Battery life while in storage

[Dobmatt]

Not false or BS but fact.
I have been over this in detail many times on the forum.

• Lipos loose capacity over time whether they are used or not.
• How well they are stored governs their capacity loss over a time period
• Well stored packs will only deminish circa 1 - 2% over a 12 month period
• Poorly stored cells can lose up to 10% or more over the same period.

Yes, manufacturing date has a influence on the capacity remaining in a pack.
Lipo cells start loosing their ability to take a full charge/capacity from the moment they leave the production line, whether they are used or not. In fact, the very article you link to highlights differing capacity loss over a year at 40% charge at differing temperatures of storage with the worse being a 25% loss of capacity over a 12 month period.

These are facts and just a well documented physical nuance of Lithium Polymer cell chemistry/technology.

Yep, nothing but true. No matter how well they are stored and maintained during between-the-seasons hibernation, they will loose the capacity. And yes, they're not made equal. Some may keep charge for 100+ cycles, others may retire around 50. I tend to believe that TB47/48 batteries average lifespan is about 3 years. I just learn that with my set. TB47 has about 60% of total capacity, two TB48's are at around 75% and only one TB48 keeps little above 5000 mAh. All are about 3 years old, having average 50 charging cycles counted and deep cycled recently. Well, time for replacement, I guess ...

However, one question is bothering me ... Shortened flight time and frequent "Motor overload" messages aside, what potential danger is lurking behind usage of ageing LiPo's? Will I risk an rapid battery failure mid flight, catastrophic voltage drop and my beloved Inspire's funeral in result?

 

[The Editor]

Yep, nothing but true. No matter how well they are stored and maintained during between-the-seasons hibernation, they will loose the capacity. And yes, they're not made equal. Some may keep charge for 100+ cycles, others may retire around 50. I tend to believe that TB47/48 batteries average lifespan is about 3 years. I just learn that with my set. TB47 has about 60% of total capacity, two TB48's are at around 75% and only one TB48 keeps little above 5000 mAh. All are about 3 years old, having average 50 charging cycles counted and deep cycled recently. Well, time for replacement, I guess ...

However, one question is bothering me ... Shortened flight time and frequent "Motor overload" messages aside, what potential danger is lurking behind usage of ageing LiPo's? Will I risk an rapid battery failure mid flight, catastrophic voltage drop and my beloved Inspire's funeral in result?

Well looked after (and stored) packs should only really exhibit shortened flight times.
Although the internal resistance of the cells increases with age, this will simply have the effect of the pack not giving up its charge so readily under heavy load conditions. So in reality you will see less performance during fast climb outs etc.
As long as you keep an eye on your cell voltages you should be fine.
The time to retire the pack is when you just do not get useful flight times out of your packs or the cells do not balance/track closely during use.
Hope that helps.

 

[Dobmatt]

Well looked after (and stored) packs should only really exhibit shortened flight times.
Although the internal resistance of the cells increases with age, this will simply have the effect of the pack not giving up its charge so readily under heavy load conditions. So in reality you will see less performance during fast climb outs etc.
As long as you keep an eye on your cell voltages you should be fine.
The time to retire the pack is when you just do not get useful flight times out of your packs or the cells do not balance/track closely during use.
Hope that helps.

And that's exactly what I need to know. I was observing cells behavior (in Go app) during test flights and indeed some of my batteries do not deliver enough juice for aggressive maneuverings, decreased capacity aside. Once i push the throttle, cells voltage may go down from green to yellow, some may even hit red zone. When flying conservatively, however, I can still get some usable flight times. So, as long as I'll keep cells voltage display open for constant monitoring, I should be fine until the battery in question will start showing some alarming off balance, temperature increase or disability to deliver reasonable current.

Thank you, Sir.