MaxAmps Race Edition Lipos - Page 3 - RC-Monster Forums

slimthelineman · 10.15.2010, 03:16 PM

not at all. like i said its a step in the right direction for MA and the fact that they are producing info is even better. hopefully other companies will follow suit. sorry for seeming so skeptical it in my nature....

thzero · 10.16.2010, 10:05 AM

Yes, would be nice to see every reputable battery manufacturer step up and document the individual cells in the pack, supply graphs for the pack as a whole, etc. and work together to come up with a standard testing package.

PBO · 10.15.2010, 03:19 PM

Whichever way you consider the 150C claim it's a quantum leap from known high performing cells...and let's be honest who wouldn't want cells that capable

I'd love to see rootar make ihobby with the Hyperion cells. I have the same 6500 & if they can trump those babies I'm sold

josh9mille · 10.15.2010, 03:28 PM

I just think its too soon for 150c lipos to be out, if they came out like 2 or 3 years from now it might be easier to believe. I mean what was the highest true c rating before these....like 60c or something? Seems like a pretty big jump!

10.15.2010, 03:51 PM

Brandon,
I have to admire that you would come here and try to push the MA packs, you do like a challenge. Personally I have a hard time believing that MA has a battery at more than triple the out put as Neu Energy's strongest battery which is 46/92 (constant/pulse). Also to be honest based on how MA has done things in the past, I would like to see an independent 3rd party do the test and compare to other high end brands. I look forward to seeing the tests.

sikeston34m · 04:55 PM

The 150C rating is ludicrous considering current technology.

Let's just run some numbers. Simple Math.

We have a 150C 6500 mah Lithium Polymer cell.

At a 975 amp discharge rate, each cell is capable of 4095 watts of power.

If we discharge our fully charged cell at the 150C discharge rate, it will be fully drained in 24 seconds. (If anyone is interested in the formula for calculating any of this, I'll post them up.)

I am a Refrigeration/Maintenance Engineer for a Distribution Center here in Missouri.

It's very common for me to deal with Techs and Sales Reps from industrial battery companies such as IBP and Deka.

Batteries have always fascinated me, so I ask alot of questions and stick my head in the books.

Here is a comparison for you. The battery in question is a 36 volt 1000ah lead acid Industrial Truck battery weighing in at 2850 pounds.

Each main power lead is about as big around as a fat cigar. Cross sectional area comparable to a Nickle.

It takes a well co-ordinated forklift driver about 6 hours to drain one of these batteries. Obviously alot of energy.

The question that I posed to IBP and Deka Techs:

What is the maximum discharge rate limit before damage occurs?

Answer: Right around 750 amps. It is at this point, it blows the jumper bars off the cells.

Jumper Bars are the intercell connections. Each unit is made up of 18 - 2 volt cells connected in series. Total of 36 volts.

They use pairs of jumper bars to jump from one cells positive posts to the next neighboring set of negative posts.

EACH jumper bar is around 2" wide and 1/2" thick and about 6" long. They are made of lead.

I've witnessed several accidents where the main power leads were crush/pinched to the point where a dead short condition occured.

Never have I seen the jumper bars blow off, but a battery this size can discharge enough amps to snap 1/0 leads in a shower of sparks. I have seen this happen. It's quite scarey.

Now, back to the 150C rating. We are going to discharge a 6500mah Lipo Pack at 975 amps continuous?

How are we going to test that since the entire discharge process will only last 24 seconds?

These numbers are off the scale and highly impossible IMO.

thzero · 10.16.2010, 10:08 AM

Go for it. Better to be more transparent than the next guy. Formulas, unless wrong, are hard to argue with. Numbers and claims can always be manipulated.

Quote:

Originally Posted by sikeston34m

If anyone is interested in the formula for calculating any of this, I'll post them up.

sikeston34m · 10:52 PM

Quote:

Originally Posted by thzero

Go for it. Better to be more transparent than the next guy. Formulas, unless wrong, are hard to argue with. Numbers and claims can always be manipulated.

Each cell is 4.2 volts and if we discharge at 975 amps, we get 4095 watts.

4.2v X 975amps = 4095 watts (Note: this would make a 4S pack, capable of 16,380 watts of power.

1 electric horsepower = 746 watts of power

This would make a single 4S pack capable of producing 21.96 horsepower!

22 electric horsepower would not only start your car, but it would be enough to push a small car fairly well.

The Industrial Lift Trucks I mentioned earlier have a 6.6kw drive motor. That's less than 9 horsepower and the truck weighs almost 10,000lbs. Top Speed of 9.5 mph, but still ALOT of weight.

All Batteries have an amp hour rating or on the smaller types of batteries we use, a mah rating.

Mah rating is amp hours divided by 1000. Since Mili means 1000.

A 6500 mah pack can also be called 6.5 amp hours.

The "hour" term is added to show how much amp draw it can sustain in 1 hour. A 6.5 amp hour pack can hold a 6.5 amp discharge for 1 hour.

As long as we know this, we can play with the numbers and calculate how long the pack can sustain any rate of amperage discharge.

The same pack can sustain a 1 amp discharge for 6.5 hours.... and so on.

Now, how do we calculate how long it can sustain a 975 amp discharge?

6.5 amp hour pack / 975 amp discharge X 60 (discharging minutes) X 60 (discharging seconds) = How long the charge will last at that level of discharge.

6.5 / 975=.006666666666666666666666667 X 60 = 0.4 X 60 = 24 seconds

You can play with this formula any way you like, for any size pack, for any amp draw rate.

So, in conclusion. If the 6500mah of charge ONLY lasts for 24 seconds. This should change the warranty to pretty much an unconditional warranty as far as the discharge rate is concerned.

No more should anyone hear "Well your gearing was wrong and it was too much load on the pack".

Because evidently, if you don't discharge the ENTIRE charge in less than 24 seconds, you are safe within the confines of the discharge rating.

I'm very sure this kind of amperage is enough to smoke and cook every FET from the power board of ANY ESC if the esc fails and the powerboard goes into runaway meltdown.

gixxer · 01:05 AM

Quote:

Originally Posted by sikeston34m

So, in conclusion. If the 6500mah of charge ONLY lasts for 24 seconds. This should change the warranty to pretty much an unconditional warranty as far as the discharge rate is concerned.

No more should anyone hear "Well your gearing was wrong and it was too much load on the pack".

Because evidently, if you don't discharge the ENTIRE charge in less than 24 seconds, you are safe within the confines of the discharge rating.

That is the exact point I was making on the car action site. Cant see anymore complaints about gearing.

molak · 05:06 PM

Thirth party or nothing .. is well known that we cant trust MA ...

Just to give an example. A while back i bought 2 factory remanucatured packs from MA ebay user. I got a puffed pack and an unbalanced one...

975 amps over a 12awg... lol.

An awg 12 wire will explote into sparks with such a discharge...

sikeston34m · 10.15.2010, 05:47 PM

Quote:

Originally Posted by molak

975 amps over a 12awg... lol.

An awg 12 wire will explote into sparks with such a discharge...

That's kinda like saying:

"I'm gonna pull your truck outta the ditch with this piece of fishing line."

What's_nitro? · 10.15.2010, 07:37 PM

I just figured I would add this as the OP...

I did not start this thread with the intent of taking shots at MA's new product. That being said, I still think the rating of 150C is quite ridiculous for ANY battery pack that small, not just this one from MA.

If we are talking about a <5ms spike rating then yes, the cells probably can do that. Any longer and the tabs would most likely melt off.

A [universal] method of rating the continuous AND peak discharge of a battery is the way to go. Rating a cell/pack for just one or the other does not provide enough information.

mistercrash · 10.15.2010, 10:56 PM

I have to ask this question. How long has it been since anyone here has bought a brand new Maxamp lipo? Has anyone bought a Maxamp lipo very recently? I'm just thinking of Hyundai. They've come a long way since the Pony and Excel. Maybe Maxamp has changed. I doubt the 150C claims are true for now. Like it was said, if a lipo capable of that kind of discharge was available, the military and automotive industry would get hold of it way before the RC industry. Let's just wait quietly and see if everyone here has to eat their hat or if we're in for a good laugh.

Bondonutz · 10.16.2010, 10:26 AM

Quote:

Originally Posted by mistercrash

I have to ask this question. How long has it been since anyone here has bought a brand new Maxamp lipo? Has anyone bought a Maxamp lipo very recently? I'm just thinking of Hyundai. They've come a long way since the Pony and Excel. Maybe Maxamp has changed. I doubt the 150C claims are true for now. Like it was said, if a lipo capable of that kind of discharge was available, the military and automotive industry would get hold of it way before the RC industry. Let's just wait quietly and see if everyone here has to eat their hat or if we're in for a good laugh.

I have 2 3s 5200 MA packs that are new(4mos old, have dated reciept), I aquired them via trade.
My Turnigy 30C 5000mah Packs perform better and charge/balance better
The MA packs are very warm and slightly puffy after run, the Turnigys in same RC are ambiant temp and normal after run.
NO B.S. !

My expectations are not high at all but I will not pass judgement till I see facts/graphs on these new 150C packs

Semi Pro · 10.16.2010, 04:49 PM

Quote:

Originally Posted by mistercrash

I have to ask this question. How long has it been since anyone here has bought a brand new Maxamp lipo? Has anyone bought a Maxamp lipo very recently? I'm just thinking of Hyundai. They've come a long way since the Pony and Excel. Maybe Maxamp has changed. I doubt the 150C claims are true for now. Like it was said, if a lipo capable of that kind of discharge was available, the military and automotive industry would get hold of it way before the RC industry. Let's just wait quietly and see if everyone here has to eat their hat or if we're in for a good laugh.

i have and i am not happy with it, max amps does not stand behind there warrenty on the 5250 packs, i would love to test out the new packs on my high kv topspeeder but im sure that would void the warrenty on the new packs too