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Old Aug 11, 2007, 06:03 PM
No Guts, No Glory
flyin C's Avatar
Simi Valley, CA
Joined Feb 2007
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yep, I got so tired waiting that i just set it to .75. i started charging it at 40% left
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Old Aug 11, 2007, 08:01 PM
War Eagle!
Spackles94's Avatar
Birmingham, Alabama
Joined Feb 2007
7,876 Posts
Quote:
Originally Posted by flyin C
yep, I got so tired waiting that i just set it to .75. i started charging it at 40% left
I've been having similar instances with my Cellpro 4S when I set it to 1C. Sometimes it'll start charging and go up at more than 2C and eventually come down, and sometimes it'll stay at about .8C or so on some other packs. No biggie, it's not like I'm in a huge hurry and need the packs right away...

I used to set the charge rate manually, back when most of my cells were in the 900 mAh to 1300 mAh range. I'd just set it at 1A and be done with it. Then I got some 200mAh packs (if you can call them that ) and I figured that I wouldn't want to take my chances and accidentally charge them at 5C! So now I let the 1C thingy do the work... even if it oscillates back and forth. I trust the Cellpro enough, though I do wait a few minutes after I plug it in, just to make sure everything's OK.
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Old Aug 12, 2007, 12:28 AM
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Ventura, CA
Joined Jul 2006
1,854 Posts
Quote:
Originally Posted by flyin C
yep, I got so tired waiting that i just set it to .75. i started charging it at 40% left
Set your Cellpro to 1.0C, connect your pack, wait for it to finish, and stop looking at the display!

Seriously, your Cellpro sounds like it's working fine. It hunts, it overshoots sometimes at first, sometimes it undershoots. Overall you'll charge at about 1.0C, maybe a bit higher, maybe a bit lower. Again, it can't read the label on the pack and needs to figure out the capacity. I haven't heard of a cellpro damaging a pack yet, but I have heard it stop charging because the pack itself was bad, crashed, low, etc.

DON'T WORRY ABOUT IT!! Really.

Dave
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Old Aug 15, 2007, 04:21 PM
Lipo abuser ... smoke on!
gp125racer's Avatar
Joined Feb 2005
1,921 Posts
my first lipo fire

I had my first lipo fire with a 3s pack out at the field during my formosa maiden. The fire was a result of my own mistake, I was using a hatpin to secure the canopy and pushed it down into the fully charged pack. The flames arent really visible in the photos, but they wre present and fairly substantial.

The pack went off like a firework, in stages. When the first cell went off it was really pumping and after about 15 seconds or so it dwindled, only to be followed by a maddening surge from cell number 2.

Please be safe with your lipos, I have a new outlook on how volatile they are.


gp125racer
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Old Aug 15, 2007, 04:34 PM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
21,182 Posts
Thanks for posting your experience. Many modelers still don't believe that puncturing a lipo can cause it to ignite. Hopefully, your experience and posting will prevent it from happening to someone else.
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Old Aug 15, 2007, 08:51 PM
Watts is life...
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Actually many of the lipo user that I know reuse puffed packs regardless of what I’ve warned them about… They are mostly glow fliers moving to cheap electrics because they can fly earlier in the morning.

I hate to say this, and don’t want a flame war but old timer IC guy’s are the worst abusers of lipo safety. Just for the record, I’ve been flying as far back as Kraft radios.

Bob
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Old Aug 16, 2007, 12:06 AM
characters welcome!
Mark Wood's Avatar
United States, CA, Bear Valley Springs
Joined Feb 2000
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Bob, I wouldn't argue your point for a second.

mw
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Old Aug 16, 2007, 09:43 AM
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The Northeast Kingdom, Vermont
Joined Jun 2004
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Maybe I'm the exception to the rule here guys
Been flying glow since the 50's (CL) and started with E-powered gliders almost 20 years ago (you definitely were the butt of a lot of jokes back then)
When I decided to go with lipos, I did the homework and have had very good results. OK maybe I cheated a little, as I'm a retired electronics tech.
BTW Bob, I lived for 41 years in Monmouth/Ocean, know the turf well
Do you fly at Dorbrook park? I flew with the Pine Barren Modelers for many years at Coyle Field out on Rt.72, Mofflers? We don't neeeed no steenking mofflers
Regards,
Pete
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Old Aug 16, 2007, 12:59 PM
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Joined Dec 2004
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Bob,

I appreciated your post above and agree with your comments. I knew Phil Kraft personally and flew with he and others like Howard Bonner, Bob Dunham, Cliff Weirick and others in the Larks R/C club when I first started in R/C. I guess that qualifies me as an old timer. I still fly glow but lately I have enjoyed the convenience and performance that is now available with electric. Before I built my first modern electric I spent a lot of time reading everything I could find on the subject. This board has been invaluable to me and continues to be so. I read the new posts nearly every day. I highly recommend it to any newbie to electrics as the best source available. What I read here quickly convinced me to respect and follow the safety requirements for this new technology and I have avoided any problems so far.

Dick J.
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Old Aug 16, 2007, 01:39 PM
Watts is life...
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I felt that I needed to expand a bit more on what type of “risks” I regularly observe.

The field has several park benches/tables which are really nice to have, you can work on them, sit, have lunch, etc. It’s also a magnet for folks to leave lipo packs out in the backing sun for hours at time.

Electric setups are still a black box to folks, I sometimes get asked about how hot my packs are after a flight. Then I’m shown a pack they have which is very hot after a flight, and most times it’s puffed. When I explain that the cause is likely over current , which leads to explaining ”C” ratings, which leads to the need for checking a setup with a watt meter, etc. The outcome is usually something like “fuel is simpler”, or what size pack should be used. Again, I come back the say response; you need to put a watt meter on the setup to see what the current draw is…

Packs are rarely stored in a manor that I would consider, reasonably safe. For example, I’ve seen half a dozen packs tossed in a wooden box with a good amount of rc stuff, tools, screwdrivers, small bolts, screws, hardware, glue, etc.

Rarely do I see packs charged in anything that resemble a fire safe container. Mostly its charger and pack sitting in the back of the hatch back of the car, which of course is also exposed to the backing sun.

Now, I tend not to say much at the field. Part of the reason is that I’d prefer to spend quality time with the club members, enjoy the day flying, etc. Electric is still small part of the 140+ member club, but it continues to grow. This is good for me as it becomes more acceptable from the IC fliers to welcome the e-guy’s

I still to this day, fly at times when the field is likely to be less crowded, so I can feel more comfortable landing a belly flopper. The club is great, and almost all the folks are fun to be with, so I stay low on the comments about lipo use, fly my stuff, and call it a day.

Bob.
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Old Aug 16, 2007, 11:17 PM
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Groton NH USA
Joined Feb 2002
238 Posts
cautious Li-Po's

The posts here are invaluable. You guys come together to share info and warn others.

Great thread for sure.

I do glo, ni-cad (old stuff now) nimh (getting pretty old stuff) and now in the past two years Li-Po.

We run Helis,planks,foamies,boats,4x4 trucks,2x cars. Converting to brushless and Li-po has just opened up a whole world for us.

Now the weight factor on a repair is not so criticle.

Planes that were too heavy because of my too many repairs, now screams accross my back yard view.

We have had our close calls. Li-po's are not something to take lightly.

I use a Wally World fire proof strong box for our charging. Drilled through the side (should seal with silicone after) and mounted wire and charging jacks from my chargers into the box.

This way I can lock it up on a charge cycle.
I even have another strong box (fire proof) that I use to store the li-po batteries in.

We have charged on hand at any point in time around 20 Li-poly batterys.

The nimh and nicad batteries have become very complacient with all of us.
I suppose in a couple of years we would treat Li-poly the same.

As for now, I have way too much invested in my workshop to take a chance while charging Li-Poly batteries.

I wouldnt let my Jeep warm up inside and neither would you.
I wouldnt use a kerosine space heater to heat my house and neither would you.
I wouldnt use a BBQ inside and neither would you.

lol
If you did, you won't be around long.

Keep up the good work guys! keep the sunny side up on anything your doing.
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Old Aug 17, 2007, 11:40 PM
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Joined Aug 2007
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I think if your friend used the balance charger, the accident can be avoid. Besides, I have purchased some device called " Power Indicator". That can indicate the li-po battery power independently, then the battery will never be discharger. So I like this one.
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Old Aug 21, 2007, 01:52 PM
No Guts, No Glory
flyin C's Avatar
Simi Valley, CA
Joined Feb 2007
2,024 Posts
So I charged my battery at 1C. It started charging at 32% and withing 4min it was at 76%. I came back to check on it and it was charging at over 2C!! At 2.4 amps on my little 2s 900mah battery. I guess I will just charge it at .75amps...

They say that the Cellpro 4s is basically impossible to damage your batts. But if its charging at over 2C then its IS damaging my battery, is it not??
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Old Aug 21, 2007, 02:42 PM
Frankenstein recycled packs
rampman's Avatar
USA, AZ, Gilbert
Joined Jan 2006
8,849 Posts
Yes, it is. Buy a true balancing charger and be safer. Consider yourself lucky you caught this.

Rick
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Old Aug 21, 2007, 02:57 PM
Micro Flyer "Q"
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United States, MD, Silver Spring
Joined Sep 2003
1,416 Posts
Quote:
Originally Posted by Toywizard
The posts here are invaluable. You guys come together to share info and warn others.

Great thread for sure.

I do glo, ni-cad (old stuff now) nimh (getting pretty old stuff) and now in the past two years Li-Po.

We run Helis,planks,foamies,boats,4x4 trucks,2x cars. Converting to brushless and Li-po has just opened up a whole world for us.

Now the weight factor on a repair is not so criticle.

Planes that were too heavy because of my too many repairs, now screams accross my back yard view.

We have had our close calls. Li-po's are not something to take lightly.

I use a Wally World fire proof strong box for our charging. Drilled through the side (should seal with silicone after) and mounted wire and charging jacks from my chargers into the box.

This way I can lock it up on a charge cycle.
I even have another strong box (fire proof) that I use to store the li-po batteries in.

We have charged on hand at any point in time around 20 Li-poly batterys.

The nimh and nicad batteries have become very complacient with all of us.
I suppose in a couple of years we would treat Li-poly the same.

As for now, I have way too much invested in my workshop to take a chance while charging Li-Poly batteries.

I wouldnt let my Jeep warm up inside and neither would you.
I wouldnt use a kerosine space heater to heat my house and neither would you.
I wouldnt use a BBQ inside and neither would you.


lol
If you did, you won't be around long.

Keep up the good work guys! keep the sunny side up on anything your doing.
That is what I told my next door neighbor when we were invited over for tea. They were keeping the tea hot by having the kettle atop an electric burner that in turn was sitting on a small wooden box "on" their living room carpet. We own a duplex and although both dwellings share a common firebreak wall, it scared me to see that electric burner (visible in pix #7) so close to the carpet.

Two months later I smelled a very strong odor of gasoline coming from their house while I was in my basement. It was rather scary, so I went and knocked on their door to warn them about the smell. When they opened the door, all of them were on all fours, scrubbing the hardwood floors with a mixture of gasoline and kerosene in preparation for "refinishing" it. I was told everything was OK, that they "knew" what they were doing and that I was worrying tooo much.

Last month on the 19th there was a conflagration in that house that began around 4am. It took the fire department until past 1PM to finish putting the fire out.

Why am I telling you this? There are many out there that have their craneal cavity filled with rotten sewage instead of brains. Unfortunately we have a few of these in the RC hobby, I hate to think of them and Li-Pos. A dangerous combination to say the least.
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