POWER4 LiFePO4 cells

[maximus-rc]

Hi all !
Here are the curves made for us by an independant tester on our new MR1100QX. :D
We think they are good enough :rolleyes:
of course, we are looking for distributors worldwide ;)

http://maximusracing.free.fr/fr/files/maximus-rc_lifepo4-1100mah_qx.jpg

Our MR2300QX are not bad too..this time is the good curve...thancks Franck !!!
http://img211.imageshack.us/img211/682/maximusrclifepo42300mahtk1.jpg

bye
Maximus

[Carlyle Harper]

Ok, I'll bite, what is the price per cell of each then?

[leif-mindy]

Your website doesn't have any prices. How much are they?

[maximus-rc]

Ok, I'll bite, what is the price per cell of each then?

Opening price :D
7.99$ for 1100mAh
12.00$ for 2300mAh

Max

[maximus-rc]

Your website doesn't have any prices. How much are they?

You can go directly to our new website (sales not yet openend to end users)
www.maximus-racing.com

We are still testing other cells...


Maximus

[rcjetpilot]

Oh my, I see you have other capacity LIFE cells, like 4500 :)

Subscribed, will see where this thread goes...

Bob

[maximus-rc]

Oh my, I see you have other capacity LIFE cells, like 4500 :)

Subscribed, will see where this thread goes...

Bob

Yeah !
the curves of bigger "blue" cells will be made shortly (thank you Franck ;) )
These red curves of our site are "factory" curves for the moment.... :rolleyes:

Anyway, we have an other model (not yet on website) 22650 - 62g, 1700mAh that gives 25C - 42.5A at 2.6Volts.
Will be very good in 4S under TREX canopy in replacement of 3S-2100 Lipo...

The curves of these models QX sent by our factory are same as those we made...

Maximus

[tai626]

Is the charge rate limited to 2C?

[maximus-rc]

Is the charge rate limited to 2C?

Factory said 5C...without insisting and claiming more than 2C :D

[cmulder]

tried to enter text on that eu webform but no caracter showed up
using 2.0.0.4 firefox btw under xp sp 3 (ish)

can you do a torture test on these cells like done with the a123 ones in the beginning (cycle them 2 3 k times way over spec)
how do you solder them ?

and shipping cost to ireland ;)

[rpage53]

Are these made with Phostech electrodes? The curves look good and so are the prices.

Thanks,
Rick.

[kgfly]

Very interesting! Anyway, we have an other model (not yet on website) 22650 - 62g, 1700mAh that gives 25C - 42.5A at 2.6Volts.
Will be very good in 4S under TREX canopy in replacement of 3S-2100 Lipo...Fit and balance will still be a little challenging with those. Total pack weight will be up around 270g. A 4S brick lying down on the lower tray *might* fit but balance will be hard to achieve even with the ESC moved to the rear. A 4S brick standing up on the lower tray will fit and possibly balance but I suspect will still need some weight on the tail. Estimated flight time around 4.5 minutes.

Looking forward to seeing photos and flight reports maximus-rc ;)

I think perhaps these 1300mAh might be better for a 450-class heli:LIP26430P... This cell can handle 26 Amps continous discharge before break in at 2.6 volts, with over 30 Amps at >2.5 volts during 30 second pulses.
The cell is rated at 3.2 nominal volts and 1100mAh.
The internal impedance is less than 9.0 mohms. This battery is 26.2mm D x 43.2mm H and weights 50.5 grams (with a card board sleeve).Except the text and description differ, are these 1100mAh or 1300mAh ?

A 4S 1300mAh pack would weigh in at about 222g and the shorter size will help with fitting under the canopy. If the pack will hold above 10V at 20A-30A it will be fine for sport flying but not hard 3D. Short flights, maybe around 3.5 minutes.

Anyway it is exciting to see more vendors and more size/capacity options in this area and if these batteries prove to perform well and take abuse like A123 then at these prices they will fly out the door...fingers crossed :)

[maximus-rc]

Are these made with Phostech electrodes? The curves look good and so are the prices.

Thanks,
Rick.

Yeah !
Lithium - Iron - Phosphate

[maximus-rc]

Very interesting! Fit and balance will still be a little challenging with those. Total pack weight will be up around 270g. A 4S brick lying down on the lower tray *might* fit but balance will be hard to achieve even with the ESC moved to the rear. A 4S brick standing up on the lower tray will fit and possibly balance but I suspect will still need some weight on the tail. Estimated flight time around 4.5 minutes.

Looking forward to seeing photos and flight reports maximus-rc ;)

I think perhaps these 1300mAh might be better for a 450-class heli:Except the text and description differ, are these 1100mAh or 1300mAh ?

A 4S 1300mAh pack would weigh in at about 222g and the shorter size will help with fitting under the canopy. If the pack will hold above 10V at 20A-30A it will be fine for sport flying but not hard 3D. Short flights, maybe around 3.5 minutes.

Anyway it is exciting to see more vendors and more size/capacity options in this area and if these batteries prove to perform well and take abuse like A123 then at these prices they will fly out the door...fingers crossed :)

Do you think the 26500 size rated 1700mAh and 65g should fit better in heli ?

@+
Maximus

[maximus-rc]

tried to enter text on that eu webform but no caracter showed up
using 2.0.0.4 firefox btw under xp sp 3 (ish)

can you do a torture test on these cells like done with the a123 ones in the beginning (cycle them 2 3 k times way over spec)
how do you solder them ?

and shipping cost to ireland ;)

Text was white on white :( updated this morning...

The torture test will be made of course !!! We are just at the beginning of this story !!!
The soldeinr is sooo niiice !!!
Franck who made the apcks and tests told me he took ONE minute for making a pack :D

@+
Maximus

[kgfly]

I was able to fit A123 4S 2300 (26650) brick pack (2x2) standing up on the lower tray but I had to drill canopy mount holes about 1cm further back in the canopy. I also had to tape about 50g of coins to the tail fin to fix the CoG. Now that pack weighs about 360g.

Using 4S 1700 26500 would mean the pack would be a little shorter (by 15mm) and hence the canopy may fit with like normal. At 65g each the pack will weigh about 280g, quite a lot less than mine and hence might balance, only testing will tell. One possibility is to shorten the tail servo pushrod to move the servo right out towards the end of the boom, but is more exposed to damage and harder to swap back to a LiPo setup.

Certainly it will be worth trying. I would be happy to test out any or all of the options and report back along with FDR logs of both flying and charging, just send me the cells ;)

[eheli.com.au]

Very Interesting!
Maximus, you have a PM ;)

[maximus-rc]

Very Interesting!
Maximus, you have a PM ;)

Replied ;)

[maximus-rc]

3S pack on testing bank...quite simple !!!
http://img174.imageshack.us/img174/7403/bancglobalfa6.th.jpg (http://img174.imageshack.us/my.php?image=bancglobalfa6.jpg)

Maximus

[maximus-rc]

Certainly it will be worth trying. I would be happy to test out any or all of the options and report back along with FDR logs of both flying and charging, just send me the cells ;)
I make them come from factory....and will send you free.
Just ask you to take part in transport cost ;)
Maximus

[haltered]

Replied ;)


Could you reply to mine sir?

[maximus-rc]

Could you reply to mine sir?
I think I have replied asking you your direct email for sending file...:D

[haltered]

Nope, and I sent my email in the first PM.

[haltered]

Email in, thank you sir!

[maximus-rc]

I will have other surprising cell for testing :rolleyes:
http://www.rcgroups.com/forums/showthread.php?t=875220

[JohnMuchow]

3S pack on testing bank...quite simple !!!
MaximusMaximus, I noticed that the load for the testing appears to be a set of light bulbs. Alone, bulbs don't provide a constant-current (CC) load. The current through the bulbs drops as the pack voltage drops. Am I missing something in the picture that keeps the load current steady until the cutoff voltage is reached?

If not, then the current values used on the graphs you supplied are only the starting currents? What did the current levels drop to by the time the cutoff voltage was reached?

Without using a CC load, it's very hard to compare the results you show on that graph with results from other tests that do use a CC load. Especially since a bulb load is a "lighter" load (no pun intended) and would show longer run time for that pack than a CC load would.

[maximus-rc]

Raaaahhhh I made a terrible mistake of 2300 curves !!!!!!!
Updated

[franck.aguerre]

Am I missing something in the picture that keeps the load current steady until the cutoff voltage is reached?

Hi John,

I'm Franck, the tester of QX battery. The datalogger used for theses tests is the eFlightWatt from MileHighWings ( http://milehighwings.com (http://milehighwings.com/) ), which has a dedicated function for battery testing, that controls the current in close loop. So, of course, the curves are made with constant current all along the discharge :)

Regards,

Franck.

[JohnMuchow]

Hi John,

I'm Franck, the tester of QX battery. The datalogger used for theses tests is the eFlightWatt from MileHighWings ( http://milehighwings.com (http://milehighwings.com/) ), which has a dedicated function for battery testing, that controls the current in close loop. So, of course, the curves are made with constant current all along the discharge :)

Regards,

Franck.Excellent! Thanks Franck.
I tried zooming in on the photo of the test rig to see what logger was being used but didn't recognize the "MHW" logo. I appreciate you taking the time to test these cells. :)

[kgfly]

Franck, will you be testing the rest of the range and if so, how soon until you have some results to show us ?

[franck.aguerre]

Hi kgfly,

Yes, I have to test all the other QX batteries. I think I will have some reliable results about the small capacities next week-end.

Regards,

Franck.

[kgfly]

Great, I look forward to seeing them :)

[franck.aguerre]

Hi All !

I made a comparison between QX and A123 cells :

http://img141.imageshack.us/img141/1905/qxa1231100bj7.png

http://img141.imageshack.us/img141/8673/qxa1232300mn5.png
(as I didn't test myself A123-2300 batteries, I use values form CBA tests published on RcGroups : http://www.rcgroups.com/forums/attachment.php?attachmentid=883612 )

Not so bad for the QX :D

Regards,

Franck.

[maximus-rc]

oops

[eheli.com.au]

I don't think you can really make a comparison on the same graph if you are not physically testing the different cells under the same conditions with the same equipment - better to wait & do it properly IMO than leave yourselves open to any suggestion your are 'cooking' the results!

[kgfly]

Those are very encouraging results, thanks for getting them out so quickly and for being open about the source of the data for the A123 2300 cells.

I agree with eheli that it is necessary to have your own test results for the A123 2300 cells to make a really valid comparison and look forward to seeing that chart soon :)

[Carlyle Harper]

So did Franck, run the 1100QX and the A123 1100 cell on his test equipment or was that graph borrowed too?

Franck, as a diehard A123 user and to avoid confusion later you need delete those graphs from this thread, and when you have tested for yourself both the A123-2300 and 1100 cells, then come back and post your own genuine graphs including the 1100 tests all in one post. If you do this, your results will be lots more credible, and if you then get the same results, all the much better for these new cells and the more convincing your tests will be for me.

If the new cells hold up to the real life torture test, the little extra weight they have over real A123's would be justified in the extra 100mah you seem to be getting.

But you've got a lot, and I mean a lot of catching up to do. Charles should be over the 500 cycle mark by now with his poor old A123 pack, and you know what he does to A123 cells, don't you?

[franck.aguerre]

Hi all,

For the 1100 : I tested both the A123 and the QX, with exactly the same equipment (connectors, wire, datalogger, etc...) and exactly the same conditions (same room temperature, 6 charge-decharge cycles at low amp before test). So theses curves are comparable unambiguously.

As I said, the curves of the A123-2300 didn't come from my tests, so the comparison is as it is. No more.
But I have to clarify something, about my testing conditions : connectors and wires are the same you should use on a plane, the wires are not exaggeratedly short, the connection between cells use a solded wire, etc... In the same time (it's wrote in my testing conditions), I wait anly 15min after a discharge before charging, and 5min after a charge before discharging. So it represent something very close to the real use, and not perfect conditions that optimize the results.
So my curves are pessimistics compared to many others, that's why I allow myself to do the 2300 comparison.

Regards,

Franck.

[Gustave Flaubert]

Good job done but when these promising cells will be available and at what price ? Thank you !!!
.

[rpage53]

Thanks for posting the discharge graphs and I think the 2300 graphs are a good start. Don't mind the criticism -- lithium cells have attracted a large contingent of "police" that find the slightest reason to attack someone.

There are a few Chinese companies with agreements to use Phostech electrodes and they should produce cells virtually equal to A123 at much lower prices. R/C is not a market they have any interest in, especially with oil prices skyrocketing.

A123 themselves are moving to the auto sector (for the GM Volt) but they are reported to be having production problems. And DeWalt is rumoured to have given up on A123.

So bring on the alternates to A123,
Rick.

[maximus-rc]

Good job done but when these promising cells will be available and at what price ? Thank you !!!
.

PM sent

[bergaliv]

Great!!
A new line of lifepo cells.
I've been flying with a123's in my heli for a while now, and i can't see me going back to lipos again. This is what I have been waiting for, more variations in mAh, so I can convert the plank fleet to lifepo as well.
When can I buy some cells to test them out on the planes, and the heli? I can't wait to abuse them to see if they are up to pair with the A123's. I'm spoiled with the 6min flights, 6min charges of those :)
I'm exited, can you tell? :D

[maximus-rc]

Great!!
A new line of lifepo cells.
I've been flying with a123's in my heli for a while now, and i can't see me going back to lipos again. This is what I have been waiting for, more variations in mAh, so I can convert the plank fleet to lifepo as well.
When can I buy some cells to test them out on the planes, and the heli? I can't wait to abuse them to see if they are up to pair with the A123's. I'm spoiled with the 6min flights, 6min charges of those :)
I'm exited, can you tell? :D

Hi !
First batch of 1100 and 2300 is coming from factory.
which size are you interesting in ?
We are still testing the big capacities...

Maximus

[bergaliv]

I'd be interested in 2300's, to compare with my current A123 setup in the helis, and 1300's for some smaller planes.
Just to avoid any missunderstandings, i'm not a dealer, so i'm just interested in bying a couple of setups for testing. I'm quite happy with my A123's, but heck, if someone does it as good, or better for a better price, i'm game :D

I will abuse the cells to the maximum to see if they can take the fast charges of the A123's. That's the reason for using those cells. So, being a happy hobby flyer, i can't afford to buy that many cells before I know how much it'll take to kill them :)

[maximus-rc]

I'd be interested in 2300's, to compare with my current A123 setup in the helis, and 1300's for some smaller planes.
Just to avoid any missunderstandings, i'm not a dealer, so i'm just interested in bying a couple of setups for testing. I'm quite happy with my A123's, but heck, if someone does it as good, or better for a better price, i'm game :D

I will abuse the cells to the maximum to see if they can take the fast charges of the A123's. That's the reason for using those cells. So, being a happy hobby flyer, i can't afford to buy that many cells before I know how much it'll take to kill them :)

Abusing tests are interesting for us too !

[bergaliv]

Great. give me a good price, and I'll do what it takes to kill'em. When I say that, i mean in situations the packs will get to see in "real life". No point in sticking a nail through them :).
What "normal" users want is fast charge(the main reason for going A123), and safety. So, i'd be testing them using a higher charge rate then factory, and keep track of any loss in capacity, and so on.
Like I said, give me a fair price, and I'll post ongoing results as I get them.
Don't get me wrong, i don't mind paying full price, but the postings about results might be a tad further apart then :)

[drfish]

Hi !
First batch of 1100 and 2300 is coming from factory.
which size are you interesting in ?
We are still testing the big capacities...

Maximus

I would have said that the 950mah cells would be interesting, as there is no other small capacity LiFeP04 alternative yet, but with a weight more than the 1100's, I dont see their purpose. If the weights listed are in fact a typo (not likely as there is a photo on a scale as well!) then maby they would be interesting, but they would have to be lighter than the 1100's to even be of possible use.

[maximus-rc]

I would have said that the 950mah cells would be interesting, as there is no other small capacity LiFeP04 alternative yet, but with a weight more than the 1100's, I dont see their purpose. If the weights listed are in fact a typo (not likely as there is a photo on a scale as well!) then maby they would be interesting, but they would have to be lighter than the 1100's to even be of possible use.

Hi drfish !
The photo of the 22430 size really shows the right cells...40.6g each :o
You're right, same weight as 1100mAh for only 950mah....but we not have not tested by ourselves yet, it will certainly be made in the following days.
Anyway, only the short size can be interesting for some planes that need shorter and fatter cells...
We'll test the 26500 - 1700 mAh (QX serie) in about 10/15 days. Factory curves are also very "interesting" and we hope they can be very good alternative for helicopters instead of 3S-2100mAh Lipos...

[rpage53]

These presumably have traditional nickel-steel casings which are heavier than the aluminum of A123 but much easier to solder. The short cells have the same case so are proportionately heavier. They may still test out well on power density even if the energy density is lower.

Rick.

[BEC]

Interesting.....

I'm curious why the 950 mAh cells are heavier than the 1100 mAh cells.

Either way, this is worth watching and eventually trying. So far I've not gotten into LiFePO4 cells, though I do have at least one charger that can charge them.

[maximus-rc]

the tests are in hand...results are coming in one or two days....

[maximus-rc]

http://img372.imageshack.us/img372/2686/qx1100cyclingvj6.jpg

[Tipover]

I'd be interested in doing a comparative test of 10s1p QX 2300 against my A123 packs. I've been flying A123's in my Funtana 90 now going on 3 years.

Motor is Hacker A50 16L with an APC 20 x 10 prop drawing 60 amp peaks at WOT. Should give the batteries a good workout and make for a valid test. Graph below shows a typical flight doing a mix of pattern and 3D flying with the 2300 A123's.

Please pm me if interested.

Thanks

Kevin

[maximus-rc]

I'd be interested in doing a comparative test of 10s1p QX 2300 against my A123 packs. I've been flying A123's in my Funtana 90 now going on 3 years.

Motor is Hacker A50 16L with an APC 20 x 10 prop drawing 60 amp peaks at WOT. Should give the batteries a good workout and make for a valid test. Graph below shows a typical flight doing a mix of pattern and 3D flying with the 2300 A123's.

Please pm me if interested.

Thanks

Kevin

Hi Tipover !
It seems you like torque rolling !!!
I wonder how you could compare the cells with this kind of flight :confused:

Maybe our MR2200TK should fit better your kind of flight...

Little lower capacity than QX serie, but better acceptance of high currents...

Maximus

http://img206.imageshack.us/img206/1680/maximusrclifepo42200mahvh5.jpg

[Tipover]

Hi Tipover !
It seems you like torque rolling !!!
I wonder how you could compare the cells with this kind of flight :confused:

Maybe our MR2200TK should fit better your kind of flight...

Little lower capacity than QX serie, but better acceptance of high currents...

Maximus

http://img206.imageshack.us/img206/1680/maximusrclifepo42200mahvh5.jpg


Maximus,

Yes there is some torque rolling in there, followed by
some WOT pullouts. Torque rolling near the ground
should actually give a very good dynamic reference
point for comparing voltage drop under load between
the two cell types.

But what type of flight would you prefer for testing?

The MR2200TK cells look very interesting. I'm not
seeing these on your website? Do you have them available, and and how are they priced?

Kevin

[maximus-rc]

Maximus,

Yes there is some torque rolling in there, followed by
some WOT pullouts. Torque rolling near the ground
should actually give a very good dynamic reference
point for comparing voltage drop under load between
the two cell types.

But what type of flight would you prefer for testing?

The MR2200TK cells look very interesting. I'm not
seeing these on your website? Do you have them available, and and how are they priced?

Kevin


Same price as MR2300QX....for the moment !!!

[Tipover]

Same price as MR2300QX....for the moment !!!

You have stock on hand? How much would shipping be on 15 cells to 54812?

Kevin

[maximus-rc]

You have stock on hand? How much would shipping be on 15 cells to 54812?

Kevin

Will be in stock in France in about 2/3 weeks, but I can arrange shipment directly from factory, it should be faster.

From France, for more than 1 kg, cost is 27.25usd with Postexport.
I will know tomorrow for direct shipping (TNT).

[Tipover]

Including shipping it looks like the cost is going to be right up there with current A123 prices here. A little steap for me until they are proven the same or better quality as A123's.

Kevin

[maximus-rc]

Including shipping it looks like the cost is going to be right up there with current A123 prices here. A little steap for me until they are proven the same or better quality as A123's.

Kevin

I will PM tomorrow...

[maximus-rc]

I would have said that the 950mah cells would be interesting, as there is no other small capacity LiFeP04 alternative yet, but with a weight more than the 1100's, I dont see their purpose. If the weights listed are in fact a typo (not likely as there is a photo on a scale as well!) then maby they would be interesting, but they would have to be lighter than the 1100's to even be of possible use.

Hi,
The 950mAh we have tested are ....too bad, to be shown :(
Seems like a bad serie.....
We'll test again when we'll get new samples from the factory...

[maximus-rc]

Here are the discharge curves of our 1300mAh, TK serie....
Very "good enough" to be shown :D


http://maximusracing.free.fr/fr/images/p008_1_00.jpg
http://maximusracing.free.fr/fr/files/maximus-rc_lifepo4-1300mah_tk.jpg

Maximus

[maximus-rc]

Samples of 1100, 1700"long" and 1700 "fat" sent today to kgfly for testing...
We'll have our curves for the 1700QX serie within some days...thanks to Franck ;)
Maximus
http://img392.imageshack.us/img392/1517/mr1100qxrv4.jpg
http://img509.imageshack.us/img509/2130/mr1700qxlkz8.jpg

http://img509.imageshack.us/img509/6465/mr1700qxfsm9.jpg

[maximus-rc]

Hi all !
good news again for the testing of the 1700QX serie that shows very good results.
The F (fat) cell has discharge curve just little less good that "L" Long one...
See below pics and curves.
http://img210.imageshack.us/img210/1597/maximusrclifepo41700mahgo0.jpg
these 2 cells has been sent to Kenneth-kgfly for testing last week...

http://img183.imageshack.us/img183/5701/mr1700qxlrt4.jpg
http://img210.imageshack.us/img210/9724/mr1700qxfgi4.jpg

[kgfly]

I am excited about the opportunity to test these cells, the curves look promising, thank you Maximus-rc.

I have reconfigured my Trex450 with a new ESC to support the testing. I have an A123 4S 1100 shotgun pack to use as a baseline reference. Due to some persistant bad weather, I have not been able to get any baseline data yet but hope to soon.

[write2dgray]

Those are nice looking curves - very flat and good voltage retention. What kind of temps are reached on the higher C discharges? I'll be interested to see some third party testing. Also, what are the high current charging properties like for these guys?

- David

[Mr.Pibb]

Any test results yet?

[maximus-rc]

Any test results yet?

I hope kgly will publish his results...

He told me that:
Well I have 10 cycles on the 4S 1700 pack (with a new Deans plug!) and
things are going well. Performance on the Trex450 is comparable to my
slightly worn KP 3S 2200. Which means fine for general sport/aerobatic
flying but not up to 3D. The cells are coming down from flight just
comfortably warm (ambient around 15-18C). Flight duration is quite
acceptable, 6min sport flying at 2800rpm headspeed. Similar duration
to the KP 3S lipo pack which I also fly for only 6min but could
probably get 7min without over-stressing the pack.

But he should have more flights now...
Maximus

ps: I have persuaded my factory to produce some 1700mah - 22650 - "Maxion type" - Voltage 3.7V...(cf my MAXION 1100 (http://maximusracing.free.fr/fr/files/maximus-rc_limn-imr1100.png) °
The first samples has been produced some days ago and tested in factory...seem to be good :D
I am waiting them for making our own discharge curves ;)

[kgfly]

Sorry folks, other aspects of life have rudely interrupted my RC hobby time and I have been unable to spend time with the testing or writing up the results. Haven't flown for over a month :( On top of that my EagleTree data logger is acting up affecting the results and I have to replace some worn parts on my heli to eliminate a vibration problem.

I hope the craziness will tame somewhat soon so that I can return to it and get all the issues sorted out and the testing back on track.

My apologies especially to maximus-rc who kindly provided the cells for testing and for whom my lack of progress is no doubt frustrating.

[write2dgray]

Sorry to hear you haven't been getting any flying in Kenneth. Hopefully there is light at the end of the tunnel ahead.

FYI : Eagle Tree voltage data is erroneous below 5V. Ask me how I discovered this! I suspect you may be experiencing calibration issues below 5V, this is simply a limitation of the ETV3 that is recognized in the product specs.

- Dvid

[kgfly]

Thank you David. No, it's the RPM sensor that's not working properly. I am not running the cells down below 2V (4s = 8V) so staying within the ET voltage range, but thanks for the heads-up.

[write2dgray]

Well, look what arrived from France on Friday! -

http://i85.photobucket.com/albums/k48/write2dgray/Maximus.jpg

This was a nice little surprise especially the cells shown in the attached pic. I am curious to see how test results compare to the exceptional results published here by the manufacturer.

Maximus, could I get some specs. for the Maxion cells shown in the attached pic (max. charge voltage, min. discharge voltage, max. cont. C rate, etc.)?

I'll post results to this thread as they become available.

Cheers,
David

[maximus-rc]

Well, look what arrived from France on Friday! -

http://i85.photobucket.com/albums/k48/write2dgray/Maximus.jpg

This was a nice little surprise especially the cells shown in the attached pic. I am curious to see how test results compare to the exceptional results published here by the manufacturer.

Maximus, could I get some specs. for the Maxion cells shown in the attached pic (max. charge voltage, min. discharge voltage, max. cont. C rate, etc.)?

I'll post results to this thread as they become available.

Cheers,
David

Hi David,
Here are our discharge curves of Maxion serie.
the 1100mAh was charged up to 3C.

http://www.maximus-racing.com/fr/files/maximus-rc_limn-imr1100.png

http://www.maximus-racing.com/fr/files/maximus-rc_limn-icr1300.png

Cheers Maximus

[kgfly]

Comparing your data for the LiMN 1100 cells to the LiFePO4 (QX) 1100 cells the LiMN offer significantly higher voltage with only slightly greater voltage depression from 5C to 25C. The weight and size is practically the same so if the cost is comparable then the LiMN 1100 cells have quite an advantage. By my estimate from the graphs they deliver about 25% more power and 15% more energy at 20C. If they can tolerate at least 3C charging and 20/25C discharging for a decent number of cycles then they will be a very attractive alternative in this format.

[maximus-rc]

Hi all,
I will receive Maxion 1700mAh format size this week for testing...
We'll make curves and post them here....thanks Franck ;)

Maximus

[write2dgray]

By my estimate from the graphs they deliver about 25% more power and 15% more energy at 20C. If they can tolerate at least 3C charging and 20/25C discharging for a decent number of cycles then they will be a very attractive alternative in this format.Agreed Kenneth, the increase in power due to a higher nominal voltage certainly makes the LiMn appealing if they can demonstrate some of the qualities of a good LiFePo4.

There are some interesting things to note on the graph, including the incredibly low claimed IR of 11 milliohms (for an 1100 mAh cell!) and the presence of a 30C bar in the legend, but not as a series on the graph. This makes me curious how these graphs are made. Maximus, can you reveal the software used to generate these graphs (i.e. Excel, LogView, Numbers, GMT "Generic Mapping Tools," MS Paint)?

It would also be very hepful to clarify the specs on the LiFePO4 and Li-Ion cells prior to extensive testing. The max. charge voltage is the most critical. Right now I am taking the max. charge voltage of your LiFePO4 cells as 3.65V, although this information is not published anywhere. Can you confirm this charge cutoff voltage for the LiFePO4?

The nominal voltage of the Li-Ion is printed on the cells as 3.6V, which is typical for many Li-Ion cells, while the graphs describe a nominal voltage of 3.7V. What is the correct nominal voltage for these cells and what is the reccommended max. charge voltage, 4.10V or 4.20V? The minimum advised discharge voltage would also be helpful.

- David

[maximus-rc]

Agreed Kenneth, the increase in power due to a higher nominal voltage certainly makes the LiMn appealing if they can demonstrate some of the qualities of a good LiFePo4.

There are some interesting things to note on the graph, including the incredibly low claimed IR of 11 milliohms (for an 1100 mAh cell!) and the presence of a 30C bar in the legend, but not as a series on the graph. This makes me curious how these graphs are made. Maximus, can you reveal the software used to generate these graphs (i.e. Excel, LogView, Numbers, GMT "Generic Mapping Tools," MS Paint)?

It would also be very hepful to clarify the specs on the LiFePO4 and Li-Ion cells prior to extensive testing. The max. charge voltage is the most critical. Right now I am taking the max. charge voltage of your LiFePO4 cells as 3.65V, although this information is not published anywhere. Can you confirm this charge cutoff voltage for the LiFePO4?

The nominal voltage of the Li-Ion is printed on the cells as 3.6V, which is typical for many Li-Ion cells, while the graphs describe a nominal voltage of 3.7V. What is the correct nominal voltage for these cells and what is the reccommended max. charge voltage, 4.10V or 4.20V? The minimum advised discharge voltage would also be helpful.

- David

Hi,
I will ask my tester Franck to show you how the curves are made... Of course NOT made with Ms Paint :mad:

The LiFePO4 cells must be charged at 3.60V +/-0.05 (Max discharge 2.0V)

The Mx serie (LiMn and LiMnCo) at 4.2V +/-0.05 (Max discharge 2.5V)
The MX1100QX was not tested at 33A... :cool:
and the 1300, neither 20, nor 25, nor 30C ;)

Bye Maximus
ps: be cool during charging the 4500mAh 2C max....after cycling

[maximus-rc]

:eek:

[write2dgray]

Hi,
I will ask my tester Franck to show you how the curves are made... Of course NOT made with Ms Paint :mad:

The LiFePO4 cells must be charged at 3.60V +/-0.05 (Max discharge 2.0V)

The Mx serie (LiMn and LiMnCo) at 4.2V +/-0.05 (Max discharge 2.5V)
The MX1100QX was not tested at 33A... :cool:
and the 1300, neither 20, nor 25, nor 30C ;)

Bye Maximus
ps: be cool during charging the 4500mAh 2C max....after cycling
Cool, Maximus - that helps a lot. Sorry about the MS Paint jab, it was meant to be comical and not offensive :) . It was also that I struggle to understand how to make things visible in a legend and not on the graph using conventional software.

I have performed two 1C cycles so far terminating both at C/20 and 3.65V. All future testing will reduce the charge cut-off voltage for the LiFePO4 cells to 3.60V.

It's nice to see that the recommended charge cut-off is 4.20V (like std. LiPos) on the Maxion cells and not 4.10V like most Li-Ions. This will provide slightly more power while allowing more people to charge them using their current charger designed for LiPos.

- David

[maximus-rc]

It's nice to see that the recommended charge cut-off is 4.20V (like std. LiPos) on the Maxion cells and not 4.10V like most Li-Ions. This will provide slightly more power while allowing more people to charge them using their current charger designed for LiPos.
- David

Yeah ! You can use your standard Lipo charger with the Maxions !!!

@+
Maximus

[franck.aguerre]

Hi all !

Paint, what a very strange idea :confused: My curves are made with MS-Excel, with datas imported from eFlightWatt datalogger. Excel allows me have much more accurate graphics than what I can have with EFW alone, as I use an integrator filter as shown in the example bellow :
http://www.zimagez.com/miniature/posttraitementefw.png (http://www.zimagez.com/zimage/posttraitementefw.php)

Best regards,

Franck

[rpage53]

I have performed two 1C cycles so far terminating both at C/20 and 3.65V. All future testing will reduce the charge cut-off voltage for the LiFePO4 cells to 3.60V.
The LiFePO4 cells can handle 3.65V and you will get more power and capacity than at 3.60V if you test them right away. Might be worth comparing both. If over-charged they will self-discharge in a day or so like Ni cells. The point is that the charge method will affect the results but less so than other Li.

The LiMn cells, on the other hand ,are safer to over-charge than the standard cobalt cells but will retain their voltage, so as you increase the cutoff voltage you also increase the power in a fairly linear manner.

Rick
PS These batteries and all LiPo are "lithium ion".

[maximus-rc]

Here is the Maxion 17000 discharge curve...for quite flights :rolleyes:
http://img363.imageshack.us/img363/1364/maxion1700curveseh6.jpg

Maximus