Parallel wiring..perhaps a unique scenario?

[ebike11]

You are confused in thinking you can multiply the Ah capacity of your pack (20Ah) times the contiuous discharge rating (12C) and arrive at an amp rating for a 240amp Controller. Using a 480amp Controller with both 28S packs paralleled could result in your 28S 40Ah pack going up in flames.

Could you please detail exactly how using the packs within their capabilities is going to cause them to "go up in flames"?

Unless there is some other exacerbating factor not accounted for, if using two paralled packs at twice the current would do so, then so would using a single unparalleled pack at the original current.


The "C rating" is exactly that--a multiplier for the capacity rating that gives you the max current the cells / batteries can support.

If the cells (or packs) are rated at 12C, then the output current capability of a single 20Ah pack is 12 x 20, or 240A.

If you parallel two of those packs, you can then output a max of 2 x 240A, or 480A.

The math has the same results if you use the 12C x 40Ah of the total of two paralleled 20A packs: 480A.



Note that there *are* scenarios with two paralleled packs with *separate BMSs* that could cause various problematic situations in the event of one pack shutting down, but if two packs are fully paralleled at the cell level and monitored by the same BMS, they are effectively one pack (assuming no electrical interference with balance leads if they are long) and those scenarios dont' apply.

This is also what I assumed as well but wanted to verify. However the other poster disagrees

 

[eMark]

2 x 28S packs. At the moment they arent connected together.

I was assumption that Ah x C rating gives max. Current ouput. I thought ive read that many times

These packs have a 12c continuous and 20c 10 sec.burst

Turnigy High Capacity 20Ah 6S 12C Lipo Pack

HOW DID YOU FIGURE 28S ?

28 of these individual lipo cells in series would be 103.6V nominal (3.7V/cell) and 117.6V fully charged (4.2v/cell). Your Turnigy 20Ah 12C Lipo is 22.2V (3.7V nominal x 6s = 22.2V). To arrive at a 24s you would need 4 of these Turnigy 6s packs connected in series. Five of these 6s Turnigy 20Ah 12C packs in series would be 30s.

Previously it was mentoned that you may only use a BMS on just one of the Packs. Even if you have the correct BMS wired for both paralleled packs is NO guarantee your BMS couldn't malfunction. More than a few have referred to a BMS as a "BatterstyMurderingSystem" either due to manufacture error or operator DIY error.

Here's the other thing to consider. There's no way you want to use a 480amp Controller with your two paralleled packs for continuous discharge. Pylon racing RC pilots going for a Club speed record may use their lipo pack at near maximum continuous discharge, but ONLY for seconds or a minute and even then the pack will get warm/hot.

I've answered your questions and then some. So please return the favor by answering these 3 questions:

1. How many minutes do you hope to use your two Turnigy paralleled packs at continuous discharge with a 240amp Controller or a 480amp Controller?

2. How many discharge cycles do you hope to achieve at a continuus discharge using a 240amp Controller?

3. If you plan to use an occasional 10sec burst than according to your figuring you'll need an 800amp Controller for a paralleled battery (20Ah x 20C = 400amps x 2 paralleled packs = 800amps).

Are you aware that using the 12C discharge continuously and 20C burst discharge will significantly reduce the cycle life of your two paralleled (?28s?) 20Ah 12C Turnigy Lipos ? Do you know why these RC Lipo manufactures (12C-24C) don't ever list the average number of expected charge/discharge cycles? Do you realize your two paralleled Turnigy 20Ah 12C packs using a 480amp Controller could still burst into flame even with a BMS that's supposedly protecting both paralleled packs??

HOW DID YOU ARRIVE AT 28s? Do you realize that your use (240amp or 480amp Controller) with a 28s1p 20Ah 12C Turnigy lipo pack or a 28s2p 40Ah 24C Turnigy battery pack will result in a shorter cycle life than you may have hoped to achieve? Do you realize that by using a 480amp Controller on your paralleled pack you won't be able to achieve a 10sec burst at 20C? It seems you would like the best of both worlds ... long cycle life and an occasional 10sec burst at 20C.

WHAT DO YOU REALLY WANT? ... Maybe 5C continuous Discharge is more practical ... 20Ah x 5C = 100amp Controller. A 100amp Controller is suitable for salvaged VOLT [lipo] pouch battery. IMO not suitable for RC Turnigy 20A 12C 6S 22.2V Lipo packs. How many of these 6s packs were you using to arrive at 28s - ?????

 

[ebike11]

2 x 28S packs. At the moment they arent connected together.

I was assumption that Ah x C rating gives max. Current ouput. I thought ive read that many times

These packs have a 12c continuous and 20c 10 sec.burst

Turnigy High Capacity 20Ah 6S 12C Lipo Pack

HOW DID YOU FIGURE 28S ?

28 of these individual lipo cells in series would be 103.6V nominal (3.7V/cell) and 117.6V fully charged (4.2v/cell). Your Turnigy 20Ah 12C Lipo is 22.2V (3.7V nominal x 6s = 22.2V). To arrive at a 24s you would need 4 of these Turnigy 6s packs connected in series. Five of these 6s Turnigy 20Ah 12C packs in series would be 30s.

Previously it was mentoned that you may only use a BMS on just one of the Packs. Even if you have the correct BMS wired for both paralleled packs is NO guarantee your BMS couldn't malfunction. More than a few have referred to a BMS as a "BatterstyMurderingSystem" either due to manufacture error or operator DIY error.

Here's the other thing to consider. There's no way you want to use a 480amp Controller with your two paralleled packs for continuous discharge. Pylon racing RC pilots going for a Club speed record may use their lipo pack at near maximum continuous discharge, but ONLY for seconds or a minute and even then the pack will get warm/hot.

I've answered your questions and then some. So please return the favor by answering these 3 questions:

1. How many minutes do you hope to use your two Turnigy paralleled packs at continuous discharge with a 240amp Controller or a 480amp Controller?

2. How many discharge cycles do you hope to achieve at a continuus discharge using a 240amp Controller?

3. If you plan to use an occasional 10sec burst than according to your figuring you'll need an 800amp Controller for a paralleled battery (20Ah x 20C = 400amps x 2 paralleled packs = 800amps).

Are you aware that using the 12C discharge continuously and 20C burst discharge will significantly reduce the cycle life of your two paralleled (?28s?) 20Ah 12C Turnigy Lipos ? Do you know why these RC Lipo manufactures (12C-24C) don't ever list the average number of expected charge/discharge cycles? Do you realize your two paralleled Turnigy 20Ah 12C packs using a 480amp Controller could still burst into flame even with a BMS that's supposedly protecting both paralleled packs??

HOW DID YOU ARRIVE AT 28s? Do you realize that your use (240amp or 480amp Controller) with a 28s1p 20Ah 12C Turnigy lipo pack or a 28s2p 40Ah 24C Turnigy battery pack will result in a shorter cycle life than you may have hoped to achieve? Do you realize that by using a 480amp Controller on your paralleled pack you won't be able to achieve a 10sec burst at 20C? It seems you would like the best of both worlds ... long cycle life and an occasional 10sec burst at 20C.

WHAT DO YOU REALLY WANT? ... Maybe 5C continuous Discharge is more practical ... 20Ah x 5C = 100amp Controller. A 100amp Controller is suitable for salvaged VOLT [lipo] pouch battery. IMO not suitable for RC Turnigy 20A 12C 6S 22.2V Lipo packs. How many of these 6s packs were you using to arrive at 28s - ?????

Oh i have 4 of these and also another 4S pack of the same cells 28S in total...fully charged is around 117V.

Ive bever said i wanted long cell life. So therefore i dont need the best of both worlds. Performance is more important for me. But of course the longer the better.

Controller power isnt a problem...the Fardriver I have can push out 800amps easily but of course I limited the power in the settings and will gradually increase depending on what I can get from the battery pack

 

[eMark]

Controller power isnt a problem...the Fardriver I have can push out 800amps easily but of course I limited the power in the settings and will gradually increase depending on what I can get from the battery pack

We need to correct some confusion that still exists. So here goes ...

20Ah x 12C = 240Ah ... not 240 energy amps (theoretically) being delivered to the motor via the Controller. It doesn't work multiplying 20Ah times the energy A drain rate (12C) to arrive at a 240A Controller. To arrive at a Contollers' amp rating you would multiply the cells' energy density A rating times the rate of current drain. A cells' energy dense A rating (e.g. 20A) is NOT the same as 20Ah. You can't take 20Ah times a cells' energy dense allowable A drain rate (e.g. 12C) to arrive at the Controllers' amp rating (e.g. 240amps, 480amps or 800amps).

So 12C can have different meaning/application which can be confusing ... as has happened in this thread. In other words there's a difference between Ah capacity of a cell and the cells' A energy rating. An RC lipo pack can have an inflated Ah capacity rating as high as 20Ah while the cells A energy rating may be as low as 3-5amp. Thus Turnigy can claim a continuous discharge rate of 12C (5A x 12C = 60amps, but only for a few minutes (3-10) depending on discharge rate.

You are confusing Ah capacity rating with the A energy drain rating of each cell in that 6s1p Turnigy battery. Turnigy doesn't provide a datasheet of the cells' energy dense amp rating in their 6s1p 20Ah 12C pack (for good reason). Here's my best guess as to why figures don't lie, but why RC Lipo manufactures will lie and won't divulge a cells' true A rate for achieving best cycle life longevity ...

Lets say Turnigy rates that 6s1p pack at a cell energy amp rating of 5amps (not 20amps). 5A x 12C = 60amps continuous discharge available for say 3 minutes before the pack exceeds a dangerous temperature (+100 degrees F). Doubt Turnigy will divulge the cell energy amp rating they use to arrive at 12C. It's probably not more than 5A, if that much. The other thing they will never divulge is the average number of discharge cycles possible at continuous discharge for say 3 minutes. They would be quick to say, "There are too many variables" and they would be correct in large measure to their own inflated values.

IMO, a RC Lipo mnufacturer that has a 20C discharge rate for a 10sec 20C burst rating is inflated ... unless the only benchmark concern is the critical temperature so as not to expand the cell, while the packs' short cycle life is of no concern to Turnigy.

Oh i have 4 of these and also another 4S pack of the same cells 28S in total...fully charged is around 117V.

One of those Turnigy's can cost $200. You have two 28s1p Turnigy packs you plan to parallel. All told that includes 8-6s1p and 2-4s1p or $1,600 just for 8 of those RC Turnigy 20Ah 12C 6s1p Lipos ... https://hobbyking.com/en_us/turnigy-high-capacity-battery-20000mah-6s-12c-drone-lipo-pack-xt90.html

You should've used the money you spent on those 8-RC Lipo 20Ah 12C 6s1p Turnigy and 2-RC Lipo 4s1p Turnigy to purchase the best ebike Battery available for less money and longer cycle as well as ebike riding enjoyment. Plus far less concern for your 28s2p (paralleled) DIY RC Turnigy battery pack possibly going up in flames using a 480A Controller (according to your figuring).

Unfortunately the RC herd mentality is apparently such that WHY use an ebike battery to power their ebike when a 28s2p DIY RC Turnigy 40Ah 20C DIY Lipo battery pack provides 800amps of power (at least for a few seconds at 20C) according to OP's misguided figuring; which he may still believe is correct thinking. Even the other poster was misled if he actually thought 20Ah x 12C = [theoretically] up to 240amps available for a 240A Controller.

BOTTOMLINE: The use of RC Lipos rated from 12C-24C were never intended to use for powering an ebike motor. In fact no RC Lipos no matter how impressive the specs are applicable for an ebike powerplant. The use of RC Lipos is only applicable for a few minutes of RC Hobby Toy use. The less discharge rate (e.g. 5C instead of 12C)and less continuous discharge the longer battery time, longer cycle life and less chance of cell swelling.

The OPs, example of 240amps, 480amps or even a 10sec burst at 800 amps (40Ah x 20C) using both of his 28s1p packs paralleled goes to show how RC Lipo manufacturers can so easily fool users by telling them what they want to hear/believe instead of what they would be far better off knowing before they spend $200 on a 20Ah 12C 6s1p RC Lipo.

Read unfavorable review of the OP's Turnigy 6s1p 20Ah 12C ... https://www.amazon.com/Turnigy-High-Capacity-20000mAh-Multi-Rotor/product-reviews/B07DRDG7V8?reviewerType=all_reviews

 

[ebike11]

Controller power isnt a problem...the Fardriver I have can push out 800amps easily but of course I limited the power in the settings and will gradually increase depending on what I can get from the battery pack

We need to correct some confusion that still exists. So here goes ...

20Ah x 12C = 240Ah ... not 240 energy amps (theoretically) being delivered to the motor via the Controller. It doesn't work multiplying 20Ah times the energy A drain rate (12C) to arrive at a 240A Controller. To arrive at a Contollers' amp rating you would multiply the cells' energy density A rating times the rate of current drain. A cells' energy dense A rating (e.g. 20A) is NOT the same as 20Ah. You can't take 20Ah times a cells' energy dense allowable A drain rate (e.g. 12C) to arrive at the Controllers' amp rating (e.g. 240amps, 480amps or 800amps).

So 12C can have different meaning/application which can be confusing ... as has happened in this thread. In other words there's a difference between Ah capacity of a cell and the cells' A energy rating. An RC lipo pack can have an inflated Ah capacity rating as high as 20Ah while the cells A energy rating may be as low as 3-5amp. Thus Turnigy can claim a continuous discharge rate of 12C (5A x 12C = 60amps, but only for a few minutes (3-10) depending on discharge rate.

You are confusing Ah capacity rating with the A energy drain rating of each cell in that 6s1p Turnigy battery. Turnigy doesn't provide a datasheet of the cells' energy dense amp rating in their 6s1p 20Ah 12C pack (for good reason). Here's my best guess as to why figures don't lie, but why RC Lipo manufactures will lie and won't divulge a cells' true A rate for achieving best cycle life longevity ...

Lets say Turnigy rates that 6s1p pack at a cell energy amp rating of 5amps (not 20amps). 5A x 12C = 60amps continuous discharge available for say 3 minutes before the pack exceeds a dangerous temperature (+100 degrees F). Doubt Turnigy will divulge the cell energy amp rating they use to arrive at 12C. It's probably not more than 5A, if that much. The other thing they will never divulge is the average number of discharge cycles possible at continuous discharge for say 3 minutes. They would be quick to say, "There are too many variables" and they would be correct in large measure to their own inflated values.

IMO, a RC Lipo mnufacturer that has a 20C discharge rate for a 10sec 20C burst rating is inflated ... unless the only benchmark concern is the critical temperature so as not to expand the cell, while the packs' short cycle life is of no concern to Turnigy.

Oh i have 4 of these and also another 4S pack of the same cells 28S in total...fully charged is around 117V.

One of those Turnigy's can cost $200. You have two 28s1p Turnigy packs you plan to parallel. All told that includes 8-6s1p and 2-4s1p or $1,600 just for 8 of those RC Turnigy 20Ah 12C 6s1p Lipos ... https://hobbyking.com/en_us/turnigy-high-capacity-battery-20000mah-6s-12c-drone-lipo-pack-xt90.html

You should've used the money you spent on those 8-RC Lipo 20Ah 12C 6s1p Turnigy and 2-RC Lipo 4s1p Turnigy to purchase the best ebike Battery available for less money and longer cycle as well as ebike riding enjoyment. Plus far less concern for your 28s2p (paralleled) DIY RC Turnigy battery pack possibly going up in flames using a 480A Controller (according to your figuring).

Unfortunately the RC herd mentality is apparently such that WHY use an ebike battery to power their ebike when a 28s2p DIY RC Turnigy 40Ah 20C DIY Lipo battery pack provides 800amps of power (at least for a few seconds at 20C) according to OP's misguided figuring; which he may still believe is correct thinking. Even the other poster was misled if he actually thought 20Ah x 12C = [theoretically] up to 240amps available for a 240A Controller.

BOTTOMLINE: The use of RC Lipos rated from 12C-24C were never intended to use for powering an ebike motor. In fact no RC Lipos no matter how impressive the specs are applicable for an ebike powerplant. The use of RC Lipos is only applicable for a few minutes of RC Hobby Toy use. The less discharge rate (e.g. 5C instead of 12C)and less continuous discharge the longer battery time, longer cycle life and less chance of cell swelling.

The OPs, example of 240amps, 480amps or even a 10sec burst at 800 amps (40Ah x 20C) using both of his 28s1p packs paralleled goes to show how RC Lipo manufacturers can so easily fool users by telling them what they want to hear/believe instead of what they would be far better off knowing before they spend $200 on a 20Ah 12C 6s1p RC Lipo.

Read unfavorable review of the OP's Turnigy 6s1p 20Ah 12C ... https://www.amazon.com/Turnigy-High-Capacity-20000mAh-Multi-Rotor/product-reviews/B07DRDG7V8?reviewerType=all_reviews

There are a bunch of bikes with big motors using these packs.
This youtuber who builds bikes often uses these.

https://youtu.be/M9kHbHZYvqM

https://youtu.be/iPsxvFEz4SU

I prefer the flexibility of these packs because of the size. Of course i could have made 1 large pack but the problem is mounting space. With these I can have a pack on the rear rack and another in the frame.

Also connectivity is a breeze. Just connect the power leads with small pieces of copper to crimp the wires together without needing to solder.

Also the link only had 2 reviews. 1 was positive and 1 was negative mainly due to a reseller. So i wouldnt rely on that to make my decision. The packs have been doing well so far but i havent pushed them that hard yet.

I get most of my info from reading on here. I didnt say 100% that i know for certain thats the calculation to get battery current amps..its what ive read on here in a bunch if different threads. Amberwolf essentially is saying the opposite of you and he has been here for over 10 years with 34000 posts.
So would he also be misguided?
I think both of you are very knowlegable

 

[nicobie]

AW and eMark are talking about two aspects of the same thing. IMO they are both right.

 

[eMark]

I get most of my info from reading on here. I didnt say 100% that i know for certain thats the calculation to get battery current amps..its what ive read on here in a bunch if different threads. Amberwolf essentially is saying the opposite of you and he has been here for over 10 years with 34000 posts. ... So would he also be misguided? ... I think both of you are very knowlegable

Amberwolf is far more knowledgeable than i will ever hope to be. That said i still think you and others are incorrect in multiplying 20Ah times a 6s1p discharge rate of 12C to arrive at 240amps of potential energy requiring a Controller rated at 240amps according to your figuring (20Ah x 12C discharge = 240amps equates to a 240amp Controller).

Do you really believe spending over $1600 for your two DIY 28s2p (paralleled) RC Turnigy lipo battery will give better performance and cycle life longevity than a 1st rate, top quality ebike DIY battery costing less than $1600 using EV pouch cells.

No where on the label of that Turnigy RC Lipo does it imply 12C computes to 240amps of available energy to theoretically power your motor via a 240amp Controller (20Ah x 12C). Your 20Ah x 12C = 240amps is bogus thinking if you still believe your 28s1p Turnigy battery is capable of supplying from 200amps to 240amps of continuous discharge amperage to your high rpm qs273 motor.

IMO, your high rpm qs273 motor is more deserving of a DIY EV Lipo pouch $1600 battery THAN a two 28s1p Turnigy RC lipos paralleld as a Turnigy 28s2p DIY RC battery when it comes to both cycle life longevity and performance.

 

[amberwolf]

That said i still think you and others are incorrect in multiplying 20Ah times a 6s1p discharge rate of 12C to arrive at 240amps of potential energy requiring a Controller rated at 240amps according to your figuring (20Ah x 12C discharge = 240amps equates to a 240amp Controller).

It doesn't "require" a controller of a specific current to match a battery's maximum discharge rate--the controller simply has to be limited to *at most* the maximum battery discharge current; preferably less. You don't *have* to use all the current the battery can output...but if the battery is capable of it, then you *can* do so, as long as it's not exceeding the battery's capabilities.

(this doesn't take into account sellers over-rating their products, or aging of the cells, voltage drop during max current draw, etc. It is only about a cell's actual capabilities.).

That said, the only thing I refer to in my previous posts about general battery capability is the battery (cell) capability itself, not what controller should or shouldn't be used with them.

Whether it is a good idea (for whatever reason) to use the specific cells the OP has the way they want to use them, I can't say.

The only thing I can say is that if a cell is rated at a particular C-rate, then to determine the actual Amps it can output, the capacity of the cell is multiplied by the C-rate.

The only cells I have personal experience with that are different from that are lead-acid, which are rated with a *20-hour* C-rate, not 1-hour C-rate.like the rest of them.

So for typical lithium cells of any type I am aware of, If you have 1p of a 1Ah cell, capable of 1C, regardless of the number in series (even just 1s), the battery made from them is capable of 1A.

Thus for typical lithium cells of any type I am aware of, If you have 1p of a 1Ah cell, capable of 5C, regardless of the number in series (even just 1s), the battery made from them is capable of 5A.

And so for typical lithium cells of any type I am aware of, If you have 2p of a 20Ah cell, capable of 12C, regardless of the number in series (even just 1s), the battery made from them is capable of 480A.

If the C-rate for a specific cell model / brand is defined differently than this by the manufacturer, then that definition applies, and not the general rule above.

 

[ebike11]

I get most of my info from reading on here. I didnt say 100% that i know for certain thats the calculation to get battery current amps..its what ive read on here in a bunch if different threads. Amberwolf essentially is saying the opposite of you and he has been here for over 10 years with 34000 posts. ... So would he also be misguided? ... I think both of you are very knowlegable

Amberwolf is far more knowledgeable than i will ever hope to be. That said i still think you and others are incorrect in multiplying 20Ah times a 6s1p discharge rate of 12C to arrive at 240amps of potential energy requiring a Controller rated at 240amps according to your figuring (20Ah x 12C discharge = 240amps equates to a 240amp Controller).

Do you really believe spending over $1600 for your two DIY 28s2p (paralleled) RC Turnigy lipo battery will give better performance and cycle life longevity than a 1st rate, top quality ebike DIY battery costing less than $1600 using EV pouch cells.

No where on the label of that Turnigy RC Lipo does it imply 12C computes to 240amps of available energy to theoretically power your motor via a 240amp Controller (20Ah x 12C). Your 20Ah x 12C = 240amps is bogus thinking if you still believe your 28s1p Turnigy battery is capable of supplying from 200amps to 240amps of continuous discharge amperage to your high rpm qs273 motor.

IMO, your high rpm qs273 motor is more deserving of a DIY EV Lipo pouch $1600 battery THAN a two 28s1p Turnigy RC lipos paralleld as a Turnigy 28s2p DIY RC battery when it comes to both cycle life longevity and performance.

I dont understand why you keep saying or recommending things that im not concerned about. Im not worried about the life cycle or longevity as long as I get my use out of them somewhat then Ill be happy.

This is the reason as I mentioned above why I wanted to use them:

I prefer the flexibility of these packs because of the size. Of course i could have made 1 large pack but the problem is mounting space. With these I can have a pack on the rear rack and another in the frame.

Also connectivity is a breeze. Just connect the power leads with small pieces of copper to crimp the wires together without needing to solder.

Sometimes simplicity and convenience are worth the extra money since hobbyking can ship straight to my door from another country without hassles of dangerous goods category

Also no advertised cell on the market I have seen prints the current amps that it can make..only C rating most of the time

 

[ebike11]

AW and eMark are talking about two aspects of the same thing. IMO they are both right.

How so? As far Im reading, Amberwolf is saying in my case that the packs wired in parallel would theoretically put out 480A of battery current however eMark disagrees

 

[ebike11]

[/quote]Amberwolf is far more knowledgeable than i will ever hope to be. That said i still think you and others are incorrect in multiplying 20Ah times a 6s1p discharge rate of 12C to arrive at 240amps of potential energy[/quote]

Isnt that what he is saying? By others wouldnt you be including him as well?

 

[eMark]

I dont understand why you keep saying or recommending things that im not concerned about. Im not worried about the life cycle or longevity as long as I get my use out of them somewhat then Ill be happy.

That logic sums up the mindset of the majority of RC Lipo hobbyists, but certainly not the majority of ebikers. Ebikers want their expensive battery and intensive DIY labor to endure hundreds of cycles before they have to invest mucho $$$$ into another expensive DIY ebike battery pack.

It's only a minority of RC users that would intentionally abuse that Turnigy 20Ah battery for 10-15 minutes (if that long) at a continuous discharge of 240amps ... unless money to buy several more $200 Turnigy 20Ah battery after a few such cycles is no problem.

These packs have a 12c continuous and 20c 10 sec.burst

How many minutes of riding time do you now get at a continuous discharge rate of 12C with just one of your Turnigy 28s battery packs powering your high rpm qs273 hub motor?

FWIW ... here's a few reviews of that Turnigy 20Ah at 12C discharge rate ...

• Some guys over at the efoil forum use it, some with success, some burned it up. They tend to puff if operated at or close to the rated specs. It really isn’t a high discharge lipo. Use Graphenes if you want reliable high discharge.

• In my experience with lipos all have overstated discharge rate but the best ones I’ve used so far have been gens tattu lipos.

• Do you know how many cycles you have on yours? My turnigys got the slightest bit puffy on their 2nd or 3rd charge and now its past 50 charges I can barely close my enclosure <|.

• FWIW a 20Ah pack at 12c constant should give you 240A output.
  I’d divide that number by 5 because manufacturers of lipo exaggerate A LOT on discharge rating.

It would be most helpful if Turnigy would inform users how long their 20Ah 6s battery can endure a continuous discharge at 12C (240amps). IF you have no intention of ever pulling 240amps or 480 amps or 800 amps (10 sec burst) as previously posted then maybe you should ask the following questions ...

• 1. What is a reasonable continuous discharge amperage drain on a 28s2p Turnigy 40Ah battery pack for 5-10 minutes being i'm not interested in cycle life longevity as much as raw performance?

• 2. What is a reasonable fast charge rate for my paralleled 28s2p 40Ah battery pack being i'm not as interested in cycle life longevity as long as the charge rate doesn't cause swelling/puffing?

• 3. What about using a 200amp Controller (40Ah x 5C) with my 28s2p 40Ah Turnigy powering my high rpm qs273 motor to achieve 50mph for at least five minutes?
  
  Amberwolf is more qualified to answer such questions. Wishing you good success in accomplishing your objectives ... so will bow out of this thread :thumb:

 

[ebike11]

As I mentioned 2 times before, the reason i chose these packs are because of ease of connectibility and flexibility to mount in different areas of the bike as well as ease of purchase buying packs from another country.

Of course im not going to be pulling maximum Amps all the time. Im just wondering if the rule of thumb is generally Ah x C rating to get battery current output and if so, does it double from 240A to 480A when 2 separate packs are connected together in parallel.
I never intend to use the whole packs energy in 10-15 minutes constantly...just trying to calculate what is possible at full throttle

I can be a responsible rider and control power settings on the controller etc. but I first am trying to determine "roughly" the max. current I will be able to have.

I also can find many positive reviews of the same packs so with most lipo packs there is gonna be risks of damage. Plus who know how they used them.
One the reviewers also mentioned that 12C is 240A according to the Ah x C

 

[john61ct]

wondering if the rule of thumb is generally Ah x C rating to get battery current output and if so, does it double from 240A to 480A when 2 separate packs are connected together in parallel.

C-rating from the mfg is useless, always double or triple optimistic at least, needs to be tested IRL by a knowledgeable user.

Given that, yes paralleling multiplies current amps , just as serial connections multiply voltage.

 

[john61ct]

MCSGUY is the definitive tester, but only for relative quality, his usage patterns dictate only very short lifespans

https://www.rcgroups.com/forums/showthread.php?p=49072963

https://www.rcgroups.com/forums/showthread.php?p=48102561

 

[ebike11]

wondering if the rule of thumb is generally Ah x C rating to get battery current output and if so, does it double from 240A to 480A when 2 separate packs are connected together in parallel.

C-rating from the mfg is useless, always double or triple optimistic at least, needs to be tested IRL by a knowledgeable user.

Given that, yes paralleling multiplies current amps , just as serial connections multiply voltage.

Ok...a member who posted in this thread said it doesnt so I want to make sure..but as you said, take the c rating with a grain of salt

 

[john61ct]

No, what I said is those ratings need to be completely ignored.

Choose your LiPo packs from the very short list of IRL-tested well performing units reco'd in that thread, after you gain an understanding of the test methods and various factors.

Easily means getting 5x or 10x greater value, or IOW not throwing your money away.

 

[ebike11]

No, what I said is those ratings need to be completely ignored.

Choose your LiPo packs from the very short list of IRL-tested well performing units reco'd in that thread, after you gain an understanding of the test methods and various factors.

Easily means getting 5x or 10x greater value, or IOW not throwing your money away.

Thanks for those links!
However I was not able to find any infor on the Turnigy 6S 20000Ah pack?

 

[eMark]

Im just wondering if the rule of thumb is generally Ah x C rating to get battery current output and if so, does it double from 240A to 480A when 2 separate packs are connected together in parallel.

Yes, but how many seconds do you think a 170lb ebike (w/rider) can be powered along a dirt trail pulling 240amps from your 28S1P 20Ah battery at 12C discharge (240amps) or 28S2P 40Ah battery at 12C (480amps) or 20C (800amps) ... your usage specification.

I never intend to use the whole packs energy in 10-15 minutes constantly...just trying to calculate what is possible at full throttle

The saying that figures don't lie, but Lipo marketeers can figure is no lie when it comes to claiming a discharge rate from 12C to 24C ... BUT FOR HOW LONG ?? Those 12C-24C discharge ratings have some relevance to RC flight times in seconds, but not applicable to your ebike riding times. Just consider the difference required to power a 5lb hobby plane through the air for a few seconds compared to powering an ebike w/rider total weight of 170lbs over a dirt trail ... 240amps at "full throttle" on an ebike with rider (170lb). Do you really think you can pull even 240amps from your RC Turnigy 28S2P 40Ah battery for 10-15 minutes.

To get a better idea of how this would work here's my figuring. It's not any more of a reliable benchmark than the figuring of Lipo Marketeers, but you'll get the general idea. 60 minutes divided by 12 (20Ah x 12C = 240A) equals 5 minutes at 240amps under super ideal conditions. IMO, 5 minutes is inflated by 12C. Even 25 seconds may be too long as the pack temp has already reached 160 degrees F with pack swelling pulling 240amps.

As a conservative guessimate start with a 40 or 30amp Controller with your 28S2P Turnigy 40Ah battery. This will give you a better idea of your speed objective and for how long at that speed. You might find the followng thread of some interest ... https://endless-sphere.com/forums/viewtopic.php?f=14&t=117062 ... using EV Lipo pouch cells with a 100amp Controller.

Reread the previous posts by john a few times until it registers with you ... :thumb:

However I was not able to find any infor on the Turnigy 6S 20000Ah pack?

That's because RC Lipo cells are for RC hobbyists who are more impressed by "240amps", 480amps", or "800amps" rating then how to treat a RC Lipo battery to get the most cycle life longevity instead of the most discharge.

 

[ebike11]

Im just wondering if the rule of thumb is generally Ah x C rating to get battery current output and if so, does it double from 240A to 480A when 2 separate packs are connected together in parallel.

Yes, but how many seconds do you think a 170lb ebike (w/rider) can be powered along a dirt trail pulling 240amps from your 28S1P 20Ah battery at 12C discharge (240amps) or 28S2P 40Ah battery at 12C (480amps) or 20C (800amps) ... your usage specification.

I never intend to use the whole packs energy in 10-15 minutes constantly...just trying to calculate what is possible at full throttle

The saying that figures don't lie, but Lipo marketeers can figure is no lie when it comes to claiming a discharge rate from 12C to 24C ... BUT FOR HOW LONG ?? Those 12C-24C discharge ratings have some relevance to RC flight times in
seconds, but not applicable to your ebike riding times. Just consider the difference required to power a 5lb hobby plane through the air for a few seconds compared to powering an ebike w/rider total weight of 170lbs over a dirt trail ... 240amps at "full throttle" on an ebike with rider (170lb). Do you really think you can pull even 240amps from your RC Turnigy 28S2P 40Ah battery for 10-15 minutes.

To get a better idea of how this would work here's my figuring. It's not any more of a reliable benchmark than the figuring of Lipo Marketeers, but you'll get the general idea. 60 minutes divided by 12 (20Ah x 12C = 240A) equals 5 minutes at 240amps under super ideal conditions. IMO, 5 minutes is inflated by 12C. Even 25 seconds may be too long as the pack temp has already reached 160 degrees F with pack swelling pulling 240amps.

As a conservative guessimate start with a 40 or 30amp Controller with your 28S2P Turnigy 40Ah battery. This will give you a better idea of your speed objective and for how long at that speed. You might find the followng thread of some interest ... https://endless-sphere.com/forums/viewtopic.php?f=14&t=117062 ... using EV Lipo pouch cells with a 100amp Controller.

Reread the previous posts by john a few times until it registers with you ... :thumb:

However I was not able to find any infor on the Turnigy 6S 20000Ah pack?

That's because RC Lipo cells are for RC hobbyists who are more impressed by "240amps", 480amps", or "800amps" rating then how to treat a RC Lipo battery to get the most cycle life longevity instead of the most discharge.

Im not riding on a trail..i never said that.
I only ride on smooth streets and highway.

Also i meant that the Turnigy 6S pack was not on the RC forums battery chart. They seemed to have tested smaller sized packs. If hobbyking packs are a main sourse of batteries for RC hobbyists then it makes sense that someone has tested it..have to search more.
I didnt mean that there wasnt a lot of info on the pack on endless.

 

[eMark]

Also i meant that the Turnigy 6S pack was not on the RC forums battery chart. They seemed to have tested smaller sized packs. If hobbyking packs are a main sourse of batteries for RC hobbyists then it makes sense that someone has tested it..have to search more.

Again, for the hundreth time RC hobbyists aren't interested in the average number of discharge cycles they can expect from their RC Lipo pouch battery. Thus Turnigy and all other RC Lipo manufactures realized long ago (at the GETGO) that [inflated] high discharge C rates for a few seconds at "Full Throttle" is what turns the crank (interests) of your typical RC enthusiast ... NOT the average number of discharge cycles and cycle life longevity that can be expected from a RC Lipo battery.

On the backside label of my Turnigy 3s1p 2200mAh Lipo it says not to exceed 160 degrees F. Like has any RC hobbyist ever checked the temp of their Lipo to determine what C discharge for 60 seconds initiates swelling/puffing? That kind of data would be of interest to someone building a Turnigy 28s2p Lipp battery using those 20,000mAh cells supposedly rated at continuous discharge of 20amps. Would Turnigy ever publish such data for their 6 cell 20,000mAh Lipo ... not a chance even though they've done tests and have the data.

Turnigy never imagined that eight of their 6s 20,000mAh 22.2V, 444W (22.2V x 20C = 444W) and two 4s 20Ah would be used to build this ebike powerplant: 28s2p x 3.7V (nominal) = 103.6V ... 103.6V x 40A = 4144W. Theoretically a discharge rate of 20C (103.6V x 800A = 82,880W (28s2p). Even at a full throttle discharge rate of only 2C (28s2p) you'd theoretically need a motor capable of handling 8,288W. You can recheck my 2C discharge rate for your Turnigy 28s2p battery and let me know if my figuring is off and by how much.

Your mention of 240amps, 480amps and 800smps is for a brief time (seconds). At FULL throttle you would most likely end up in the hospital and possibly a fried motor depending on how long you were able to stay aboard your ebike. That's assuming you were using 6awg wiring and even then it would get HOT providing 480amps (28s2p).

Here's what i learned from your thread as to how Lipo manufacturers rate the MCD amperage that i never realized (knew) before that being ... The MCD energy density amperage of an RC Lipo is apparently identical it's Ah capacity rating. That isn't the case with Li-ion cyclindrical cells (e.g. 1865s & 2170s) ...

• Samsung 30Q 3000mAh high energy dense cell has a MCD rating of 15amps.

• LG M#6 3600mAh mild-mannered cell has a MCD rating of 6.1amps (Batemo spec).

• Molicell P42 4200mAh high energy dense cell has a MCD rating of 45amps (close to the same).

Just for the heck of it WHY not post on DogDipstick's thread ... https://endless-sphere.com/forums/viewtopic.php?f=14&t=117062 ... the following question: If you didn't use a Controller what theoretically is the maximum Watts you could pull from your EV Li-po pouch battery at FULL Throttle? It would be interesting to see if he would even answer and if so what kind of answer :wink:

Apparently your objective is: "Full Throttle for 10 to 15 minutes" and "480 amps (28s2p)" is IMO unrealistically, illusory, impractible ... an unachievable goal.

Mucho years ago as an RC flying hobbyist by the seat of my pants i got hooked and took the bait. Couldn't rest until i bought their latest Tenergy High Discharge (25C) and Fast Charge (3C) Lipo. Only read the 160F WARNING years later (never abused it). After years of collecting dust it's still in fair to good condition (typo error ... should read Tenergy not Turnigy).

 

[eMark]

With more powerful RC Lipos for drones i now see the logic of using them for a DIY KIS(spot-welding not needed) ebike battery build. You probably could have got by using eight Turnigy 5000mAh 8S (65~130C) in a 16s4p 20Ah configuration. Total battery cost $1,224 ...

The following youtubes are an interesting experiment using just two Turnigy 6S 6000mAh Lipos for a DIY KIS(no spot-welding needed) 12s1p 6Ah battery to power a Bafang BBS02 using a 60amp 3000W Castle Creation controller ...

https://www.youtube.com/watch?v=fqFWTAH6tZA
https://www.youtube.com/watch?v=DgH8X90WYGs
https://www.youtube.com/watch?v=91fXYn_V6Zk
https://www.youtube.com/watch?v=Zew0RXjyAqU
https://www.youtube.com/watch?v=V66BIL5cbMA

Check out his site at: https://www.youtube.com/c/brunopoweeer

With that Turnigy 16s4p 20Ah with its 8s1p [inflated] discharge rate of 65C-130C it becomes somewhat realistic with 4 in parallel. With just a 2C continuos discharge rate (40amps) 500 discharge cycles becomes realistic; especially if continuous discharge is limited to your "10 to 15 minutes". 67.2V(full charge) x 20A discharge rate = 1344W. 20A x 2C = 40A x 59.2V(nominal voltage) = 2368W. Castle Creations doesn't make a 16s 60A Controller. A 48-72V 2000W Controller should suffice ??

 

[john61ct]

I was not able to find any infor on the Turnigy 6S 20000Ah pack?

Yes he only tests a specific weight range.

A. Extrapolate based on brand / line similarities

B. Learn how to test yourself and post results to benefit the community

or C. parallel known-good smaller units to get to your desired size

Perhaps you meant 20 Ah (20K mAh)?

 

[john61ct]

Just be aware LiPo is 10000x more likely to burst into flame as they wear, or even brand new if not cared for properly.

Many RC hobbyists have burnt down their homes / office buildings, apartment buildings.

As the danger becomes more public knowledge expect restrictions to grow, why we can't have nice things.

Best practice is outdoors, fireproof shed, well away from any human habitation.

Never charge unattended.

Always monitor / test SoH, CC cap tests, ESIR changes

when in doubt recycle early before obvious externally visible symptoms appear

 

[ebike11]

I was not able to find any infor on the Turnigy 6S 20000Ah pack?

Yes he only tests a specific weight range.

A. Extrapolate based on brand / line similarities

B. Learn how to test yourself and post results to benefit the community

or C. parallel known-good smaller units to get to your desired size

Perhaps you meant 20 Ah (20K mAh)?

Yes sorry I meant 20An x 2 in parallel