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GallopingGhost
11-02-2005, 03:34 AM
As a new user to Li Po's I have noticed a problem turning up in several 11.1 packs I have been using. Not knowing how to properly check them after seeing a power loss I checked the voltage. They all check out around 12.3 to 12.6. I have a 1050MAH 11.1 pack that still runs fine and it checks at 12.3. Is it something I am missing here or could I have a charger problem?

roccobro
11-02-2005, 06:40 AM
Two things, first what capacity pack is it in question, and how much capacity is it currently putting out? The difference in capacity between a pack charged to 12.3 and another pack the same size at 12.6 is quite a bit. Some have noticed (mostly under tests) a difference in capacity between a pack charged to 12.5 and one to 12.6. You can test the capacity by first charging to a full 4.2V/cell (12.6 for a 3s), then discharging it at a metered and timed rate (or use an wattmeter as it logs the mah taken). If no Wattmeter, you can discharge it at x-amps for x-time, you can calculate the mah used at teh end when the pack reaches 3V/cell (9v for a 3s).

Second-Are there any voltage taps so you can check the individual voltage? I had 2 3s Gen TP packs (no taps) that were showing lowered capacity. They would hit the LVC sooner, and had lower voltage under load than normal. They were rated for 1900 and only took in during a charge and put out 1450 under discharge tests. These cells had only about 6 charges in the last year so I opened them up. Sure enough, one cell in each pack was lower than the rest. When this occurs, the low cell never gets a full charge, and subsequently hits the "danger zone" of 3v under load before the rest do (below 3v there is almost zero capacity and voltage drops FAST). As long as the cell hasn't been too damaged, a slow charge (.1-.5C) to match up to the rest of the cells can (temporarily) fix the problem.

Should there not be a cell out of balance, or after the cell balance has been fix and there still is the reduction in cell capacity (a loss of more than 20% caoacity) they might just be "on their way out" and you'll need a replacement someday. It sucks to loose such a big investment, but the good news is there are some great cells on the market now, and they aren't as expensive per cell as they were back when the 1050 was king. :)

Hope this helps some. :)

Justin

watt_the?!
11-02-2005, 07:18 AM
good reply 'bro.. me thinks that the question might be ''why can we charge to 12.6V for an 11.1V pack?

unless im missing something of course...which wouldnt be the first time.

roccobro
11-02-2005, 07:22 AM
Ah Frap! :D We'll see....

Justin

Rugar
11-02-2005, 09:03 AM
What has the air temps been where you live? Colder then normal? Lipo's will produce much less power when cold. I notice a decrease in performance at anything below 60 deg F or so. I set my Lipo's on the dash of the truck on the way to the field in the winter to keep them warm, and I live in SoCal. I heard from alot of flyers last winter who live in much colder climates, who said that there Lipo's were hardly flyable.

Gerald

Rugar
11-02-2005, 09:09 AM
Ah Frap! :D We'll see....

Justin

Justin,
We need to hook up sometime. We have talked on both message boards now, we live in the same town, and I was even keeping a eye on your wife for you :p, and we have never met!

Now, back on topic :D.

Gerald

GallopingGhost
11-03-2005, 03:24 AM
Thanks for the replies, I have a feeling the BP21 is asking too much in amps and perhaps it is a charging issue since it is also happening with a almost new TP 730. I have a friend that just ordered a $200.00 Graupner charger that we will give a try. As for temperature its been in the 60's here in NC which should be ideal. Sorry not voltage taps on the TP 730 or the generic 1050's. For the most part the packs are at about 1/2 power from a fresh charge even though they test at 12.3 to.6. I must admit these were mostly Ebay Chinese Lipo's made for the E-Sky Heli.
I have passed through your neck of the woods going from Vegas to L.A. I remimber stopping at the Hwy 66 and I-15 burger place in Rancho Cucamonga, any idea what Rancho Cucamonga means in English? What ever the burgers were good there! My hat is off to you if you drive L.A. to San Bernardino in rush hour traffic!

Rugar
11-03-2005, 04:06 AM
Thanks for the replies, I have a feeling the BP21 is asking too much in amps and perhaps it is a charging issue since it is also happening with a almost new TP 730. I have a friend that just ordered a $200.00 Graupner charger that we will give a try. As for temperature its been in the 60's here in NC which should be ideal. Sorry not voltage taps on the TP 730 or the generic 1050's. For the most part the packs are at about 1/2 power from a fresh charge even though they test at 12.3 to.6. I must admit these were mostly Ebay Chinese Lipo's made for the E-Sky Heli.
I have passed through your neck of the woods going from Vegas to L.A. I remimber stopping at the Hwy 66 and I-15 burger place in Rancho Cucamonga, any idea what Rancho Cucamonga means in English? What ever the burgers were good there! My hat is off to you if you drive L.A. to San Bernardino in rush hour traffic!

I dont have a clue what RC means. :confused:
No traffic for me. I work from my house. :D

Since its all your packs with the problem, I would look harder at the low temp issue. How cold does it get at night where your packs are stored? It could be that the packs get so cold at night that they dont warm up much before use if your only in the 60's during the day. If they were to get down to say in the 30's at night and the packs got that cold, it would take them along time to reach 60deg. I keep my packs in the house so they are always at room temp before leaving for the field. Try to get a pack warmed up to around 90deg before flying and see if your issue goes away or not.

Gerald

roccobro
11-03-2005, 04:17 AM
Traffic is for the birds! I would shoot myself if I had to trek that commute. :D Rancho Cucamonga- Where the hoyty toyty live. Used to work there, nice place just to rich for my Foamy blood. :p

Gerald, name the place and I'll be there. I have very few appointments in my schedule for the next couple weeks. Gotta get some planes airworthy and that would be a great excuse. :)

GG- What are the temps of your batts after a flight? Hot or warm? Have you ever tried "preheating" your packs like Gerald mentioned? If I am in the groove, I heat a neck pillow that has sand in it, and put my packs in it for the trip to the field. Makes a difference in the lipo voltage, even a noticeable difference in a single cell Wattage Microflyer or Rookie.

Justin

EDIT: Gearld posted while I was typing! :p

qban_flyer
11-03-2005, 04:24 AM
good reply 'bro.. me thinks that the question might be ''why can we charge to 12.6V for an 11.1V pack?

unless im missing something of course...which wouldnt be the first time.

A freshly charged single Li-Po cell should measure 4.2 volts for a short period of time under load. It's a native characteristic of the beast! 4.2 times 3 equals 12.6V.

GallopingGhost
11-03-2005, 05:12 AM
I store my stuff in my basement workshop around 65 degrees. I'll try the same packs on a E-flite 400 outrunner and E-Flite controller and see if they work on that combo. I have a feeling they can't deal with the BP21 draw.

roccobro
11-03-2005, 07:17 AM
With an GWS 8040 prop, my BP-21 was pulling a little over 12amps on 3s. Do you know what your is with the prop you use? Might be too big a current draw for that pack.

Justin

hoppy
11-03-2005, 02:01 PM
I store my stuff in my basement workshop around 65 degrees. I'll try the same packs on a E-flite 400 outrunner and E-Flite controller and see if they work on that combo. I have a feeling they can't deal with the BP21 draw.

They probably will choke on that speed 400 too. You probably would need about a 1500-1800mah capacity pack to comfortably provide 12A continuously (without damaging the pack).

GallopingGhost
11-03-2005, 10:52 PM
With an GWS 8040 prop, my BP-21 was pulling a little over 12amps on 3s. Do you know what your is with the prop you use? Might be too big a current draw for that pack.

Justin

I've been running a 9 3.8 on it most of the time. A 10 3.8 has been used and it got both the pack and motor a little warm but didn't seem to be any worse. I dropped backto the 9 3.8 before the batteries started showing problems. I haven't checked the current draw but it seems to be the problem at least in the packs I have. Some newer Lipo's may be able to stand it.

Matt Kirsch
11-04-2005, 01:09 PM
I can tell you right now that that's your problem, GG.

Balsa Products posts a chart on their website for the BP21. They call for 13.1 Amps on a 3S LiPoly (11.1V) with the stock 8x4 prop. You're running an even bigger prop than that, and I'd expect your current to be around 15 Amps if your packs could handle it. Bigger prop, more Amps.

The 730 and 1050 packs you're using are probably rated at 10C, no more than 12C. Multiply the C rating of the pack by its capacity in mAh, then divide by 1000 to get how many Amps the pack is capable of producing. The 1050 pack can only handle 10.5 Amps if it's rated 10C, and the 730 pack can only handle 7.3 Amps. These values are the hard limit, not something that you can ignore if "it's only a little bit more." The packs are being overstressed, plain and simple.

When planning an electric power system you have to make sure the packs are rated to handle AT LEAST as many Amps as the motor will draw. Then if you're going to cut it close to save weight, you need to practice throttle management and not roar around at full throttle from launch until the battery goes dead. If you want to roar around at full throttle, make sure the battery pack is rated for at least TWICE as many Amps as the motor will draw. Anything else is just plain expensive...

GallopingGhost
11-06-2005, 07:16 PM
I can tell you right now that that's your problem, GG.

Balsa Products posts a chart on their website for the BP21. They call for 13.1 Amps on a 3S LiPoly (11.1V) with the stock 8x4 prop. You're running an even bigger prop than that, and I'd expect your current to be around 15 Amps if your packs could handle it. Bigger prop, more Amps.

The 730 and 1050 packs you're using are probably rated at 10C, no more than 12C. Multiply the C rating of the pack by its capacity in mAh, then divide by 1000 to get how many Amps the pack is capable of producing. The 1050 pack can only handle 10.5 Amps if it's rated 10C, and the 730 pack can only handle 7.3 Amps. These values are the hard limit, not something that you can ignore if "it's only a little bit more." The packs are being overstressed, plain and simple.

When planning an electric power system you have to make sure the packs are rated to handle AT LEAST as many Amps as the motor will draw. Then if you're going to cut it close to save weight, you need to practice throttle management and not roar around at full throttle from launch until the battery goes dead. If you want to roar around at full throttle, make sure the battery pack is rated for at least TWICE as many Amps as the motor will draw. Anything else is just plain expensive...

Ok, looks like I may be better off buying a Watt meter and watching what is going on. I understand the math but I like the idea of checking with a meter. Is the AstroFlight Super a good one?

qban_flyer
11-07-2005, 12:58 AM
Ok, looks like I may be better off buying a Watt meter and watching what is going on. I understand the math but I like the idea of checking with a meter. Is the AstroFlight Super a good one?

It definitely is worth its price of addmision. I have one myself and it comes in handy all the time. Would not live without it!:)

Rugar
11-07-2005, 01:20 AM
Ok, looks like I may be better off buying a Watt meter and watching what is going on. I understand the math but I like the idea of checking with a meter. Is the AstroFlight Super a good one?

It sure is. I used mine several times today.

GallopingGhost
11-07-2005, 02:03 AM
It sure is. I used mine several times today.

I'll be in business in about 5 days, got one coming. I ordered some extra connectors so it will work with JST and Deans Ultra. I still amazed the JST's have been up to the task as small as they are.

roccobro
11-07-2005, 06:12 AM
As long as they are new (or not sloppy) they work great. I have put some to test with 20 amp draws. I don't keep them very long before the Deans micros go on. :)

Justin

qban_flyer
11-07-2005, 07:40 AM
As long as they are new (or not sloppy) they work great. I have put some to test with 20 amp draws. I don't keep them very long before the Deans micros go on. :)

Justin

I had several JST connectors melt on me before they reached 9 amps. Switched to Deans Micros and have pushed them to 15 amps without them getting barely them warm.

I use Dean Micros exclusively on everything under 12 amps. Above that I go to Deans Ultras.

GallopingGhost
11-07-2005, 11:09 PM
As a update to my original battery woes. I have a friend that just got a new Graupner $200.00 charger that is running tests on them. Most come up 1/2 or 1/3 rated capacity. One TP 730 pack was reading over 14 Volts! Two of the packs were Chinese Ebay specials that never made a flight!

qban_flyer
11-08-2005, 12:40 AM
As a update to my original battery woes. I have a friend that just got a new Graupner $200.00 charger that is running tests on them. Most come up 1/2 or 1/3 rated capacity. One TP 730 pack was reading over 14 Volts! Two of the packs were Chinese Ebay specials that never made a flight!

A freshly charged Li-Po "individual cell" should read 4.2 volts. If your Thunder Power pack is four cells then it's no inconceivable that it should read 14V as when freshly charged it will deliver 4.2X4=16.8V.

You don't mention what the cell count on the T/P 730s is so I can't comment any further on them. Regarding the Chinese packs you purchased through eBay, all I can say is that one gets what one pays for. I will never buy unknown products from unknown manufacturers and or distributors, especially when it comes to Lithium battery packs.

I have never had any problems with Thunder Power or Kokam batteries.

roccobro
11-08-2005, 07:59 AM
Regarding the Chinese packs you purchased through eBay, all I can say is that one gets what one pays for.

:eek: Careful there are some that think price has no bearing on quality. I had one gent on another forum (guess which :rolleyes:) that was so upset by a similar statement I made that he went and bought a whole bunch of the product in question to spite me. Man, that hurt my feelings. :p But I agree. Caveat Emptor- Buyer beware

Justin

qban_flyer
11-08-2005, 05:31 PM
Man, that hurt my feelings. :p But I agree. Caveat Emptor- Buyer beware

Justin

HE, HE, HE!

Bet it hurt bad, didn't it? Was that other site the forbidden zone or the forbidden group? :D

GallopingGhost
11-08-2005, 11:38 PM
A freshly charged Li-Po "individual cell" should read 4.2 volts. If your Thunder Power pack is four cells then it's no inconceivable that it should read 14V as when freshly charged it will deliver 4.2X4=16.8V.

You don't mention what the cell count on the T/P 730s is so I can't comment any further on them. Regarding the Chinese packs you purchased through eBay, all I can say is that one gets what one pays for. I will never buy unknown products from unknown manufacturers and or distributors, especially when it comes to Lithium battery packs.

I have never had any problems with Thunder Power or Kokam batteries.

The TP 730 was a 3 cell. We are going to run it down to around 9 volts and cycle it on the Graupner whizz bang $200.00 charger. The date on the pack is 0604 so it was over a year old when I got it. It was bought as new from a guy in Florida that operates a on line shop. Got me thinking bad thoughts about buying from him again. So in this case maybe I didn't get what I paid for.......

roccobro
11-08-2005, 11:58 PM
Group. They fight dirty there. :p

Heard some great things about Dualsky/Vampower packs. I really wanna try some now! :D

Justin

qban_flyer
11-09-2005, 12:07 AM
The TP 730 was a 3 cell. We are going to run it down to around 9 volts and cycle it on the Graupner whizz bang $200.00 charger. The date on the pack is 0604 so it was over a year old when I got it. It was bought as new from a guy in Florida that operates a on line shop. Got me thinking bad thoughts about buying from him again. So in this case maybe I didn't get what I paid for.......

So in your case the 14V reading was not out of line. If your T/P pack has its voltage and capacity listed on a yellow highlighted band on the cell,you have the 10C-12C type which means it can withstand 7.3 amp draw continuously and 8.76 amps for no more than 15 to 20 seconds.

If you drew more than their rated capacity for longer periods of time, the pack is damaged beyond hope. Li-Pos do not tolerate being abused and give up the ghost rather quickly.

According to what I know about T/Ps and for what Matt says about your motor, I am afraid your batteries are damaged since that motor draws over 13 amps. You were drawing 179% of their safe current discharge rate, it's something no Li-Po will ever tolerate.