Lipos

[leccyflyer]

11 hours ago, Diamond Geezer said:

Leccyflyer

my other batteries charge ok

 

My post was recognition that checking the individual cell voltage is an important part of lipo battery care and management and far better at monitoring battery health that just checking what percentage of the capacity has been used.

 

From the information supplied this particular pack is very severely unbalanced. If it's a pack you have had for a while something has happened to cause that. If it's a newly purchased pack then, as advised above, it's good practice to check the voltage of individual cells before charging for the first time. If it's so badly out of balance it warrants return to the vendor for a refund.

[EarlyBird]

14 hours ago, Diamond Geezer said:

How do i run a balance charge cycle if I connect the battery by balance lead only it says no battery connected 

From this I assume that balance charge has never been used and that it has been charged multiple times, judging by the apparent age of the charger in the photo. 

An important lesson, always balance charge. This not only prolongs the life of the battery but also reduces the risks associated with lipos.

Another lesson I learned was always return to storage charge after flying, including those that were charged and not used.

 

Good advice from George at 4-Max.

 

Advice from Josh Bixler at Flite Test 'look after your batteries and they will look after you'.

 

George and Josh are two people who know what they are talking about so I follow their advice.

 

[leccyflyer]

Mostly good advice, but I disagree with the advice to always return packs to storage charge if they won't be used in the next three days. That simply is not borne out in practice and >3 days is not an extended period, by any stretch of the imagination.

[EarlyBird]

12 minutes ago, leccyflyer said:

Mostly good advice, but I disagree with the advice to always return packs to storage charge if they won't be used in the next three days. That simply is not borne out in practice and >3 days is not an extended period, by any stretch of the imagination.

That's not good advice for me as in the last few years my memory is not as good as it used to be. I had a charged battery and expected to fly the next day so didn't put it on storage charge circumstances changed and I did not go flying for two weeks, when I found the slightly puffed and slightly out of balance battery. I have learned to have a routine and stick to it, part of which is doing things when I think of them or they get forgotten. An age thing I am told.

 

I assume the >3 days is simply because a number was required and this is on the safe side maybe. Immaterial to me as I now always return to storage when I get back from flying. 

 

Sorry @leccyflyerbut I will follow George's advice as so far it has proved to be good advice.

[Jonathan M]

I'm with EB on this one - probably also an age thing!

 

Its a simple matter of routine after an electric flying session to put all four LiPos on the quad charger and let the machine bring them all down (or up if need be!) to storage voltage.  I can then forget about them, whether for a day or a year.

 

I'm less persnickety with the single cell 700mAh LiPos I use for my very lightweight thermal soarers, but I'm still not comfortable leaving them on full charge for more than a few days - can't imagine that would be any good for the cell at an electro-chemical level.

 

 

Edited October 8, 2021 by Jonathan M

[Nigel R]

I store my batteries fully charged. Life's too short. I accept the small reduction in cell lifespan. That said, only two of my lipos are puffed. Oddly enough, its the pricey Overlander ones that have gone that way... not the "cheap far east cells" from HK.

 

Temperature of storage counts for a lot too (seems to be missed from the 4max list).

 

[Diamond Geezer]

I have always balance charged my batteries never discharged them though as my charger don’t do discharge that’s why I bought the other one

[MattyB]

24 minutes ago, Diamond Geezer said:

I have always balance charged my batteries never discharged them though as my charger don’t do discharge that’s why I bought the other one

 

OK. Roughly how many cycles has the battery that is out of balance done? From your earlier post that stated "...I have never discharged it..." I took it that it was a new pack, but it sounds like what you meant was it had never been discharged on a charger/discharger. If it has done any more than 20-30 cycles and is that out of balance I would say it probably won't recover and is one for the bin (after it's been fully discharged to <1V/cell first). The only way to know for sure though is to do a slow rate discharge on your discharger, then a slow balance charge afterwards and see if that evens things out.

Edited October 8, 2021 by MattyB

[EarlyBird]

40 minutes ago, Diamond Geezer said:

I have always balance charged my batteries never discharged them though as my charger don’t do discharge that’s why I bought the other one

In that case it is at the end of it's life and as others have said bin it as like me you will lose a model because the expected power was not there when it was needed, tip stalled and cartwheeled badly in my case. 

[Mike Blandford]

One other way of trying to bring the cells to balance is to charge each cell individually, through two connections of the balance lead (assuming you are able to make up a suitable cable). I would then suggest charging each cell at 1A (the balance connector won't handle high currents), and see if they then come up to 4.2V.

 

Mike

 

[MattyB]

4 hours ago, leccyflyer said:

Mostly good advice, but I disagree with the advice to always return packs to storage charge if they won't be used in the next three days. That simply is not borne out in practice and >3 days is not an extended period, by any stretch of the imagination.

 

3 hours ago, EarlyBird said:

That's not good advice for me as in the last few years my memory is not as good as it used to be. I had a charged battery and expected to fly the next day so didn't put it on storage charge circumstances changed and I did not go flying for two weeks, when I found the slightly puffed and slightly out of balance battery. I have learned to have a routine and stick to it, part of which is doing things when I think of them or they get forgotten. An age thing I am told.

 

I assume the >3 days is simply because a number was required and this is on the safe side maybe. Immaterial to me as I now always return to storage when I get back from flying. 

 

Sorry @leccyflyerbut I will follow George's advice as so far it has proved to be good advice.

 

We have discussed lipo storage many times on this forum - the list of threads is extensive! It always comes back to the fact no one person has enough carefully collected data to truly un derstand the effect of storage at elevated SOC, so any view we hold will be coloured by our own personal experience. For instance I am a believer in storing at no more than 3.7V/cell, mainly because someone I know toasted their entire inital set of 3S 2200s bought for their first electric model within 18 months (but with relatively low number of cycles) after charging them straight after use every time. I have also had a couple of (high C rated) lipos puff prematurely after they were stored at elevated SOC for ~1.5 weeks. Does that mean the same will happen every time though? Probably not - other factors like storage temp and rate of discharge also play into battery life in a big way. Separating those factors out would require a much more scientific stufy with far more packs and users than anyone has done to date.

 

What can be said with absolute certainty is this - the big boys in the automotive sector who are investing billions into battery development for EVs (Tesla, Nissan/Renault, Hyundai etc) DO believe that storage of Li packs at elevated SOC affects battery lifespan. Nissan found this out to their cost with the first gen Leaf when it was used in warmer climbs - see this item on the Battery University site. Obviously the cell type and chemistry is a little different to lipos, but they are close enough; in fact based on what I've read on BU and elsewhere lipos are probably more vulnerable than the Li-ons packs in EVs because of the gelled electrolyte layer. More on that here.

Edited October 8, 2021 by MattyB

[leccyflyer]

I don't have a problem with storing packs at storage voltage if they are going to be stored for weeks, or months on end. That has undoubted benefits in terms of safety -less energy in the packs - and probably in pack longevity. It's what I do too.

 

What I do take issue with is the arbitary >3 days =extended period. Many flyers, with lots of lipos charge them up at the weekend and do not discharge any unused packs on getting back from the field, but they aren't reporting packs puffing up on day five before they get to go flying again.

 

The other piece of advice that I'd take issue with -from direct personal experience - is that old saw that with every thing in life, you only get what you pay for. That did used to be something of a catch phrase for me, but with lipos that has certainly been disproved as far as I can see. The best lipos I've ever had were the Loong Max packs, sold by Giant Cod, which must be over ten years old now -they were inexpensive and worked superbly, for many years and many flights. They came out top in BMFA's test of various lipo packs. In stark contrast the overhyped, overpriced Flight Power packs that I had were fading fast after half a dozen flights and cost more than 3x the Loong Max packs. I know others who had the same experience with them. When the last ones were being sold off I mentioned to an electric flying pal that they were having a half-price Flight Power sale. His reply was "Don't you mean a Half-Power, Flight-Price sale?"

 

[MattyB]

2 hours ago, leccyflyer said:

I don't have a problem with storing packs at storage voltage if they are going to be stored for weeks, or months on end. That has undoubted benefits in terms of safety -less energy in the packs - and probably in pack longevity. It's what I do too.

 

What I do take issue with is the arbitary >3 days =extended period. Many flyers, with lots of lipos charge them up at the weekend and do not discharge any unused packs on getting back from the field, but they aren't reporting packs puffing up on day five before they get to go flying again.

 

I have a strong suspicion that the "don't leave it for more than x days fully charged" recommendation is as you say somewhat arbitrary. It was probably put out there as an easy rule of thumb to remember. However, based on Nissan's expereince what seems more important is the overall time a pack spends at elevated SOC (where accelerated degradation occurs due to dendrite growth etc) vs. how long it spends below the "electrochemically stressed" level (normally considered be around 4V/cell).

 

Example - A Sunday afternoon flyer who charges the night before he flies will have the battery at elevated SOC for ~19/168 hours per; that's ~11% of the time. A pilot who flies exactly the same packs in the same model and in the same style but charges on a Sunday evening after flying will have them at elevated SOC for about 162/168 hours per week, or 96% of the time. That is an enormous difference that according to the automotive research must have an effect over time, especially if you are operating in warmer climbs.

 

2 hours ago, leccyflyer said:

The other piece of advice that I'd take issue with -from direct personal experience - is that old saw that with every thing in life, you only get what you pay for. That did used to be something of a catch phrase for me, but with lipos that has certainly been disproved as far as I can see. The best lipos I've ever had were the Loong Max packs, sold by Giant Cod, which must be over ten years old now -they were inexpensive and worked superbly, for many years and many flights. They came out top in BMFA's test of various lipo packs. In stark contrast the overhyped, overpriced Flight Power packs that I had were fading fast after half a dozen flights and cost more than 3x the Loong Max packs. I know others who had the same experience with them. When the last ones were being sold off I mentioned to an electric flying pal that they were having a half-price Flight Power sale. His reply was "Don't you mean a Half-Power, Flight-Price sale?"

 

Couldn't agree more. We know for a fact that there are very limited numbers of factories that actually produce our lipos, so the vast majority are rebadges and the information on those labels (particularly C ratings) is very often highly questionable based on the actual IR measurements. I also have spoken to an industry insider who has state that he knows that many of the barnds choose their providers on a batch by batch basis depending on the availability of the factory to manufacture and the wholesale price, and that different levels of cell matching and quality on the construction are offered.

 

I certainly think that is likely;  I've had "identical" packs from the same brand purchased at different times that had very different IR ratings and perfirmance in the air from new. When dissembled it was clear they had different constructions and welding stds. YMMV, but I don't think we should kid ourselves that the high price brands are any more or less likely to be better performing overall.

[Diamond Geezer]

On 07/10/2021 at 15:32, MattyB said:

Wow, those are miles out of balance. If your charger just run it on a balance cycle only (no charge), then once that finishes run a balance charge again and see if all 4 cells get to 4.2V again. My suspicion though is that the pack is probably not long for this life...

 

How many cycles does it have on it, and what kind of C ratings do you discharge it at? Has it ever been discharged below 3V/cell?

 

[Diamond Geezer]

Hi Matty

balanced charge only battery is back to 4088-4071-4185-4070.

thanks

[Andy48]

49 minutes ago, Diamond Geezer said:

Hi Matty

balanced charge only battery is back to 4088-4071-4185-4070.

thanks

 

Time for the recycling bin methinks, after discharging each cell fully of course.

[Diamond Geezer]

Is it no good then

[EarlyBird]

51 minutes ago, Diamond Geezer said:

Hi Matty

balanced charge only battery is back to 4088-4071-4185-4070.

thanks

How long did it take?

For me life is too short to spend time bringing old batteries to a balanced state. I will keep them going to the point where the balancing part of the charge takes less than half an hour.

 

[Andy48]

1 hour ago, EarlyBird said:

How long did it take?

For me life is too short to spend time bringing old batteries to a balanced state. I will keep them going to the point where the balancing part of the charge takes less than half an hour.

 

Maybe life is too short, but a friend of mine burned his shed down trying to charge an unbalanced battery.

[Andy48]

1 hour ago, Diamond Geezer said:

Is it no good then

Personally, I wouldn't use it. Each cell voltage should be within a couple of hundredths of a volt of the rest after balance charging.

 
Could try balancing it again, some chargers have a time cut off and it may have stopped the balance charging due to this.

 

Edited October 11, 2021 by Andy48

[EarlyBird]

21 minutes ago, Andy48 said:

Maybe life is too short, but a friend of mine burned his shed down trying to charge an unbalanced battery.

There is that as well. For me being out of balance is an indication that it will lack power possibly resulting in a lost model. There are many good reasons not to keep them going.

[PatMc]

Does anyone ever think to check that the individual cell voltage displays are uniformly calibrated ?

I once lost several lipos before realising the charger calibration was out causing one cell to be overcharged during supposed balancing. I tracked down the maintenance menu for the charger but found the alteration limits too narrow to do set the calibration accurately enough.   

[Andy48]

22 minutes ago, PatMc said:

Does anyone ever think to check that the individual cell voltage displays are uniformly calibrated ?

I once lost several lipos before realising the charger calibration was out causing one cell to be overcharged during supposed balancing. I tracked down the maintenance menu for the charger but found the alteration limits too narrow to do set the calibration accurately enough.   

Yes, very common, most chargers and battery checkers have lousy calibration. If in doubt I always use a decent accurate multimeter.

[Martin Harris - Moderator]

My personal impression is that battery “genes” and balance charging are the likely main factors in service life.

 

I have a couple of Rhino packs which were probably old stock when I bought them a decade or so ago. They are old style 4S2P configuration packs which have been left discharged and fully charged at random and still work well after countless cycles in my most regularly used electric hack. Since obtaining a charger which measured them a few years ago, IRs have remained fairly consistent at between 8 and 10 mOhms - although a lot higher than a new high rate pack at @3 mOhms measured on the same (balance calibrated) charger, performance is quite acceptable. 

 

During the years I’ve used these, other makes and sized packs have come and gone and some are still in regular use. 

[Trevor]

One cause of a battery going out of balance that hasn’t been mentioned is a poor connection somewhere in the balance leads (usually wear and tear of the connectors on the balance board). When starting the charge, I always check the cell voltages are somewhere near balanced. If they aren’t, then try re-seating the balance plug in the board. If that does the trick, it’s time to order a new balance board!