MaxAmps.com 35C 4200SS 7.4V Pack - ROAR Approved!

[BrandonWilcox]

http://img365.imageshack.us/img365/5673/maxampsyi0.jpg

http://img413.imageshack.us/img413/5985/battjm1.jpg

MaxAmps 35C 4200SS 7.4V Pack

MaxAmps.com (http://www.maxamps.com/) presents the ultimate “Sanction Spec” racing pack that has been approved by ROAR. As you racers know, the most important factor for your batteries is voltage under load. This pack boasts a 35C constant rating for all your amp hungry racing setups. It will maintain higher voltage under load than any other pack on the market.

In addition, it comes with your choice of “leaded and unleaded”. The leaded option offers 6 ounces of additional weight added to the bottom of the pack. This allows racers to keep their current NIMH setups without throwing off the balance of your setup or having to add weight to make weight requirements.

• 35C Constant Discharge(147amps)
• Hard Outer Case
• 139mm x 47mm x 25.1mm
• 7.4 Volts
• 4200mah Capacity(plenty for racing)
• 8.8 ounces(unleaded)
• 14.8 ounces(leaded)

As with all MaxAmps packs, you choose your plug, tap, and wire options and your pack is built to order within 24-48 hours of placing your order on the website at www.MaxAmps.com (http://www.maxamps.com/)

[SS Pede]

Quick, someone buy one and put a 35C load on it! If it's like some other Maxamps packs, it may fall considerably short of its rated output. But if it survives, this would be one of the highest-rated LiPo packs out there. Personally I have never seen anything over 30C.

[austinelse]

The discharge data for our cells can be found here via discharge graphs, FYI.

http://nitrokillers.com/forumdisplay.php?f=117

[ElectricThunder]

So at 60 amps, it delivers 3600mah. I would've figured that there'd be some sort of condition under which the cells are 35C continuous (like the cells will deliver 90% of capacity at whatever their continuous C rating is; this is what SMC does- they also write the average voltage and resistance of each pack on its label since they supposedly cycle the pack under a 35 amp load, not unlike what is done with NiMH cells).

So let's see. A 60 amp load is approximately 14-15C load. At that C rate, the pack is delivering 3.6AH; 3.78AH is 90%, so the pack delivers approximately 85% of capacity at a 15C load.

I'm still confused as to what C rating will get you the 4.2AH capacity, and under what conditions can you label these cells as 35C continuous (essentially, what is your definition of a 35C cell; does voltage have to stay above 3.0v/cell, does the pack have to not exceed a certain temperature, or what)?

Now, let me also say that realistically, no one is going to be drawing even 15C continuously with these packs in a ROAR race (if you are, you may have some serious issues?). So in that respect, these packs will probably perform quite well for ROAR racing.

I would also like to note that without resistance numbers, test standards (such as "this pack delivers XX% of capacity at such and such of C rating"), etc., it makes these claims pretty iffy IMO. It's nice that maxamps posted some graphs, but it's not enough because there is simply a lack of standards for cell performance. I think ROAR or some other sanctioning body needs to impose test rules and start monitoring C ratings to see if they're true or not.

That's my two cents.

[jocktheglide165]

Quick, someone buy one and put a 35C load on it! If it's like some other Maxamps packs, it may fall considerably short of its rated output. But if it survives, this would be one of the highest-rated LiPo packs out there. Personally I have never seen anything over 30C.

next your gonna tell me a pack that does promis its load...right....come on...tell me then your gonna tell me where the website is at. then tell me, "you should buy these to run in your electric revo".........wait for it.....wait.................

[rccardude04]

The discharge data for our cells can be found here via discharge graphs, FYI.

http://nitrokillers.com/forumdisplay.php?f=117


We've already discussed that graph.
The discharge rate was only like 20A, which was LOTS LESS than what you guys thought it was.

Time for some real testing equipment that will actually draw what it says it will.

-Eric

[porra]

Give good thought on ratings lipo packs before someone gets hurt. Don't make this hobby a danger zone. I've been using lipos for a long time and I was probably the first to use a 12,000mAh pack and at the time everyone was saying crap, but look at where we are now. Please keep your ratings to a realistic level so nobody gets hurt. PLEASE.

[MattHiggins]

I've run a lot of LiPo packs and I've run a lot of MaxAmps.com LiPo packs, and I have never had one fail--ever! I have subjected MaxAmps.com packs to some serious abuse in some seriously high-amp-draw applications. I don't know what else to say other than I have consistently found MaxAmps.com packs to exceed my expectations and their stated performance claims.

With all the bad hype about LiPo packs, the only serious problem I ever had with a battery was with a NiMH pack that exploded during charging and started a fire.

[MattHiggins]

I think ROAR or some other sanctioning body needs to impose test rules and start monitoring C ratings to see if they're true or not. I don't see ROAR doing that. That's not really their purpose. Good thought, though. A third party to certify packs would be great, but it would need funding, standards, etc.

[MikeWest]

Reading these posts has given me a huge headache. And I also realized that I don't care about ANY of this rating stuff. I'm not getting near the limits of my LiPo packs even with my high-power BL cars, so I could care less about a technological pissing match between a web expert and a battery maker. But I do know that this thread is doing a great job of making new drivers feel overwhelmed by battery technology, and filling their heads with questions they shouldn't even have. "Maybe I'm just not smart enough for RC. I can't keep my nitro car running, and this electric stuff is like a science project." Good work, a few less pesky noobs for us super-experts to deal with. We're saving RC from noobs! Yay!

[austinelse]

A couple of notes regarding the 4200.

1. At a 35C constant discharge, your run time would be a little over a minute and a half. Unless you are drag racing, running at 35C constant would not be much fun.

2. The equipment we are using is the industry standard for this sort of testing. It is a CBA with a 10X amplifier. We will be posting a graph at the max amp draw on a single 4200 cell this morning. The max for the CBA is 120 amps(30Cish) and the 4200 cells are holding very good voltage at this rate.

3. I agree that there is no industry standard for these ratings. It is frustrating for us also. That is why we are posting data via a graph along with our ratings.

Best Regards,

Austin

[rccardude04]

A couple of notes regarding the 4200.

1. At a 35C constant discharge, your run time would be a little over a minute and a half. Unless you are drag racing, running at 35C constant would not be much fun.

2. The equipment we are using is the industry standard for this sort of testing. It is a CBA with a 10X amplifier. We will be posting a graph at the max amp draw on a single 4200 cell this morning. The max for the CBA is 120 amps(30Cish) and the 4200 cells are holding very good voltage at this rate.

3. I agree that there is no industry standard for these ratings. It is frustrating for us also. That is why we are posting data via a graph along with our ratings.

Best Regards,

Austin

I know the equipment you are using, but Jason had posted a thread elsewhere a couple weeks back, and your "35c 126A test" had taken 8 minutes, not 1.8 minutes like it should have been, and the cells were over 100 degrees. This would make me think the packs are only good for about 15C.

If the battery will not put out 35C, don't say it will. It's as simple as that. The only reason these numbers are jacked up is to cell batteries, and the manufacturers know that people eat up the higher numbers. It's like horsepower on nitro engines.

There NEEDS to be a standard testing method. Or at least each company needs to tell us how their packs are rated. Common Sense is pretty good at this, but nobody else really seems to be.

Suggestions:
C Rating where pack stays under 130F
C Rating where pack maintains rated capacity (4200mAh)
C Rating where no cells are destroyed at the end of the test
C Rating where the cells maintain a certain average voltage (3.7/cell?)
Etc...

Honestly though, if you set up the test correctly, you can make IB4200 cells have a higher discharge voltage than even some good lipos, as well as hit cooler temperatures at the end.

It needs to be fixed.

Also, I really appreciate you guys being willing to come here and discuss this with us. Most companies that I have asked about this type of stuff just stops responding, probably because their numbers are just as jacked up as yours are.

-Eric

[austinelse]

Eric,

I think that the test you are referring to with Jason was done in a vehicle with an eagle tree data logger. That is not the same as this CBA setup that we are using for these tests.

We finished a new test this morning on the 4200 at 120 amps. It put out 3500mah and held an average around 3.2V. For me, that is proof that it can handle a 35C discharge as it is rated. Of course, as I said earlier, its kind of a mute point since most guys are not looking for a little over 90 seconds of total run time.

The fact that it can do it only tells us that it will maintain higher voltage under load during normal circumstances and that it can handle normal drains without breaking a sweat.

The graph should be posted in a few minutes.

-Austin

[austinelse]

Here is the graph at around 30C FYI,

http://nitrokillers.com/showthread.php?t=1527

[ElectricThunder]

A couple of notes regarding the 4200.

1. At a 35C constant discharge, your run time would be a little over a minute and a half. Unless you are drag racing, running at 35C constant would not be much fun.

Best Regards,

Austin

Already kinda mentioned something along these lines in regards to no one is going to be pulling a 35C load in a ROAR race; that's a given. I'm looking forward to that 35C graph though.:)

Matt- It may not necessarily be their function, but it would be nice. Maybe the manufacturers will have a meeting of the minds one day and start labeling their cells with such data.

It's always nice to know what we're all paying for.

Austin- Nice graph. How come the test starts at 3.73v instead of the "regular" 4.2v?

[ElectricThunder]

Reading these posts has given me a huge headache. And I also realized that I don't care about ANY of this rating stuff. I'm not getting near the limits of my LiPo packs even with my high-power BL cars, so I could care less about a technological pissing match between a web expert and a battery maker. But I do know that this thread is doing a great job of making new drivers feel overwhelmed by battery technology, and filling their heads with questions they shouldn't even have. "Maybe I'm just not smart enough for RC. I can't keep my nitro car running, and this electric stuff is like a science project." Good work, a few less pesky noobs for us super-experts to deal with. We're saving RC from noobs! Yay!


That's a bunch of garbage. I'm simply questioning a battery rating. If you do not like it, you do not have to read it.:) There are NO other cells that claim 35C at the time I write this that I personally know of, and of all places, I'm suprised to see maxamps claim it (since flightpower is the one who tends to have some very high C ratings on their cells; even those I'm a bit skeptical about). That's why I'm questioning it. Don't you think it's good to have the facts at hand as opposed to buying blindly?

Is it such a crime that I question a product's performance?:huh:

[LongRat]

The problem is using the C rating to try to infer performance. C rating should be used as a SAFETY rating only. So this pack should not burn, explode or cause any other type of damage at 35C continuous discharge. If you want to know the available capacity under a certain current draw, that's another type of rating needed in my opinion.

[Jason MaxAmps]

Austin- Nice graph. How come the test starts at 3.73v instead of the "regular" 4.2v?


The 3.73 you see in the upper right corner is the cell voltage at the end of the run not the start. The initial voltage was 4.2. You can see from the graph at the start at 119.8 amps that the voltage starts at about 3.4 volts under that high of a load.

Jason

[SS Pede]

The 3.73 you see in the upper right corner is the cell voltage at the end of the run not the start. The initial voltage was 4.2. You can see from the graph at the start at 119.8 amps that the voltage starts at about 3.4 volts under that high of a load.

Jason
I'm afraid I'm missing something here. The plotted line neither starts at 4.2V nor ends at 3.73 volts. I'm guessing 4.2V was the starting resting voltage and 3.73 was the ending resting voltage?

If this is a true 35C pack, it is a worthy accomplishment. I just hope Maxamps understands why some people are skeptical. It sounds too good to be true, given that none of the premier LiPo manufacturers have released any packs over 30C. Maxamps, while a good, popular company, hasn't really been on the "bleeding edge" in terms performance. And some claim that other Maxamps packs do not live up to their 20C ratings.

[rccardude04]

How long did the test take?

-Eric

[ElectricThunder]

The 3.73 you see in the upper right corner is the cell voltage at the end of the run not the start. The initial voltage was 4.2. You can see from the graph at the start at 119.8 amps that the voltage starts at about 3.4 volts under that high of a load.

Jason

Ok, now I see. The cell's voltage rebounded toward the end of the test since it's not under load. I thought that was a start voltage.:huh:

Makes more sense. Thank you. 3.4v under a 120 amp load is definitely not too shabby from a fully charged pack. If we do the math, that means one of your packs is good for at least around 800 watts roughly (6.8v multiplied by the current). That's quite a bit of power on tap.

Do you guys do "head to head" comparisons with other manufacturers' packs against your own behind closed doors?

[rccardude04]

Eric,

I think that the test you are referring to with Jason was done in a vehicle with an eagle tree data logger. That is not the same as this CBA setup that we are using for these tests.

-Austin


The one I was referring to was actually a claimed 126A (12.6 * 10) test on a 2s pack that lasted about 8 minutes, and the pack hit 100+F, which was only about 40A if I remember right...

-Eric

[Jason MaxAmps]

The one I was referring to was actually a claimed 126A (12.6 * 10) test on a 2s pack that lasted about 8 minutes, and the pack hit 100+F, which was only about 40A if I remember right...

-Eric

Eric as I said earlier that test was done wrong. After spending some time on the phone with the owner of West Mountain we figured out the problem and the test has been redone. I don't understand why you keep bringing that up. The test that was performed and is posted now is 119.8 amps the whole run. If your still not happy sorry but there isn't any more that I can do. We know the cell performs and we proved it.

Best regards,

Jason

[Jason MaxAmps]

Do you guys do "head to head" comparisons with other manufacturers' packs against your own behind closed doors?


No sorry we don't do any head to head testing.

Jason

[Jason MaxAmps]

I'm afraid I'm missing something here. The plotted line neither starts at 4.2V nor ends at 3.73 volts. I'm guessing 4.2V was the starting resting voltage and 3.73 was the ending resting voltage?

If this is a true 35C pack, it is a worthy accomplishment. I just hope Maxamps understands why some people are skeptical. It sounds too good to be true, given that none of the premier LiPo manufacturers have released any packs over 30C. Maxamps, while a good, popular company, hasn't really been on the "bleeding edge" in terms performance. And some claim that other Maxamps packs do not live up to their 20C ratings.


When you throw a cell on the CBA unit the voltage of the cell is shown in the upper right corner of the screen. When you start the run the volatge drops to the point on the graph where the line starts. The number you see in the upper right corner of the screen is the voltage of the cell after the run.

Jason

[The_Mini_Me]

Maybe we are getting to the point that soon when all packs are truly 30c+ that performance will be measured the same as ni-mh. With internal resistance, time, and average voltage for each pack listed (maybe even printing the curves on the pack since there is enough room on the top for one). C rating will be a thing of the past at that point.

SMC seems to have started this trend. What the battery community needs to do though is decide at what amp draw to do this at and what cut-off. Also decide on the same technology basis (Competition Electronics, West Mountain, whomever).

[rccardude04]

I'm just asking how long the test duration was. How long did the cell take to discharge?

-Eric

[Jason MaxAmps]

As Austin said here in this thread and what I answered in the other thread it took about 1 1/2 minutes at 119.8 amps. And as Austin said you'll never do that in any rc car. This test shows that the cell can clearly take high amp draws with no issues meaning that for those that are racing with these they get better performance from these packs because they will run cooler and more efficient.

Jason

[rccardude04]

See, that wasn't so hard was it? :)

Well, if it did take a minute and a half, that's pretty darn impressive.

-Eric

[LongRat]

C rating applies to any cell regardless of chemistry. The fact that nobody uses it for NiMh cells maybe just reflects that people aren't so worried about safety with those.

[ElectricThunder]

C rating applies to any cell regardless of chemistry. The fact that nobody uses it for NiMh cells maybe just reflects that people aren't so worried about safety with those.


Heh... IB4200s aren't exactly that safe.;)

[LongRat]

:) absolutely

[DCLXVI]

C rating are mostly used on NiMN's when refering to charge amperage...

[jocktheglide165]

just curious though why would anyone care if its over 20c or not? Isnt 20C good enough I Mean werent nimh 20C themselves?

[SS Pede]

In theory, the higher the C rating the less stressed the pack is going to be when you use it, even if you're only drawing 10 or 15 C most of the time. You might see a performance difference. Even if you don't, LiPo is dangerous enough when mistreated that having a little headroom is not a bad idea. And for the hardcore brushless guys who will truly be pushing their batteries, nothing but the best is acceptable.

[porra]

I would love to see a 20C and 25C test. This will be more realistic for a constant rating instead of the 35C. Most people got used to the usual 25C constant and 50C burst so in a sense they would think the 35C constant cells are good for 70C burst. This is where safety in a conservative rating would play a major role in keeping this hobby safe.

[rccardude04]

What kind of wires/connectors did you guys use for the test?

-Eric

[jocktheglide165]

In theory, the higher the C rating the less stressed the pack is going to be when you use it, even if you're only drawing 10 or 15 C most of the time. You might see a performance difference. Even if you don't, LiPo is dangerous enough when mistreated that having a little headroom is not a bad idea. And for the hardcore brushless guys who will truly be pushing their batteries, nothing but the best is acceptable.

I see thanks for that info.....

[Jason MaxAmps]

What kind of wires/connectors did you guys use for the test?

-Eric

If you read the description of the test this was done on one single cell. It was bolted directly to the CBA amplifier via the cell tabs. There was no plug or wire used.

Jason

[Jason MaxAmps]

In theory, the higher the C rating the less stressed the pack is going to be when you use it, even if you're only drawing 10 or 15 C most of the time. You might see a performance difference. Even if you don't, LiPo is dangerous enough when mistreated that having a little headroom is not a bad idea. And for the hardcore brushless guys who will truly be pushing their batteries, nothing but the best is acceptable.

Yes basically if you took a pack that had a say an 80 amp max rating and ran it hard in a car chances are that that pack will come out hot say around 130 degrees. Now take a 35C rated pack that can handle 147 amps in the same car it'll come out a lot cooler. Our initial testing is showing temps of around 85 to 90 degrees on these packs proving that they will and do perform.

Jason

[chewie]

thx for bringing out a roar safe lipo i know ill be purchasing three of them very shortly..


KEEP UP THE GREAT WORK MAXAMPS

[Jason MaxAmps]

Your very welcome.....

Best regards,

Jason