Li-on vs Li-po?

[Paul Taylor]

Does capacity change when going from Li-po to Li-on?

If I'm currently using a 5 cell 2800 Li-po 25c, would I use the same in a li-on pack?

[Howard Rush]

Five Molicel P-30Bs should do the trick. I switched from 6-cell LiPo 2800 mA-hr batteries to 6-cell P-30Bs with no problem. I do have some space between cells for cooling.

[Brent Williams]

If you are currently using a 5s2800 Li-po and are considering Li-ion, plan for a move up to a 6 cell setup.  The weight of the 6s li-ion pack is about the same as a 5s Li-po, and you get the benefits of the increase in system voltage and much lower amp draw. 

As Howard mentioned, the P30b is a great cell and prices are coming down, thankfully.  You will get good results from the P28a and P28b, but the P30b is the best current 18650 cell offering.
I'm still running the older p26a cells, but my Hubin FM9 system and BA wood 2-blade prop doesn't demands as much as the active Igor/Fiorotti systems and 3 blade props.

[Ken Culbertson]

Does capacity change when going from Li-po to Li-on?

If I'm currently using a 5 cell 2800 Li-po 25c, would I use the same in a li-on pack?

They are pretty close to the same.  Two differences I have noticed, and they are somewhat related.  First the Li-Ion will allow you to practically run it down to zero capacity and not damage the battery.  On Lipo I tried to keep my reserve around 20% depending on the wind.  On Li-Ion I go down to about 3% with no problems.  The other is that Li-Ion are not as even over the run as Lipo.  They will start to "sag" some (about .1 Lap time) towards the end.  The timer will keep that under control but I have found that the boost is not as fast starting after the hourglass.  You can also set your low voltage cutoff to 2.8 vs 3.0, in fact you should.  AND...the weigh less.

Ken

[Ken Culbertson]

Five Molicel P-30Bs should do the trick. I switched from 6-cell LiPo 2800 mA-hr batteries to 6-cell P-30Bs with no problem. I do have some space between cells for cooling.

Let me guess, you have printed separators.....  Does it help?  I am finally recognizing that everything I knew about IC is just taking up space in an aver shrinking memory bank.  Battery cooling is a real art form and a lot of our planes really don't do it very well, especially conversions.    Anybody that can feel 1 gram of tip weight in wind has to have a better battery box.  Pictures?  or not.

Ken

[Dan McEntee]

  I last worked part time at the local hobby shop in 2015. Leading up to that, we carried all sorts of batteries for all sorts of uses. We had a display for a long time that was just for Li-on batteries, that were flat packs, mush like the typical Li-po's are. I don't think we ever sold a one of those in any size. I tried to find out information about them so I could try to sound intelligent about them if someone asked,  but really couldn't nail down the "why" we even stocked them. I think they were eventually sent back for credit and they haven't had anything like that since. Then fast forward to recent times and many stunt grunts are using Li-on batteries. So, what goes around comes around again someday?
   Who's got a quick, short history on who started using these first and when? My memory of them is being mention by Paul Walker a few years ago, but is that where the use started ? Is any other part of the hobby using them for flight packs? The R/C pattern guys maybe?? I'm just curious to know.
  Type at you later,
  Dan McEntee

[Paul Taylor]

Dan
I think the FPV quad guys use them. Propbuster (aka - Ryan) flys FPV quads and he uses a few along with Li-Po's
I think they want them for long range.

[Brent Williams]

    Who's got a quick, short history on who started using these first and when? My memory of them is being mention by Paul Walker a few years ago, but is that where the use started ? Is any other part of the hobby using them for flight packs? The R/C pattern guys maybe?? I'm just curious to know.
  Type at you later,
  Dan McEntee

Dane Martin got the ball rolling on Li-ion's for serious stunt in 2020-early 2021.  Paul was one of, if not the first big-gun to go all in.  https://stunthanger.com/smf/gettin-all-amp'ed-up!/newer-li-ion-batteries/msg612392/#msg612392

Long range FPV planes and non-racing drones use them.  It sometimes simply comes down to the amp draw that one needs to satisfy the task at hand.  Li-ion has some limitations in that regard, but the technology is getting better all the time. 

[Brett Buck]

    Anybody that can feel 1 gram of tip weight in wind has to have a better battery box.

       The way that went was Ted and I were wandering by the circle during a Howard practice flight, and I guessed that he needed about 2 grams, just casually eyeballing it. He added 3, then it started hinging the other way.

    I had nothing to do with it, so I will let those involved show what they want to. It is not a trivial difference - I think Dennis and Jim saved something like 2 ounces and the gaps kept the cells much cooler.

     Brett

[Dennis Nunes]

It is not a trivial difference - I think Dennis and Jim saved something like 2 ounces and the gaps kept the cells much cooler.

     Brett

As usual, Brett is correct. I was using Thunder Power ProLiteX 6-cell 2800 mAh batteries in my Circulas 61e. I have some of the older TP 6-cell battery that weigh 12.30 oz. Thunder Power's current 6-cell batteries weigh 13.00 oz. This is .7 oz heavier and .125" taller than the older packs. Some modelers, with tight clearances for their batteries, found out the hard way when they received the new TP batteries and would fit in their models.

My latest Li-Ion 6-cell battery packs that I've made weigh 10.70 oz. These packs use the Molicel INR-18650-P30B 3000 mAh cells. These packs are 2.30 oz. lighter and have more capacity than the TP packs, which is substantial. These packs, so far, have worked extreme well.

One clarification, Jim (Uncle Jimby) and Howard Rush have made 5-cell and 6-cell Li-Ion packs with end caps (no shrink wrap around the pack) that create space between each cell for cooling. I'm still making the "traditional" triangle shape 6-cell packs with shrink wrap (no spacing).


Dennis

ps: I have 8 Used Thunder Power ProLiteX 6-cell 2800 mAh batteries with XT-60 connectors in good condition for sale. See https://stunthanger.com/smf/classifieds-92/8-used-thunder-power-prolitex-6-cell-2800-mah-batteries/ for further information.

[Howard Rush]

Let me guess, you have printed separators.....  Does it help?  I am finally recognizing that everything I knew about IC is just taking up space in an aver shrinking memory bank.  Battery cooling is a real art form and a lot of our planes really don't do it very well, especially conversions.    Anybody that can feel 1 gram of tip weight in wind has to have a better battery box.  Pictures?  or not.

Some pictures are at https://stunthanger.com/smf/plotters-and-cut-files/what-have-you-printed-lately/ . 

My P30Bs end a flight at just over 3.5 volts/cell.  As I recall, they get to about 120 degrees F.  At lower voltages internal resistance, hence heating, goes way up. 

I didn't like the way people were making Li-ion batteries. They wouldn't fit in my airplanes, they were of inconsistent shape, they were covered in heat-shrink blankets, they had balance cables of no use in flight, and they had unnecessarily heavy and long wires.  Printing the end caps (Brent's idea, I think) allowed space for cooling (not as necessary as I feared), allowed the balance connector to be mounted on the battery, allowed mounting provisions to be printed in, and made the overall battery shape consistent.  Consistent shape made mounting them easier.  I am still figuring out better ways of holding them down, and the closer tolerance of printed parts really helps. 

[Dennis Toth]

Is there a commercial vendor selling the Li-on packs?

Best,   DennisT

[Ken Culbertson]

I am still figuring out better ways of holding them down, and the closer tolerance of printed parts really helps. 

You are feeding my overwhelming desire to make absolutely everything adjustable.  Endgame 5 is on the drawing board.   Is there any reason the power wires to the esc could not just plug into an XT60 that is part of the pack like your balancing plug which is way cool!  With the fuselage nose designed right you could have a drop in power pod like a lawnmower.  You make a valid point.  We design batteries to fit our planes.  Wrong! I am going to design to fit the battery this time.  Going to be fun!

Ken

PS - are there dimensions for those caps?  I need to design the mounts for the leads and the battery.

[Brett Buck]

My latest Li-Ion 6-cell battery packs that I've made weigh 10.70 oz. These packs use the Molicel INR-18650-P30B 3000 mAh cells. These packs are 2.30 oz. lighter and have more capacity than the TP packs, which is substantial. These packs, so far, have worked extreme well.

    And, whatever the effect (weight or, more likely CG), it flies much better now!

     Brett

[Howard Rush]

Is there any reason the power wires to the esc could not just plug into an XT60 that is part of the pack like your balancing plug which is way cool!

Good idea. If you don’t have a separate arming plug and the battery is enclosed by a hatch, though, you would need to open the hatch to disarm the system. You could mount the arming connector on the battery and have a window on the side of the plane for the plug.

Another consideration is the ability to change an LRU in time for your next flight if you take an attempt.   I think this is Paul Walker’s requirement.  This causes extra connectors. Putting more stuff in the battery assembly might be a better way to meet this requirement.

PS - are there dimensions for those caps?  I need to design the mounts for the leads and the battery.

Do you have CAD?  If not, remind me of your postal address.

[bill bischoff]

Howard, which costs more if you leave it at the field? 

[Ken Culbertson]

Howard, which costs more if you leave it at the field? 

A full can of fuel!

Ken

[Howard Rush]

Howard, which costs more if you leave it at the field? 

You’re mean.

[bill bischoff]

Not meant to be mean, Howard, just "jiving" with you. 

[dave siegler]

Does capacity change when going from Li-po to Li-on?

If I'm currently using a 5 cell 2800 Li-po 25c, would I use the same in a li-on pack?

The big thing is the 25c.  You have to look at the discharge rate

Li-ion typically Lithium nickel manganese cobalt oxides (NMC) has a slight lower discharge rate for the same size, and can  e a little heavier.
Li-po has the highest discharge performance, then Li-ion, then LI-Fe.  But to compare exactly the same batteries with different chemistries is not easy. 

But while in theory LI-Po are higher performance fort the weight and discharge rate, the NMC cells are catching up.  NMC cylindrical cells have several fail safe features that i think make them worth the slight dip in performance.  NMC is the choice for high discharge applications like power tools.

We routinely put 200+ cells in a single battery assembly and I would never to do that with a lipo. 

[Paul Taylor]

Ok I printed some 18650's to see if the footprint would fit in a SV.
I'm using a TP 5s 2800 and was hoping to maybe to try a 5s Li-ion.
From what I'm reading going to a 6s is the way to go but did not want the extra weight. Am I going out in left field again?

[Ken Culbertson]

Paul:

My 6s 2800 Li-Ion batteries weigh about the same as my TP 5s 2800 Lipos.  The TP Estimated weight says 290grams, mine all weigh between 295 and 302.  My Li-Ions are around 304.  Could be the connectors.  I have yet to have moving from 5s to 6s do anything but save battery and improve performance.  "Just me - and I could be wrong" - Ken

[Brent Williams]

Ok I printed some 18650's to see if the footprint would fit in a SV.
I'm using a TP 5s 2800 and was hoping to maybe to try a 5s Li-ion.
From what I'm reading going to a 6s is the way to go but did not want the extra weight. Am I going out in left field again?

The allure of a 5s li-ion pack that weighs under 9.5oz is undeniable, but it comes with a few requirements pertaining to ESC cutoff voltage settings and cooling.  I think Jim Aron is the only guy that has really tested them in a full boogie, high level stunt application.  He has run them in his amazing 61oz Systrema-3 with a Badass 2826-820kv motor, using the latest Igor active timer system and Igor 3-blade 12x5 flat-back prop.  His packs are built with the P30b cell which is more capable than the p28a/b.  His printed end cap setup allows for excellent airflow around the cells.  With the voltage sag that is part of the nature of Li-ion operation, you must adjust your ESC cutoff point to well below 2.8v in this application to avoid an unplanned shut-down.  Some ESC's allow for customized settings or a no cutoff setting.  Jeti SPIN ESC's can be set to 2.0v on the cutoff.  Jim mentioned that the combo works well and doesn't overheat, but it nearly cost him the plane in testing.  Likely due to the voltage cutoff setting, Jim experienced an unplanned shutdown at one of the worst times during a pattern.  With sheer luck, talent and nerve, he saved the plane.  Learn from Jim's experience and mind your ESC settings if you go down this 5s route.

[Igor Burger]

it nearly cost him the plane in testing.  Likely due to the voltage cutoff setting

It is necessary to set cut off to "slow down", it gives enough time to react when it slows down.

[Paul Taylor]

The allure of a 5s li-ion pack that weighs under 9.5oz is undeniable, but it comes with a few requirements pertaining to ESC cutoff voltage settings and cooling.  I think Jim Aron is the only guy that has really tested them in a full boogie, high level stunt application.  He has run them in his amazing 61oz Systrema-3 with a Badass 2826-820kv motor, using the latest Igor active timer system and Igor 3-blade 12x5 flat-back prop.  His packs are built with the P30b cell which is more capable than the p28a/b.  His printed end cap setup allows for excellent airflow around the cells.  With the voltage sag that is part of the nature of Li-ion operation, you must adjust your ESC cutoff point to well below 2.8v in this application to avoid an unplanned shut-down.  Some ESC's allow for customized settings or a no cutoff setting.  Jeti SPIN ESC's can be set to 2.0v on the cutoff.  Jim mentioned that the combo works well and doesn't overheat, but it nearly cost him the plane in testing.  Likely due to the voltage cutoff setting, Jim experienced an unplanned shutdown at one of the worst times during a pattern.  With sheer luck, talent and nerve, he saved the plane.  Learn from Jim's experience and mind your ESC settings if you go down this 5s route.

Good to know.
Thanks

[Ken Culbertson]

In all the reading I have done it has been recommended that the low voltage cutoff for a Li-Ion battery should be around 2.8 and as Igor suggested a soft cutoff.  I found that out the hard way but saved the plane.  After setting it to 2.8 I still encountered the sag but could fly through it.  A few boost changes and the Fiorotti timer I was using gave me relatively equal power to the end.  Typically I landed with 3.1 to 3.2 volts per cell far from the 3.4 target.  A cleanup of the airflow greatly improved both the sag and the reserve.  To me this was a lesson that heat is as big an enemy to a li-ion battery as was the wrong prop.  I am working on both but what I have not been able to eliminate is the "sag". It is now flyable on my twin but I still do not have the same power on the last vertical leg of the clover as I did on the first vertical of the OH8.  Even if the battery was sagging, which it was, the timer should raise the boost.   On my most recent full pattern flight on my twin using a 5s 4200 battery I landed with 3.4v per cell yet I still had a 5.4 starting lap time vs a 5.6 lap time at the end with noticeable sag starting with the overhead 8.  Recharge added back 3004ma. What am I missing?  I have also noticed, perhaps incorrectly, that Li-Ion batteries have a faster recovery than Lipo.  Even after one lap of level flight I can feel it.  This is a long-winded way of asking it the ESC actually delivers what the timer requests if the battery is tired.  Is this also perhaps a case where a higher voltage is part of the answer?

Ken