Looking for maintenance and care advice for Lithium ion battery pack

[novarider]

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Be aware that a lot of info in the RC/hobby world is outdated, e.g. many RC chargers use cloned firmware that still has the ancient distinction between Li-ion(3.6/4.1) vs LiPo(3.7/4.2).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

Yes it is true you just did it again. Ncr18650b batteries are not what he was asking about. What your saying is that EVERY SINGLE lipo manufacturer including the highest quality and most respected companies are all wrong and your right. simply because you saw a data sheet for 18650 batteries which is not even what we're discussing.

Do some searching for info on lipo batteries NOT 18650 and you will see they recommend 3.85v for storage. This comes from the battery manufacturer.

A quick Google search for lipo battery care and this is from the first link: For the longest life of the batteries, LiPos should be stored at room temperature at 3.8V per cell.

Scroll down to the 3rd result and you get this
Maxamps website says: Storage Procedure: When not using your LiPo/Life battery pack, store it at 60-70% of the pack’s rated capacity.

There are many more if you care to look.

 

[Tachead]

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

+1

 

[Tachead]

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).

He is asking about Lithium Polymer Gauss, not other chemistries:shakehead. 3.85V is what most, if not all, lipo manufactures recommend for storage.

 

[Tachead]

Yes it is true you just did it again. Ncr18650b batteries are not what he was asking about. What your saying is that EVERY SINGLE lipo manufacturer including the highest quality and most respected companies are all wrong and your right. simply because you saw a data sheet for 18650 batteries which is not even what we're discussing.

Do some searching for info on lipo batteries NOT 18650 and you will see they recommend 3.85v for storage. This comes from the battery manufacturer.

A quick Google search for lipo battery care and this is from the first link: For the longest life of the batteries, LiPos should be stored at room temperature at 3.8V per cell.

Scroll down to the 3rd result and you get this
Maxamps website says: Storage Procedure: When not using your LiPo/Life battery pack, store it at 60-70% of the pack’s rated capacity.

There are many more if you care to look.

+1, good post with accurate information.

Gauss is a known trouble maker. He has been reprimanded and banned several times but, still causes trouble. I suggest you don't waste your time arguing with him:thumbsup:

 

[Tachead]

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!

I recommend checking your packs resting voltage after you fly. You only want to drain your lipos to 3.7-3.75V per cell if you want the best life and performance out of them. Store them at 3.85V if you plan on not using them for more then a day or two. Most hobby chargers have a storage mode to do this automatically for you.

Get yourself a simple tester like this one...

http://media.hyperion.hk/dn/sentry/

It will show you the voltage of each cell in your packs by plugging in the balance connector. That way you can monitor both the voltage and how well your charger is balancing the individual cells. A tester like this and a high quality charger is a must for every RC hobbyist imo.

 

[olemil]

I recommend checking your packs resting voltage after you fly. You only want to drain your lipos to 3.7-3.75V per cell if you want the best life and performance out of them. Store them at 3.85V if you plan on not using them for more then a day or two. Most hobby chargers have a storage mode to do this automatically for you.

Get yourself a simple tester like this one...

http://media.hyperion.hk/dn/sentry/

It will show you the voltage of each cell in your packs by plugging in the balance connector. That way you can monitor both the voltage and how well your charger is balancing the individual cells. A tester like this and a high quality charger is a must for every RC hobbyist imo.

Great advice, thank you. :thumbsup: I've had my EOS Sentry for years and love it, a must have for the money to monitor your packs easily.

 

[Tachead]

Great advice, thank you. :thumbsup: I've had my EOS Sentry for years and love it, a must have for the money to monitor your packs easily.

No problem:thumbsup:. RC helicopters are one of my other hobbies and I have had my EOS Sentry and another tester for years as well. A high quality charger and a good tester are definitely essential to properly maintain your lipos and keep safe in the RC hobby. Lipo batteries can be very dangerous and even more care should be taken then with normal cylindrical lithium ions like 18650's.

 

[Gauss163]

@Tachead Yet more unfounded ad hominem attacks are not the proper way to dispute scientific claims. As always, if anyone has any questions about any claims then please feel welcome to ask and I will provide further data to back up those claims (beyond HKJ's voltage vs SOC graphs above).

A couple more points deserve mention regarding shipping/storage SOC. One of the reasons that rewrappers and other Li-ion battery resellers employ a very conservative shipping/storage charge around 55% SOC is due to the fact that these packs/cells may sit on the shelf in (possibly hot) warehouses for quite some time, so they use a more conservative (higher) shipping voltage charge to make sure they do no drain too low even if they do not sell for some time. It also makes sense to recommend more conservative storage values to users, so that they don't have to deal with warranty claims and/or complaints from users who forgot to recharge their batteries after leaving them in storage for too long (which often occurs).

Note that the self-discharge rate depends on many factors, temperature, chemistry, BMS quiescent current , etc. Generic storage SOC recommendations (e.g. in a charger manual) have to account for all these variations, so are typically less optimal than recommendations that are specialized to specific chemistry and BMS, etc.

Finally, it goes without saying that battery sellers make more money when batteries have shorter life, so they don't have a strong incentive to provide information that yields maximal lifetime. For example, Dell laptops once had a built-in timer that would wrongly claim that the batteries needed replacing - which led to a lawsuit; further they did not supply battery saver software until forced to do so by competition. Accessories like batteries are a huge source of profit for battery-powered devices, so manufacturers typically do the least possible when it comes to educating consumers about how to optimize calendar or cycle life.

 

[olemil]

No problem:thumbsup:. RC helicopters are one of my other hobbies and I have had my EOS Sentry and another tester for years as well. A high quality charger and a good tester are definitely essential to properly maintain your lipos and keep safe in the RC hobby. Lipo batteries can be very dangerous and even more care should be taken then with normal cylindrical lithium ions like 18650's.

Nice to see a fellow RC heli enthusiast on here. Yes LiPo fires are very scary to say the least!! I store mine in vented ammo cans which are stored in a large metal cabinet. Sorry to drift off topic.

 

[Tachead]

@Tachead Yet more unfounded ad hominem attacks are not the proper way to dispute scientific claims. As always, if anyone has any questions about any claims then please feel welcome to ask and I will provide further data to back up those claims (beyond HKJ's voltage vs SOC graphs above).

A couple more points deserve mention regarding shipping/storage SOC. One of the reasons that rewrappers and other Li-ion battery resellers employ a shipping charge a bit higher than 50% SOC is due to the fact that these packs/cells may sit on the shelf in (possibly hot) warehouses for quite some time, so they use a more conservative (higher) shipping voltage charge to make sure they do no drain too low even if they do not sell for some time. It also makes sense to recommend more conservative storage values to users, so that they don't have to deal with warranty claims and/or complaints from users who forgot to recharge their batteries after leaving them in storage for too long (which often occurs).

Also, depending on chemistry, there will be some variation in self-discharge rates (which are strongly dependent on ambient temperature), which play a (minor) role.

Finally, it goes without saying that battery sellers make more money when batteries have shorter life, so they don't have a strong incentive to provide information that yields maximal lifetime. For example, Dell laptops once had a built-in timer that would wrongly claim that the batteries needed replacing - which led to a lawsuit; further they did not supply battery saver software until forced to do so by competition. Accessories like batteries are a huge source of profit for battery-powered devices, so manufacturers typically do the least possible when it comes to educating consumers about how to optimize calendar or cycle life.

Gauss, as said, we are not talking about cylindrical lithium ions in this thread. We are talking about lithium polymer hobby packs. Therefore, HKJ's chart you posted does not apply here and is off topic. Most lithium polymer hobby pack manufacturers recommend 3.85V be used for storage. Most high end hobby chargers(not clones) also use this voltage for their storage modes. Your posts are off topic in this thread, are riddled with misinformation on this topic(Lipo hobby packs), and your disrupting yet another thread in the battery forum. Please stop posting about off topic subjects and derailing this thread.

 

[Gauss163]

Gauss, as said, we are not talking about cylindrical lithium ions in this thread. We are talking about lithium polymer hobby packs [...]

Which is not relevant, because the storage voltage does not depend on the enclosure but, rather, on chemistry and other factors that I enumerated above.

 

[Tachead]

Nice to see a fellow RC heli enthusiast on here. Yes LiPo fires are very scary to say the least!! I store mine in vented ammo cans which are stored in a large metal cabinet. Sorry to drift off topic.

Sure is nice to see some other RC enthusiasts. You are not off topic. The OP should know the dangers of lipos and the precautions that should be taken to stay safe and keep them healthy. Hope this info helps you ifoxbox:thumbsup:

 

[Overclocker]

i agree w/ gauss163 here. "lipo" is just a generic term for pouch cells. there are TONS of different formulations out there yielding different curves. the 3.85v "storage" setting on hobby chargers is just a rule of thumb. it isn't necessarily the optimal storage voltage for all flavors of lipo

but then again it's just a small pack so don't worry about it too much. when you start having larger packs then it starts to make sense to try to maximize its life. perhaps the biggest factor is temperature, so keep them cool.

 

[Tachead]

Which is not relevant, because the storage voltage does not depend on the enclosure but, rather, on chemistry and other factors that I enumerated above.

The Lipo packs the OP is talking about are not the same as 18650's Gauss. Modern lithium polymer and graphene lithium polymer packs can handle up to 95C discharge rates. Some of the best high drain 18650's on the market like the Sony VTC6 can only handle like 5-10C. The manufacturers of these cells recommend 3.7-3.9V for storage so, that is what they should be stored at. These Lipo packs also shouldn't be discharged as low as common 18650's. The minimum recommended resting discharge voltage for many lipo batteries is 3.3V vs. 2.5V for most 18650's.

As always, the manufacturer of a particular cell or pack lists recommendations for charging, storage, usage, etc. for their products and these recommendations are the ones that should be studied and followed. Not the recommendations some guys on a forum because as you can see opinions, beliefs, and knowledge can vary.

 

[Tachead]

i agree w/ gauss163 here. "lipo" is just a generic term for pouch cells. there are TONS of different formulations out there yielding different curves. the 3.85v "storage" setting on hobby chargers is just a rule of thumb. it isn't necessarily the optimal storage voltage for all flavors of lipo

but then again it's just a small pack so don't worry about it too much. when you start having larger packs then it starts to make sense to try to maximize its life. perhaps the biggest factor is temperature, so keep them cool.

Most lipo manufactures recommend a 3.7-3.9V storage voltage. 3.85V is right in the middle of this recommendation with a little extra added to allow for self discharge during extended storage. This is probably why most high end charger companies chose this voltage for their storage modes. Is this voltage the exact best storage voltage for all chemistries and ambient temperatures? No but, it is a pretty good rule of thumb and there is no point in splitting hairs here imo.

I wouldn't exactly call a 5350mAh 4S $235 lipo a small pack:thinking:. That's a pretty significant expense even compared to one of our 4 x 18650 lights using the best cells.

 

[Gauss163]

Most lipo manufactures recommend a 3.7-3.9V storage voltage. [...]

RC/hobby pack manufacturers (unlike the big guys Panasonic, Sony, LG etc) do not have large research labs that can do accelerated degradation testing etc. The recommendations they supply are very conservative generic ballpark figures that they have been supplying since the early days. But many improvements have been made since then (e.g. lowering self-discharge rates). The optimal storage values are often far from those generic values (but the specifics depend on many parameters). If you know what you are doing you can attain significant longetivity gains by using more optimal values.

 

[Tachead]

RC/hobby pack manufacturers (unlike the big guys Panasonic, Sony, LG etc) do not have large research labs that can do accelerated degradation testing etc. The recommendations they supply are very conservative generic ballpark figures that they have been supplying since the early days. But many improvements have been made since then (e.g. lowering self-discharge rates). The optimal storage values are often far from those generic values (but the specifics depend on many parameters). If you know what you are doing you can attain significant longetivity gains by using more optimal values.

I'm sorry Gauss but you are talking out your butt now. You have no idea what lipo manufacturers have for research labs or what equipment they use. You also have no idea how accurate or dated the recommendations they supply are. Lithium polymer cells are used in a lot more then just the RC industry and are the main cell used in most cell phones, tablets, and laptops these days. They are far from old tech and are constantly being researched and improved just like cylindrical cells. In fact some of the newest battery technology(graphene enhanced lithium ion) has been readily available in lithium polymer RC packs for a while now but, is yet to be incorporated in any commercially available cylindrical products(18650's) that I am aware of.

There is no need to overthink this or split hairs OP. Storing Lithium polymer packs anywhere between 3.7 and 3.9V, like their manufactures recommend, is fine and I would trust them over Gauss. The 3.85V storage mode on most chargers is a reasonable and well thought out value imo considering all the different conditions, storage times, and chemistries that an average user might encounter. Gauss can calculate right down to the 0.001V what is the ideal storage voltage for his particular cell and ambient temperature if he wants and he will likely see little benefit. Us normal folk have better things to do imo.

 

[Gauss163]

I'm sorry Gauss but you are talking out your butt now. You have no idea what lipo manufacturers have for research labs or what equipment they use. You also have no idea how accurate or dated the recommendations they supply are [...]

It's your prerogative to believe whatever you desire. My knowledge on these topics was garnered from a couple decades professional experience working in this industry, including many conversations with engineers from top-tier manufacturers (including Panasonic, Sanyo and LG). That's not "talking out of your butt". Rather, it is passing along intuition gained from leading experts in the industry.

 

[Overclocker]

I wouldn't exactly call a 5350mAh 4S $235 lipo a small pack:thinking:. That's a pretty significant expense even compared to one of our 4 x 18650 lights using the best cells.

well to me that's small haha. right now i'm building a 204-cell pack. 17-series 12-parallel for an electric lightweight motorcycle. i just keep the cells NEAR their optimal "storage" voltage. no need to be anal about keeping them within 1 millivolt

the OP might want to refrigerate his packs. based on what i read the temperature is a bigger factor than voltage. that's why electric car packs have chillers

 

[novarider]

RC/hobby pack manufacturers (unlike the big guys Panasonic, Sony, LG etc) do not have large research labs that can do accelerated degradation testing etc. The recommendations they supply are very conservative generic ballpark figures that they have been supplying since the early days. But many improvements have been made since then (e.g. lowering self-discharge rates). The optimal storage values are often far from those generic values (but the specifics depend on many parameters). If you know what you are doing you can attain significant longetivity gains by using more optimal values.

If your going to tell people lipo battery manufacturers are wrong at least be able to back it up. Do some googling and post here what you find. Again lipo batteries not 18650.

"someone once told me" is not proof