What did you fly today?

[f4u ausie]

Dave I had that Sunday morning with my 90 fms Avanti 6s. I had a flight with an almost new 5000 HRB all good.. second flight. A 5 year old same HRB.. got off ground good but under continued load burbs and hesitation.. so landed... All cells equal... And checks as u would expect.. last flight. An almost new again. Not any trouble at all.
So think battery is capushca. Must learn how to check resistance. I will b honest 5 years is a good go at it... Have fun b safe

[xviper]

Must learn how to check resistance.

The easiest way to check IR (internal resistance) is to let your LiPo charger do it for you. Of course, this is contingent upon your charger having this feature, which most modern chargers do. Once you get a LiPo started charging (it takes between 15 to 30 seconds for it to measure and display the IR, you should be able to scroll or flip through the various menu items without interfering or interrupting the charging process. (Or you can buy an Internal Resistance meter that will take a reading on its own. These can be purchased in places like Amazon or a hobby shop. They run around 30 US bucks, give or take, depending on how fancy you want to go.)
Here is a photo of my charger in action, showing the IR of one of my 5 year old 3 cell LiPos. The measurement shown tells me that this particular battery has very good IR. When the numbers start to get into double digits, you are looking at a LiPo that may be on it's final legs.

[f4u ausie]

Thanx viper. Have 3 charger's.. I'm sure 1. Will do it and I guess comparing new lipos. To that old 1. Will also give a hint

[davegee]

Dave I had that Sunday morning with my 90 fms Avanti 6s. I had a flight with an almost new 5000 HRB all good.. second flight. A 5 year old same HRB.. got off ground good but under continued load burbs and hesitation.. so landed... All cells equal... And checks as u would expect.. last flight. An almost new again. Not any trouble at all.
So think battery is capushca. Must learn how to check resistance. I will b honest 5 years is a good go at it... Have fun b safe

Thanks, Craig. It appears to me that my battery is going bad, especially when I tested it and another 6S battery of equal power and the suspect battery duplicated what I saw in the air on two flights when I exercised the flaps. The other new battery did not have any issues doing the same thing. If I had had another charged battery I would have taken it up again for the "acid test" of nailing the suspect battery and pull it out of the rotation.

Too windy today, so I'll try later in the week for the tests. .Everything is waiting in my truck for a good, calm, morning to test this.

Cheers

Davegee

[davegee]

The easiest way to check IR (internal resistance) is to let your LiPo charger do it for you. Of course, this is contingent upon your charger having this feature, which most modern chargers do. Once you get a LiPo started charging (it takes between 15 to 30 seconds for it to measure and display the IR, you should be able to scroll or flip through the various menu items without interfering or interrupting the charging process. (Or you can buy an Internal Resistance meter that will take a reading on its own. These can be purchased in places like Amazon or a hobby shop. They run around 30 US bucks, give or take, depending on how fancy you want to go.)
Here is a photo of my charger in action, showing the IR of one of my 5 year old 3 cell LiPos. The measurement shown tells me that this particular battery has very good IR. When the numbers start to get into double digits, you are looking at a LiPo that may be on it's final legs.

Thanks for that info, XViper. I hope to improve my knowledge on batteries and power systems, going forward.

Cheers

Davegee

[xviper]

Thanks for that info, XViper. I hope to improve my knowledge on batteries and power systems, going forward.

Cheers

Davegee

For me, batteries is still a learning in progress kind of thing. It's taken me years just to figure out some of the intricate details on the subject. New information still come to light that squashes old ideas and make me scratch my melon and wonder how I ever thought that to be right. There's still a lot of "magic" and oddness to battery tech in my mind. It's sometimes hard to stop listening to "old wives".

[davegee]

The wind died down this evening so I went out to the field to test my F9F Cougar to confirm its problems yesterday were with a recalcitrant battery and not something tougher to determine the cause of the sudden power loss after takeoff. Turns out, it looks as I thought; with a new battery, it flew its best, as usual. No problems whatsoever. I did the first test flight with no ordnance, and when I got it back on the ground, I put all the bells and whistles on it to see if that might cause any problems. They didn't, both flights were great. XViper, I appreciate your helpful comments regarding what might have been wrong with my airplane. It was a battery, all right!

Photo taken after the second test flight with all the ordnance and refueling probe installed.


Cheers

Davegee

[f4u ausie]

Good work Dave. Just bit of trivia 4 U.. my (bad battery). Has the same resistance as all my 8s batteries. Except the 2 brand new ones...which r way lower.. the 8s r working flawlessly. There must b other thing at play. Time Will tell. The new battery resistance between 2 and 3. Older ones between 4 and 5

[xviper]

Good work Dave. Just bit of trivia 4 U.. my (bad battery). Has the same resistance as all my 8s batteries. Except the 2 brand new ones...which r way lower.. the 8s r working flawlessly. There must b other thing at play. Time Will tell. The new battery resistance between 2 and 3. Older ones between 4 and 5

IR is but once parameter that comes into play. Certainly, a consistent low IR can be an indicator of how well a battery will accept a charge and how evenly the cells will charge up. However, there's something else that can contribute to what has been talked about here. This has to do with power loss after take off, be it sudden or very early in the flight. I'm talking about "sag", something that I'm not completely well versed in but have noticed myself. I have batteries that have acceptable IR and charge up as they should - even cell voltages. Some are even not very old (a year or 2). I believe this sag is related to the "C" rating of the battery. We all know that C ratings are very often over-exaggerated with almost all brands of batteries. One brand's C rating may say 50C on the label but when loaded, they may only be 20C (as an example) and as they age, this discrepancy gets worse. Another brand's C rating may say the same 50C but when under load, may only 35 or 40C. Guess which one might sag worse. The interesting thing about some of these "high sag" batteries, is that when the power drops off, you land right away. Once down and disconnected for a minute, they can still read 70% or more. At times too, I've noticed these same batteries, after landing, would have very hot connectors. That becomes another tell tale sign of something amiss - haven't quite figured out precisely what that might be - maybe degrading soldering?
Brands that I have that don't seem to exhibit this (early) "sag", even older ones, are high C Admirals, SMC and ChinaHobbyLine.

[f4u ausie]

As always thanx viper.. I believe HRB 50c r way lower than that.. it did fly well at 50 percent..
I do normally fly older batteries in props. Which makes sense.... Need some more new lipos and planes and just more stuff . B safe thanx again