Very interesting and informative stuff Dave and thanks again. I have been looking at some fairly cheap lipos but think I will bite the bullet and splash a bit more to ensure endurance and reliability. I must say moving to lipos transformed my sports boats and I may even look at one for a weight and space saving solution in my little Mistral.

Yes, Derek I always balance charge too as I found that cells could be a little unbalanced sometimes with a plain charge. I'm not sure if the cells have to be absolutely spot on or if there's a tolerance of say 0.1 volt. I have a small watt meter which will balance the cells (again at Dave's suggestion) and I find it invaluable. Also good for checking current draw in the bath.

Thanks all,

Ian

HI Derek, its not that its a slower charge, just controlled, the battery and the charger work together

Mark

HI Ian
Yes I did help you move to LiPos and am pleased to hear you have had few problems. I only recently watched a technical presentation from one of the LiPo developers and realised the importance of correct storage voltage.
I am aware the fly boys like to dunk their batteries and I also believe they cut off the connectors close to the battery, one at a time I hope! A bulb is my preferred choice.
As you rightly surmise you get what you pay for. All manufacturers will have production runs where the process falls short of spec. The batteries may still be useable at reduced capacity so they are sold off in bulk without any markings. Resellers buy and after a quick check repackage often with misleading markings and probably without any real checks on capacity. This is reflected in the price and for many users the battery will perform OK.
If however you want max performance you may well be disappointed and end up having to buy another, probably at a higher price.
This is the same for all types of batteries, and I have purchased many batteries over the years.
Dave

Should add that I now never charge through the power out leads (with balance leads connected). Only ever use a balance charger. I assume it's a slower more gentle way of charging.

One way that is allowable for disposal, is to place in a bucket of salty water overnight. This discharges the cells. And as there is nothing dangerous in the lipo. Place in your non recycling bin. I always cut the wires short after soaking. I did have an instance of a lipo fire whilst charging. Thinking afterwards that I may have had the charge rate set too high, but will never know as it destroyed the charger also.

Thanks Dave for your valued advice on this. You may remember it was you who encouraged me in the use of lipos in the first place- always grateful.

I tend to store my four lipos in storage mode but it's sometimes difficult to predict when one might want to use them, so in the summer they tend to be charged as and when. This might be the cause of my one puffy lipo. I am fastidious over charging and always find a job to do in the workshop when charging lipos and use a charging bag. I won't even leave an SLA battery charging overnight.

I have been told the best way to discharge of them is to dunk them in a bucket of water! Sounds a bit drastic to me but the gent who mentioned it is a very experienced flyer of many years standing. I think I might prefer the complete discharge with a light bulb method. interesting to know that lipos contain no harmful chemicals so I will check with my local recycling centre- still commonly referred to as the 'dump'.

Finally, I notice huge variations in prices for lipos- does anybody know if the quality is reflected in the price or is it more to do with economies of scale? I tend to think one usually gets what one pays for, but somebody may have direct experience to help.

Thanks again for the valuable input on this subject.

Ian

HI All
I agree with all the advice given. The web link is to a useful article.

The only issue I have is his thoughts on charging unattended, especially as it is in his house. All the warning devices he has will not prevent the event only tell him after it has happened. The destruction is of a chain reaction type in that once started all the energy in the battery is dissipated almost instantly. Fires are usually caused by the red hot bits of metal ejected causing nearby flamable items to ignite, so the charging bags are very useful in preventing this happening. The other by product is a copious amount of white/grey smoke that you really don't want in your house.

If you are doing other jobs then stay close and charge on a fireproof surface with any easy and quick access to a door or window.

Even if you follow the basics regarding max charge voltage and min discharge voltage the cells can become puffy. it would appear that the technology is very stable at 3.7v per cell, which is why 3 cells are sold as 11.1v, but become less stable and prone to internal chemical changes at higher or lower voltages. I used to charge my batteries ready for next use so they were often stored in a charged state. As a result over time some became puffy and were discarded.

The advice given in the article is correct but it perhaps needs emphasizing as it is an important parameter to keep batteries safe.

Fully discharged batteries are safe to dispose locally and contain no harmful chemicals. Do check that it is permitted to use your local disposal point.

Dave

HI all,

Yes, that's the view I shall take and will find a way to dispose of the one that has gone slightly puffy. As you rightly point out they are pretty cheap now and places like Hobby King seem to have a wide choice and it will give me an opportunity to get something with a higher capacity.
It was quite a decision to go over to them in the first place as I had heard so many horror stories but I'm certainly glad I did as the increase in performance is brilliant. The article that Craig linked to is very helpful and I shall save it for future reference.

All the best...Ian

HI Ian, yes we both recommend disposing of your duff lipo, when they go puffy they have an internal problem, they have been known to catch fire usualy when being re-charged, the article was right in saying use until the performance drops but I would not trust the battery. they are cheep enough to replace, dont take the chance, either with your house or your model.
Plenty of you tube vidios of lipo's with thermal runaway burning out of control
Mark

It happens LIPOs are best considered limited life disposable items.

The are not mechanically or electrically robust. Dropping one can cause damage.

Thanks for the prompt replies all.

Craig, the article you link to is very helpful- had a quick skim but will study in more detail tomorrow. My battery is nothing like as swollen as the one in the article- it's barely noticeable but still puffier than its identical twin. The article says that puffy lipos are OK as long as performance isn't affected.

Jarvo and Haverlock you both recommend disposal and I think to be safe I will get some new ones. I'd have been interested to know why it happened- I have tried to be scrupulous in the matters of balance charging, storage charging and the use of low voltage alarms and I suppose it's just one of those things.

Thanks again for the help.

Ian

puffy LIPO == dispose ASAP.

in Technical terms its cream crackered
and Donald ducked.

Some places have disposal/recycle bins for batteries if possible check first and see if they will /can take it.

HI Ian, Very carefully take the battery to the tip and dispose of it in there sealed container, it could potentialy catch fire

Mark

You might find this an interesting read 😊

http://www.tested.com/tech/502351-rc-battery-guide-basics-lithium-polymer-batteries/