RC LiPo Care
 

<center><b style=""><u>RC LiPo Care</u>[/b]</center>

Being new to the electric RC world, I could not find any good articles that truly explained about LiPo batteries. So after days and days of reading forum posts, online articles, manuals, trying things myself, and talking to my LHS... I have came up with the following to help other RC noobs avoid the headache. If you can think of anything that needs to be added in, let me know, and if you think it's good enough to be stickied, please let the admins know. Enjoy...

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<center><u>WARNING AND DISCLAIMER</u>
ALWAYS follow the manufacturer's suggested LiPo care instructions foremost. They override anything and everything you may hear or read otherwise.
If you choose to read on, you are agreeing that I am not liable in any way, and to use this material as simply a guide.</center>

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First of all, many people like NiMH (Nickel-metal hydride) batteries for their ability to be ran down, overcharged, etc., with out the worries of ruining the batteries or catching fire. However, LiPo (Lithium Polymer) batteries are just as safe with proper care for them... plus they provide much better speed and acceleration over NiMH batteries and weigh much less.

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<u>What Current Should I Charge / Discharge At?</u>

Like any battery chemistry, the faster you charge and discharge the packs, the fewer cycles you will ultimately get. That being said:

<li type=circle>Charging (or discharging) at or less than 1C will prolong the battery cycle life. This is also recommended if you do not know the "Max C" of your battery.
<li type=circle>Charging (or discharging) at around 1.5C will still maintain about the average battery cycle life that the manufacturer states, while getting a slightly faster charge. <u>Make sure your manufacturer states that the battery can handle charge (or discharge) rates greater than 1C!!!</u>
<li type=circle>Charging (or discharging) at 2C is about the max you want to charge your LiPo packs at for a quick charge and it will ultimately reduce the battery cycle life. <u>Make sure your manufacturer states that the battery can handle charge (or discharge) rates greater than 1C!!!</u>

To figure out what amperage equals 1C for your battery, do the following:

1C (CURRENT ) = [Battery mAh /1000]A (amps)

Example:

<u>SMC Sport-Max 7.4V 9000mAh 28C Hard Case LiPo Battery Packs:</u>

1C = 9000 mAh / 1000
1C = 9A (amps)
1.5C = 13.5A (amps)
2C = 18A (amps)

Note - LiPo cells can be charged up to 4.2v per cell. So if your charger states the charge on a 2s 7.4v pack is 8.4v... no worries, you're fully charged. Here is a chart that shows the normal voltages of LiPo packs:
1s= 3.7v (Can be charged up to 4.2v)
2s= 7.4v (Can be charged up to 8.4v)
3s= 11.1v (Can be charged up to 12.6v)
4s= 14.8v (Can be charged up to 16.8v)
5s= 18.5v (Can be charged up to 21.0v)
6s= 22.2v (Can be charged up to 25.2v)
7s= 25.9v (Can be charged up to 29.4v)
8s= 29.6v (Can be charged up to 33.6v)

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<u>Do I need to break in my batteries?</u>

Some people and / or manufacturers will say "no" while others say "yes".

Here is a link to a thread where an experiment was done to prove whether breaking in the batteries really helped or not: [link=http://www.rcuniverse.com/forum/m_7001137/anchors_7001137/mpage_1/key_/anchor/tm.htm#7001137]Click Here[/link]
Considering the length and technical aspect of the thread, it may just be easier to say the result: breaking in the batteries yielded slightly better results.

So if you do decide to break in your batteries, I recommend discharging them to roughly 50% for the first 3-5 cycles. If it helps, it helps... the only thing you lose is a little play time the first few cycles.

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<u>Do I need to balance my battery pack(s)?</u>

LiPo battery packs with multiple cells can become unbalanced. If this is the case, some cells can become overcharged and explode. Using a balancer at ALL times is highly recommended. If you choose to not balance the packs every charge, at least do it every 5th time.

Balance Taps are different between brands and must be matched or a proper adapter used. This is not just because of the size and shape of the connector but because of the way the leads are connected to individual cells within the pack. Using the wrong connectors can cause major problems.
Here is a link to a chart about [link=http://www.rcaccessory.com/pdf/Battery%20Tap%20Configuration%20Guide.pdf]Balance Tap Compatibility[/link].

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<u>Battery Care:</u>

<li type=circle>If your charger has a TCS (Terminal Capacity Selection), setting it to 90-95% can increase battery cycle life.
<li type=circle>Charging the last few mAh back into the pack takes a LOT more time than the first few mAh did, so set the TCS to 90-95% to get back in the action quickly with a slightly less run time. However, the time saved by not charging the remaining portion will benefit you in RC run time throughout the day. If it takes 10 minutes to charge up the last 10%, but it only cuts down your run time by 3 minutes, then you have just saved yourself 7 minutes.
<li type=circle>ALWAYS store LiPo packs at ~60% capacity. Some chargers have a STORE Mode to achieve this. It is especially harmful to store lithium packsfully charged, and should be avoided for more than a day or two at most. If you store for longer than this, the chemicals will change causing the batteries to puff up.
<li type=circle>AVOID discharging cells beyond 3.0v to 3.5v per cell. If you have an LVC (low voltage cutoff), use it as a backup. Run the car until you see some power loss and then recharge the batteries. If you constantly run until you hit the LVC, you might incurr damage, because under heavy use, the voltage spikes and can momentarily reach under 3.0v per cell before the LVC can detect it. Personally, I think setting the LVC to 3.0v is too low... most people have their LVCs set at 3.2 to 3.4v. NEVER fully discharge lithium packs.
<li type=circle>Never charge a LiPo battery beyond the safe "MaxC" for your LiPo pack. Check with your manufacturer to see if you can charge above 1C if it is not stated anywhere on the package or battery!
<li type=circle>Do not exceed 140 degrees Fahrenheit with LiPo batteries! This is not only when using them, but also when storing them. Cars and attics get very hot and will most likely result in a fire.
<li type=circle>If you wreck your car/truck, check the LiPo batteries and make sure the batteries are not damaged. Do not run them if damaged!
<li type=circle>To dispose of LiPo batteries, discharge them and place them in salt water for several hours, then tape up the terminals and place them in the trash.
<li type=circle>If you are running two LiPo packs in parallel, ALWAYS use the same technology, capacity, cell count, and output voltage. Generally speaking, it is safest to use two of the same packs.
<li type=circle>ALWAYS charge a LiPo battery with a LiPo charger. If you charge with a NiMH charger you will majorly damage your batteries!!! If you have a charger that charges different types of batteries, make sure it's set to charge a LiPo.

RE: RC LiPo Care
 

This is a great idea for a thread. Thanks!

RE: RC LiPo Care
 

Nice I vote STICKY! [&:]

RE: RC LiPo Care
 

AGREED!!!
this is some great info
and thanks for posting it around on other forums well area's of this forum at least

the lug

RE: RC LiPo Care
 

Thanks guys for the sticky votes! I had it in a few other areas of the forum too, but the mods took down all of them but two. Oh well, as long as it gets stickied somewhere for people to view.

RE: RC LiPo Care
 

Thanks for all the great info. I ran into the same thing when I was trying to learn about LiPos, seems like noplace really tried to teach about the LiPos they assumed that everyone already knew. Heres another vote for the mods to STICKY this.

RE: RC LiPo Care
 

When the batterys are sold are they at a safe storage charge?
Also I hadthought it was better to have them charged, or safer than being undercharged.I checked them and the dont seem to have swolen.
I only have 2s and 3s lipos if that makes any difference? Should I put them in car and run the, a bit..my charger doesnt have a discharge on it...
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RE: RC LiPo Care
 

katzcratch,
If you keep them fully charged when you are not using them, you may not see any damage to begin with... but the chances of them swelling up on you here in the first couple months is very good. If you do not have a discharge feature on your charger, then yes, run them in your RC car / truck for a bit. If you can normally run them 40 minutes a charge, then run them for about 16 minutes... and thats about where they need to be stored at. Same rules apply whether they are 2s, 3s, or anything else.... 60% is about where you want to store them at.

As for your question about whether or not manufacturers sell them at the storage charge, typically the answer is yes... but I can not guarantee that for all manufacturers. I would definitely check with the manufacturer for your specific battery.

One other thing to note... Make sure you do NOT leave any batteries (NiMh, LiPos, etc.) plugged in when not in use. Even though everything might be turned off, they are still losing juice until they are unplugged. When unplugged, LiPos do NOT lose their charge nearly ask quick as a NiMh does when just lying around. Hypothetically, a NiMh might lose 60% of its charge over a weeks time from just sitting there not plugged in. Whereas a LiPo might lose 1 or 2% of its charge.

Hope this helps. Give a vote for a sticky if it does. ;)

RE: RC LiPo Care
 

+1 sticky

RE: RC LiPo Care
 

+1

RE: RC LiPo Care
 

thanks for the post very helpful, i myself just learning about lipos. will have to save this post.

RE: RC LiPo Care
 

I am new to electrics and Lipos. One question I can't seem to get an answer to is "how many times can a lipo be recharged if it is maintained properly?" Any info you could pass on would be appreciated.

Thanks,
mesaman4

RE: RC LiPo Care
 

Generally lifetime is rated to 20% degradation in capacity of the battery. And that point is reached at some point at or after 300 full discharges, or 5 years time.

RE: RC LiPo Care
 

Bump.. and +1 also for a sticky..

RE: RC LiPo Care
 

Read this www.batteryuniversity.com very very helpfull, and beyond!

RE: RC LiPo Care
 

I've read a few articles concerning lipo storage and it seems to differentiate between 40 and 60%. I decided that 4V per cell should be close and thats how I have my lipos set.

Should I have any concern?

RE: RC LiPo Care
 

40% to 60% charged is the general range where damage to the battery over time is minimized. This tends to be about 3.7-3.9 volts per cell open-circuit. But it can depend on the battery type, age, and so on. The safest way is to use the 'max charge capacity %' feature of your charger if it has one. Ie. with a battery that is "fully discharged" from a fresh run, set the max charge capacity to 40% and make sure the capacity is entered properly. The charger will stop after a 40% charge by capacity.

RE: RC LiPo Care
 

I vote this should be a sticky! Very informative!

RE: RC LiPo Care
 

idk if i've allready voted on stickyness but i'm all for it

the lug

RE: RC LiPo Care
 

I vote sticky, great info...

RE: RC LiPo Care
 

question, this seems like a good place to post this, is there any harm in overcharing your lipo's for cell life other than the obovous risk of explostion??? i was charing my zippy on my MRC super brain 977 with my blinky (plugged in while charging) and i let it do its thing, i have a zippy 2s 5000, and it hit 5000 and kept going i've seen this happen before with this batt, and many other ni packs (ep 4200's have hit 4900) arond 5200 i expected it to stop, it kept going until about 6600 when i got back into my room expecting it stopped and it was still going, it was reading 8.95V with a little (very little only noticible if you placed on hard surface and rocked it) so i let my blinky drop the voltage down to 8.85 or so then put it in my B4 for a bit (15t brushed setup) after about 2 min of light running it was down to 8.65v and i let my blinky bring it down to 8.5v which is the blinkies cutoff voltage, (4.25 per cell) i ran the pack last night in my evader with my SW 4600 ran great no issues plenty of power and runtime, i didn't put it on the charger yet, thats for tonite (forgot last, i got called in for dinner just as after i swapped packs and never went out after), so is my pack ruined, the puffing has gone down my shink wrap isn't as loose at it used to be (there was a little air under it but now none...), the pack didn't get more than 90* during charging or running
any help would be great thanks

the lug

RE: RC LiPo Care
 

Yes. LiPo are another type of Lithium-ion batteries and all these -ion batteries contain Lithium only in the ion form (under normal circumstances). Contrast to the lithium-metal type batteries like AA's you buy in the department store, they have lithium in the metal form and are not rechargeable.

The danger is that as you overcharge, to beyond around 4.3V per cell, the lithium ions start to electroplate onto the anode in the form of lithium metal. The cell isn't designed for this, and typically once the lithium becomes metallic, there is no way for it to go away, it will just sit around. So, any number of bad things can then happen down the line. Anytime a cell is overcharged beyond 4.3V, it poses a future danger (premature catastrophic failure) and should be retired. It may not be a problem right now, but in weeks, months, or a year, something bad could happen.

RE: RC LiPo Care
 

do you know if there are any symtoms of this happening so i can be warned before the big boom happends... ??

thanks


the lug

RE: RC LiPo Care
 

Hey Guys,

I just bought a Dynamite Passport Ultra charger and a LiPo 3200mAh with 25C. To put it on my daughters Stampede with the 1/10 scale mamba monster pro BL. Got home late from the races the other night and decided to go ahead and charge the Battery and install the BL system... you know to see what it would do. Charged the battery up to like 3400mAh the first time and ever since then I cant seem to get the mAh up past 0780. Not sure what I am doing wrong or what else needs to be done. Any suggestions would be greatly appreciated.
I have read through the manual like 5 or 6 times messed with a couple of the settings but its not charging to full capacity and run time is only maybe 4 to 6 min compared to the first run.

RE: RC LiPo Care
 

You are probably not discharging it very much. The mAh on the charger does not tell you what is in the battery at the end. It tells you what the charger put in it. So if you discharge a little, it will only charge a little until it is full again.