MaxAmps Race Edition Lipos

[bryan]

Originally Posted by Bondonutz

Fine idea but ROAR doesn't give a shizz about C-rateings, safety and playing fair is whats most important. MA packs fit the critera since they just puff not explode.

Small pooff . I was hoping Brandon was going to come to the table with some
astranoumical graphs but i guess maxxamps has decided that it may be in there best intrest to leave this thread alone?Go figure ,I wouldnt buy a friggen double a battery from them.

Mr. Mike do you have any input on this yet?

[Team Pie 420]

I am not convinced that these hold any advantage over the "Others" as far as lipo's go.
Just more Corporate Hype IMO.

[JERRY2KONE]

WOW where did Brandon go to get these graphs and other info to show us how great these new batteries are, China? He must be walking, right? Whats it been a month already since the release of these packs, and promises that they would show us the beef? What a great improvement over their previous reputation. I guess sales must be going so well that he just has not had the time to provide reasonable, honest facts that can show all of us in some way that these new "Race Ready" LiPos really are what they are being advertised. Restored my faith completely, thats for sure.

Hey I have a great idea guys. Lets pull our resources together and go out and purchase some $5 cells somewhere, setup some 4S, 5S, & 6S packs, call them TRUE 500C LiPos with racing flames for wraps, and sell them for lets say 1000% markup, and just tell everyone that the specs will be out soon. After we sell about 1000 packs or so we can just be real quiet and hope that no one will expect us to follow through on any of our advertised Hype, get rich, and then continue making up false claims and advertise even more Hype for some new upcoming products. Sounds like a good company plan to me, what do you guys think?

Sorry I am just trying to think of how to get one of these executive jobs and get rich quick scemes all together in one package/job like we see on TV. Oh wait that's right, that was on that TV's "Most Wanted" show for criminal behavior. I guess it works for some though, right? I wouldn't be able to sleep at night myself. Never mind.

[Arct1k]

I'd posted this up a while back but hadn't mentioned which batteries... These were 6500mah 150C's

And everyone please keep it civil...

[BrianG]

Originally Posted by Arct1k

I'd posted this up a while back but hadn't mentioned which batteries... These were 6500mah 150C's

And everyone please keep it civil...

Chris, it's hard to see the numbers on the graph so could you post several current/voltage points at various points (preferably not at the very beginning or end)?

Ideally, it would be nice to have the voltage/current immediately before a current spike, and then the voltage/current during a spike.

I'd like to calculate pack internal resistance at various current levels. This will give up an inkling of what to expect at various loads. If we see IR increase dramatically at X amps, it means the pack is getting close to its max discharge value so we can then use that as the "true" C rate.

Could you also confirm cell count and wire gauge and length from battery to ESC. Normal 12GA wire can introduce substantial voltage drop at 178A and would be nice to take that into consideration.

[snellemin]

So is that 5000 watts @ 27.6V. So .5 Voltage drop per cell under that that peak amperage. Any chance of you pulling a brick to keep the ampdraw high?

[suicideneil]

What size is that lipo pack that was tested- kinda difficult to tell / determine the voltage drop per cell & generate some actual c ratings without knowing it; 32.3v starting voltage is odd...

Imma pretend that its an 8s lipo pack ( seems if 32.3 / 4.2 = 7.6s, and its several minutes into the run, so... ) for the purposes of this post:

8s lipo = 33.6v

minimum voltage recorded is 27.6v, so thats 3.45v per cell ( minimum voltage, under maximum load )

The highest current ( load ) recorded is 178.1 amps

So, 178.1amps / 6.5amps ( 6500mah lipo ) = 27.4C @ 3.45v per cell

Thats pretty shockingly bad considering these are rated for 75C @ ...3.2v per cell say? ( since MA dont specify the cell voltage held under the 75c load ).

Well, there you go, more false claims by MA, what a suprize.

[BrianG]

Originally Posted by suicideneil

What size is that lipo pack that was tested- kinda difficult to tell / determine the voltage drop per cell & generate some actual c ratings without knowing it; 32.3v starting voltage is odd...

Imma pretend that its an 8s lipo pack ( seems if 32.3 / 4.2 = 7.6s, and its several minutes into the run, so... ) for the purposes of this post:

8s lipo = 33.6v

minimum voltage recorded is 27.6v, so thats 3.45v per cell ( minimum voltage, under maximum load )

The highest current ( load ) recorded is 178.1 amps

So, 178.1amps / 6.5amps ( 6500mah lipo ) = 27.4C @ 3.45v per cell

Thats pretty shockingly bad considering these are rated for 75C @ ...3.2v per cell say? ( since MA dont specify the cell voltage held under the 75c load ).

Well, there you go, more false claims by MA, what a suprize.

Neil, you math looks good, but the max load will probably happen when the cells are freshest and are able to deliver that, while min voltage will happen towards the end of the discharge cycle where the pack is weakest. This is why we need a number of current/voltage samples across the cycle to get a better data sample.

[Arct1k]

If you look at the time series this is about 10 mins into play time hence battery voltage down... However this is where the largest amp spikes were - I zoomed and increased the upload resolution.

In real world terms these packs do seem to work well with the MMM-XL in this application.

[Arct1k]

And the first large spike of the run...

[brushlessboy16]

Ehh dropping to less than nominal voltage

Going by the max wattage (assuming that max amp draw coensides with the lowest voltage)

3958/30.0= ~132amps.

30/8= 3.51v per cell if I have you setup correct


What are these cells rated for?

[Arct1k]

Originally Posted by brushlessboy16

Ehh dropping to less than nominal voltage

Going by the max wattage (assuming that max amp draw coensides with the lowest voltage)

3958/30.0= ~132amps.

30/8= 3.51v per cell if I have you setup correct


What are these cells rated for?

kids today 30/8 = 3.75V @ 135 amps

they are 6500mah packs which probably means 6000mah usable i.e. 135/6000 = 22.5C spike

[brushlessboy16]

Originally Posted by Arct1k

kids today 30/8 = 3.75V @ 135 amps

they are 6500mah packs which probably means 6000mah usable i.e. 135/6000 = 22.5C spike

my mistake I was going by the 28.2v Min voltage. was looking at the wrong graph and did my wattage calculations off that one.

[BrianG]

Those cells don't seem too bad. It's still hard to get exact V/A testpoints, but I calculate pack resistance somewhere between 1.4mOhms-3mOhms.

We can't forget that's pack resistance, and includes the wires and connectors. I don't know why they'd use 12AWG on cells with 150C claims, but 200mm of 12AWG wire will introduce around 1mOhm of resistance by itself.

That brings pack resistance to between 0.4mOhms and 2mOhms. Not bad at all for an 8 cell pack IMO.

Although, I still don't think these are truly "150C" rated. Given the price, I know I still won't be buying them anytime soon.

[suicideneil]

They arent 150C packs though, only 75C / 150C burst...

Still, holding nominal voltage at a mere 22C load isnt exactly great is it, I'd love to see what the voltage dips to with closer to a 40c load- I'd make these solid 30-35C packs at best, meaning they are overrated by about 120% ; nice marketing work but you cant fool us Maxamps!