Lipo battery safety info

[tk5028]

I have only been on this forum for a couple of months but been into R/C helis for about 6 years. As more people are coming into crawlers I am seeing more questions about LiPo's. Here is some info I have compiled. The first is from MaxAmps.com. You can find the origional here.
http://www.maxamps.com/lipo-care.php
Below that I have added some extra info that was not incuded.

I think that this would make a good sticky and if anyone has something to add please do. These can be dangerous batteries and we need to keep people informed.


"Connection: You must be sure that the correct polarity is observed when connecting battery packs to charger or speed controller.

PINK / RED = POSITIVE (+)
BLUE / BLACK = NEGATIVE (-)

Charging: Lithium Polymer batteries have specific charging requirements and ONLY chargers rated for Lithium Polymer cells may be used. The best chargers are those which require the user to manually select cell count and charge rate for each pack of cells, then automatically check to see that the settings are correct. The Hyperion EOS Charger line belongs to this category. Chargers which use only automatic detection of cell count (and on that basis set charge voltage) are prone to error, and can damage cells or cause a fire due to over-voltage charging of cells. We recommend that these chargers be set manually, if used. Other chargers are set manually, but do not include a safety circuit to oversee that setting. These are prone to user error, and should also be checked very carefully to insure proper use.
Lithium CC/CV chargers, like those in the Hyperion EOS Charger line, must be used. These charge initially at a constant 4.2V and constant 1C rate, then taper the charge rate as the battery nears full capacity. Cells are about 90% charged in one hour, and can be left connected for another 20-30 minutes to complete the charge. The maximum permissible charge voltage per cell is 4.2V. The maximum recommended charge rate for Lithium Polymer cells is 1C (ex: 1.5A for a 1500mAh pack). Please do not charge your lithium polymer at any rate higher than 1C. Doing so may reduce the capacity and life cycle of the cells, with very little savings in charge time.
Discharging: Any battery including lithium polymer must be discharged within rated current and voltage limits. Failure to do so will result in damage to the battery, at least, and could even cause an accident.

• Use a motor speed controller which has auto-cut feature for lithium polymer. Auto-cut should be set at 3.0V per cell. A three-cell pack, therefore, should be set for 9.0V auto-cut, for example.
• Don’t leave battery pack plugged into vehicle while not in use. The pack can still discharge to an unsafe level and damage the pack even if all components are turned off.
• Make sure to cycle your packs at least once per month since leaving them on the shelf for a prolonged period can cause the packs to get severely out of balance or even go dead.
• Do not exceed the manufacturer's rated maximum continuous discharge rating!
• USE AN AMPMETER, like An Eagle Tree Data Logger, to confirm the maximum amperage drawn by your motor-batter-propeller combination
• Do NOT count on "unloading" during flight to greatly reduce the current drawn. In most cases this effect is MINIMAL. In the case of High pitch props at high RPM, the in-flight amperage may actually RISE substantially. Factor this into your calculations.

Taps on Lithium Polymer Packs: All MaxAmps Lipo packs come standard with Hyperion/Apache style balancing taps (white connector). This tap can be used with the Hyperion LBA10 Balancer and also with the Apache 505 Balancer. Always balance your pack before each use to prevent the possibility of over-charging or over-discharging. This also “matches” the voltage of each cell to give you the highest performance and longest life.
Lithium Polymer Safety Tips: Lithium Polymer cells are a tremendous advance in battery technology for RC use. However, due to the chemistry of lithium cells, there is a possibility of fire if charging is not properly done. It is unavoidable due to the nature of lithium itself. This is no different from many things we use in daily life – knives, kitchen cleaners, automobiles, for a few examples – which are inherently dangerous, but which can be used safely by adhering to simple rules and precautions.

• Be absolutely sure that the Lithium Polymer charger settings are correct for the battery pack being charged – both voltage and current settings
• Lithium Polymer must be CHARGED and STORED in a fire-safe container like a Lipo Sack
• Do not charge batteries near flammable items or liquids
• Keep a dry fire extinguisher nearby - or a large bucket of dry sand, which is a cheap and effective extinguisher
• Never charge inside an automobile even when parked
• Batteries should NEVER be left unattended while charging
• KEEP BATTERIES AWAY from children and pets at ALL times

Handling Cautions: New cells may have a high initial charge, and care must always be taken to insure that loose cells are not short circuited.

• Never leave batteries inside a car on a hot day, nor any other place where ambient temperature may exceed 140F / 60C.
• Although environmentally friendly, lithium polymer cells must be FULLY discharged before disposal. Use a resistor setup (light bulbs, for example) to accomplish this, to avoid the possibility of a short-induced fire after disposal.
• Immediately discharge damaged batteries at 1/2 C rate and dispose.
• Do not put the loose cells in a pocket, bag, or drawer where they could short-circuit against other items, or the battery tabs could be pressed against each other.
• Do not place the loose cells on any conductive surface, such as a metal-topped table.
• We recommend purchasing pre-assembled packs rather than assembling packs from loose cells.
• Take care that the cells are not punctured, especially by metallic objects like hobby knives.
• If the electrolyte in the cells should get on your skin, thoroughly wash with soap and water. If in the eyes, rinse thoroughly with cool water. Immediately seek medical attention for this, or for burns."

I would like to add you should only use %80 of your batteries capacity, Ex: if it is a 3000 mAh you should only use 2400 mAh to keep the cells above 3.0 volts. Check how much mAh is put back into the battery when charging and use a timer to limit your time to keep it under %80. I have seen many people say they will stop flying/driving/crawling when they notice a drop in power. That is too late. Using the %80 rule will greatly extend the life of your LiPo.

Also, when ever you roll, crash, ect......check your LiPo for damage. A bump from a rock, stab from a stick or any other damage can render your LiPo "dangerous" so keep a good eye on them and watch for anything unusual.

Bulging or swelling, also known as "puffing" is a serious condition. If you see this remove the battery from the vechile/charger, take outside and keep an eye on it. After deemed "safe", usually anout 1/2 hour, follow Handling Cautions as stated above. NEVER try to use or charge a LiPo that has puffed. If you do be forwarned you could lose your R/C vehicle, car/truck, house or get seroiusly burned.

If anybody else has anything to add please do. You cannot have too much info on these batteries.

 

[Scratch]

Agreed this should be stickied, new to RC and rock crawling. I was thinking about using LiPos' on my steering axle but not so sure now...

P.S thanks for the informative post.

 

[tk5028]

There safe as long as you follow the rules. Been using them in my helis for over two years now with now proplems.

 

[666]

And then.....

 

[Access]

That info seems a bit old, I think it misses some of the newer stuff.

Storing LiPos is fine, but not fully charged. Discharge to 40% or so and then store them. When bringing them out of storage, Be sure to re-balance. If you store a LiPo fully charged, it will lose approximentally 20% capacity every year. If you store a LiPo only half charged, it will lose approximentally 4% capacity every year. Do not store fully discharged.

The best way to re-balance is to charge each cell individually. For routine charging, you can uses a balancer, but be aware most balancers will only do so much.

Most balancers work as a voltage clamp, when the cell voltage gets above 4.23V it will draw up to a current limit and blink a light or something like that. This current limit is often quite low, ie. 100mA. Therefore you must watch the balancer and if the light becomes solid disconnect stop charging the battery and instead charge each cell individually.

New LiPos that have never been used before should be 'broken in'. This means no more than 6C discharge for the first few cycles. A LiPo stored for long periods may need to be treated similarly.

Watch your temperature and don't overstress the cells. For batteries with 3 cells or more, be aware that even if the battery itself feels only warm, the center cells have much less exposed area and don't dissipate heat as well as the ones on the outside.

Cheaper LiPos (like the $50. 3s 4000mAH) often lie about the 'C' rating. They may claim to be 25-35C or so when in reality they are only good to about 12C.

When a cell is reaching the end of its life, it will take longer to charge. It will spend less time of the charge in the CC part and more time in the CV part. Its Capacity will drop and its internal resistance will rise, effectively dropping the 'C' rating. When a cell has lost 20% of its original capacity, it is time to retire it.

Even batteries that claim to be 2C or 3C charge capable will last a longer cycle life if charged at only 1C. Likewise, a battery that is only partly discharged will last significantly longer than one that is fully discharged. If you do half discharges, you can expect the cell to have a cycle life of 4x or more than if you did full discharges. If you want true fast charge capable cells, consider A123 cells as an alternative.

 

[Timmahh]

great thread. love the lipo info.
thanx for the education.

Timmahh

 

[SVEN]

It's already in the stickies....

http://www.rccrawler.com/forum/showpost.php?p=316016&postcount=2
http://www.rccrawler.com/forum/showthread.php?t=124138

 

[tk5028]

Good info Access."thumbsup"

Sven, I was aming for a sticky that was more upfront as soon as you go under electronics it would be there and not burried in another thread. There seems to be alot of questions from newbies or those new to LiPo's. These batteries are dangerous enough it should be upfront without having to dig through other threads to find it.

 

[JohnRobHolmes]

There are too many stickies to have them up front. How about 40 sticky threads when you get into the electronics forum? The info you provided is already in the battery sticky, verbatim.

Good info though, thanks for posting it up!

 

[Chris_The_Battery_Man]

In all actuallity, these days, lipo safety can be said short and sweet. Thus not scaring or boring people. Generally I start when a customer asks with "Well if your not an idiot, you wont have to worry about a fire" Lipo fires only are a result of USER ERROR during charging. Lipos can not and will not spontaneously catch fire or catch fire because of a short, puffed, or punctured cell. Thats a big mis-conception. Fires will only occur during those circumstances if the pack is near something flamable and the back is punctured or shorted. The lipo in it self will not catch fire(Trust me, we screw with lipos ALOT at work and have been for almost 5 years now) Out of the almost 7 years I have been building batteries, I have only ever seen 1 lipo fire... and it was because of USER ERROR. The charger was not setup right and needless to say, there was a sweet inferno8) So with that said, you follow the below suggestions, and you whould be fine.. It's all honestly just common sense. If you plan on charging on your homework, in your bedroom, without a ballancer, or a good lipo charger, then your asking for a fire.


Hearing about the "DANGERS" of lipos are getting old. Too many people are you tube whores and only see the same storys repeated or people trying to get lipos to catch fire in a manner that on one in their right mind would do, then video tape it. . . Not the good. Yeah, if you charge a lipo with a charger that charges the lead acid battery in your real car, it will catch fire, but whos going to do that?!?!? Dont let youtube scare you, or as I like to call them, the lipo police. Dont be an idiot and your fine.


-Always use a GOOD(Not cheap or any super brain or astro chargers) lipo capable charger using the lipo charging finction

-ABSOLUTELY ALWAYS charge at 1C(ie 1000 mah = 1amp 2000mah = 2 amp) and ALWAYS use a ballancer. Not using a ballancer will dramatically increase the risk of a fire.

-NEVER charge or store a damaged lipo near ANYTHING flamable... EVER(had several customers charge lipos incorrectly in their bedrooms, and none the less, they had to re-do their homework for algebra)

-NEVER run a lipo pack in a car that does not have an LVC(Low Voltage Cutoff) thats set to 3v per cell.

-And finally, with all the different taps(Ballancing plugs), make sure you mate up the correct plugs with your ballancer and cell ammount



.

 

[fred0000]

am I doing it wrong?

(sorry to bump an old thread, but the thread with the 80% preacher goofball i'm looking for is gone)

i've had these lipo's charge up to 1630+ mah in the past. never ran bellow 3.4v per cell and always ballance charged.

 

[racerrandy]

The lipo's are rated at 1600 mh but thats just a rating. They could be above or below that. If you charge at a lower amperage it will put more milliamps in the pack as well. At least with sub c's its that way, and I am assuming its the same for lipo's. Maybe have to test that out. "thumbsup"




Randy

 

[WIDELOAD]

am I doing it wrong?

(sorry to bump an old thread, but the thread with the 80% preacher goofball i'm looking for is gone)


i've had these lipo's charge up to 1630+ mah in the past. never ran bellow 3.4v per cell and always ballance charged.

Nope your not doing it wrong. I've got heaps of Turnigy batts that always take over what their stated capacity. Its weird, i've only ever had my turnigys do that. Even my intellect race packs never took more than their 5000mah stated capacity.