Folks I could use your help with this problem.

Last year I used Arrowind motor 3226-685KV and  TP 5S ,2700 MAH,  25C batt

 I Could only get about 25 or 30 flight until I started getting  a “soft shutdown” at the end of the flight or in the clover and could not use the battery any longer

This year I switched to Scorpion motor and Genesis batt   -- same problem at 20 flights  on the batt I get a “soft shutdown “prior to the true FM9 cutoff at 5:40  flt time.   I Don’t see the problem on batteries with less than 20 flights on them

Both set ups use a Castle, ICE 50 controller and  FM9  timer

All flight time set for 5 minutes 40 seconds


I don’t hear others complaining of only 20 flights per batteary  so I must have something messed up


Can you help??

Here’s my specs;
Motor : Scorpion 3026-710 KV

Batt: Genesis 5S,  2800 MAH, 40 C

Motor settings:
 Timing:  5 per motor Mfgr
PWM : 8Khz per motor Mfgr


Cutoffs:

Auto Li-Po   3.2 V   ( changed this to 3.0 V with only a slight delay of the “soft cutoff”)

Current limiting : Sensitive  (60A)

Governor  Gain:  36

Head speed change:   8



Prop APC 13X4.5   old style – F2B


RPM  around 9400


Battery usage  about 1950 with wind about 2170 with no wind

Plane is an SV 11 weight about 66 OZ--  Flys Great !

What charger are you using?

Hi Dick,
Hmmm ...

For starters, the numbers need to start agreeing. Right now, the only consistent thing is that packs go west on you after only a few dozen flights.

1
For starters, charge a pack that has demonstrated the problem ... you are using the balancing feature, right??? ... and then immediately afterward check each individual cell voltage for balance and a full 4.20 +/- 0.03V.
2
Put in a flight and after the annoying slowdown, set the pack aside for a full 1/2 hour, so the cells revover their post-flight resting voltage and THEN read each individual cell and report.
We will be trying to figure out whether you are really pulling the battery down lower than the 70% used that your charger is reporting.
3
Have you messed with any datalogging? Please log the voltage, current and total capacity used at the once per second rate.
At first, don't turn on any other recording parameters because we don't want to tax the ESC's processor. Then let's look at the data.
4
Take a good look at your setup: are there any sources of unwelcome electrical resistance in the path from battery to ESC?
The currents we run can cause big voltage losses under maneuver loads.
Which deadman switch (if any) are you using?
Are the connectors all crudded up with spark welds?
Are the wires long?
Are the solder joints clean, or are there possibly some cold joints between battery and ESC? Bad crimps if that type connector?
5
Question ... just before the cutoff, how is the power? Do you suspect that the ESC is lying about the undervoltage or not?

We are on the case!
take care, and fly carefully so as not to lose the ship.

Dean

Hi Dick,
Do you have another voltmeter that lets you look at those post flight voltages with at least two decimal places of resolution?
Either the cells are all unbalanced by as much as a tenth of a volt, or they are all crowded around 3.75 V. We just can't tell with those numbers.

The chase is on.

Dean

Dean

Don't know why I dropped the last two  digits- too many numbers for me I guess    !!
The numbers  at flight end are :
1    3.754
2    3.784
3    3.812
4    3.806
5    3.802

Dean

Don't know why I dropped the last two  digits- too many numbers for me I guess    !!
The numbers  at flight end are :
1    3.754
2    3.784
3    3.812
4    3.806
5    3.802

Hi Dick,
Those voltages look like somewhere between 40 and 50% of capacity remaining.
I am only a little concerned to see almost 60 mV difference between the high and low cells, but this is probably not the problem.
I would have loved to have these numbers for the pack when it was new: maybe it is a significant change in 20 flights.
Try charging at the 1C rate to see if that spread tightens up, but I don't think you are suffering from one wimpy cell in the pack.

Regards,
Dean

Russell

It was 100 degrees F on the ESC

Dean

I have 4 of these batteries and the newer  two have only about 10 cycles. I'll measure the # 1  oldest and # 4 newest and send comparison.

I am suspecting the Maxx switch . I had this issue on two set ups both with different batteries and motors . The only two common things  are the switch and the ESC

 I took a switch apart and it does have two  crimps on the end where the plug goes in. Both crimps look tight and well done, . Two ends use Deans and look fine. The plug in socket  looks suspicious to me. The two plastic pieces that are joined are restricted and captured buy the plastic, unlike the Deans springs these can lose tension and the plastic connection will not allow the spring to adjust.


Along with the other tests I have for tomorrow , I'll bypass the switch and see what happens

Dick

It could be resistive, Bob. 10's of milli-Ohms are enough to cause grief.
Dean P.

Castle logs

log 3

Bob

Thanks for  the input.  My actual flight time is running at 5:40 .   If the time scale is in seconds your calculation looks correct, but does not agree with actual flight time.

The RPM logging was turned off.  The only thing I had turned on were  Volts and Current.  I don't know why RPM showed up.  The plane flew normal. I would have had lots of issues if RPM was that low.  9400 RPM was recorded with a tac at original set up but not checked each flight

Lots I don't understand , but will stay on the hunt. I will reset everything before the next flights ( tomorrow I hope)

Thanks

Dick

Hi Dennis

The controller is set for 5S  lipo 15.5 V and the Cut Off was  set to 3.0 v per cell.

I now have it set for total volts  at 14.5 volts vs  Auto Lipo at 3.0 per cell to test  a theory. Since both  premature shutdown flights show  a bump down to 14.9 volts I think the ESC is  seeing that low volt and cutting off even though  each cell seems to be well above 3.5v


Very strange goings on

Dick

I know I may be drummed out of the core for this comment - but what's wrong with a cheep speed controller (such as the Turnigy Plush) and a KR timer/governor?  Doesn't have data logging but doesn't need it because this setup seems to be trouble free.  And it doesn't take a degree in software engineering to get consistent reliable runs.   

Dick,
 Just for kicks try turning on your throttle record feature. It may be able to show when the throttle goes low. I got a funny feeling something may be interfering with the throttle signal sent to the timer. I don't see the end of flight warning(500 rpm drop 5 sec. before the timer shuts the system down)where it's  supposed to be on your recorded data.

Hi guys

 Got in 4 flights yesterday.

Auto Lipo at 3.0 v  per cell was turned off

Cut off voltage was set at 14.5 v . The charts on previous flights showed a  soft cut out at 14.9V

ESC temp turned on

Temp looked fine the high was 130F and only a spike, the average about 118F

Batt 1, 22cycles, batt 2, 17 cycles,,batt 3, 11 cycles . Batt 4, 10 cycles

Batt 1   got a more normal shut down   After about 8 laps following the clover it bumped and powered down after two laps. I have known this to be normal, BUT this was not completely normal. The bump and shut down were not as crisp as I see on the newer batteries—suspect low voltage

Batt 2 same as 1

Batt 3 normal shut down

Batt 4 normal shut down

I won’t bore you with the charts (unless someone wants to see one)

What this tells me is that the ESC looks for a 15.0 V min even when Auto Lipo is selected by cell.    Batt 1& 2 are dropping below that  value as low as 14.9 . 
When the low limit is  set to 14.5 it did not result in a soft shut down. Think it delayed shutdown long enough for the timer to shut it down

The Mystery??

When I check the “bad”  # 1 battery after flight the TP610C charger shows it at 18.680 V  total and every cell above 3.7 . This has been true after every flight

I could understand a low voltage spike if it was while the system is stressed in a stunt, but it’s happening after several level laps after the clover- Something to do with time?

QUESTION

When armed is the ESC supposed to beep signifying the number of cells it sees??  I seem to remember this from somewhere.

I benched checked this with both Batt # 1 and a TP 5S 2700 mah batt neither one gave cell count just a little happy tune   Should it count?

QUESTION

This is a tight install almost all wires touching others.  Could I be getting cross talk?


Next steps

The only thing I soldered were the bullet connectors on the motor. I removed shrink and all looked good, but I re-soldered all anyway. Good shiny joint – no voids , full cup

One flight with batt # 1 ; Genesis  5S 2800  40C

One flight with TP 5s 2700  25C

Turn on Throttle record (Bob)
   
Check voltage drop  across all flights on both batteries

Check for hot connections after flight (Chris)

Try to isolate the ESC a bit better from wires

Dick,
One thing you might try is to reduce the prop diameter by 1/2 - 1". I had the same problem on one of my ships, I kept trying to push the diameter and finally had to do the prop change. If you clip the prop, round the corners and sand the last 1/16" of the tip angled up from the bottom to the top, if left square it may cause more drag then the diameter reduction creates. If the ships is a little slow pull in the lines 1 -2 ft. You might also try a different brand or style of prop to reduce the load.

Best,     DennisT

Hi Dick,
i know that additional weight ain't no fun, but try going up on capacity to maybe 3300.
using less percent capacity is always good for the batteries.
So is doing a break-in on either a cycler or in the plane using no more than 40 or 50% capacity.
Do you suspect any particular reason you saw poor cycle life with the TP's last year?
Dean

Try calling Thunder Power. They are very good at supporting their product. I had 2 of their 5S2700 65C batteries do this. I sent them to them and they confirmed that the battery was bad, and soon I had 2 brand new 70C batteries. Each of those had about  35 flights on them when they went. The remaining 4 have over 100 each  and are still fine.

Batteries are improving constantly. I used the "new" G8 5S2700 25C in my Predator at the Nats this year. That battery weighed just 10.5 ounces yet flew the 66 ounce Predator perfectly. They used  ~2200 per flight. We'll see how long they last, as I use about 2300 per flight at home. Small price to pay for that significant weight savings.

That's interesting.  I bought three TP G6 Pro Power 2700 5S  65C batteries last year.  One went bad last fall, and the other two are failing now.  I haven't abused them much, and typically put 2100 to 2200 mAh back per charge.  Thunder Power replaced the first one free.  They'll probably replace the other two also, but their failure comes at an inconvenient time. 

Dick,
I was using the G6 5S 2700 25C battery all last year.  At the start of this year, 2 of the batteries developed bad cells.  I sent them back to Thunder Power for evaluation and they replaced them with the new G8 versions.  The G6 batteries had about 50 charge/discharge cycles.  Paul had ask me about them when we were in Portland early this year.  I since had 2 more of the G6 batteries go bad and Thunder Power replaced them also.  Spending money on good batteries makes sense when they warranty them like that.  I am now testing some new 3B props very similar to what Paul uses and the new batteries are being taxed like his with between 2200 and 2300 mAh being used per flight.  We'll see how the new G8 batteries hold up.
Alan Resinger

I was wondering about the new TP G8's . I was thinking about the 2700 70C.

I bought a couple of the 45Cs and have one 70C.  They are the same size (both are 1/8" narrower than the G6 65C), and same weight, which is the same as that of the G6 65C.  I use all three types interchangeably.  Although I need the weight in the nose, I don't need all those C's.