UnitedHobbies 4s batts. - $37.95??

[sgomes]

Any thoughts on this battery??

http://www.unitedhobbies.com/unitedh...idProduct=2133

Thx.

Steve

[Jermo]

I use their 3S 2200mAh packs with ok results.

[pcar993]

$37.95?? I see $43.95USD on the link you provided. Did it go up in price maybe?

[Efliernz]

If you have ordered before and "logged in", the price you see is the "gold-members" price.

ie. a little discount for coming back, automatically.

[Efliernz]

Yup, just looked, then logged-on and confimed it...

[pcar993]

Yup i now see it when i logged on. Thanks. Will this work for my trex450se? What's the advantage and disadvantage of this 4s vs. the hextronic 3s?

[noguy]

I ordered 3 of the 4s packs last week to run on my mini titan.
Watch out for the shipping. there are 2 options. #1 normal ship & #2 express ship
I almost did my usual, get the cheapest shipping.
Then I noticed that normal ship can take up to 30 days from HK.
The express is worth the extra $ for 3-5 days ship.

These batts are a little on the heavy side. I also heard that people with the earlier verisons from united hobbies were only getting 100 cycles (+-50). They supposedly are a stronger pack now. Anyways for the price I figured it cant hurt to try them out. I will be running them at well under 15C (probably under 10c for hover) with my mini titan so I hope they hold out for a decnt cycle life. Well see.

Someone needs to figure out how to get a123's on a diet... :?
fast charging and 2000 cycles

[noguy]

Note: my 3 paks came to $36.50 each. and when I just logged on now to check my shipping status it said they were $35.59. Either they are dropping the prices daiy or your get some sort of frequent customer discount.
At $36.50 (even though they are heavy) how can I not try a few of these packs.

[Raydee]

I have read countless posts that these cells are prone to just puff up for no reason at all. If I find the link to the threads I will post them. I am a firm believer that with Lipo's you get what you pay for....MOST of the time.

[noguy]

Yes I heard this also about yellow wrapped packs. I have also heard that the packs they are currently selling (blue wrapped) have shown signs of being a better product. Hopefully. I figured since I wont be putting a high draw on them they will do alright. I shouldn't be pulling over 10C max with my setup in my mini titan. I also ordered a eagle tree so I'll know for sure.

Anyways mine just showed up. Fast shipping concidering they came from HK. (5 bis days). They were well packaged for shipping. Each pack individually bubble wrapped then grouped togeather and wrapped in cardboard, then bubble wrapped again.

Well I plan to test these in my mini Titan and do some eagle tree readings from time to time so I'll post results as I get them.

Noah

[noguy]

Originally Posted by Raydee

I have read countless posts that these cells are prone to just puff up for no reason at all. If I find the link to the threads I will post them. I am a firm believer that with Lipo's you get what you pay for....MOST of the time.

"You get what you pay for" is almost always true with most everything.
But somehow I have to reprove this theory to myself quite often.

[Raydee]

Guys go on the RC Groups board and look at the United Hobbies thread in the manufacturers support section. There isn't a lot of good posts about these guys.

Noah I am all for cheaper product that works the way it is supposed to but when it comes to Lipo cells there is just to much at stake to "take a chance". THe last thing I need is a burned up heli or WORSE a burned up house. I know this can happen with any lipo but it seems the cheaper chinese cells are known to have it happen a heck of a lot more.

There is also a new Lipo that is coming out now on Cheapbatterypacks.com made by Elite Batteries. No they aren't as cheap as the Hex cells but they are supposed to be real good and cheaper than the TP, Poly and Enerland cells.

Noah I hope you have great luck with the Hex cells and as long as you aren't pulling a ton of amps out of them they should do fine...just keep a eye on them.

[noguy]

Raydee, Thanks for the input, It's well taken. I am well aware of the risks involved with cheapo lipo's. My main reason for rolling the dice with thse pasks is the fact that I will be keeping them t about half of the supposed 20C rating. I paid 1/3 the price of a quality cell and mainly plan on useing thes to test my heli on 4s and then will invest in some prolites or similar if I like the 4s setup.

note: I checked all 3 packs individual cell voltage and so far the results look ok.
pack 1: 3.71v on all 4 cells
pack 2: 3.71v on two 3.70 on two
pack 3: 3.71v on two and 3.70v and 3.69v

I am changing my pinion out and will be bench testing with the eagle tree today.
I'll try ad get some graphs & temps up tonight.

[noguy]

OK, I have my first 4s bench test complete. This is with the CC esc in fixed endpoint mode so that I could verify my gearing is ideal for the target headspeed. all @ zero degree pitch.

- at 75% throttle I was getting about 2400rpm @ this headspeed volts were ~14.6v & amps were ~7.4amps
- at 85% throttle I was getting about 2600rpm. @ this headspeed volts were ~14.5v & amps were ~8.3amps
These are headspeeds that seem plenty fast for my flying. Actually this is my first heli that will even turn these kind of HS's and it was a little unnerving at first spooloing things up this fast. I kept waiting for some part of the heli to fly off and embed into my wall. I did run it up to 2800rpm (peak amps= ~11amps) but this would require a step up to a 11t pinion to allow ample headroom for the governer. Also There was some sort of noise(squeky grind sorta sound) at this headspeed. I dont know where the sound was comming from but after the inspection of the heli there were no signs of damage or wear anywhere????????? [:o]

Once I get my esc dialed in I will run down a whole pack on the bench with some pitch on the blades to see what the battery puts out under load.
Here is the chart from the eagle tree.

[noguy]

Hextronik 4s 2200mAh Pack #2 & pack #3 result from bench testing on TT mini Titan

PACK #1
CC p35 set at 13v cutoff
start volts: c1=3.72v c2=3.72v c3=3.72v c4=3.70v total=14.85v
end volts: c1=3.15v c2=3.16v c3=3.15v c4=3.09v total=12.9v
didnt get mah reading from this pack

PACK#2
ccP35 set to 13.2v cutoff
start volts: c1=3.72v c2=3.72v c3=3.72v c4=3.72v total=14.87v
end volts: c1=3.37v c2=3.18v c3=3.27v c4=3.26v total=13.09v
1383mAh used after 9min @ 2600rpm

both packs were ~115F after 9+ minute run (95F ambient temp)

While pumping the collective hard there was a peak 257watts at which point the peak amp draw of 18.4 amps was pulled off the pack.
This is only 8.4C for a 2200 mAh pack. so for the 20C rating on these packs????
I cannot vouch for that and I'm sorry guys I dont have anything to push the packs to a 44amp draw. But I would venture to geuss that 20C would over do this pack.
I dont know how starting out a 95F affects things but my pack rose ~20degrees' in a few minutes and then stabilized. I dont know how much more they would heat at over twice the draw?????

So my first impression is that:
These things are as cheap as they come
They are well packed for shipping and arrived in good shape
The cells seem to be matched decently.
They seem to stay balanced well enough after discharge.
They are heavy compared to brand name 20c packs
I dont think(but dont really know) they would really last long at 44amp(20C) useage

I dont think people would have soo many probs with there batts and other electronics if they weren't always trying to milk the max out of stuff. ie. pulling 30+ amps constant on a 35amp esc and 40amps off a 20c 2000mah pack.
Headroom is a very good thing for electronics.

Anyone out there who is really pushing these packs, I would like to know what you think of them? And again I say, for me, How many cycles I get out of these will be the deciding factor as to weather or not they are worth the $35.
If I get 100+ cycles I'll be satisfied
If I get 150+ cycles I'll be thrilled
If I get 200+ cycles Ill crap myself (That would be over 120hours of flight for me @ $110) thats less than a $1 per hour of flight.
Also hard 3D flyer will not like the weight of these at all.

Happy flyin all, Noah

[noguy]

Ok, So I fianlly got out to fly these guys.

I ran out all 3 packs over the 80% rule. I dont have a charger that tells me how much I put back, I am basing this off the eagle trees' mah data. the voltages seemed in a safe range though.

Starting voltage for all cells was 3.95volts (I dont know if the charger is not fully charging or if my volt meter is off) The eagle tree said that the peak voltage with no draw was 16.4v which is 4.1v per cell??? I am trying to find a better volt meter to use so I can figure out what is going on with my charger/voltmeter.

Ok so
Pack 1: 13.5 min run, 2013mAh used c1=3.24v c2=3.47 c3=3.41 c4=3.41
Pack 2: 11.5 min run, 2100mAh used c1=3.38v c2=3.39 c3=3.34 c4=3.36
Pack 3: 11.0 min run, 2009mAh used c1=3.42v c2=3.29 c3=3.28 c4=3.34

The max amps drawn was on pack 3 @ 26amps which yealded a max 364 Watts.

All three packs came in @ ~120-125 degrees F.

For $35 I say so far so good. I definately noticed the weight of these packs though.
This will be a concern for those who are looking for a lean heli.

I will update again when I get a good 40-50 cycles on these guys.

Here are the graphs

[ChasHeliCop]

I ordered some, on July 10th my order shipped. It arrived 07-17-07. That was regular shipping via airmail..... 7 days. I think I paid $29.95 and $15 shipping for 3 batteries. $107.22 That was 3s packs

[yuppy flyer]

I have two of these 4S 2200 batteries (yellow wrap), I use them in my T-Rex 450SE with Medusa motor running head speed 3100rpm, apart from their marginally heavier weight I can see no performance difference from my FP2170 Evo battery.

After about 30 cycles on each over the last two months there is no detectable deterioration at all, 5 minutes of heavy 3D leads to about 1400mah put back in with charger.

[ChasHeliCop]

Just ran my firsst pack, I was rather impressed. Of course I had to re-trim a little, but overall performance was outstanding. The biggest thing that surprised me was they were not even warm, not even comparable to the Aligns.

[noguy]

Originally Posted by ChasHeliCop

Just ran my firsst pack, I was rather impressed. Of course I had to re-trim a little, but overall performance was outstanding. The biggest thing that surprised me was they were not even warm, not even comparable to the Aligns.

Any idea how many amps you are pulling off them?