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peterf
10-21-2005, 03:58 AM
I have 3 Polyquest 2200 mah 3 cell battery packs that failed to deliver rated 10C to 12C current of 22 amps at a mild temperature of 50 degrees f. Battery voltage dropped below BEC cutout set for 9 volts. Almost crashed my Mini Funtana. Motor cut out after approx. 30 seconds. Checked the battery with an Astro Wattmeter and sure enough battery voltage would decrease to 9 volts with a current draw of only 14 amps. Normally the battery delivered 23 amps at full throttle.

Only have 20 flights on each of the battery packs. Got a new battery and it tested OK at the same 50 deg temp.

All 3 batteries charged up OK and the voltage for each cell in the packs was 4.2 volts +/- .01 volt. Used Thunder power TP-405 balancer when I charged the cells. Are tthe batteries now throw aways? Any suggestions from you experts?

hoppy
10-21-2005, 04:28 AM
Hello peter,
No expert, but here's some data. Sanyo has a 1C graph of temperature effects on voltage and capacity. It does show a degradation which I assume will be magnified at higher discharge rates.
http://www.sanyo.com/batteries/pdfs/polymer_E.pdf
It would be interesting if you warmed the packs to say 80F and tried them again. They should warm up at a 10C draw.

Are these the slim packs? I think PQ had some 4C rated 2200's. They were the fat packs as opposed to the new "slim" 10C packs.

20 flights is a bummer. Got any 6C applications?

Glacier Girl
10-21-2005, 11:57 AM
Peter,
If I read your post correctly you were pulling 23 amps from a 2200 pack.
That's above the recommended 80% of max output,that most suppliers recommend for pack life. It could be the combo of temp and what you are trying to draw from the pack is contributing to short life span.
Temp will definetly affect performance. I fly all winter, packs are kept in a case with a hand warmer to keep them warm until used. But even with this, duration does drop off.

Matt Kirsch
10-21-2005, 02:06 PM
peterf, while cold weather does affect the performance, it doesn't ruin the packs. The performance should normally return with warmer weather.

50 degrees F doesn't seem to me like terribly cold weather, though. You shouldn't have any noticeable performance loss until you get down to where it's uncomfortable to fly with bare hands...

How are you using these packs? Are you expecting them to provide 10 to 12C on a continuous basis? Unfortunately, "continuous" doesn't mean continuous in this case... It's only truly continuous in perfect lab conditions with ways to keep the packs from heating up past their ideal operating temperatures.

If you use 'em hard, you gotta expect to replace them often, I'm afraid. People often wonder why we need 20C cells....

Unbalanced prop
10-21-2005, 05:01 PM
I have noticed a large drop off in lipoly performance when temps are in the fifties. If I go flying and it is 60 or below, I usually keep a couple packs in my pocket which helps a lot. Just make sure you don't have anything else in your pocket that could short the pack:eek: Man that could HURT!

Doug

flypaper 2
10-22-2005, 01:20 AM
Last winter was flying at 10 above F at times, brrr ,hate the thoughts of it coming. Lipo would only run for 5 mins. to cutoff didn.t matter what capacity they were. So I made an envelope from that thin foam that some electronics devices come wrapped in. About 1/8 in thick made to fit the size of the batt. Just scotch taped together with the closure held with velcro to change batts. Batt. generated enough heat to keep itself warm. If weather warmed up, closure wasn't closed quite so tight. Envelope was velcroed in or on the outside of the fuse. Made a great handwarmer after a flight:D Felt would probably work too.

qban_flyer
10-22-2005, 01:38 AM
I have 3 Polyquest 2200 mah 3 cell battery packs that failed to deliver rated 10C to 12C current of 22 amps at a mild temperature of 50 degrees f. Battery voltage dropped below BEC cutout set for 9 volts. Almost crashed my Mini Funtana. Motor cut out after approx. 30 seconds. Checked the battery with an Astro Wattmeter and sure enough battery voltage would decrease to 9 volts with a current draw of only 14 amps. Normally the battery delivered 23 amps at full throttle.


HE, HE, HE. What you refer to as "mild" 50 degrees some of us, "Ye Olde Fartes" consider freezing, especially to those of us with cardiac conditions.

Since I don't go to the field anymore once the temps drop below 55 degrees, I have on opinion to render on this subject, though in the days when I was flying NIMHs (2002), I found them to give me less than their optimum in colder temperatures as compared to Summer.

peterf
10-22-2005, 04:17 PM
Hoppy

Thanks for the reply. I think I will use one of those chemicl pocket hand warmers to keep the batteries warm before I fly. Plan to heat the worst battery up to 90 deg in the oven then check the motor draw with a Astro Wattmeter.

peterf
10-22-2005, 04:24 PM
Glacier Girl

Thanks for the reply. My average flight time is 10 minutes which calculates out to be an average current of 13 amps. Only draw 23 amps taking off or going verticle. Problem seems to be cold temperature and some battery degradation. So far all the advice I have received point to cold batteries as the cause of the problem.

qban_flyer
10-22-2005, 07:27 PM
Plan to heat the worst battery up to 90 deg in the oven then check the motor draw with a Astro Wattmeter.

Careful while heating one of these up in an oven. A friend of mine accidentally left two new T/P packs inside his car during Summer. At the end of the day they looked like italian sausages, no longer flat and no longer usable.

Rugar
10-22-2005, 09:01 PM
I can feel a decrease in power anytime the temp falls below 70deg or so. I always have more power after my first flight of the day on any given pack if the temp was cool the night before making the packs cool or cold to the touch. But this is in Calif. where its usually warmer in a few hours after starting to fly for the day. I usually set a few packs on the dash of the truck on the way to the field to warm up from the defroster for my first few flights.

Gerald

peterf
10-22-2005, 10:11 PM
Qban

I Think The Oven Test Was A Bad Idea. Wasn't Thinking Rational. Wife Would Get Mad If I Blew Up Her Oven.

qban_flyer
10-22-2005, 10:39 PM
Qban

Wife Would Get Mad If I Blew Up Her Oven.

NAW! She'll love you more for having done so as the explosion will give her an excuse to "remodel" the entire Kitchen!:D :D :D

qban_flyer
10-22-2005, 10:42 PM
I can feel a decrease in power anytime the temp falls below 70deg or so. I always have more power after my first flight of the day on any given pack if the temp was cool the night before making the packs cool or cold to the touch. But this is in Calif. where its usually warmer in a few hours after starting to fly for the day. I usually set a few packs on the dash of the truck on the way to the field to warm up from the defroster for my first few flights.

Gerald

I have always noticed that effect with all types, including the good old Sanyo SCRC nicad packs. Less power, less duration and longer charging times once the temps fell below 60 degrees.

Why? I have no clue as to what causes it, but I know it does happen.

hoppy
10-23-2005, 12:15 AM
Qban

I Think The Oven Test Was A Bad Idea. Wasn't Thinking Rational. Wife Would Get Mad If I Blew Up Her Oven.

You could put it in a Ziploc bag and place it in a bucket of 100F water....

qban_flyer
10-23-2005, 12:29 AM
You could put it in a Ziploc bag and place it in a bucket of 100F water....

Now, that's what I call a brilliant idea if one wanted to test what effect heat vs. cold have on a battery pack's performance theory.

The very reason I love Watt Flyer, someone is always bound to come up with a solution to somebody else's dilemma.

flypaper 2
10-24-2005, 02:07 AM
Flying buddy bought one of those little insulated boxes that will refrigerate or heat. Thermostatically controlled and runs off a 12 volt batt. Set thermostat for, i think around 90 F. Keeps the batts. warm for an afternoons flying with those batt. socks I mentioned above. :D Four Batt chargers run off the same batt.

qban_flyer
10-24-2005, 03:05 AM
Flying buddy bought one of those little insulated boxes that will refrigerate or heat. Thermostatically controlled and runs off a 12 volt batt. Set thermostat for, i think around 90 F. Keeps the batts. warm for an afternoons flying with those batt. socks I mentioned above. :D Four Batt chargers run off the same batt.

Can you elaborate on those marvelous boxes you are talking about? Who makes them and where can we buy them?

Thanks

flypaper 2
10-24-2005, 04:15 AM
I'll give him a call tomorrow and get more details.

flypaper 2
10-24-2005, 05:55 PM
http://www.walmart.com/catalog/product.do?product_id=3942757 Not sure if this is the same one but the same idea. Hope this helps.

Unbalanced prop
10-24-2005, 07:07 PM
http://www.walmart.com/catalog/product.do?product_id=3942757 Not sure if this is the same one but the same idea. Hope this helps.

Now that looks really "cool" or "warm". :D I might have to check one of these out.

Doug

qban_flyer
10-24-2005, 07:20 PM
http://www.walmart.com/catalog/product.do?product_id=3942757 Not sure if this is the same one but the same idea. Hope this helps.

That's a rather nice thing to have in one's car for all occasions, and to be used for battery testing purposes too.

Thanks

peterf
10-25-2005, 04:34 PM
Hoppy

Good idea.

Pete

Brodjack
10-27-2005, 04:24 AM
hi,new to this forum.Running a 3s2p 5000mah pack in a heli,not drawing more than about 35 amps.
After reading the posts here and 'elsewhere' about dimished capacity in cool weather.My packs come down, after 12 min.or so, barely warm,almost no increase in temp! The packs have the spacers inbetween the cells and are strapped under the landing gear,getting full 20-50mph wind flow all the time.
Question,am I damaging them and reducing cycle life running them cold like this?
The packs are 'Tornado' 10-12C .15C bursts.Quite recently purchased,been told they are latest ones 'Flightpower'supplies.thanks......

flypaper 2
10-27-2005, 05:05 AM
Cooler temps. just shorten the run time. Yours are running just about ideal, I'd say. Welcome to the club.:p

qban_flyer
10-27-2005, 05:12 AM
hi,new to this forum.Running a 3s2p 5000mah pack in a heli,not drawing more than about 35 amps.
Question,am I damaging them and reducing cycle life running them cold like this?
The packs are 'Tornado' 10-12C .15C bursts.Quite recently purchased,been told they are latest ones 'Flightpower'supplies.thanks......

Usually brand new Li-Pos take a few cycles to develop and deliver their full power. That may be the case with yours. I know it is with my Thunder Powers. That could be why after 12 min of flying time they begin to peter out. IMHO, I would consider this normal.

10C of 5 amps (5000mAh) is 50 amps and 15C would be 75 amps. Since you are not drawing more than 35 amps I see no reason why your packs would get damaged. You have't even reached their maximum constant current draw yet, much less their allowed burst limit.

It hasn't been proven that running Li-Pos in cold weather damages them either. Perhaps we may not be getting their full power as opposed to using them in warmer weather, but damage? I would think not.

Does your pack spec sheet/owner's manual gives the safe ambient temperature operating range? If not, then I would not worry about it.

peterf
10-28-2005, 05:39 PM
Brodback

Read some good info published by FMA direct on Lipo Batteries (3 documents). Learn all you can before investing in Lipo's otherwise you can get burned (financially) in addition to other hazards.

When you buy Lipo's, take the discharge ratings of 8C, 10C or 20C as a guideline only. For long life the Lipo ratings should be derated 20% to 50%from the continuous rating (ie. 10C should be derated to 8c or 5C).
The projected life of a cell derated by 50% is over 500 charge/discharge cycles.

If you have lots of bucks run the hell out of the batteries at their specified ratings and expect to buy more batteries sooner than you anticipated.

qban_flyer
10-28-2005, 06:15 PM
Brodback

Read some good info published by FMA direct on Lipo Batteries (3 documents). Learn all you can before investing in Lipo's otherwise you can get burned (financially) in addition to other hazards.

When you buy Lipo's, take the discharge ratings of 8C, 10C or 20C as a guideline only. For long life the Lipo ratings should be derated 20% to 50%from the continuous rating (ie. 10C should be derated to 8c or 5C).
The projected life of a cell derated by 50% is over 500 charge/discharge cycles.

If you have lots of bucks run the hell out of the batteries at their specified ratings and expect to buy more batteries sooner than you anticipated.

If I had had all that info available to me before I spent a small fortune on Li-Pos I would have either stayed the hell away from them, or treated them differently.

The industry at large touted them as the batteries to end all batteries. Discharge rates with Li-Ion was rather modest, but at least I will like to believe it was honest.

Enter the Li-Pos and everything went through the roof. I should have known better than to trust everything that was being printed. It's too late for that now, though. I've been burned again.

It also explains the high failure rate and lackluster performance of some brands over others, and how eager some of them are to replace the 'defective' packs.

Their names shall remain in obscurity, for it is not my province to disclose it, most consumers will do that on their own. In the end these unscrupulous manufacturers will lose the consumer's trust.

I feel sorry for the guys I know have spent hundreds of $$$ on packs and fancy pant chargers for their really big birds.

:o :o :o

Unbalanced prop
10-28-2005, 06:28 PM
Right on qban!! Some lipolys measure up to their claims and some don't.:confused: It's just a shame I have to spend a bunch of money to find out the truth. I have been burned some, but not tooooo much. Beware of the "bargain" lipolys. Some have an honest C rating and some don't, and some last and some don't.

I will agree with peterf........don't abuse them too much and most cells will last longer, but some cells won't give good service unless you use them to power your cell phone. That being said, (good) lipolys have sure made electric flying much better and a lot more fun. End of rant!!

Doug

qban_flyer
10-28-2005, 07:24 PM
Right on qban!! Some lipolys measure up to their claims and some don't.:confused: It's just a shame I have to spend a bunch of money to find out the truth. I have been burned some, but not tooooo much. Beware of the "bargain" lipolys. Some have an honest C rating and some don't, and some last and some don't.

I will agree with peterf........don't abuse them too much and most cells will last longer, but some cells won't give good service unless you use them to power your cell phone. That being said, (good) lipolys have sure made electric flying much better and a lot more fun. End of rant!!

Doug

So far I have decided to stick with Thunder Power Li-pos. They have served me well and so far have proven to be reliable.

One thing I have been doing from the get go with Li-Pos is to charge them at 70% of "C". Unfortunately, when it comes to discharge rates I took some manufacturer's discharge rates as listed on their packs to be the gospel truth, only to find out through some of Watt Flyer's postings that those discharge rates, as claimed by some manyfacturers, is their burst rating, not continuous.

Can you imagine what I have been doing to some of those packs? You can rest assured they won't be getting my money unless the continuous as well as burst rates are printed on the packs!

Thunder Power gives both ratings. May not look impressive when compared to some others, but I am not buying Li-Pos because I am impressed with a rating that although "great looking on paper" might be as phony as a three dollar bill.

I want and demand honesty from manufacturers. The ones who cheat me, won't get my $$$. They have dissapointed me, and as far as I am concerned, they don't exist.

Brodjack
10-28-2005, 10:59 PM
Hi thanks for the advise,I,ve actually been running lipos for about 30 months.Have about 14 packs.Got'stung' first few 'large' 3s2p 5000 packs running them in series in a large heli.Burnt tabs,running them down completely,just didnt know! Lasted less than 15 cycles!
Now i dont use more than 2/3 capacity,charge at 50% C rating.Had no problems.Run them in gently etc.
I think the 'smaller' packs do seem to behave better, could be less volts,amps,watts through the tabs on the cells.Possibly staying in balance better also.
Certainly wouldnt like to run 10s2p packs like the powerful large heli guys do.Too risky,too much money.I went to 20 cell nimh in mine after the lipo disasters,could run them down completely and fast charge in 1/2 an hour.
Lipos are great for the smaller planes,helis.though.3s is the max.I would use.
Hopefully not ruining my latest ones running them too cool.........
Brodjack.........

qban_flyer
10-29-2005, 12:01 AM
Now i dont use more than 2/3 capacity,charge at 50% C rating.Had no problems.Run them in gently etc.
I think the 'smaller' packs do seem to behave better, could be less volts,amps,watts through the tabs on the cells.Possibly staying in balance better also.
Certainly wouldnt like to run 10s2p packs like the powerful large heli guys do.Too risky,too much money.I went to 20 cell nimh in mine after the lipo disasters,could run them down completely and fast charge in 1/2 an hour.
Lipos are great for the smaller planes,helis.though.3s is the max.I would use.
Hopefully not ruining my latest ones running them too cool.........
Brodjack.........

Good practice.

Too bad some "manufacturers" have been less than candid with us regarding the true rating of their packs both in continuous current as well as burst rates.

Running them too cool won't hurt them at all. That's the way I run mine.

Steve
10-29-2005, 01:49 AM
Well...to get back to the original question...running in cold weather. I've seen some research that shows batteries in cold weather running at lower voltages and max amps. It makes sense really. If you take a battery off the charger then keep it relatively warm, it should be fine. It'll warm up when you're flying, so that will help as well.

I guess the other issue is how cold the ambient temp is. Big diff between 35degF and -0degF!

fallsflyer
10-29-2005, 02:20 PM
Appreciate the thread. I flew an e-converted Nitro Rascal (the ~48" WS variety - a very delightful setup, to be sure!) on skis all last winter. On a couple of occasions at -10 degrees off of Rainy Lake in northern Minnesota. Used TP 1320 3-cell with no problem other than about a 5 min. decrease in duration (normally 20 min. down to 15 min.). I attributed the difference to the same factors that decrease my auto gas mileage in winter - increased friction on the moving parts. I did pay attention to keeping batteries warm preflight, but also found that the battery does maintain its own heat as it gives up amps.