** LIPO BASICS ** Read me first!

[Slyster]

For a more complete education.. be sure to visit tjinguys site:
http://sites.google.com/site/tjinguy...arging-how-tos

Cheat sheet for lipos

• Lipos are shipped with an inhibitor for safe transport. So always break in new lipos.. charge to full and then discharge to storage level (3.8V/cell) five times.
  

• New packs do arrive unbalanced sometimes. Do the break in procedure and they will be fine.
  

• Lucien Miller of Scorpion motors states it takes 8-10 cycles before a lipo realizes its full capacity.. so go easy the first 10 flights.

• Never store a pack fully charged for more than 48 hours.. some knowledgeable people find even storing fully charge more than 24 hours that they will never perform the same.
  

• Always store at ~50% (3.8-3.9 v/cell). Most chargers have a storage level feature that will charge or discharge as needed to get to 50%.

• Buy a cell spy.. very cheap and very important... these tell you the voltage per cell as well as overall lipo voltage. Here is an example of one. http://helidirect.com/maxpro-battery...ew-p-22041.hdx

• Follow the 80% rule. Take out no more than 80% of the lipos capacity.

• To figure out acceptable flight times to keep to the 80% rule... fly for exactly 3 mins (after breaking in the lipo) and see how much you put back in using your charger. Then you divide by 3 and now know many mah you use per minute. Adjust your timer accordingly.

• Generally a lipo flown down to 20% will end up between 3.6-3.8 v/cell. Never discharge for any reason below 3.0V/cell resting voltage. They then die forever.

• Many people today use parallel cables and high watt chargers to charge 1 to 6 packs (of equal cell count) for fast charging. The charger only needs to balance the packs as one larger capacity pack so you save a lot of time. Packs must be close in voltage to use this method. I use two 125Ah deep cycles to power my charger for fast field charges and with my iCharger 306b I can charge four 6s5000mah packs in 30 minutes. See Tinjguys site for much more info.
  

• Many ask about chargers that plug directly to AC... not really a good option.. since they only put out 50W. You really need a power supply... a great source (especially for high watt chargers) is http://feathermerchantrc.com.
  

[Slyster]

Anyone with additions, changes, or corrections please PM me!

[Mercuriell]

Generally very good advice, personally I have never done preflight discharge/charge cycles otherwise I would agree with these guidelines. It is essential if you do multiple pack charging that each pack is correctly connected to the charger balancer and verified by reference to the charger display. Hyperion Duo chargers are designed just for this.

[Slyster]

Thank you mods!

If anyone has things I should delete or add or changed let me know.... so this can be an accurate guide for the new guys that are always coming through.

[flyinghigh450]

Awesome write up Sly ..

[willlig756]

Originally Posted by flyinghigh450

Awesome write up Sly ..

+1

[DominicD]

I wouldnt leave lipos charged for more than a day, after 3 days you will lose alot of power.

[FuntanaS]

I would add that the damage from leaving a battery fully charged in cumulative. Every hour that it is left fully charged adds up. Leaving a battery fully charged for 6 hours a day for a year is equivalent to leaving it charged for 3 months straight.

[Slyster]

Funny.. I actually had that in there and someone told me i was being too long winded so I took it out. I'll add it again.

[gonepostal-]

I must be doing this wrong 80 percent of 2650 is 2120 I'm using 281.3 per minute that is like 1 minute 45 seconds no way us that true

[Slyster]

Originally Posted by gonepostal-

I must be doing this wrong 80 percent of 2650 is 2120 I'm using 281.3 per minute that is like 1 minute 45 seconds no way us that true

281mah/minute? That equates to a 7.5 minute flight before hitting 80% capacity used. That sounds reasonable. I would set my timer to 6.5 mins to be safe. And as skills progress.. so does mah consumption. So monitor your charger periodically.

[gonepostal-]

Do you think you can post the way the exact way you did the equation? I fly with a turnigy typhoon 3500kv w/10 pinion and a turnigy dlux 40amp esc, zippy flightmax 2650Mah 3s batterys. I've been draining my batterys down to 3.82v the lowest i ever got was 3.73v that is Flying for 7.30 min. Thanks for the help love this website and always interested in talkin helis and makin friends!

[Slyster]

Here's an example using a 6s5000mah pack.

Putting back 80% capacity into a 5000mah pack would be 4000mah. Thats as far as you can go (for the sake of the lipo). Generally you don't want to even go that far.

So after a 5 minutes flight lets say you put back 3200mah. Divided 3200mah by 5 minutes and you get 640mah per minute.

Now divide the safe draw on 4000mah by 650mah and you get a total flight time of 6:09 minutes. But that is MAX. So in that example I'd probably set my timer to 5:30.

Some helis can't even go 4 minutes. So it might be wise to fly 3 mins for your first lipo test and divide the mah put back in by 3.

[kdfi]

How do you store your lipos? Fire proof safe, Lipo sack, etc? Do you store them in you garage, home or a hobby shed if you have one?.

thanks you.

[Slyster]

It is important to store lipos safely. Most often fire incidents occur during charge or after a crash.. but there have been a few confirmed reports of a lipo just going off in storage!

Some use ammo cans, fire safes, gun safes, lipo sacks. Just make sure there are holes for gasses to escape otherwise you just might have a container explode as well!

My cheap bulletproof method... $10 or so.. and with some tests done on YouTube.. lipos burning up in a cinder block barely makes the concrete even warm.

Make sure you have flat blocks for the bottom and top.

[FlyingFiz]

Hey Slyster

After I finish an average flight my batts are around 3.7 to 3.9 volts per cell, and then within 6 hours I charge them to 4.1 volts and leave for a week (or sometimes more)until I use again.

However, going on the initial Lipo rules you set out I should be using my batts, and when I have finished flying I should leave them at say 3.8 volts and not charge until the night before or day I want to fly again??, Or should I use them, then charge to 4.1v and then discharge to 3.8 for the weeks storage??

Thanks

[Slyster]

Why charge to 4.1v? I just wonder where you got number. Full is 4.2v/cell. I would always charge (or discharge) to storage level at the end of the flying day... regardless if I am going to fly in a day or a week or a month.

[FlyingFiz]

Sorry, typo 4.2 v

[Slyster]

Yeah... full... even for a few days.. and your packs just won't have the same punch again.

[FlyingFiz]

Ok thanks,

I'll discharge the batts by flying them down to the average of 3.8 v and just leave at that until I want to fly again. I thought that storage requirements was for longer periods, like a month or more.

Interestingly I haven't had any batts deteriorate from my charging and leaving for a week! Maybe just lucky or maybe the damage will manifest itself later in the batteries life.

Phil