Just finished running all my Lipos (that i don't plan using soon) through my chargers storage cycle. Do you guys store yours like this and exactly what is it doing to make ready for storage ? Dropping the charge down to a certain volt or what ?

Yup. Lipos don't like to be stored at full charge.

Storage voltage 3.85 volts per cell.
http://www.rcgroups.com/forums/showthread.php?t=1142622

Originally Posted by rick.benjamin

Storage voltage 3.85 volts per cell.
http://www.rcgroups.com/forums/showthread.php?t=1142622

I "put them away" around 3.85 volts/cell.
After a day of flying 8 or 10 different Lipos and knowing I won't be using them for quite a while, I put them on "storage" cycle.

The only thing is... the last .01 or .02 volt/cell takes forever to achieve. So, if they're 3.85, 3.86, 3.85 and 3.84 (4 cell battery), I terminate the program and put them aside.

Yep, same here, "storage mode" takes forever. Once in the neighborhood of 3.84 I'll just call it quits. If I end up with fully charged packs after a morning (maybe the wind kicked up or I broke a prop) I'll just put them in the refrigerator until the following weekend. I'll never store them at room temp more than 2 days.

I do the same...seems to be beneficial because I have batteries approaching 2 years of age and they still perform great. During the winter when they arent being used, I check on em every few weeks or so and they stay balanced

Leaving a pack at too high a charge state will cause accelerated breakdown of its "guts", which raises internal resistance and reduces performance, capacity, and overall lifespan. A lipo at storage voltage in a cool temperature (~35-60F or so) will last a VERY long time with minimal degradation.

I use my wattmeter, some alligator clips, and a piece of nichrome to discharge the odd pack that's showing a little more voltage than I want. Don't hate. It works. It's also fully adjustable from tiny amounts of current to huge discharge levels. Maybe not great for the packs, but it's better than leaving them charged indefinitely.

The problem with the discharging features in most chargers is that there is a LOT of energy in those packs, even if they're only a little above 3.7V/cell, and the charger has to get rid of it all as heat. Too high a discharge rate will require massive heat release and will cause the pack's voltage to sag far below its "resting" level (which results in inaccurate discharging), but too low of a rate obviously takes a loooong time.

I never know when I will get a chance to fly, so most of my lipos are ready to go with a full charge year around. No issues so far. Missing a chance to fly because of uncharged batteries would bum me out way more than loosing a tiny fraction of voltage.

Originally Posted by Bloosee

Yep, same here, "storage mode" takes forever. Once in the neighborhood of 3.84 I'll just call it quits. If I end up with fully charged packs after a morning (maybe the wind kicked up or I broke a prop) I'll just put them in the refrigerator until the following weekend. I'll never store them at room temp more than 2 days.

Can you clear up something I heard...

Lipos should be kept above 45 degrees (something I heard early in my Lipo experience).

Is there a low temperature we should NOT go below with Lipos?

I never know when I will get a chance to fly, so most of my lipos are ready to go with a full charge year around. No issues so far. Missing a chance to fly because of uncharged batteries would bum me out way more than loosing a tiny fraction of voltage.

Well, it's not exactly a "tiny fraction of voltage". You're doing a lot more damage than you seem to think, but if you haven't noticed a drop in performance and you don't mind replacing dead packs very prematurely, then I suppose there's not much harm Just keep in mind that you ARE damaging those batteries whether you notice it or not, and they won't stand up to it forever.

If you don't believe me then I'd recommend trying an experiment, at the very least: Select one or two packs to take GREAT care of (charging-wise), and occasionally compare them in flight to the ones you leave charged all the time.... just to get a rough idea

Originally Posted by C₄H₁₀

Well, it's not exactly a "tiny fraction of voltage". You're doing a lot more damage than you seem to think, but if you haven't noticed a drop in performance and you don't mind replacing dead packs very prematurely, then I suppose there's not much harm Just keep in mind that you ARE damaging those batteries whether you notice it or not, and they won't stand up to it forever.

If you don't believe me then I'd recommend trying an experiment, at the very least: Select one or two packs to take GREAT care of (charging-wise), and occasionally compare them in flight to the ones you leave charged all the time.... just to get a rough idea

Oh I believe you, I'm just not too worried about replacing a $20 lipo every couple of years.

does the storage thoughts also include the micro 1s batts? i'm guessing so, but i'm like scotti 1/2 the time mine are charged up and they seem to be fine even a few weeks later. I know they are only $1.60 ea. but i'm still curious if its true with them little ones?
thanks
boats

I never leave my LiPos fully charged for more than a few days. If I don't use them in that time I'll discharge them to storage voltage.

I don't generally charge them 'up' to storage voltage though, I just leave them at 3.7-3.8v as they come off the plane, unless maybe i know i wont be using them for weeks when I may do a storage charge.

It seems that some batteries are more sensitive to being stored fully charged. Higher c rating ones seen the most susceptible. Also if you are not pulling high amps from your battery you probably wont even notice the damage done anyway, so I take the stories of the guys who say they always store fully charged 'and it does no harm' with a big pinch of salt.

Storing charged can kill batteries pretty quickly. I killed some in about 20 cycles that way. I once bought a model second hand with three 'new' LiPos that the guy had kept fully charged for 6 months (he diligently topped them up every month), those LiPos were rendered useless and had only a few cycles.

Originally Posted by scottieusa

I never know when I will get a chance to fly, so most of my lipos are ready to go with a full charge year around. No issues so far. Missing a chance to fly because of uncharged batteries would bum me out way more than loosing a tiny fraction of voltage.

A man after my own heart. Life's too short to spend it discharging batteries so I can charge them again when I'd rather be flying. With our weather, we just never know when we will fly next. Nothing worse than having Joe call an hour before dark wanting me to go fly with him and having to tell him ok, but I've got to charge my batteries first. Only been involved a couple of years, but thus far only lost one battery and have way too many.

I used to keep 6 Zippy 3S 2200 20C packs charged up virtually all the time in the name convenience so I can fly on a whim, but also stored them charged up due to ignorance at that time. Their performance may have been reduced but I never drew more than ~16 amps from them over the course of 2+ years, so the performance loss wasn't really noticeable. However, I've recently retired 4 of them cause they're puffy and a couple of them had difficulty balancing. I got my $8 of use out of them, though.

Now that I have better, higher C-rated packs, I make it a point not to store them charged, to preserve their perfomance/lifespan but the inconvenience of charging them up when needed is just awful as it can take a couple hours, and by that time the wind may be howling.

So now I'm considering a 20A iCharger unit so that I can parallel charge them all simultaneously and live in lipo harmony