Lipo vs Lion

[DogDipstick]

I could do this, a datalog of a "HK" "Lipo" ( Pulse, 6s 5000mAh, or Turnigy blue, or Graphene) on a direct comparison of a "EV" "Kia" 4.5Ah lipo. I would have to use a 25oomAh 18650, I only have powertool 18650 here, I could do a pair inparallel for a single graph, of 5Ah.

All at 0.2C... ( dont know where or why you like this low arbitrary number, (Puekert? w lithium? IDK. Standard to quote mebbe?) ) I like to test at 0.5C).

Let me find the log.. or I'll do three controlled new tests on the powerlab.. I'll update this post with three graphs with Ah over TIme.. I can generate a PID controlled SOC map for al three cells and show you that toto.

 

[john61ct]

Please don't go to any trouble on my account

 

[DogDipstick]

Please don't go to any trouble on my account

Ok I wont.

 

[HK12K]

72 volt (18s) lipo pack operates over a 74 - 65v range. (4.1 - 3.6v per cell)
A 72v volt (18s) Lion 18650 pack operates over a 74 - 54v range ( 4.1 - 3.0v per cell)

I'm confused. For 18S I only get around 65-66V nominal, the 72-75V range is only for charging.

For nominal 72V, that's 20S, and gets charged at 81-84V

Right?

Afaik, right.

 

[Hillhater]

thanks, that "mAh per mV drop" metric is very interesting, but the timeline going right to left. .

Right to left (“X” axis). is Voltage,...not timeline !

 

[HK12K]

I could do this, a datalog of a "HK" "Lipo" ( Pulse, 6s 5000mAh, or Turnigy blue, or Graphene) on a direct comparison of a "EV" "Kia" 4.5Ah lipo. I would have to use a 25oomAh 18650, I only have powertool 18650 here, I could do a pair inparallel for a single graph, of 5Ah.

All at 0.2C... ( dont know where or why you like this low arbitrary number, (Puekert? w lithium? IDK. Standard to quote mebbe?) ) I like to test at 0.5C).

Let me find the log.. or I'll do three controlled new tests on the powerlab.. I'll update this post with three graphs with Ah over TIme.. I can generate a PID controlled SOC map for al three cells and show you that toto.

I *think* the .2C rate is how they get the labeled capacity out of them, to see if they're performing as advertised. Something like that anyway, I believe.

I agree though, it seems a fairly useless metric otherwise. Who discharges at .2C? Lol

 

[Hillhater]

I agree though, it seems a fairly useless metric otherwise. Who discharges at .2C? Lol

Yes , 0.2C is a defacto industry standard to allow comparisons
Who uses it in practice ?... possibly a few million laptops, and a few billion cell phones ?
Not everyone rides an Ebike or drives a EV.

 

[HK12K]

I agree though, it seems a fairly useless metric otherwise. Who discharges at .2C? Lol

Yes , 0.2C is a defacto industry standard to allow comparisons
Who uses it in practice ?... possibly a few million laptops, and a few billion cell phones ?
Not everyone rides an Ebike or drives a EV.

In oe applications perhaps, but from a lithium powered hobbyist perspective it's remarkably low. Flashlight geeks pull more than 2c. You're not wrong though.

 

[john61ct]

thanks, that "mAh per mV drop" metric is very interesting, but the timeline going right to left. .

Right to left (“X” axis). is Voltage,...not timeline !

Yes but it is a graph generated by discharging. . .

 

[john61ct]

Yes , 0.2C is a defacto industry standard to allow comparisons

As stated I want that or lower, to reduce the impact of the voltage sag "while loaded" aspect.



Ideally this approach (from DrkAngel)

shows bounce-back to resting.

But I believe I haven't seen it used for RC LiPo's

 

[john61ct]

With that information, the "under load" LVC can be better calibrated to result in a given target **resting** voltage

that suits the owner's preference balancing between minimum capacity sacrifice and maximum longevity

for any given use case / C-rate

 

[Hillhater]

0.2C RC lipo discharge curve...generic “common” graph format.

 

[john61ct]

Thanks

 

[flat tire]

Non-lipo gives you more capacity for a given weight and volume but drops more voltage under heavy C-rate, drops much more voltage as capacity is used which may affect your top speed, and is readily available inexpensively including very reputable brands of cell.

Lipo does better under high C-rates, keeps a higher voltage for the entire discharge, finishing around ~3.6v/cell. It is much more consistent and applicable to high performance applications with small packs. An additional advantage of lipo is it is very easy to configure high capacity packs using simple diy wiring harness vs all the crap required to build your own canned cell pack (the most readily available bang for your buck li-ion). Make sure you get high discharge lipo of reputable brand like Turnigy Graphene.

Anyway the short answer is how much power do you want to draw vs pack size? If it's a lot go lipo. If not then you will get more battery for $ pound and ml (to mix my units) with canned cells, with the caveat that assembly may blow.

For an intermediate choice go Turnigy Multistar. Lipo with the capacity (good) and performance (worse) of a canned cell and including the form factor and pre installed connectors that make it very easy to build a big battery yourself.

 

[DogDipstick]

...reputable brand like ...

..ore battery for $ poun...

For an intermediate choice go Turnigy Multistar. Lipo with the capacity (good) and performance (worse) of a canned cell and including the form factor and pre installed connectors that make it very easy to build a big battery yourself.

Multistars are the worst of the worst , or close to it IMO. Dont buy those if you expect power or longevity. Much better choices ou there.

 

[DogDipstick]

0.2C RC lipo discharge curve...generic “common” graph format.

Lamest graph ever. No references, old, out of standard, unreliable. My store bought lipos from HK act very differently..... Very.

...Want one that is a little more referenced, in standard datasheet, reliable.. Screenshot?

Here is the data for an old cell, the EIG LiCoMnO2 Co2o. Powerfull cell I have been studying for a while, for sale here currently on the forum, by our peers, absolutely a real POLYMER battery. SSC for over 600A. This screen shot only shows the deviation of a group of cells serialized and not a multiple current discharge. This is all at 4C.

Loads of capacity to 3v. A "Hk lipo" curve would be much different. They junk. Voltage would fall at about 3.6v.. not 3.0v.....

 

[DogDipstick]

Here is multiple discharge rates. 4600 W/L... Lol. Poly want a cracker?

 

[Hillhater]

Yes they are “old” generic charts,..but HK lipo is old chem....so they are still relavant.
Maybe you didnt read the OP, ..or johns, question closely enough before posting ?

I was specifically asking for ones that verify the assertion that hobby **LiPo** cells hold insignificant mAh capacity below 3.6V
even at low discharge rates, say 0.2C to 0.1C

 

[Addy]

Multistars are the worst of the worst , or close to it IMO. Dont buy those if you expect power or longevity.

I disagree. My ebike pack is using 4x 6s 10Ah multistars, in a 2S2P arrangement so I end up up with a 12s, 20Ah battery pack.

I've been using this pack for 2 years now commuting to work, with over 4000 km on them. I don't have a BMS of any kind, I've just been checking the balance of the cells occasionally. I don't pull more than 60A from them, so about 3C. They get charged up to about 4.1V/cell

Right at the 2 year mark I used a hobby charger to balance charge my multistars because they had finally started to get out of balance somewhat - the biggest difference was about 100mV between different cells in one pack. I haven't tested their remaining capacity, but they haven't lost much because I see the pack voltage drops down to about the same voltage after each commute to work and back.

I would say that if you draw reasonable currents from them and treat the cells right, they will last a long time.

 

[DogDipstick]

Please don't go to any trouble on my account

That is what I heard, read, understood.

I offered. Top of the page.

Also posted a low c rate lipo graph from a manufacturer that shows the discharge of a lipo at lo c rate. True, not a "hk lipo" but yes, a lipo.

 

[DogDipstick]

Multistars are the worst of the worst , or close to it IMO. Dont buy those if you expect power or longevity.

I disagree.

I don't pull more than 60A from them, so about 3C. They get charged up to about 4.1V/cell

Right at the 2 year mark I used a hobby charger to balance charge my multistars because they had finally started to get out of balance somewhat -

I would say that if you draw reasonable currents from them and treat the cells right, they will last a long time.

Correct, I did say "power" ( >100A). I pull over 2x (3C) on my bike regularrly. 6.6c around. Aiming for more. 10-20C on the current pack size.

yeah. 2 years? Tat is the lifespan when charged to 4.10V?

My cells are 5 years old atm. NO ir or cap change from baseling at my level of use, neglect, ect. Full charged beat all season. Not cooled.

They wont'even hold a good RC heli in the air. That is why they are marketed to "drone". 'Stars.

Sure, baby them and you may get happy. Opinion is what matters, and be happy with yours, if we dont have visible fact.

You are absolutly entitled to your opinion. Can I ask if you have tried anything else, with the capability to pull the power.. ( > 10Kw)? the 'stars would certainly fail in under 50 cycles.

 

[Addy]

yeah. 2 years? Tat is the lifespan when charged to 4.10V?

Who said that? I said that I've been using my multistars for 2 years so far and they're doing great.

Sure, baby them and you may get happy. Opinion is what matters, and be happy with yours, if we dont have visible fact.

You are absolutly entitled to your opinion. Can I ask if you have tried anything else, with the capability to pull the power.. ( > 10Kw)? the 'stars would certainly fail in under 50 cycles.

This pack is in my first ebike build, so I haven't tried anything else yet.

These multistars are listed as 10C max discharge. If you really believe chinese product ratings and run these packs at 10C discharge continuously, you might right into problems with lifespan (or fire!)

 

[Hillhater]

You are absolutly entitled to your opinion. Can I ask if you have tried anything else, with the capability to pull the power.. ( > 10Kw)? the 'stars would certainly fail in under 50 cycles.

Your posts are bordering on a commercial advertisement ?
The number of Ebikers who have any interest in >10kw battery ability, is a very small group, and certainly not the subject of this thread
Multistars are used by many ebkers for multiple reasons, value, consistency , long life, ease of pack build, etc etc .
I have used various other cells for Ebikes , Lipo, Lifepo4, Lico, !8650, etc etc.....each have their pro and cons, but Multistars are the best value, readily available, go to solution for many reasons.

 

[flat tire]

The number of Ebikers who have any interest in >10kw battery ability, is a very small group

Plenty of people here have ebikes with peak power of 10KW, or at least in that neighborhood.

Yes multistar do not do well with high C rate. That is very well known. If you have a more mild application they are quite convenient, being readily available, very easy to assemble, cheap, and with OK energy density.

If you want a small pack to put out a lot of power you want a battery that does high C-rate like turnigy graphene or any other high discharge lipo. Multistars are not high discharge, they are high capacity (for an RC battery).

 

[DogDipstick]

Your posts are bordering on a commercial advertisement ?

Who selling who what again? Lol.

I just hate seeing people overpay and get underpower'd. That is all friend. I build reliable high power lipos and alos have experience with many cells and applications. I am just a hobbiest, keeping the discussion alive, and killing batteries for every cent they are worth fast as I can afford for the rest of my life. Friend.

Just speaking of experience here, and if you buying, I'l find something to sel you if you really want.

I would say an ebike starts getting to be alot of fun round 10K.