Looking for maintenance and care advice for Lithium ion battery pack

I recently got a phantom drone for Christmas, and was wondering if the same rules for care and maintenance apply for a battery pack as it does for single cells? The specs of the battery are below:

• Voltage of 15.2 Volts (4) 3.8v cells inside pack
• Max Charging Power – 100W
• Net Weight – 462 G
• Energy Level – 81.3 Wh
• Capacity of 5350 mAh.
• Operating Temperature of 14 degrees to 104 degrees Fahrenheit (-10 to 40 celsius)
• Battery Type – Lithium Ion Polymer LiPo 4S

My main questions are:

Is it OK to drain down to 20% capacity left during each use? I've read that you should never go below 80% discharge for max overall battery life. Is that right, or should that number be lower?

I know for long term storage it is a good idea to store at 50%, but if I will be using them at least every week or two, would I be better off keeping them stored fully charged?

Lastly, is it a good idea to do a full discharge every few months or so?

Thanks in advance for any advice you can give!

Hello Ifoxbox,

I think the 20% left is a good target to shoot for.

Long term storage is usually longer than 1 week. If it is not too much trouble it is better to store at 50% and charge prior to use. If that is not convenient just charge them and use them.

No full discharge is necessary or recommended.

Tom

LiPo packs like to be stored at 3.85v per cell.

SilverFox said:

Hello Ifoxbox,

I think the 20% left is a good target to shoot for.

Long term storage is usually longer than 1 week. If it is not too much trouble it is better to store at 50% and charge prior to use. If that is not convenient just charge them and use them.

No full discharge is necessary or recommended.

Tom

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Thanks Tom! I was hoping you would chime in. I always value your input! :thumbsup:

So after I drain the battery down to 20%, I should just charge it back up to 50% and then finish the charge the next week before I plan to use it again?

olemil said:

LiPo packs like to be stored at 3.85v per cell.

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Thanks for the info!

Based on numerous studies, the general rule of thumb for Li-ion batteries is: to maximize life, minimize the time that the battery spends at extreme voltages and high temperatures (which accelerate internal processes that cause degradation). For example, one of the worst things you could do is to keep your cells floating at 100% SOC on standby charge (or frequent top-ups), since this means that the cells will spend most of their life at the highest extreme voltage. Better to design a charging regimen that maximizes the time they spend near 50% capacity (e.g. store at 50% then top-up as close to use as is practical). See this later post for specific data from studies.

olemil said:

LiPo packs like to be stored at 3.85v per cell.

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That is too high SOC (70%) for storing some common chemistries. The optimal storage range is between 40-50% SOC. To determine the corresponding resting voltages see e.g. HKJ's page for a few common chemistries.

I think a voltmeter would be in order but since you have a battery pack not sure how you would measure it and even if you can what would the optimal voltage be, since they are in series, as I understand. Hoping that each battery has the same discharge rate but if they don't and have say a 20% difference that is too much of a difference between the batteries in the pack. The 18650 I have I measure each one individually, the lights I have only take 1x18650.

Gauss163 said:

That is too high SOC (70%) for storing some common chemistries. The optimal storage range is between 40-50% SOC. To determine the corresponding resting voltages see e.g. HKJ's page for a few common chemistries.

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Lipo charges have a storage setting which charges them to 3.85v and this is the widely accepted voltage for long term storage.

novarider said:

Lipo charges have a storage setting which charges them to 3.85v and this is the widely accepted voltage for long term storage.

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Look at datasheets, etc. and you will learn that cell manufacturer's recommend storing at between 40-50% SOC (and that's what they are typically shipped at). The voltages corresponding to 40-50% SOC depend on the chemistry.

For many chemistries (esp. older ones) 3.85V is about 55% SOC, but for many newer chemistries it is much higher - about 70%, whereas 50% is about 3.65V. Hobby chargers cannot determine the chemistry so if they have a fixed storage voltage target value then that has to be a compromise value that suffices for most chemistries. e.g. they cannot choose 3.65V since that is only about 6% SOC for older chemistries. If you want optimal storage values you need a charger with programmable storage charging (or a general CC/CV charger).

To the OP: You might want to have a look here, lots of valuable info on Lipo packs including safety tips. Also there are many threads on Multi-rotors so you can probably pick a few tips on your Phantom. Not sure where you are located but if you are in the US, you are supposed to register with the FAA to make it legal to fly.

Gauss163 said:

Look at datasheets, etc. and you will learn that cell manufacturer's recommend storing at between 40-50% SOC (and that's what they are typically shipped at). The voltages corresponding to 40-50% SOC depend on the chemistry.

For many chemistries (esp. older ones) 3.85V is about 55% SOC, but for many newer chemistries it is much higher - about 70%, whereas 50% is about 3.65V. Hobby chargers cannot determine the chemistry so if they have a fixed storage voltage target value then that has to be a compromise value that suffices for most chemistries. e.g. they cannot choose 3.65V since that is only about 6% SOC for older chemistries. If you want optimal storage values you need a charger with programmable storage charging (or a general CC/CV charger).

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Funny I have about $1000 worth of LiPo packs for my RC hobby. Every pack I have ever bought (NEW) shipped at a storage voltage of 3.85v/cell. Must be a lot of LiPo battery companies that don't know what the hell they are doing. All the hobby chargers I have owned over the years have an adjustable storage voltage setting ( for various battery chemistries ) including my current one, ICharger 308 DUO. PS, the default storage voltage for LiPo batteries is 3.85v/cell.

LiPo settings Taken from my 308 DUO manual:

Storage Cell Voltage:
3.7V/Cell-3.9V/Cell;
Default: 3.85V/Cell
Storage Compensation:
0V/Cell-0.2V/Cell;
Default: 0.01V/Cell

olemil said:

Funny I have about $1000 worth of LiPo packs for my RC hobby. Every pack I have ever bought (NEW) shipped at a storage voltage of 3.85v/cell. [...]

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Again, optimal storage voltage depends on the particular Li-ion chemistry of the cells. Probably your LiPo pack recommendations are based on the fact that most of the chemistries used in the RC/hobby packs were/are close to 50% SOC around 3.85V. But that is not true for many other common modern Li-ion chemistries, where 50% SOC is about 3.65V. For example, this is true for all of the 18650 cells except the first two in HKJ's SOC vs Voltage page. This includes many common cells used in flashlights, vaping, powerbanks, laptops, etc (Panasonic CGRs and NCRs)

For example, below is a table from said page. Notice that the first two columns shows chemistries like your LiPo, where 50% SOC occurs between 3.8-3.9V, but the final three columns shows cells where 50% SOC occurs between 3.6-3.7V.

Which Phantom do you have? White DJI battery? My Phantom 2 flashes red lights and lands itself when down to about 20%. And yes charging back to about 50% and fully charging the night before use would be the best way to store them. No benefit in running them down every few months etc.

Gauss163 said:

Again, optimal storage voltage depends on the particular Li-ion chemistry of the cells. Probably your LiPo pack recommendations are based on the fact that most of the chemistries used in the RC/hobby packs were/are close to 50% SOC around 3.85V. But that is not true for many other common modern Li-ion chemistries, where 50% SOC is about 3.65V. For example, this is true for all of the 18650 cells except the first two in HKJ's SOC vs Voltage page. This includes many common cells used in flashlights, vaping, powerbanks, laptops, etc (Panasonic CGRs and NCRs)

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Ok

PapaLumen said:

Which Phantom do you have? White DJI battery? My Phantom 2 flashes red lights and lands itself when down to about 20%. And yes charging back to about 50% and fully charging the night before use would be the best way to store them. No benefit in running them down every few months etc.

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Yes, it is the white DJI battery. Mine has an option to choose when to give the low battery warning. I have it set to 30%, and monitor it from there to be sure I land at 20%. I will charge back up to 50% later that day and then do a full charge before the next use.

Thanks everyone for all the help!

Gauss163 said:

Again, optimal storage voltage depends on the particular Li-ion chemistry of the cells. Probably your LiPo pack recommendations are based on the fact that most of the chemistries used in the RC/hobby packs were/are close to 50% SOC around 3.85V. But that is not true for many other common modern Li-ion chemistries, where 50% SOC is about 3.65V. For example, this is true for all of the 18650 cells except the first two in HKJ's SOC vs Voltage page. This includes many common cells used in flashlights, vaping, powerbanks, laptops, etc (Panasonic CGRs and NCRs)

For example, below is a table from said page. Notice that the first two columns shows chemistries like your LiPo, where 50% SOC occurs between 3.8-3.9V, but the final three columns shows cells where 50% SOC occurs between 3.6-3.7V.

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Your trying to prove your right on a subject he didn't even ask about. He's asking about his lipo pack not 18650 batteries.

There are millions of lipo packs sold and they all are shipped at 3.85v. The recommended storage charge is 3.85v.

novarider said:

Your trying to prove your right on a subject he didn't even ask about. He's asking about his lipo pack not 18650 batteries.

There are millions of lipo packs sold and they all are shipped at 3.85v. The recommended storage charge is 3.85v.

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Thank you. :thumbsup:

novarider said:

Your trying to prove your right on a subject he didn't even ask about. He's asking about his lipo pack not 18650 batteries.
There are millions of lipo packs sold and they all are shipped at 3.85v. The recommended storage charge is 3.85v.

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Not true. I supplied the industry standard optimal storage targets, typically 35-50% SOC (depending on storage time, ambient temperature).

Be aware that a lot of info in the RC/hobby world is outdated, e.g. many RC chargers use cloned firmware that still has the ancient distinction between Li-ion(3.6/4.1) vs LiPo(3.7/4.2).

Even for higher voltages chemistries typically used in RC packs (where 3.85V is about 55% S0C), this is not the storage SOC that is optimal for prolonging life. Rather, optimal storage SOC is typically between 35-50% SOC (about 3.77-3.82V). For example, if you look at the datasheet for Sanyo/Panasonic NCR18650BE you will see that they are shipped at 35% SOC, i.e. slightly over one-third capacity.

ifoxbox, please do yourself a favor and go to the site I posted in post #10, there is a vast amount of hands on knowledge there on LiPo packs. LiPo packs are not something to misuse, if you don't believe me do a search on YouTube for LiPo fires. Hope you are enjoying your Phantom, I have a DJI F450 and love it.

olemil said:

I feel bad paying $280 for my charger now knowing it has outdated/ancient firmware......NOT!!!!!!! It's funny my charger has several types of battery chemistries to choose from for charging, discharging, storage charge and they all have different voltages depending which chemistry you choose.

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Which has nothing to do with what I wrote.

I've owned over 30 RC/hobby charger models, ranging from earliest models (Bantam, Victor, etc) to more recent models (iChargers, Hyperions, etc). In my opinion, there has been very little innovation since the early days (primarily because of rampant cloning).

You won't learn much about battery electrochemistry from hobby charger manuals. The hobby charger engineers are electrical engineers - not experts in battery electrochemistry. If you want to learn about finer points of battery electrochemistry you should look elsewhere.