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Old Mar 16, 2005, 06:38 PM
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I take everything I hear from everyone here with a grain of salt. No one knows it all.
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Old Mar 16, 2005, 07:36 PM
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Walled Lake, MI, USA
Joined Feb 2000
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Quote:
Originally Posted by willhaney
I take everything I hear from everyone here with a grain of salt. No one knows it all.
Good philosophy. There's a reason why healthy skepticism is considered healthy. Truth is, we should all have more questions than answers, because none of us is even close to knowing the answers to even half of the questions. That's why I get out the family size salt shaker when I see someone who almost always has answers and almost never asks questions.
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Old Mar 16, 2005, 08:12 PM
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Haralson County GA. USA
Joined Oct 2004
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Quote:
Originally Posted by Dave Hederich
Good philosophy. There's a reason why healthy skepticism is considered healthy. Truth is, we should all have more questions than answers, because none of us is even close to knowing the answers to even half of the questions. That's why I get out the family size salt shaker when I see someone who almost always has answers and almost never asks questions.
I thought that was a strange kind of snow that has falling on me. Guess I better come up with a list of questions.

Why does a Li Poly battery say on the label that it is 1200 mAh 11.1 volts and is rated 10C which implies that it should believer 1200 mAh at 12 amps. but it only takes 1050 mAh to recharge it after being ran don to a LVC of 9volts. I checked after landings and it still said it was mostly full.,since volts were 11.04 and it was only 12.52 when I started the flight. Seems like I only used a little bit of the charge.
Charles
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Old Mar 16, 2005, 09:41 PM
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Walled Lake, MI, USA
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Charles, you ask questions all the time, and your CBA provides answers.
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Old Mar 16, 2005, 10:47 PM
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Gig Harbor, Washington, United States
Joined Sep 2003
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Quote:
Originally Posted by everydayflyer
I thought that was a strange kind of snow that has falling on me. Guess I better come up with a list of questions.

Why does a Li Poly battery say on the label that it is 1200 mAh 11.1 volts and is rated 10C which implies that it should believer 1200 mAh at 12 amps. but it only takes 1050 mAh to recharge it after being ran don to a LVC of 9volts. I checked after landings and it still said it was mostly full.,since volts were 11.04 and it was only 12.52 when I started the flight. Seems like I only used a little bit of the charge.
Charles
I know the answer to that one!

The label was on the wrong side - turn the battery over and it will work much better

Larry

P.S. Thanks for letting me now what you were doing Dave - I thought I had dandruf
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Old Mar 17, 2005, 12:03 AM
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North Las Vegas NV
Joined Mar 2002
500 Posts
It would seem that my question is answered

Thanks to all you for coming in on my question re balancing of Lipo stacked cels.

It seems clear that the unbalance problem is progressive unless attended to.

Here is what I have gleaned.

To reduce possible problems from unbalanced cels:

1. I need to add exit wires for each of the battery junctions.

2. I would need to charge each cel separately, at a low rate

3. This process would seem to have safely charged each of the cels. I will trust that my charger will repeat full charge characteristic each time.

4. This separate cel charging is something to be done on a basis of, say, every 3 or four full stack charge cycles. That is only a guess, but it is a lot better than I am doing now.

5 This notion gives me the option to comfortably field charge and pretty much quit worrying - as I have been doing.

Happy building and fun flying to all,
Richard
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Old Mar 17, 2005, 06:02 AM
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Haralson County GA. USA
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Quote:
Originally Posted by rick121x
Thanks to all you for coming in on my question re balancing of Lipo stacked cels.

It seems clear that the unbalance problem is progressive unless attended to.

Here is what I have gleaned.

To reduce possible problems from unbalanced cels:

1. I need to add exit wires for each of the battery junctions.

2. I would need to charge each cel separately, at a low rate

3. This process would seem to have safely charged each of the cels. I will trust that my charger will repeat full charge characteristic each time.

4. This separate cel charging is something to be done on a basis of, say, every 3 or four full stack charge cycles. That is only a guess, but it is a lot better than I am doing now.

5 This notion gives me the option to comfortably field charge and pretty much quit worrying - as I have been doing.

Happy building and fun flying to all,
Richard
Sounds like you have a good understanding of this now. If you leave a little extra in the battery so that resting volts is 3.7 volts per cell 5 minutes after a flight the cells will tend to stay in balance better. It also appears that some Li Poly brands and generations of cells tend to stay in balance longer.

Charles
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Old Mar 17, 2005, 07:53 AM
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Walled Lake, MI, USA
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Quote:
Originally Posted by rick121x
4. This separate cel charging is something to be done on a basis of, say, every 3 or four full stack charge cycles. That is only a guess, but it is a lot better than I am doing now.
Measure individual cell voltage frequently and balance with individual cell charging as required.

After a period of frequent measurement, you may find that some or all of your packs do not require any balancing.

If individual cell voltages appear to be in balance and stable, you may decide to decrease the frequency of measurement.

Do not ever assume that packs that have remained in balance over time will never go out of balance.
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Old Mar 17, 2005, 10:48 AM
Hey ya'll watch this!
OneHump's Avatar
Danville, CA
Joined Mar 2002
361 Posts
I'm not new to R/C, but I am just now venturing into the world of LiPo. Despite my understanding of "taps" and cell balancing, I am constantly eluded by the method with with you are tapping your cells.

-Do you buy them tapped?

-Do you cut the casing open <gasp> and tap them yourselves?

It seems like a lot of work to me. IMHO, there is one of two issues at play here:

1) People are being a bit too paranoid, or turning LiPo technology into a hobby and taking things to extreme.

2) The multitude of vendors who are pushing these batteries and chargers with little or no warning are setting themselves up for a massive liability.

My guess is that we're somewhere in the middle.

I have no doubt that LiPo cells go out of balance, but it seems you have to be an EE, or at least an electrical enthusiast, to keep them in balance.

Unless I'm able to learn more about this procedure, I think I might simply use them as-is until I get a failure. I will, of course, be extremely careful with how I charge them to avoid any damage beyond a lost pack.

As wreckless as that sounds, I'm quite sure less than 1% of us share the incredible amount of knowledge you all have that allows you to balance your cells with accuracy.

Any reasonable advice is certainly appreciated.

-OneHump (LiPo "noob")
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Old Mar 17, 2005, 11:29 AM
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San Jose Ca / RSA flyer
Joined May 2003
8,030 Posts
Larry Has Right to Assume Anything He Wants

But I am not RCGUY01

U can verify this by his last post about MOOSHOO
Why should I ask myself about this delicacy ?

Astrobob and I have verified the fact that LIPO packs can be reconditioned back to normal service thru a certain current level SLOW CHARGE at 50 ma and even as high as 100 ma. This is good medicine for " SICK LIPOs " but not a miracle cure for LIPOs that have gone to " HEAVEN", not even the "MAN" upstairs can do anything about it.


FB

Too bad U miss Tom"s burn n crash Spitfire last month, it was a spectacle, 1HP LIPO pack made its own grave in the dirt.

For all LIPO users

If U have the time to slow Charge, do it
1C fast charge will be expensive

Good luck to YOU ALL anyway
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Old Mar 17, 2005, 11:50 AM
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Fountain Valley, California
Joined Feb 2004
10,768 Posts
I use the Triton charger and slow charge my packs. However, if I set the amperage too low I get the “time out” error and lose the amount of charge applied to the pack (I log charge and discharge times along with mah quantities).

What is the lowest fraction of C that could be used to charge packs safely? (¾, ½, 1/4)

If I charge multiple times, due to time outs, at very lower rates, could this damage the pack? Can a charge be too low? If not, are there chargers out there that charge packs for longer periods of time?

I just want to treat my pack as best as I can. I want them to live a long and healthy life.

BTW: I use PloyQuest packs with PCM guard.

Thanks.
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Old Mar 17, 2005, 12:19 PM
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everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,726 Posts
Quote:
Originally Posted by willhaney
I use the Triton charger and slow charge my packs. However, if I set the amperage too low I get the “time out” error and lose the amount of charge applied to the pack (I log charge and discharge times along with mah quantities).

What is the lowest fraction of C that could be used to charge packs safely? (¾, ½, 1/4)

If I charge multiple times, due to time outs, at very lower rates, could this damage the pack? Can a charge be too low? If not, are there chargers out there that charge packs for longer periods of time?

I just want to treat my pack as best as I can. I want them to live a long and healthy life.

BTW: I use PloyQuest packs with PCM guard.

Thanks.
The time out functin is adjustable and besides I did not think it worked with Li Polys,perhaps it does. My timeout set to somewhwhere around 12 hors as I slow charge 2300 mAh NI MH packs at .3 Ah.

Charles
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Old Mar 17, 2005, 12:22 PM
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Haralson County GA. USA
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Best to purchase with taps, yes some of us add them and some of us buy cells and built packs, remove bad cells from packand replace them. salvage a 3S with 1 bad cell to a 2S etc.

Charles

Quote:
Originally Posted by OneHump
I'm not new to R/C, but I am just now venturing into the world of LiPo. Despite my understanding of "taps" and cell balancing, I am constantly eluded by the method with with you are tapping your cells.

-Do you buy them tapped?

-Do you cut the casing open <gasp> and tap them yourselves?

It seems like a lot of work to me. IMHO, there is one of two issues at play here:

1) People are being a bit too paranoid, or turning LiPo technology into a hobby and taking things to extreme.

2) The multitude of vendors who are pushing these batteries and chargers with little or no warning are setting themselves up for a massive liability.

My guess is that we're somewhere in the middle.

I have no doubt that LiPo cells go out of balance, but it seems you have to be an EE, or at least an electrical enthusiast, to keep them in balance.

Unless I'm able to learn more about this procedure, I think I might simply use them as-is until I get a failure. I will, of course, be extremely careful with how I charge them to avoid any damage beyond a lost pack.

As wreckless as that sounds, I'm quite sure less than 1% of us share the incredible amount of knowledge you all have that allows you to balance your cells with accuracy.

Any reasonable advice is certainly appreciated.

-OneHump (LiPo "noob")
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Last edited by everydayflyer; Mar 17, 2005 at 12:39 PM.
Old Mar 17, 2005, 12:38 PM
Hey ya'll watch this!
OneHump's Avatar
Danville, CA
Joined Mar 2002
361 Posts
Thanks for the advice everydayflyer; it's the most direct answer I've had on the topic.

On another note...

You guys should go easy on Hall Woo. He's doing a good job staying civil considering the (LiPo?) fire he's under. I'm not saying he's right, but he's a man with an opinion and has the right to be heard, regardless of being right or wrong.

I don't know the history here so I'll share my input as an outsider and leave it at that.

I will suggest, however, that Hall keep a couple of fire extinguishers handy. That's always good advice.

-OneHump
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Old Mar 17, 2005, 12:48 PM
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Haralson County GA. USA
Joined Oct 2004
34,726 Posts
If you want to read a bunch about taps / balancing I did a thread on that subject recently. The last fe pages are a good quick read. E Tec Classic LI Polys are a good place to start for DIY project.
Thunder Powers are perhaps the hardest to do.
Poly Quest come with taps and connector and the new lower prices are fantastic. Tanics have taps but are a little pricey/ TPs wil have taps on some cells/ packs but most likely only the larger more expensive packs. I now want taps on all of my packs after seeing how much difference it can make and it is much safer also. Li Po Balancers work great ,best $40 investment I have made in LI Poly batteries. Yes I said batteries as it helpd maintain them in a healther/safer condition .I gained approximately 10% capacity from my old unbalanced packs after just a few balance cycles. I have read similiar results from others.

Taps / balancing here.
Charles


Quote:
Originally Posted by OneHump
Thanks for the advice everydayflyer; it's the most direct answer I've had on the topic.

On another note...

You guys should go easy on Hall Woo. He's doing a good job staying civil considering the (LiPo?) fire he's under. I'm not saying he's right, but he's a man with an opinion and has the right to be heard, regardless of being right or wrong.

I don't know the history here so I'll share my input as an outsider and leave it at that.

I will suggest, however, that Hall keep a couple of fire extinguishers handy. That's always good advice.

-OneHump
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Last edited by everydayflyer; Mar 17, 2005 at 06:27 PM.
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