cmoulder

Great suggestions, John. Sounds like a good testing protocol.

I just charged up a Nano and a Sky at 1C Accurate Balance on the 2 CellPro 10XP's. The Nano showed all cells a 4.189v except one cell at 4.166, and the Sky showed all in one pack at 4.201 and all in the other at 4.199

I appreciate the wealth of experience being shared.

Don McCullough

My Feedback: (1)

Bob, I recently had the exact problem with my setup two weeks ago. I noticed the packs were coming down hot and my low voltage telemetry alarm was happening much earlier in the flight. On the ground I was measuring over 20 amps increase from normal. It turned out one of my 5.5mm bullet connectors to the motor was not making contact. It had a slight residue in it and was much looser than the other two. When replaced, amps were back to normal. This was a first for me. Worth a look and a cheap fix.Don

danamania

Any luck?

cmoulder

Dana, the only thing I have had a chance to do thus far is to download the CC logs and at first glance the only odd-looking thing is that the amp draw looks LOWER than usual with 59.9A the max recorded for 3.5 flights.

The second flight I tried to replicate (as closely as I can muster) a contest-type flight, log image below. I didn't want to clutter it with all fields, so I will add that the max watts were 1856 and max RPM 6441, which is in line with the static RPM on the ground of 6210 as measured with a reliable tach. 2.22 Amps consumed, which is exactly what I was experiencing before, although I have not yet recharged the battery to see how many mAhs the 10XP puts back in. The voltage ripple was included on the graph because it seemed a bit high to me, and perhaps some of the experts out there can tell me if it is out of line, and possibly why. The second graph shows throttle and power out plots, if those are of any use.

Still, the model felt sluggish at the end of the flight with not a whole lot of oomph left over. Motor, battery, ESC not the least bit hot, nor motor bullets nor APP connectors/arming plug.

I made the mistake of setting the ESC data logging for 5hz (I thought I had set it at 2hz) and got that very annoying knock-knock-knock.

I put the OS ESC back in last evening. Next thing I plan to check are the end points and curve on the radio.

wingster

My Feedback: (26)

Bob

55A is low, 65-70A is more like it. I'd check your connectors and solder joints as Don suggested.

If those are OK I'd recommend a little more prop. In the cooler weather with good prop bite you can get by with less prop. In the cooler weather with the Advance I flew with the PT 21x13 and have now switched to a 21x 14 Falcon.

John

can773

My Feedback: (1)

For giggles, change the prop...

cmoulder

I have a Falcon 21x14 and will give that a shot, and check the throttle endpoints/curve.

Recharge on the battery was ~2800mAh with 1C Accurate, of course more than the 2220 indicated by the CC graph.

Won't happen until Monday due to family obligations tomorrow.

jgg215

Battery voltage on the curves seemed to be way down at the end of the flight (about 36.5 volts) indicating a lack of capacity. Was that a 5000 mah battery? 36.5 volts at the end is down around 10% left. The starting voltage is fairly low as well. Can you try these batteries in another plane?
John

cmoulder

John, this particular battery was a Nano 4500, far from being the best battery in the box. However, I do have the Sickle that I can fly it in for comparison purposes. I have a brand new Sky 4400 with which I will put in a few easy flights and then start to push it a little to see how the performance feels in combination with the Falcon 21x14.

Lots of family stuff on the calendar, however, and I may not get to fly again until May 23 or thereabouts.

flatlandmike

My Feedback: (17)

Have you ruled out the prop may have been damaged causing the loss? Om my imac plane in 2011 my plane wasnt making the power it once was and it turned out I had a slight delam on the 30x13. It was hard to find but when i switched to a new 30x13 the power was back and my running sound level was down.

serious power

Hi Bob,
John ,above, seems correct.
That pack, assuming the readings are accurate, is down in voltage all the way through - but hanging in there.
It looks as if it was not fully charged to begin with.
I have had a Cellpro 10S and a 10XP develop a fault ;
They would seem to charge normally but the quantity 'put in' was high.
The individual cell voltage readings were wrong and the charger was busy balancing out based on a false set of voltages.
Both chargers did this.
I still have them - must do a return - so can't say what the actual fault is/was.

Brian

cmoulder

I'm pretty sure this hasn't happened, but something else to check - thanks!

cmoulder

Brian, the voltage thing got me looking at the other logs, and for the 4 flights all the starting voltages were low, two at 40.6, one at 40.8 and one at 41, which is a Zippy Compact with about 12 cycles on it. Definitely all are down, so the chargers might well be the issue. Interesting that these batteries were charged with 2 different 10XP's which have seen a very nearly identical amount of use.

Could they both go on the fritz at exactly the same time and in exactly the same way?? Seems unlikely, but perhaps. I am using them with a 24V Meanwell PS.

jgg215

Bob, in one post you quoted close to 42 volts after charging. I assume those numbers are from the cellpro. Do you have a digital voltmeter to independantly check the voltage after charging?
Since there is some load (about 2 amps?) when you are recording and the motor is stopped, some dropoff would be expected. Any chance you can split a pack back into two 5S packs, then charge one on your charger and one on a borrowed working charger to see if the results are different. I'm skeptical about the charger being the problem but it would be good to eliminate them
John

cmoulder

John, yes that's what the chargers were indicating, and the reason I was charging at a much lower rate in hopes of getting the best possible result.

I have an old Astro Whattmeter that I have been using to check the pack voltages. I think it is pretty accurate. One of the batteries I charged last night registers 41.91v, which would seem to rule out the charging issue and suggest that the CC data logger is off base. The other pack (as used in the log graphs above) showed 41.88v.

It's some relief, at least, to know that the chargers are probably okay.

woodie

Are side bets allowed? If so, my bet is still battery capacity.... ;-)

Woodie

cmoulder

LOL! Got me thinking about the possibility that the capacity is completely fried and the voltage is dropping like a rock with any kind of load.... hmm....

Stuff like this really forces a top-to-bottom review. I can't say I enjoy it, but I'm definitely learning some stuff from you guys.

The weather forecast for tomorrow morning looks very good (although COLD!) and I will get in some flights with a brand new Sky 4400 (1 charge cycle, actually) and a Zippy Compact 4500 that has only 16 cycles thus far, plus the batteries that have been serving me well for a good while.

woodie

Any updates on your situation? We got serious money riding on the outcome!!! or at least bragging rights.. ;-)

Woodie

cmoulder

Hi, Woodie, we got back yesterday afternoon from a wedding in TN and a mini-vacation in VA on the way back.

The day before we left for TN I got a chance to fly with the Falcon 21x14 and I think there was an improvement. Just to see what would happen, I decided to fly the crap out of the batteries and to keep going after the sequence, staying high and always observant of significant power drop-off and ready for a deadstick. I was surprised to find that the batteries actually seemed to IMPROVE in performance, even an ancient set of Zippy 20C's with many, many cycles - maybe more than 200, but I really don't know - that were part of the first batch of Lipos I ever bought about 3 years ago.

Upon recharge I was consistently putting back in the neighborhood of 2800-3100mAh, with older and new batteries alike.

Got me thinking.......... I had consistently been flying the sequence and then landing, trying to be very gentle with the batteries, and it occurred to me that perhaps there is a memory problem caused by not ever really "wringing out" the batteries' capacity or pushing their potential. Is this even possible with this battery chemistry?? I have NO idea about the validity/possibility of this kind of thing occurring, but it seems to have made an observable difference. Unfortunately I was under time constraints before the trip down South and wasn't able to be more methodical and regimented in the testing. However, I am not as worried about the batteries fizzling during a sequence so the added confidence is welcome.

Jetdesign

My Feedback: (8)

Lipos are not 'supposed' to have memory related issues, but there is a new article out now that says otherwise:
(first link is an article discussing the report, second link is abstract of the published journal paper)
http://phys.org/news/2013-04-memory-...batteries.html
http://www.nature.com/nmat/journal/v.../nmat3623.html

do you ever discharge your batteries on your charger, or just fly and put them away? try a cycle or two discharging on the charger, or flying longer like you did and see what happens.

Maybe the Pletty is that good that we will need to be running 4000mah packs, lol [:'(][:@][&o][:-][][X(][&:]

cmoulder

Interesting stuff, Joe. Different chemistry, but previously thought to be immune from the memory phenomenon.

I am pretty much running out of options, and I did see a noticeable improvement with the increased load, so we'll see how it goes from here.

Still haven't tried a new motor. However, that would be a rather expensive test!

Jetdesign

My Feedback: (8)

Yeah the first time I read it, I got the impression it was not limited to just LiFe. Re-reading it, not positive.

Jetdesign

My Feedback: (8)

Hey Bob, any chance you got some wire shavings or a small screw or something in the motor?

cmoulder

Not that I could tell. Had it out of the model when checking the wires and connectors and it looks/feels/smells fine. BTW, it didn't get hot at all (nor the batteries/ESC) the day I was flying the crap out of them. The batteries were warmer (maybe 115-120*F) than usual, but previously they were barely warm, approx. 90-100.

danamania

So Bob, following what Chad said, did the prop change solve the problem described in your OP, or are you still looking for weak links? And can we give the Advance a clean bill of health here?

Last weekend Dave explained to me that to get more power or performance than a Pletty, one had to switch to a Neu, or at least any geared motor set-up vs. the even best direct drive. Word!