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Author Topic: Newer Li Ion batteries  (Read 3100 times)

Offline Fred Underwood

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Newer Li Ion batteries
« on: April 13, 2021, 03:48:35 PM »
I found an interesting Youtube video of a fellow making up Li-Ion battery packs.  He flies ducted fan jets and makes up battery packs.  He flies at higher amperage that we do, and claims brief peak draws of 80 - 100 amps on Samsung cells.  The cells are rated for 30 amp continuous and should fit within our needs.  He also claims more cycles than most of us would get.



https://liionwholesale.com/products/samsung-40t?variant=12252585885790
     about 67 grams for 4000mah

Also available are Molicel batteries with various sizes and weights to possible fit our needs.
https://www.imrbatteries.com/molicel/


https://www.imrbatteries.com/molicel-p26a-18650-2600mah-35a-battery/
     48.5 grams

https://www.imrbatteries.com/molicel-inr20700a-20700-3000mah-35a-battery/
    57.8 grams

https://www.imrbatteries.com/molicel-p42a-21700-4000mah-45a-battery/
       67 grams

Battery Universe suggests leaving about 30% for Li Ion for prolonged cycles, so one can plan battery capacity based on that.

https://batteryuniversity.com/learn/article/premature_voltage_cut_off#:~:text=Typical%20cut-off%20voltages%20for%20li-ion%20cells%20lie%20in,density%20and%20power%20delivery%20wise%2C%20namely%20the%20former%29.

Anyone have experience or interest in these higher amp cells for our use?  Our useful configuration for a pack might also be different than his, but an interesting concept with printed end caps.






Fred
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Offline John Rist

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Re: Newer Li Ion batteries
« Reply #1 on: April 14, 2021, 08:37:33 PM »
Is the voltage the same as a LiPo cell.  Also  the printed end plates are a problem.  They do appear to be smaller and lighter than what we are currently using.  At $6 per cell the price is right. However this does not include the cost of the balancing/charge cable. At some point somebody should provide built packs. Looks promising D>K.
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Offline Brent Williams

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Re: Newer Li Ion batteries
« Reply #2 on: April 14, 2021, 09:01:07 PM »
Dane Martin is leading the way on some very cool Li-Ion battery development.  Fool Throttle Batteries. 
Hopefully he will chime in.
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Offline Dane Martin

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Re: Newer Li Ion batteries
« Reply #3 on: April 17, 2021, 04:24:54 PM »
Samsung VTC6 cells are NOT rated for 30a. They are a 15a cell. In the manufacturer's data sheet, it says 15a continuous and 30a burst. Yes, you can certainly pull 80a from it for a few seconds. But those cells are very old tech in the li-ion world.

The only proven 35a continuous cell in an 18650 is the molicel P26A. It's a 2600mah.

The other molicel cells you listed are true ratings also. I build packs exclusively with molicel for flight packs.

Offline Dane Martin

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Re: Newer Li Ion batteries
« Reply #4 on: April 17, 2021, 04:26:16 PM »
Is the voltage the same as a LiPo cell.  Also  the printed end plates are a problem.  They do appear to be smaller and lighter than what we are currently using.  At $6 per cell the price is right. However this does not include the cost of the balancing/charge cable. At some point somebody should provide built packs. Looks promising D>K.

People you either know, or have heard of are testing li-ion flight packs for me now... I've been using li-ion for control line for about a year

Offline John Rist

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Re: Newer Li Ion batteries
« Reply #5 on: April 18, 2021, 08:55:17 AM »
https://www.18650batterystore.com/products/molicel-p26a    $4.50 if you buy 10


Is this the right stuff, how many to a pack, where do you get the end caps?

Do you have to space them out or can you just tape them up?

Thanks,
Motorman 8)
Also how hard is it to solder your own and where do you get the balancing connectors.   S?P  If they are the answer hopefully some one will start building packs.   y1 
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Offline Dane Martin

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Re: Newer Li Ion batteries
« Reply #6 on: April 18, 2021, 09:03:53 AM »
Also how hard is it to solder your own and where do you get the balancing connectors.   S?P  If they are the answer hopefully some one will start building packs.   y1

I've been building these for many years. Also, I'll sell the individual cells to match 18650 stores pricing if you want to build them yourself....

Offline Dwayne Donnelly

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Re: Newer Li Ion batteries
« Reply #7 on: April 18, 2021, 12:44:00 PM »
Also how hard is it to solder your own and where do you get the balancing connectors.   S?P  If they are the answer hopefully some one will start building packs.   y1

All kinds of places to buy balance connectors

https://www.banggood.com/search/balance-charging-cable.html
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Offline Fred Underwood

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Re: Newer Li Ion batteries
« Reply #8 on: April 18, 2021, 02:15:54 PM »
Samsung VTC6 cells are NOT rated for 30a. They are a 15a cell. In the manufacturer's data sheet, it says 15a continuous and 30a burst. Yes, you can certainly pull 80a from it for a few seconds. But those cells are very old tech in the li-ion world.

The only proven 35a continuous cell in an 18650 is the molicel P26A. It's a 2600mah.

The other molicel cells you listed are true ratings also. I build packs exclusively with molicel for flight packs.

I had asked about the Sony/Murata cells as because they come in 2600 and 3000ma in a 18650 cell size and weight.  The cells are rated 15 amp continuous (30 amp continuous under 80įC).  Dane has the experience and information to note that the cells will not stay in a good temperature range with over 20 amp continuous, and maybe only 15 amp.  As noted, the Molicel brand seems to be the new and best technology.  For reference, the Sony cells have been out since 2016-2017. so old in battery years.

Though Sony cells are not advised, the following Sony packs will give information about pack size, shape and weight for 6S 18650 cells.  The one 18mm dimension has to be wrong, and be approximately 37mm with wrap as the cells are about 18mm each.

https://alexnld.com/product/auline-vtc6-22-2v-3000mah-6s-30a-xt60-plug-long-rang-lr-li-ion-battery-for-5inch-7inch-rc-drone/?utm_source=bing&utm_medium=cpc&utm_campaign=Product%20Ads(BSC)&utm_term=4578022847022734&utm_content=Ad%20group%20%231

Other configurations can be made as desired.  It doesn't look like spacers or end holders were used.  Spacer or end caps shown here for reference if desired.

https://www.amazon.com/YXQ-Battery-Bracket-Storage-Protection/dp/B07QSJ8ZSP/ref=sr_1_14?dchild=1&keywords=18650+spacer&qid=1618774744&sr=8-14

As noted, we may want to wait for some results.  If the 2600s work well for 6S, the weight savings is about 60 grams versus TP 2800's.

People you either know, or have heard of are testing li-ion flight packs for me now... I've been using li-ion for control line for about a year

If you want to make up packs, consider that you will invest about $30 - $32 in batteries with shipping, then need balance leads, battery leads and plugs, and shrink wrap.  Good soldering skills (or spot welder) are needed.  You can get good practice by replacing old NiCad and NiMH packs in power tools with 2 or 3 Li Ions for equivalent voltages, and not risk an airplane  :-)
Fred
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Offline Igor Burger

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Re: Newer Li Ion batteries
« Reply #9 on: May 09, 2021, 01:08:12 PM »
Sorry, I missed this thread, so may be late, but better late than never.

18650 cells are rated "usefull" in C rating or allowed current for what we need. But there is one problem, they have also limited max temperature and when I tested them, I always reached temperature limit earlier that capacity was gone. So I completaly agree with that guy in video that those batteries will deliver that high current for only limited time.

The other problem is, that because of higher internal resistance, the voltage at our load current is signifficanly lower than LIPO. That means that the same power we will need higher current.

... at least that is my up to time experience

Offline Paul Walker

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Re: Newer Li Ion batteries
« Reply #10 on: July 17, 2021, 08:57:11 PM »
OK, so I am the one who used them at the Nat's.

When they were new, they did run hotter. After 10 or so flights they did run cooler. The one thing you have to adjust for is the discharge curve they have compared to a Li-Po. They will land at a much lower voltage than a Li-Po, but you simply drop the min voltage level in the ESC to 2.9 ish volts. Without that change, I had some sags in power in the second corner of the hourglass on my bigger plane. It sagged right when it needed the power in the corner, but came instantly back up to power as soon as the corner was finished. I have used up to a 12.6*5 3 blade prop on it with no ill effect. I used Igor's 12*5 narrow blade prop on it at the Nat's.

The plane I used at the Nat's is about 720 in^2, and weighs 65 ounces, and runs on all of 70 feet of lines.  It produced the highest score I have ever received at the Nat's,  in qualifying, at 614. That was in near stunt heaven air on a cooler morning. It used 2050 mah out of its 2600 capacity. Not even close to being an issue. Then in the top 5 flyoff, it flew in 24 to 25 mph wind, and did very well. I was very happy with its performance. This plane clearly flies better with this battery compared to a Li-Po. I did numerous back to back tests comparing this battery to both 5S and 6S Li-Pos. It is neither a weight or voltage issue that makes it fly better.

I do use an Igor active system, but this year I ran it fairly "flat"  with a sensitivity of all of 12 in the wind. The sensitivity was at 10 for the 614 flight.  Lap times were measured by several sources at 5.35 sec/lap, both in the calm and the strong wind. So, I can not answer any questions about how well it responds to a higher sensitivity and its ability to boost and brake, other than what I have observed at 10 or 12. It is just enough sensitivity to know that it is "just" working, but not overdoing it and speeding up in the wind. I was flying with David on Monday morning in 20 mph air, measured, and there were many comments on how well it "held back" in the wind. In other words, it resisted speeding up much more noticeably than some 75 powered planes....

They do have a different shape then the Li-Pos. You will have to adjust your battery mount for this. I run mine in the 3*2 lengthwise configuration. 3 cells forming a triangle shape, with another 3 stack triangle aft of the first. Long and skinny. This exposes more of the surface area of the cells casing to the air flowing by, and runs cooler than a 3 by 2 "brick". Your choice, but my long and skinny packs come down at around 120F.  I do make sure there is plenty of air flowing by the ESC and batteries.

So what is the big advantage. They weigh 303 grams. That is less than a 5S2800 TP LiPo.  It is nearly 60 grams lighter than a 6S2800 TP Lipo. That IS something worthy of consideration!

If you are using 6S2800 batteries, a switch to these is a real no brainer.  Dane Martin can supply these to you for about $50 a battery. For $50, it sure would be worth the effort to try one.

Offline Dane Martin

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Re: Newer Li Ion batteries
« Reply #11 on: July 17, 2021, 09:12:28 PM »
In reference to the Sony Murata cells, the Sony VTC5A are actually very very comparable to the molicel P26A. I've been testing them on some long range RC equipment, and getting about the same results. Just gotta make sure they're not knock off's. The VTC6A is a 3000mah but not capable of our demands in control line. The only larger capacity 18650 I would recommend trying is the molicel P28A (possibly labeled as a P28B)... however, good luck in getting some. The largest consumer of this cell is NASA. Due to it being the highest capacity and highest discharge in an 18650 can size.

Offline Fred Underwood

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Re: Newer Li Ion batteries
« Reply #12 on: July 19, 2021, 08:07:30 PM »
I also tried the Li Ion cells.  My pack was a 6 cell brick type used on/in a profile.  The plane is about 660 squares on 67.5 ft C to C lines, and about 60.5 oz with the Ion pack and about 62.5 with LiPo.  The battery fits in a 3 sided box, with the outer cells exposed and a spaced off of the back wall a small amount.  The brick gives a good amount shift for CG if needed. 

LiPos run cool without difficulty.  In the spring when the air was great, I used about 1650 - 1700 mah from the 6S TP 2800 pack, now about 1800.  On the Li Ion pack, about 8 - 10% higher.  The LiPo was about 105 - 110į with ambient about 75 - 80į.  The Li Ion was about 115 on the outer cells, 125 for the middle 2 cells, and 135į on the cells against the back wall.  I flew on a warmer day and the cells were warmer than the 140į suggested safe max.  I used about 20 cycles and the cells seem fine.  The shrink wrap blunts heat transfer and the cells don't feel that hot unless held firmly.  IR thermometer was used for the temperature.

If the cells are all external, strapped on a fuselage, I think that they would be cool enough, as the external cells.

I probably could get a long triangular pack to cool if I put one angle of the triangle on the back wall, held centered with Velcro, and let air move in the spaces created above and below.

The planes that I have seen, similar to Paul's, have the battery in a wind tunnel.  Maybe I should learn something, but again, no problem with the LiPo's.

As Paul noted, a 2 oz weight savings is great, and worth a try.  Of course that is if you can balance the CG  with 2 oz less in the nose.  But you can plan the next plane to use Li Ion  :-)
Fred
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Offline dc stunt

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Re: Newer Li Ion batteries
« Reply #13 on: July 21, 2021, 08:38:56 PM »
Big thanks to Dane Martin for making these  packs for me to try.
L-201

Offline Fred Underwood

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Re: Newer Li Ion batteries
« Reply #14 on: July 21, 2021, 10:01:28 PM »
Yes, I should have noted that Dane was great to work with.  He has good information and is willing to help, and is available by message through the forum.
Fred
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Offline Dane Martin

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Re: Newer Li Ion batteries
« Reply #15 on: August 25, 2021, 10:51:16 PM »
I actually have pics of these bad boys

Offline Chris Cox

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Re: Newer Li Ion batteries
« Reply #16 on: September 27, 2021, 12:02:45 PM »
I actually have pics of these bad boys

I have about 20 flights (between four packs) now using the Li-ion batteries, as pictured above.  Max temperature so far was about 108F.  I expect this temp to decrease with added flights, but even now it is way below any temperature limitations.  I do not have sufficient room to shift the battery pack far enough forward to compensate for the 2 ounce lighter battery, so I added clay under the cowling to keep the model (Hellcat) in balance. The model, with the Li-ion installed comes in around 64 ounces.  I use a Badass 3517 motor, Igorís active timer and a Spin 66 Jeti ESC. 5.3íish lap time and I land with around 3.50-3.55 volts per cell remaining.  Dane tells me that a good storage voltage is between 3.50-3.60 volts, so in theory, when finished flying, I do not need to do anything until ready to charge for the next session.  Nice!

So, hereís the deal.  I swap between the Li-ion and the Li-po batteries.  I canít put my finger on it, but I definitely prefer the Li-ion battery over the Li-po.  Perhaps it is the 35C rating compared to the 25C Li-po batteries? Balance is identical between the two set-ups.  It just seems to perform better.  At 50 bucks a pack and potentially 500 or more flights per pack compared to around 200 for the Li-po makes the decision pretty simple.  I ordered additional packs from Dane 😬

Possibly the only negative is the need to charge at only 1C (2.6 amps).  It takes a little longer than the Li-poís, which I generally charge at 2C. Imagine the horror of having to wait an additional 20/25 minutes to charge six batteries! 😂

Offline Dane Martin

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Re: Newer Li Ion batteries
« Reply #17 on: September 27, 2021, 12:35:11 PM »

Possibly the only negative is the need to charge at only 1C (2.6 amps).  It takes a little longer than the Li-poís, which I generally charge at 2C. Imagine the horror of having to wait an additional 20/25 minutes to charge six batteries! 😂

That is a draw back! Out of the cool news coming down the pipe for lithium tech, there's only a couple with a faster charging capability. None of which will be helpful to us. Haha

Offline pmackenzie

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Re: Newer Li Ion batteries
« Reply #18 on: September 28, 2021, 10:04:25 PM »

So, hereís the deal.  I swap between the Li-ion and the Li-po batteries.  I canít put my finger on it, but I definitely prefer the Li-ion battery over the Li-po.  Perhaps it is the 35C rating compared to the 25C Li-po batteries?

Not sure they are rated 35C.
Seems like they are rated 35A, which is only ~13C.
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Offline Fred Underwood

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Re: Newer Li Ion batteries
« Reply #19 on: September 29, 2021, 04:42:09 PM »
When I emailed with Dane, He mentioned tests done on cells by Mooch.  Mooch tests cells for use in vaping, but the data gives a way to compare cells. Those tests show the reason to use the Molicell instead of Samsung 25s.  The Molicells do well to about 25 amps continuous, and can overheat above that.  Again, that is 25 amps or about 10C.  But we fly just below that range except for peaks,  They are still better than Samsung.  In a built up fuselage, they can sit in a "wind tunnel" and seem to work well when used in the long pyramidal pack.

http://www.tasteyourjuice.com/wordpress/archives/18232

https://www.e-cigarette-forum.com/threads/bench-retest-results-molicel-p26a-2600mah-18650-beats-vtc5a-best-all-around-18650.902761/



Fred
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Offline Dane Martin

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Re: Newer Li Ion batteries
« Reply #20 on: September 29, 2021, 04:47:17 PM »
Might I add, however... the 35a rating is their "continuous" rating. A C rating of a li-po is not the continuous rating, but what it can handle as a max. So, to pull 70a on a molicel p26a puts it in the 25c rating category, which is entirely possible. But, like any other battery, you'd never pull the max C rating as a continuous draw.

Offline pmackenzie

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Re: Newer Li Ion batteries
« Reply #21 on: September 29, 2021, 05:16:44 PM »
I was not trying to be negative about these packs, just trying to be factual :)
The difference between amp rating and C rating is not always well understood.

Pretty good chance I will get some to try, based on what has been said about them on here, and by whom  ;D

Has anyone done an Ir test on these packs, as built?
That can be used to estimate what some call the "true C" rating.
It would also be interesting to see if the Ir dropped after some use, which the reporting of cooler packs would suggest.

Pat MacKenzie
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Offline Dane Martin

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Re: Newer Li Ion batteries
« Reply #22 on: September 29, 2021, 05:19:05 PM »
IR ratings are much higher than li-po. Around 20-40 is normal

Offline dc stunt

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Re: Newer Li Ion batteries
« Reply #23 on: October 05, 2021, 04:33:16 PM »
I have few flights now using this battery from Dane, and Iím loving it.
Now I have just ordered 6 more packs from Dane.

Flying my own own design weighing in at 64oz with Tempest 3515/740kv
With Pavlo Kravchenko 12.5/5.2.
Spin 55/ Fioratti timer.

Plane flew extremely linear with this set up.

Later

David
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Offline Fred Underwood

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Re: Newer Li Ion batteries
« Reply #24 on: October 05, 2021, 04:57:01 PM »
That is great news.  We can all learn from these posts, and keep Dane busy building batteries.

How about a few of the parameters.  Ambient temperature, mah used by replacement, battery temperature hottest spot ....   What was the mah use on LiPo pack?

Thanks,
Fred
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Offline dc stunt

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Re: Newer Li Ion batteries
« Reply #25 on: October 05, 2021, 05:19:47 PM »
Battery was cycled a few times per Danes  instruction prior full flight.
Esc dropped to 2.9v per cell per Paulís recommendation.

I was running TT 6s 2800 prior switching to this type of ion battery.
The biggest difference is not really which battery is better than the other,
but the overall performance that I can feel in my hand.

The plane flew very differently. I dropped 2oz from the start.
The battery is configured in a skinny triangular tube  that sits
In the middle of the fuse.  Vertical cg is much better with this type of
Configuration.
The loading in my hand is much lighter and plane is much more agile
Without losing stability, and turn much more linear than before.

I am getting 6% left with a 6mins flight time. This 12.5 draws 34 Amps on the bench.
Battery pack is warm after flight, no problem.

Iím loving it, and Iím not going back.  🤣
L-201

Offline Brent Williams

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Re: Newer Li Ion batteries
« Reply #26 on: October 05, 2021, 07:43:18 PM »
dc stunt, How much(many?) mAh did you put back in during the recharge?
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Offline dc stunt

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Re: Newer Li Ion batteries
« Reply #27 on: October 05, 2021, 07:49:27 PM »
dc stunt, How much(many?) mAh did you put back in during the recharge?
I have to check next time.
L-201

Offline Dane Martin

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Re: Newer Li Ion batteries
« Reply #28 on: October 05, 2021, 07:51:24 PM »
I am getting 6% left with a 6mins flight time

I'll assume that's 6% left as viewed with a li-po charger / checker,  which probably means 25-30% mah actually left

Offline dc stunt

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Re: Newer Li Ion batteries
« Reply #29 on: October 05, 2021, 08:15:21 PM »
I am getting 6% left with a 6mins flight time

I'll assume that's 6% left as viewed with a li-po charger / checker,  which probably means 25-30% mah actually left
Ah ok thanks Dane.  Yes I did use. Lipo checker.
L-201


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