been away for a while. Lipo's not taken care of..??

[tha5150]

moved, took a vacation, got married, went on our honeymoon, blablabla.. basically my Hyper 8 and Lipo's have been sitting in the garage, untouched for several months. i know this is not good for the lipo's. what should i do to get things back to normal? what sort of charge and use should i do? kinda a re break-in period. its a 4s 5000mah. i have 2 of them.

[wallot]

charge and use. for my 1/18 trucks I have batteries sitting on a shelf for 6 months :) I leave them half charged and they stay half charged for whole 6 months

[suicideneil]

Same here- British weather doesnt permit much regular use.

I would just chuck them on the charger, check the cell voltages to make sure they arent massively out of whack, then just do a normal balance charge to 4.2v per cell, then use 'em or stick 'em back on the shelf ( I dont bother with the 'storage charge' setting ).

[florianz]

lipo batteries should be stored at about 3,8 v or a bit higher, but not fully charged for longer time. the higher voltage stresses the cells. that's why they ship new lipos with about 3,8 v (each cell). you can store the batteries at 4,2 for a week or two, but not for months. that's bad for the performance.

[suicideneil]

My own findings say otherwise- what is it about being fully charged that stresses the cells exactly? The voltage doesnt drift up or fluctuate, its just sitting there, slowly self discharging...

[redshift]

Originally Posted by suicideneil

My own findings say otherwise- what is it about being fully charged that stresses the cells exactly? The voltage doesnt drift up or fluctuate, its just sitting there, slowly self discharging...

I'm on the fence about that myself.

In my experience, idle discharge amounts to hundredths of a volt over a few months, almost zero. My Hyperion 20C Swifts I keep at 60%, but they also have had full charge for extended periods, several weeks, and still strong as new. I have 2 Tenergy 25C 2100 packs that I DO keep full, almost as an intentional stress test, but more so I am ready to fly in a very small window lol. They are also working like new. My friend had a TP 1320 that held voltage for nearly 1.5 years, bought it, charged it , then sold the heli he was going to use it in. He sold it to a friend, he got full run no problems. Yes, you can charge your batts a year and a half in advance! These were the older 12/15C packs, but I would expect the same or better out of the newer higher discharge packs.

Run em!

[simplechamp]

I'm definitely going to follow this thread. I have always stored my packs at 3.8V/cell just because the charger had a storage feature and I assumed that was the best for the cells. Now I'm not so sure, considering I've yet to see evidence showing 4.2V storage is detrimental to pack "health".

EDIT: After doing a Google search and looking at multiple car/heli/plane forums it seems the consensus is always to store right around 3.8V/cell, yet no one ever gives a reason. It's all people saying that's what they've heard or read without any real facts or data to back it up. I'm going to keep my cells at 3.8V/cell for storage until I see evidence showing it's either (A) unnecessary or (B) there's a better storage voltage.

[BrianG]

There is a blurb at batteryuniversity.com that says storing lithium at full ~4.2v/cell charge promotes cell corrosion (on the anode IIRC). Now, that's for Li-Ion, but doesn't say either way about lipo specifically. However, I would question why manufacturers would ship lipos at ~3.8c/cell if it wasn't an issue. Plus, many battery chargers have the storage mode. Could be just marketing, but I tend to err on the side of caution. I don't think they'll puff or blow or anything, but might affect capacity over a shorter number of cycles.

[redshift]

Originally Posted by BrianG

I would question why manufacturers would ship lipos at ~3.8c/cell if it wasn't an issue.

I almost think that is strictly for safety reasons, should a pack get punctured or shorted in transit. Good question, it's hard to get definitive answers...

[BrianG]

Lol, I just did a search and came up with that exact question I posed to the maker of the TME Xtrema: http://tmenet.com/forums/index.php?t....msg800#msg800

Another bit of info on this topic, but does not state "why": http://www.kongpower.com/faq_en/show...xt01=&srhTxt02

The batteryuniversity blurb I was referring to: http://www.batteryuniversity.com/partone-5A.htm

Specifically:

-The time at which the battery stays at 4.20/cell should be as short as possible. Prolonged high voltage promotes corrosion, especially at elevated temperatures. Spinel is less sensitive to high voltage.

This page also talks about storage (towards the bottom of the page), but seems to simply regurgitate the same vague answers found elsewhere: http://www.rchelicopterfun.com/rc-lipo-batteries.html

[simplechamp]

Right now my money is still on 3.8V/cell. Since that's the generally accepted amount (for whatever reason that may be) I'm going to stick with that until I find evidence that suggests doing something different.

The problem is that it's so hard to get empirical data here, everything is anecdotal e.g. "Well this one guy at my club stored his batteries at XXX volts/cell and his lasted way longer than mine". There's so many factors to account for that it's nearly impossible to get valid data from all of us users.

And think about how long it would take to do a true standardized test: charge lipo, let it sit for 1 week or 2 weeks or 3 months? Then discharge it and repeat about 250 times? Better start on that experiment now, might get some definitive results by the time lipos are old news and we're all using some new latest and greatest battery technology.

[zeropointbug]

Well I always knew that lipo's can not be fully charged for extended periods of time... I have always seen that, like BrianG mentioned, it was an issue of cathode (or anode?) corrosion that starts to happen around 4.0volts, and increases exponentially as voltage increases... I remember reading this somewhere, but I am at a loss about where. Also, I find it convincing enough that battery makers state the same thing, as you would think they wouldn't mention anything, as the shorter a battery lasts, the sooner you have to buy a new one. Unless... it's a conspiracy on the pack makers, and it's actually damaging for them to be anything but fully charged? (highly doubtful)

[lutach]

I've been using lipos for a while now and I store them at different voltages due to sometimes being lazy. I haven't noticed any difference at all in performance. I have lipo packs that are over 4yrs old and still shows the same level of performance. I still have some older 3S2P packs without the balance leads as well and they are still awesome for 10-15C rated cells (They are rated for a higher C rate since they held over 3.5V at around 20-25C bursts).

[tha5150]

ok so i still havent done anything with them and cleaned the garage last weekend and found them again. lmao.
i will charge them up and run low and recharge again. wont get them too hot cause i am sure thats not good for them either.

[crazyjr]

Here is my 2 cents on this, i have 6 batteries sitting on my computer desk right now, fully charged and been that way for a couple months. All are three+ years old and still running strong, I have always charged fully and stored them. These are Flightpower 3700 20c's and hyperion twenty 20c 3700 mah lipo's, I had some 20c maxamps (5000 and 8000) and they all puffed within a year and a half, of buying. I personally think it's in the quality of the materials used that determine the rate of which the corrosion occurs, Hyperion and flightpower (mine are the old enerland based cells) were much higher quality than the maxamps I'm sure. On the same note, i have no experience with turnigy or zippy packs from HK, so i do not know if they are the same quality as my FP and Hyperion or not