RunRyder - Need Help with TP2100 Lipo

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e-Electric Batteries & Chargers > Need Help with TP2100 Lipo

CoastalTom
Senior Heliman
Location: Foley, AL (7 miles N of Gulf Shores/Orange Beach)

OK guys here's what's goin on.

TP2100 lipos in my T-rex. Have maybe 25 cycles/flights. Previous flight times of 6-7 mins and then put 1600-1700 mah back in through Triton charger @ 1.8 AH.

Last 3-4 flights only lsating about 4 mins til low power forces me to land. I have not balanced the pack until this morning when I finally figured out how to make a connector for the Triton to individual cells. Measured voltage before charge for: cell 1 = 3.89v
cell 2 = 3.94v
cell 3 = 2.93v (I know about going below 3)

Charged each cell @ 1.4AH

After charge voltage cell 1 = 4.11v
cell 2 = 4.12v
cell 3 = 4.06v
Pack volts = 12.22v

Flew for about 4 mins til power forced landing

After flight voltage cell 1 = 3.83v
cell 2 = 3.79v
cell 3 = 3.40v
Pack Volts = 10.97v

I have not charged the pack or cells again.

Will repeated balancing of each cell bring this pack back to normal or am I living dangerously?

Thanks for any help.

Tommy Patterson - Gulf Coast Aerials

05-10-2006 Over year old.

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Grant H
Key Veteran
Location: No where right now....

Charging individual cells is NOT balancing. As you notice, your cell voltages are still WAY out.

Yes. You will damage your cells. They are horribly out of balance.

The TP-205 will balance the cells if they get out more than .005 volts.

What you need to do is spend $50 and get a TP balancer.

05-10-2006 Over year old.

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AV8TOR
Veteran
Location: Central Ohio

Or spend $39 for the Hyperion LBA6. I have both and I like the LBA6 better. But I agree that you need to get a balancer.

05-10-2006 Over year old.

cudaboy_71
Elite Veteran
Location: sacramento, ca, u.s.

Quote
After charge voltage cell 1 = 4.11v cell 2 = 4.12v cell 3 = 4.06v Pack volts = 12.22v

this bothers me. does a properly operating charger not operate by monitoring the voltage of a pack and cutting it off at a certain point? if your 'pack' consists of one cell, then why the discrepencies?

i only have an astro 109. but, it cuts off predictably at 4.2 every single time when charging single cells.

i contend that charging individual cells with a properly functioning charger IS balancing...as you are putting each cell to a given voltage. it's just not the easiest thing in the world to do...so we have balancing devices that perform this feat through circuit management.

someone tell me i'm off here.

if it ain't broke…break it.

05-10-2006 Over year old.

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BarnOwl
Heliman
Location: Netherlands

Yeah, I agree, get a good balancer. If you have such expensive lipo's its worth it. Either a charger balancer or a good separate balancer which you setup between your lipo's and your charger. I use the Robbe Lipoly Equalizer with every charge of my TP's.

Jeroen

05-10-2006 Over year old.

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CoastalTom
Senior Heliman
Location: Foley, AL (7 miles N of Gulf Shores/Orange Beach)

Thank all of you guys for the info so far. I've been in this hobby a long time but continue to attempt to learn.

Yep, I need a balancer. Will make life easier.

The individual cell voltages after charge could be a bit misleading. The cell 3 voltage was taken this morning, after completing the charge last evening (10 hr delay). The other 2 cells were charged and measured this morning (very little time lag). Is the time difference enough to make .06 volt difference?

Do you think a balancer can re-condition this pack?

Tommy Patterson - Gulf Coast Aerials

05-10-2006 Over year old.

HOMEPAGE

cudaboy_71
Elite Veteran
Location: sacramento, ca, u.s.

balancers don't recondition. that's almost a misnomer in lipos anyway. the term came about when using Nicd & NIMH cells which display cell memory. repeated deep cycilng and charging could remove the pack's memory of what 'full' was. lithiums do not display this behavior. so, there's nothing to condition.

back to the topic of balancers. there are two types: passive (discharging) and active (charging). in either case, all the balancer does is use some electric circuitry to monitor the voltage of each individual cell (much like you are doing now with your VOM). if the balancer detects cells out of balance it simply 'quaranteens' it/them until all cells are the same voltage again.

this is needed because your charger only sees the pack as one giant cell. in the case of 3s, it would shut off at 12.6v. but, if the cells are out of balance, this could be 3 cells measuring 4.18, 4.19 and 4.23....the last one being of critical importance as you have just overcharged a lipo cell. but, to the charger everything's fine.

repeated charging/discharging of lithium cells simply uses up some of the limited cycles it has for its useful lifetime. it will do nothing to improve performance.

if it ain't broke…break it.

05-10-2006 Over year old.

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CoastalTom
Senior Heliman
Location: Foley, AL (7 miles N of Gulf Shores/Orange Beach)

Thanks Cuda,

How do I tell if one cell is bad? Do I just keep charging/discharging single cells and measuring voltage and capacity? There is no apparent physical damage (ie swelling).

Tommy Patterson - Gulf Coast Aerials

05-10-2006 Over year old.

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Hoverdown3K
Key Veteran
Location: Rochester, New York

What I find puzzleing is the fact that the cells only have 25 cycles on them.

Even if they have not been balanced 25 cycles should not result in 4 minutes of flight time.

Something else is amiss.

Is the chopper binding anywhere? You stated at best you got 7 minutes, this also seems on the low side for a new 2100mah lipo

-= I know there is Money in RC helicopters. I put it there=-

05-10-2006 Over year old.

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CoastalTom
Senior Heliman
Location: Foley, AL (7 miles N of Gulf Shores/Orange Beach)

Good point Hoverdown. Haven't changed anything so I'll start looking. Using an Aon motor and Quark esc. Usually fly in Idle 1 with 100% throttle doing mild 3d.

Tommy Patterson - Gulf Coast Aerials

05-10-2006 Over year old.

HOMEPAGE

cudaboy_71
Elite Veteran
Location: sacramento, ca, u.s.

Quote
How do I tell if one cell is bad?

depends on your defintion of bad. if you call bad not taking full charge, then it's easy. charge the cells individually and toss the one that won't reach 4.2v.

other indications of bad:

puffy
reduced current input (only way to monitor this is with a spreadheet every time you charge)

not a complete list, admittedly. but, all i can think of off the top of my head.

i agree the issue of balance is sidestepping your real problem. somethin' ain't right in your bird. in your original post you said you were putting 1600-1700mah back in after the 6-7 minute flights. but, you didnt say what was going back in after the 4 minute flights. that'd be helpful info.

if it ain't broke…break it.

05-10-2006 Over year old.

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switch26
Key Veteran
Location: CA

may i recomend this balancer,it works great for this aplication
heres the link http://www.hotheli.com/index.php?ma...635dbae60916f6b

at $24.95 is a great deal and keeps your lipos balanced every time

check out the website while youre at it,they have good prices on all of theyre heli pakages
heres the main page

05-10-2006 Over year old.

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CoastalTom
Senior Heliman
Location: Foley, AL (7 miles N of Gulf Shores/Orange Beach)

More Info

Here's more data about my battery. Still no clear answer to me.

After my charge of individual cells and then 4 min flight, I let battery cool, then charged entire pack at 1.8AH. Start Voltage was 11 and ending at 12.59v. Consumed 853MAH in 57 min. Measured each cell after pack charge. #1=4.18 #2=4.19 #3=4.20v

Made an immediate flight lasting 4:31mins til minimum power. Measured each cell after flight. #1=3.84 #2=3.79 #3=3.28v
Pack voltage was 10.88

Also here's a spreadsheet copy of my previous flights/charges. I know..... I got lazy after Jan. and didn't record all data. All charges of pack ended with 12.59 volts.

Thanks for looking.

Flt Flt Flight Chrg MAH
Mins Secs End VoltRate Input

5 0 11.47 2 987
5 25 11.39 2 1200
5 30 11.33 2 1230
7 30 11.19 2 1681
7 48 11.19 2 1693
7 48 11.13 2 1719

4 20 10.97 1.6 853
4 31 10.88

Tommy Patterson - Gulf Coast Aerials

05-10-2006 Over year old.

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cudaboy_71
Elite Veteran
Location: sacramento, ca, u.s.

wish i could help more. without more recent input data corresponding to when you started having trouble it's a little difficult to spot a trend.

but, your equipment is a little suspect. 4.18 + 4.19 + 4.20 != 12.59

i'm not saying rush out an get a new charger. i'm just saying it's a little hard to troubleshoot when the numbers dont jibe.

i'm still leaning toward some binding or some other electronic drain on the pack causing the issues. have you checked all the servos individually and confirmed they aren't missing teeth/grinding?

how's the heat on the motor and ESC after a 4 minute enduro?

how's your belt tension?

unmesh the motor from the main gear and give the head a spin. how freely does everything spool?

a datalogger could help you isolate electronics and see if something is draining your current.

just shootin' from the hip at this point.

if it ain't broke…break it.

05-11-2006 Over year old.

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CoastalTom
Senior Heliman
Location: Foley, AL (7 miles N of Gulf Shores/Orange Beach)

Thanks Cuda,

After a full charge last night, (took 845mah @ 1.6AH end 12.59v)I did a discharge through my Triton this morning. Charger set for 9V and .5AH rate. Only went down to 10.99 before cutoff, took out 760 MAH.

Cell 1 = 3.87v #2=3.87 #3=3.28

Checked out heli and all appears well with gear mesh, belt and electronics.

Bad charger? Only went to 10.99v

Bad cell? #3 is always off in voltage

Tommy Patterson - Gulf Coast Aerials

05-11-2006 Over year old.

HOMEPAGE

cudaboy_71
Elite Veteran
Location: sacramento, ca, u.s.

i vote for a bad cell. it's a cheaper bet anyway.

if you're handy with a soldering iron you can get a 4s pack of the same make and capacity and repair your bad pack and have two 3s.

you will probably have to resolder the balancer leads tho...there's a diagram on the TP balancer instructions. RR member leslie has a copy in her gallery if you cant find it elsewhere.

if it ain't broke…break it.

05-11-2006 Over year old.

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akshaw
Senior Heliman
Location: Plymouth Meeting, PA

My experience with reduced flight time on a pack is that the pack has been severely overdischarged at some point. Once it is damaged from overdischarging, there is no getting it back. The recommended safe discharge cutoff is down to 80% of the packs capacity. Going any lower might result in a damaged pack. If it's an align esc, the highest cutoff rate you have is 70%, which is 10% below the recommended safe discharge cutoff. In this case, I would go with either a different esc or a external lipo alarm.

05-11-2006 Over year old.

Rob_T
Elite Veteran
Location: ..

Cell 3 is obviously now lower capacity than the other cells. That's whats limiting your run time to 4 minutes now.

One possible solution is to replace cell #3 and then balance the pack (assuming you can get a cell and do the soldering or get someone to do it for you). The problem with going this route is that whatever caused cell #3 to fail may have also affected the other 2 cells so they also fail soon, so repairing the pack may turn out to be a false economy. Unfortunately there's no sure way to tell...

05-12-2006 Over year old.

CoastalTom
Senior Heliman
Location: Foley, AL (7 miles N of Gulf Shores/Orange Beach)

You guys have been a great help and source of knowledge. Thanks.

I called ThunderPower and am going to send the pack to them for possible replacement.

I have a TP2100 and Hyperion Balancer on order.

I am checking the Quark33 ESC settings. I discovered that the built-in BEC has a default cutoff voltage of 2.9v per cell. I'm going to bump it up to at least 3v.

Thanks again.

Tommy Patterson - Gulf Coast Aerials

05-12-2006 Over year old.

HOMEPAGE

cudaboy_71
Elite Veteran
Location: sacramento, ca, u.s.

Quote
I discovered that the built-in BEC has a default cutoff voltage of 2.9v per cell. I'm going to bump it up to at least 3v.

3v is technically the lipo cutoff voltage. but, i've understood this to be the no-load cutoff. many use 2.75v or 2.5v just fine.

since you're having trouble i dont see any harm in setting yours to 3v to see if that prevents problems in the future. but, your previous settings do not seem suspicious.

if it ain't broke…break it.

05-12-2006 Over year old.

HOMEPAGE

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