can773
Posts: 1652
Joined: 1/25/2002
From: Calgary,
AB, CANADA
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quote:
ORIGINAL: Greg Covey
ExFokkerFlyer,
I agree. I am not condemning the Saehan cells. Please keep in mind that ThunderPower is merely a pack maker and many vendors sell the same Saehan cells. For example, Impact which is distributed by RipMax in the UK.
The Kokam 4800mAh cells are new 20C cells that can deliver 100amps of current. Until recently, FMA Direct did not manufacture big packs due to liability issues which have now been resolved through cell monitoring techniques in the Cellpro and BalancePro HD lines. Recall Steve Neu's column in Quiet Flyer a year ago called, "The Good, the Bad, and the Ugly", which was about pack assembly quality. FMA's Kokam packs were the good and ThunderPower's were the ugly. A quality circuit board with proper strain relief on the discharge wires does add weight but it beats tabs soldered together and wrapped by strapping tape any day.
You can view the life cycle testing charts on RCU in this thread called, FMA Li Po Pack Life of 452 Cycles at Heavy RC Discharge Rates. It is obvious that the ThunderPower cells are over-rated.
Several units exist to monitor airborn current draw. I recently reviewed one that was easy to use on any system and simply connected to a USB port on your PC to download the data. You can read the review here. I am glad to see your passion for electric flight!
can773,
I agree. If the pack works for you, I cannot dispute that. The point that I seem to be failing to make is that a 1p solution will be superior to a 3p or 4p solution in general. The weight advantages of a 4p solution are negated and cell monitoring techniques are masked with parallel cells. Please review my links again as they are real data from independent sources. The cycle life data is from Nathan Gwozdecki. The independent sources are still setting up for automated cycle life testing. Nathan Gwozdecki has been doing this for many years now.
Running a pack for testing at 1C is no use at all. The data shown in my links makes it clear that the TP and TANIC packs get very hot, much more than a Kokam in either 3200mAh or 2P10S of the 2000mAh size. We already can show that the KOK 2000 goes 450 cycles while the TP 2100 goes 38 cycles at rated C. Adam states a 5S pack for F3A and at 60 amps he quotes that is only about 1250 watts when we know an F3A has to peak at about 2700 watts and run about 1750 watts average. I question whether Adam has ever flown an F3A airplane or equipped one to test it. I have nothing against Adam, I simply don't understand his point of view or justifications.
Some conclusions at this time:
- Thunderpower packs in the application at 2700 watts in a 3P config are drawing a peak of 75 amps or 25 amps/parallel pack. Even with cooling, the pack will reach at least 160 degrees and have a short lifespan.
- If you run a 1P pack of KOK 3200, it will reach 160 Deg F and have a short cycle life of about 50 cycles.
- If you run a KOK 2000 10S2P, that is about 35 amps and life cycle will be about 60 cycles.
- If you run a TANIC pack in 2p, it will go over 175 Deg F and fry in one or two runs.
- The KOK 3200 in 10S2P does not even warm up, delivers all that is needed in duration, and delivers by far the greatest wattage. The airplane has to be light to carry the 3.66 lb weight.
- The best pack for 2006 will be, without doubt, the KOK 4.8 AH at 2.5 lb. It will provide everything needed and give life cycle of at least 500 cycles.
Further Observations:
The only reasons that ThunderPower had any success at the competition level even at top class level can be summarized as follows:
- ThunderPower was giving away packs
- All the competitors were converting existing IC designs which were heavy airframes which meant that no KOKAM solution could be offered due to the 5 KILO weight restriction. The ThunderPower solutions were under powered on the vertical maneuvers compared to IC machines.
- The Patternship manufacturers know nothing about electrics or the art of building an electric airframe light enough but strong enough.
- A world-class F3A pattern plane draws over 90 amps on the pull up vertical maneuvers with a 10S voltage.
- At least 4Ah is needed to complete a single schedule with all likely wind conditions, 5AH is preferred for a strong finish.
- The pilot at this level needs the pack to be stiff during the schedule flight so that there is no power fade, remember these guys at top level are watching that plane like a hawk for the smoothness of flight and when he wants power it must be there immediately. They are judged on the presence of the flight .
Just read this post LOL,
Tom nailed most of it, but I would like to hit some more points
quote:
Adam states a 5S pack for F3A and at 60 amps he quotes that is only about 1250 watts when we know an F3A has to peak at about 2700 watts and run about 1750 watts average. I question whether Adam has ever flown an F3A airplane or equipped one to test it. I have nothing against Adam, I simply don't understand his point of view or justifications.
First thing....Adam has flown in two (2) F3A World Championships....and is a good friend of mine. He is extremely bright (studying engineering physics) and make solid conclusions and decisions (I am a professional engineer so I feel I have some grounds to make such assertions about him). So to come after him like that shows you have little knowledge of the person you are dealing with. If you have 1/2 the experience in F3A as he does I would be surprised 
We run 2200W peak draw which is plenty of power for F3A, that was Adam's setup. The CBA plots he has are of 5s packs as the CBA wont 1C discharge a 10s pack.
quote:
Running a pack for testing at 1C is no use at all.
Are you kidding? Ever heard of a capacity test? The point of a 1C discharge is to show capacity loss from new.
quote:
The point that I seem to be failing to make is that a 1p solution will be superior
I never argued that point, but show me one that exists first that works in F3A.
quote:
We already can show that the KOK 2000 goes 450 cycles while the TP 2100 goes 38 cycles at rated C.
Let me be perfectly clear....we dont run our packs at 15C continuous and dont do it in a white box with no cooling. These tests showing low cycle life and rediculous temperatures are meaningless.
quote:
Thunderpower packs in the application at 2700 watts in a 3P config are drawing a peak of 75 amps or 25 amps/parallel pack. Even with cooling, the pack will reach at least 160 degrees and have a short lifespan.
Now your bullets....which show you obviously need some F3A experience...
First, we dont run the packs like that, second unless you have a PhD in heat and mass transfer I seriously doubt you can conclude what the temperature of the pack will be while its flying through the air seeing turbulent flow forced convection cooling
quote:
The best pack for 2006 will be, without doubt, the KOK 4.8 AH at 2.5 lb. It will provide everything needed and give life cycle of at least 500 cycles.
LOL, post your cycle numbers when you actually know them. Come back with real world pilots who have flown these packs (which dont exist yet?) for 500 cycles....until then you are simply another manufacturer making bold claims to sell products (something you are basically accusing TP of right now)
quote:
ThunderPower was giving away packs
I placed 17th/112 in the prelims and 20th in the semi-finals at this years World Champs.....I paid for my TP packs and only recently got an agreement with TP....and I still have to pay for packs (just not as much)
To make claims that they are giving away packs is simply absurd.
quote:
All the competitors were converting existing IC designs which were heavy airframes which meant that no KOKAM solution could be offered due to the 5 KILO weight restriction. The ThunderPower solutions were under powered on the vertical maneuvers compared to IC machines.
What? The planes I flew were 9.9 lbs glow before fuel and 10.3 lbs electric with the 5300's. Underpowered...I think not....heavy airframe I think not.
quote:
The Patternship manufacturers know nothing about electrics or the art of building an electric airframe light enough but strong enough.
OMG LOL.....Jean-Pierre Zardini of ZN Line (the Z part) has flown electric power for the past two years...and is one of the biggest manufacturers of pattern kits....you know like the Oxalys...the one that just won the World Champs. Oh ya, its the Oxalys that he flies electric as well.
quote:
A world-class F3A pattern plane draws over 90 amps on the pull up vertical maneuvers with a 10S voltage.
BS....I have measured the inflight draw of my "world class" pattern ship at 60A max over the duration of the flight.
quote:
At least 4Ah is needed to complete a single schedule with all likely wind conditions, 5AH is preferred for a strong finish.
I will agree with you on that, although that is F3A-P-xx only, the lower classes can run on reduced pack sizes, as well flying F3A-F-xx can use reduce pack sizes as well.
quote:
The pilot at this level needs the pack to be stiff during the schedule flight so that there is no power fade, remember these guys at top level are watching that plane like a hawk for the smoothness of flight and when he wants power it must be there immediately. They are judged on the presence of the flight .
Really...didnt know that, good thing that my TP's do just what you say
_____________________________
Chad Northeast
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RE: Battery longevity - 
