Maximum charging amps for these ( RC Lipo ) cells

[markz]

Compression dont always help unless the pouch is fully protected or encased like a prismatic.
Hobbyking for a while sold a black plastic encased lipo battery.
When you drop the pouch on its corner, thats never good.
I saw a person trying to sell one like that, a corner of a lipo battery dented in because it had no protection. I hope no one bought it.

 

[neptronix]

I always thought increasing compression ( beyond the pack's compressive wrap ) was a very bad idea because it removes a safety / warning mechanism. I've never seen any good information showing that it improves safety. I imagine it does the opposite.

 

[flippy]

I always thought increasing compression ( beyond the pack's compressive wrap ) was a very bad idea because it removes a safety / warning mechanism. I've never seen any good information showing that it improves safety. I imagine it does the opposite.

no, sadly it does not work like that. pouches usually have a certain force that they are rated for if you compress it. generally you only find that data on automotive pouches datasheets. the hobbyking stuff will not mention that.

the force is not that high, the important thing is that the cells cant expand and delaminate. so rigidity is key. pouches will naturally expand after its first cycle even so they will find their own balance if you let them. the trick is to -not-let them. but add up a couple hundred pouches pushing so you see why cars have these insane blocks with massive steel rods to keep them together.

your saftey mechanism is still the usable capacity and the fact that its still a thin plastic bag. if it wants to go, it will. same applies to 18650. but 18650 dont need that compression form as it already has it. this is also why 18650 is more stable over time.

but yes, too much force will frock up a cell. i remember that many moons ago some university did a test with pouches and they compressed the shit out of a couple cells and it killed them pretty fast. btu they used comical levels of weight. not really relevant. it was just a couple students trying to get a thesis out the door. but the concept was pretty interesting and it had lots of expensive words.

 

[neptronix]

An 18650 is in compression all the time but never has the chance to show a warning sign.

I've owned 48 RC Lipo packs over my lifetime. They puff when stressed, dropped, or improperly constructed. It can be a sign of an imminent explosion. It was a sign of an imminent off-gas once. Another which was overdischarged began to puff very slowly upon recharge which was a sign of imminent trouble and it was put out of commission by being VERY slowly discharged to 0v.

Lipo puffing is only a safety mechanism because it buys you time to notice the imminent.

I've seen no information supporting the idea that compression makes a cell more stable over time.

 

[flippy]

you are complaining about something that simply does not happen in normal life. 18650 do not have the abillity to puff up due to abuse. its a "feature" only pouches have and not one that is desired. 18650 does not care (to a degree) if it stressed, dropped, or improperly constructed. at worst what generally happens in bad cells is that the PTC will trigger and some fluids will push out. you see this a lot with crappy chinese cells. at that point the capacity is nearly zero and will have masive self discharge wich will trigger your bms early into a fault condition. no phyical deformation so everything stays in 1 shape, a lot safer.

here is 1 paper i found with no effort that concludes that good pressure prevents delamination (wich is really bad and a 18650 inherently cannot do) and prevents creation of gases in the first place and more consistent performance over its lifespan.

https://www.researchgate.net/publication/318816856_The_effect_of_external_compressive_loads_on_the_cycle_lifetime_of_lithium-ion_pouch_cells

 

[DogDipstick]

I wrote the manual for assessing and doing second party quality control of RC Lipos but can't defend usage of them anymore because a majority of people haven't taken the memo.

Where can I find this memo to read?

Also, on top of Flippys contribution, I have posted NASA .pdf results shoing the same thing from ten years ago, on this forum. I'll link it if you are interested. Compression ( restraint) and its long term effedcts.


Lipos dont like fast chargin. no no no. I come from RC helis, where we eat 14s 400Wh packs in three min.

So we have big chargers. Big ones. That can charge fast.

charge at 5C, and it will puff 5x faster than if charged at 1C or less.



For the big cells I like "Plugin Hybrid" car lipo cells. High charge rates OeM.

Tolerance of Li-ion Pouch Cells to Varied Space Environment Pressures

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130000451.pdf

I'll update with more I got on random hard drives floating around there are a couple good ones I remember reading that i left out I know....

 

[ebike11]

I wrote the manual for assessing and doing second party quality control of RC Lipos but can't defend usage of them anymore because a majority of people haven't taken the memo.

Where can I find this memo to read?

Also, on top of Flippys contribution, I have posted NASA .pdf results shoing the same thing from ten years ago, on this forum. I'll link it if you are interested. Compression ( restraint) and its long term effedcts.


Lipos dont like fast chargin. no no no. I come from RC helis, where we eat 14s 400Wh packs in three min.

So we have big chargers. Big ones. That can charge fast.

charge at 5C, and it will puff 5x faster than if charged at 1C or less.



For the big cells I like "Plugin Hybrid" car lipo cells. High charge rates OeM.

Tolerance of Li-ion Pouch Cells to Varied Space Environment Pressures

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20130000451.pdf

I'll update with more I got on random hard drives floating around there are a couple good ones I remember reading that i left out I know....

The hobby king packs i have are the 6S 20ah ones..so 1C with 20ah packs is 20A which would be double the 10A im using now...so i think thats plenty of charging speed..

 

[Hayds13]

Going back to the original question. What is the maximum charge rate for this cell:

Turnigy High Capacity 20000mAh 6S 12C Lipo Pack w/XT90

https://hobbyking.com/en_us/turnigy-high-capacity-battery-20000mah-6s-12c-drone-lipo-pack-xt90.html?queryID=27011e202542ed7e35469d8e5812ae7e&objectID=78412&indexName=hbk_live_magento_en_us_products

If you click on the “Product Specifications” it says Max Charge Rate(C) is 2.00

 

[flippy]

Going back to the original question. What is the maximum charge rate for this cell:

Turnigy High Capacity 20000mAh 6S 12C Lipo Pack w/XT90

https://hobbyking.com/en_us/turnigy-high-capacity-battery-20000mah-6s-12c-drone-lipo-pack-xt90.html?queryID=27011e202542ed7e35469d8e5812ae7e&objectID=78412&indexName=hbk_live_magento_en_us_products

If you click on the “Product Specifications” it says Max Charge Rate(C) is 2.00

you just answerd your own question.

still, if lifespan in of any concern you should stay miles away from those rates. i dont expect such a cell to last more then 50~75 cycles before you get serious capacity loss.