009
Default

I'm confused. Why is a battery's mAh rating featured so prominently though it ignores the voltage.
Wouldn't WattHour be a more accurate measure of what a battery can do? Hope the question wasn't too dumb :o
__________________
"There's no such thing as gravity. The earth just sux"
T-Rex 250, Align FBL, T-Rex 250 DFC
500 ESP, RJX FBL

Skookum SK-720
airnoob is offline        Reply With Quote Quick reply to this message
Old 05-06-2010, 01:16 PM   #57 (permalink)
Registered Users
 
Posts: 2,781
 
My HF Map location
Join Date: Jan 2008
Default

Quote:
Originally Posted by airnoob View Post
I'm confused. Why is a battery's mAh rating featured so prominently though it ignores the voltage.
Wouldn't WattHour be a more accurate measure of what a battery can do? Hope the question wasn't too dumb :o
In terms of work done, yes Wh would be a better rating to display but that is not what is important with packs. What is most important is Ah. This the bases for figuring out discharge rates, charge rates, sizes, etc. If you only advertised the Wh of a pack instead of Ah, then the user would have to do some math in order to determine all the pertinent info themselves.
__________________
- Chris
TJinTech heli...info...news...such
Helis: TRex 450 Pro - Protos - TRex 550e
Stuff: Spektrum DX7 - iCharger 208B - Hyperion G3
TJinGuy is offline        Reply With Quote Quick reply to this message
Old 05-06-2010, 01:42 PM   #58 (permalink)
Registered Users
 

Join Date: Jul 2009
Default

Thanks, Chris

I think I've finally got my head wrapped around the basics.

Now, if I can only hover inverted...oops...that should be a new thread.
__________________
"There's no such thing as gravity. The earth just sux"
T-Rex 250, Align FBL, T-Rex 250 DFC
500 ESP, RJX FBL

Skookum SK-720
airnoob is offline        Reply With Quote Quick reply to this message
Old 05-20-2010, 11:45 AM   #59 (permalink)
Registered Users
 

Join Date: Mar 2010
Default

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.
carlocivicsi is offline        Reply With Quote Quick reply to this message
Old 05-20-2010, 12:17 PM   #60 (permalink)
Registered Users
 
Posts: 5,849
 
My HF Map location
Join Date: Sep 2005
Default

Quote:
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.
When you connect packs in series you add the voltages, but the capacity remains the same. When you connect them in parallel the voltage stays the same and the capacities add.

So you can connect two 3S packs in series to get one 6S pack. That will give you a 6S 22.2V with 2200 mah capacity. And you're good to go.

To add them in series you'll connect the red wire from one pack to the black from the other. The remaining red and black wires will be your 6S outputs.
__________________
Nothing is ever as good or as bad as it seems.
spork is offline        Reply With Quote Quick reply to this message
Reply




Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the HeliFreak forums, you must first register.
Please enter your desired user name, your REAL and WORKING email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself. Use a real email address or you will not be granted access to the site. Thank you.
Email Address:
Location
Where do you live? ie: Country, State, City or General Geographic Location please.
Name and Lastname
Enter name and last name here. (This information is not shown to the general public. Optional)
Helicopter #1
Enter Helicopter #1 type and equipment.
Helicopter #2
Enter Helicopter #2 type and equipment.
Helicopter #3
Enter Helicopter #3 type and equipment.
Helicopter #4
Enter Helicopter #4 type and equipment.

Log-in


Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On




Copyright © Website Acquisitions Inc. All rights reserved.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.

SEO by vBSEO 3.6.1