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02-07-2010 03:06 PM  8 years agoPost 1
Heli_KV

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Ottawa, Canada

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How do you discharge batteries for storage? I use heli itself, but it is painful. Any better way?

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02-07-2010 03:57 PM  8 years agoPost 2
zaw

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Lebanon, NH - USA

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just fly it.

ಠ_ಠ HBK2 built with inexpensive parts! ٩๏̯͡๏)۶ Gaui425

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02-07-2010 04:47 PM  8 years agoPost 3
tryan02

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Canton, Missouri

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02-07-2010 05:00 PM  8 years agoPost 4
Gregor99rrElite Veteran - Western Wa - My Posts: All  Forum  Topic

I try to fly, but sometimes that doesn't work out. It starts raining, or I don't get the flight in before the busy week starts. In winter with short days and now flying after work it gets harder.

When I was racing RC cars, I bought this device from Deans. It was a combo light bar (a bunch if automotive lights in parallel) and car stand. It also had an in-line device to cut off the volage called the Dean's Black Box II

But it designed for a 6 cell NiCad, so the cut off is too low for lipos. I attach a voltmeteter and just observe the voltage as it drops. Disconnect when it gets to 3.85 per cell. It works fine for 3S. But I'd need to rewire it for 6s and 8s packs so the bulbs don't blow up.

Here's another option I saw in RCG that looks like a nice alternative.

http://www.rcgroups.com/forums/showthread.php?t=1131817

The other option is that many chargers (including the upcoming FMA Powerlab 8) have a discharge feature.

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02-07-2010 05:07 PM  8 years agoPost 5
tryan02

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Canton, Missouri

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02-07-2010 05:12 PM  8 years agoPost 6
Gregor99

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Western Wa

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But who said 50% and why would you discharge a battery for storage?
This recommendation is include in some of the Hyperion charger manuals. Its also mentioned multiple times by a Hyperion rep (NipponDave) on RCGroups. Many others agree that premature puffing and capacity loss is associated with leaving packs at 100% for prolonged periods of time. Hyperion recommends no more than a couple days. With a week the maximum.

I've also found this recommendation in consumer electronic's manuals for devices that use Lithium packs, since as digital cameras and camcorders.

I've never seen a good description of the chemistry or science behind this recommendation.

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02-07-2010 05:16 PM  8 years agoPost 7
Gregor99

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Western Wa

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OK great yeah a load drains a battery. But if a cell drops below 3V its permanently damaged.
The devices and methods I describe prevent this. Discharge methods should stop when the cells are close to 3.85v per cell. If your discharge method can't monitor or stop discharge at a preset voltage, then don't use it.

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02-07-2010 05:26 PM  8 years agoPost 8
tryan02

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02-07-2010 05:49 PM  8 years agoPost 9
Heli_KV

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Ottawa, Canada

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I am not that picky to discharge lipos to 50%, but I think if it were not much painful, kind of plug, push button, it discharges and beep-beep when done, cutting drain, that would be great. And if it would be that simple, why not to discharge for storage. I found some discharger on HobbyKing, but it is too small, dischrges slowly and does not stop battery drain when done, so it is easy to end up with dead battery.

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02-07-2010 05:59 PM  8 years agoPost 10
Gregor99

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Western Wa

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That's my point greg remember they still tell us not to charge at a rate more than 1C also.
Actually, that guidance has changed in the last year or so. Most packs are now being supported at 2c to 5c. Even the higher C packs from Zippy say 5c charging is suppported.
And last I checked batteries discharge by themselves no need to help them
This is the reason to discharge them to about 50%-60%. So that thier natural self-discharge doesn't bring them down to below 3v per cell. LiPos have a very low self discharge rate. So this hasn't been an issue.

I do agree with your scepticism on this guidance. I would like to hear a clear scientific explaination of this guidance. So far its been LiPo folk lore. But since the guidance comes not only from Hyperion but also from other manufactures not related to RC, I suspect there is something to it.

The other side of this is that discharge for storage, in most cases, is not a hard thing to do. It doesn't cost you much so why not? The next time you use that pack it will have been freshly topped off. So you know its charge state regardless of how long it has been sitting.

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02-07-2010 06:06 PM  8 years agoPost 11
tryan02

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02-07-2010 06:27 PM  8 years agoPost 12
Ace Dude

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USA

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How do you discharge batteries for storage? I use heli itself, but it is painful. Any better way?
Although I have a CBA II, I just use my charger. My Hyperion 720i NET3 is capable of 80W discharge power.

The upcoming FMA PowerLab8 will be capable of 100W of discharge power.

Most, if not all, Lithium battery manufacturers recommend 50% capacity for storage. I guess it's no coincidence that packs come 50% from the factory.

  

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02-07-2010 06:36 PM  8 years agoPost 13
Gregor99

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Western Wa

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to each his own
It comes down to that. Since there isn't enough science to convince everyone to discharge for storage, many won't. If they don't experience puffing, or loss of ability to deliver capacity, then they have proved thier process to themselves.

However, others cannot weigh these anecdotal expeirences any differently then those that report premature puffing and capaciy issues with packs that are stored at 100%.

So its up to you. Weigh the cost and time associated with following the guidance, along with common sense and the potential risks assocated with not following the guidance. Then decide for yourselves.

Personally I have found many weaknesses in anectdotal evidence. It seems recently I have been involved in many discussions were someone went against a mfg's recommendation, experienced no ill concenquences and deemed thier voliation of mfg guidance as the new guidance. Because the violation provides "more for less", many unknowing forum members jump on the bandwagon and add to urban legend. If you get enough poeple doing the wrong thing, does that make it right?

More often then not these same people are later found complaining the component is flaky, does not last etc. Never taking responsibility for causing the problems they introduced.

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02-07-2010 08:58 PM  8 years agoPost 14
tryan02

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02-07-2010 09:00 PM  8 years agoPost 15
racin06

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Indianapolis, Indiana

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to each his own I have never lost or damaged a battery by leaving it fully charged so it makes no sense to me to discharge. That one discharge for storage is one less flight on that pack.
I'm with Tryan. I have always stored my lipos at 100% charge...some for over three months and guess what? These lipos perform just fine. Storing lipos at 50% capacity is an "old wives tale" if you ask me.

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02-07-2010 09:39 PM  8 years agoPost 16
Ace Dude

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USA

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Bottom line is use whatever works for you. In my experience I find following the manufacturers recommendations usually works best.

  

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02-07-2010 10:56 PM  8 years agoPost 17
tryan02

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Canton, Missouri

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02-08-2010 12:05 AM  8 years agoPost 18
Gregor99

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Western Wa

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There is a thing known as product liability that these manufacturers have to deal with.
You are going to do what you want and you are not going convince anyone that being lazy is better for lipos. Liability has nothing to do with the storage charge.

Lets just stack up the for and against.

For using storage charge
Many mfgs recommend it, including non RC vendors like Canon Cameras
It's not hard to do
No user has reported a premature puffing, pack failure, or fire caused by following this advice.
The pack is always freshly charged before its used in the model

Against using storage charge
Mfgs recommend against it
It doesn't save much effort
Premature puffing and pack degradation have been attributed to leaving a pack fully charged.
Being rebellious is fun.
Did I miss any?

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02-08-2010 12:13 AM  8 years agoPost 19
tryan02

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Canton, Missouri

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02-08-2010 12:27 AM  8 years agoPost 20
Ace Dude

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USA

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How do you know what works best if your following the manufactures recommendations?
Perhaps you could simply provide us with some factual data (i.e., non-personal opinion) to show that storage at 100% has no impact on performance or life span.
I have been breaking the rules for quite some time now charging at 2C with the Cellpro 4s and now all of a sudden it's OK to charge at that rate.
Not sure where you got that from. TP packs have been rated for 2C charging for years.

  

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