ROAR Maxamps 4200 pack?
 

Anyone hear about these yet? Supposedly rated at 35C!

I just found a discharge graph at 3C, and it seems a bit bogus...:lol:

Tell me what you guys think. I keep reading that a lot of people on here, and some on other forums, believe the maxamps packs are utterly overrated. I'm inclined to agree with them after seeing this graph.

http://www.nitrokillers.com/attachme...8&d=1217350427

So am I, too, right in thinking that these cells are overrated?

Are you sure? I think it's like their 5Ah graph where you multiply the A reading by 10...

Just found out it's through a CBA amplifier, so the load is 126 amps.

Even still, wouldn't voltage drop substantially under such a high, continuous load?

I find that graph bogus, as well. First off, if I read correctly elsewhere, Deans connectors were used, but they wouldn't handle that kind of load. W.S. Deans themselves rate them at 60amps, I think.

Second, the average voltage looks like 3.7v/cell... There's no way Maxamps could be the ONLY company selling cells that are so "seemingly" capable of 30C.

As usual this is my opinion.

They're 35C capable cells supposedly. Not even flightpower has 35C cells out yet (at least I haven't found any enerland based 35C packs yet!).

He said the pack only ran about 106 degrees too over at RCZ (I was the one to ask for graphs... and also asked for an eagletree which hopefully he'll get around to).

Glad to see I'm not going crazy thinking these are bogus claims...

I also made a little comment about the copper/aluminum (not sure which these cells have) terminals the cells have handling 126 amps... I don't think a battery bar for NiMH even handles that kind of load continuously, and those are considerably thicker (albeit not 126 amps continuous type thick...).

Methinks a rating standard/system needs to be implemented by ROAR, complete with cell information (almost like when companies match NiMH cells, they put a sticker on the cell with voltage and stuff; internal resistance would be nice too, so we can compare packs based on resistance and get a more accurate idea of C ratings)...

Agreed. That graph just seems too good to be true, especially with the quality of MaxAmps' other cells. None of the high-end brands yet have cells rated at 35C like you say, MetalMan, so I'd love to know where MaxAmps have magic'd these up from. Perhaps they are true 35C cells if that graph is completely accurate, but it's gotta be unlikely.

Ask where the voltage for the graph was picked up , and why the graph is not flat (steady) is typical of a very very slow discharge graph OR one that is not even close to the rating of the cell.

In otherwords what I'm saying is that according to the graph and temp the battery should be able to be pulled on a lot harder (maybe twice as hard).

The test should take less than 2 minutes.

Wow, what is MA doing? I would rather play it safe than sorry. This will turn out to be a marketing scam and how will they explain when people are blowing their vehicles up. They need to be careful with claims like that. The highest I've seen so far is 33C and the manufacturer of the cells even told me it's really not mature yet and they just recommended the 30 and 25C cells. Even if I had legit 30C cells, I would just go 25C max just to avoid the ones with less common sense who will over gear there system just to utilize the 30 or in this case 35C rating of the cell. I hope MA know what they are doing, but it looks like they haven't learned anything from the current cell they are offering.

This for me is much more interesting....
http://www.hobbycity.com/hobbycity/s...cing_Lipo_Pack

>None of the high-end brands yet have cells rated at 35C

Actually Kokam will start a new line up of 35C cells - they are already listed at webshops in Europe (not in stock yet). Kokam further developped their 30C cells and labelled them as 35C cells. Looking at first graphs shows that they are not quite that capable.

Kokam 3600 (35C cell)
http://www.elektromodellflug.de/akku...okam3600H5.gif

The graph is laughable and can't be close to a 30C or 2 minute discharge.

Apparently the test really wasn't a 126 amp test. The replacement graph is now flatter, less capacity , more temp increase and has a current of 60 amps (which I can buy)

It looks like about 15 or 20C will max out the temp and give a flat graph. I would like to pull either 30-35C on a pack and see what happens.

I gotta ask, why so much hate on maxamps? I have one of their packs and it seems to be a terrific performing pack. Everyone always seems to dog on them, unless I have an exceptionally good pack from them. I don't have any graphs or anything like that but in a 5.15 lb rustler with a mamba max 6900 geared extremely high (28/83) it provides every bit of torque it needs to flip the car backwards at any speed, be it take off, mid, or top end with a pull of the trigger. Or maybe my system doesn't draw as many amps as I thought, I don't know. Its a 20c 2s2p 6000hv pack, the only other pack I can compare it to is a 10c 8000 true rc pack, but that isn't a fair comparison. I've had it since February and its as good as ever, I did do a full charge on it the other day and it took 6655 mah. Not to sound like a maxamps thumper, but I've no regrets buying the battery and it satisfies my needs. Are there that many failures out there?

From what I've read , the problem seems to be with the truth in advertising or marketing. I like all my Maxamps packs. I got a good deal on them , and the ratings are about half of what they are sold as.

If one uses a 20C pack at 10C or less (like 90% of users will) then niether maxamps or user will detect that anything is wrong. I don't expect to get anything close to the rating out of my maxamps packs , so I simply compare said pack to competitors packs at whatever ratings/cost they actually are and make my choice to buy.

The trouble starts showing up when a user thinks it is ok to pull the amount of current that the pack is said to withstand. The pack will overheat, puff up and not last a few cycles , even become a danger to have around.

LOL why is it that anything less then being in love with MA is considered hate?

But since you asked... I personally feel the practice of over rating a product that is widely considered to have a high degree of inherent danger even when used as designed to be highly irresponsible of such a large US company that sells their products to a target market group consisting largely of children.

Theres any number of other reasons but w/e

as expected from crap amps

I like to question the validity of such outrageous claims. Especially when it can mean the difference between great performance for the dollar, or a big smoking heap of burnt plastic from an underrated and overstressed battery...

I ALWAYS question claims like this (may not be openly, but I always remain skeptical). Especially when it comes to RC stuff. It's nice to shed some light on how a product really performs. Plus, as a consumer, it's always in your best interest to question things. It certainly doesn't hurt.

hoober- I saw the updated graphs. Looks ok, but for about a 14C discharge, I'm not impressed with pack temperatures. Seems to me that pack resistance is higher than what a true 35C cell would be. Like you say though...many people in real life won't be pulling 60 amps continuous for approximately 8 minutes anyways, so it's a pretty invalid test as far as real world performance goes.

I asked for voltage of a single cell under a 120 amp load on another forum, so we'll see if he gets back to me with that. I want to see what the voltage looks like under such a "spike" (flipping the CBA on and off with that 120 amp load on the single cell). I figure this test is a bit more applicable to the RC world since acceleration and braking generate some decent current spikes, and it's these spikes that can hurt a pack if voltage drops far enough and often enough.

I must say, Max Amps is making an effort to be pretty up front with everyone, and are providing exactly what I'm asking for. From that standpoint, I think Max Amps is pretty good. Sure, they may put out overrated cells, but it takes some balls to put up complete tests of your packs; even when they show that they're somewhat overrated.

I re-read the post I quoted, and kind of felt the need to add this post. I have no hate for max amps, but just a legitimate curiosity and need for cold, hard, facts.

So I guess an "excellent" rating for the support by Jason, and a so-so for the pack's performance is in order IMO?

:angel:

I have sent back 90% of the maxamps pack that I bought. That is 9 out of 10. I would have sent the other back, but missed the 30 day window. I had at least one cell puff in each pack, and actually received a pack that had a puffed cell in it. Maxamps packs are fine in a 10th 2wd vehicle. 2wd just can't pull the load, or sustain it like 4wd can. Your 6k pack is 20c rated. I would love to see it produce 120amps... Therein lies the problem, false advertising...

Best to compare weight and size. That seems to be the best bet in comparing lipo ability. I was suprised when I got my first neu lipo. 3s 5000mah 25c battery was almost twice as big as a maxamps 5k 3s. After running it I can safely say that the maxamps was no where near the quality of the neu, and damn close in price. Maxamps has to pay for all of that advertising somehow... And the NitroPuffers forum...

The only reason that people say that there is maxamps hating here is becasue they just do not understand the difference. Going from nimh to a maxamps lipo is a huge step, and I think that many wonder how much better can a different lipo be. I have personally tested and owned at least a dozen different brand lipos, and know the difference. Most people do not have 5k to drop on battery testing. I have found that repeatedly that enerland cells perform, and last. I even went as far to buy the oldest 5s 3700 polyrc pack that I could find. It was maintained correctly by the previos owner, but had over 100 cycles on it. I have had it for about 8 months now, and it is still good, capcity and output are right on spec. I just cannot say the same for maxamps.

Ok, all I wanted to know. I didn't say you have to be in love with it or hate it. Wanted to know why and didn't want any attitude about it like I see on other forums. I don't own a monster truck but like hanging around here for the information provided and the courtesy I've noticed around here. Also yes there is probably a huge difference between mine and your applications and I only have one pack and not personally come in contact with several. I wish I could throw the money down on a data logger, but just can't afford to do it. I'd like to know the amps/watts/hp my truck is producing.

Although I've heard a quality lipo doesn't let you know the cut off is coming, my maxamps does. I can feel it before it cuts off and never actually hit the cutoff with it, so with that mentality then I guess it isn't one of the best ones out there. It works good enough for me. The only enerland cells I have is a 3s hyperion 16c 5350 that I sometimes run for speed with the mamba 6900, and it is altogether a different beast, but I assume it's the voltage talking more so than the cells integrity, so I can't compare the two.

As close as I can remember the first graph someone said took 18 minutes , the second one 8 minutes.

1st graph was claimed to be 126 amps , but was probably about 15 amps and 3.3C
2nd graph was claimed to be 60 amps , and probably is 60 amps. That is 7.5 C

delta for first graph was 20 deg F and 2nd was 50 deg F (125 deg F max) ]

The battery should really be able to be pulled a bit harder and will be a nice 12-15 C constant battery. It would be unrealistic to expect the full capacity at the full current. Full capacity shall be listed at very low current. sorry, that's the way it is.

2nd graph is 14.2 C (not 7.5 c)

The third graph is now up at 120 amps and 28.5C and forced cooling on cell so it doesn't overheat. It looks pretty good at 3.1 volts average and the discharge isn't flat yet.

It's a shame not many are currently testing cells anymore to compare them.

This is turning into one of the most pathetic cases of back pedaling I have ever seen.

As you may or may not recall the original graphs (shh I have copies of them as I figured they would be replaced) showed the single cell 25c 5Ah test at 120amps and holding around 3.7v throughout the discharge, and the 2s 35c 4.2Ah pack tested at 60amps and holding around 3.3vpc average throughout the discharge.

Now the graph for the 25c 5Ah cell is missing, and there is a new graph for the 4200ss. This time it is a single cell test at 120amps that shows the cell holding only 3.1v average and requiring forced air cooling to keep it from exceeding 130 degrees. The cell also gave up only 3.49Ah before hitting 3v cutoff. That works out to a test that lasted around 1.75 minutes and had a temperature delta of 50 + degrees. :surprised:

If the graphs of the 4200ss are at all representative of its typical performance I can't imagine why anyone would buy it. It does not appear to hold voltage and it's chemistry seems to be a bit volatile for my tastes. But not to fear, I'm certain that as soon as Jason realizes that his graph shows less then stellar performance he will replace it with something that portrays a better company image.

can u please host them on photobucket or something then post the links up, i missed all the graphs!!


also,

ive got a question which should fit in here nicely. its about the Hobby city Zippy packs.

how good/overrated are the new/old/h/r 20 and 25C cells? are there some bogus ones and some good value ones? also would i see much difference in performace in day to day use between a zippy and enderland? enough to be noticeable?

i dont mind if they only last me 3-6 months, id rather spend 1/3 the price on a pack, and spend another 1/3 of the price on a newer more powerful cells wich would most likely be just as good as the original enderland based pack.

thanks guys, and sorry for the hijack!

If one "plays" with the cba long enough one can figure out how to make the voltage higher on the graphs that are generated. I can conceivably pull any current on a "pack" , graph it with a cba and see what happens to said pack during the test.

One thing is for sure: life cycle tests will be very pronounced when the graphs are overlaid. One thng that's missing from the maxamps graphs is the numbers in the box on right. It is easier to leave the battery plugged on and save the graph thus saving the (somewhat meaningless numbers)

Here' the way I see it , a guess on my part:

Many users who pull high currents question Maxamps ratings.
Maxamps insists that they "are the best" without data or proof.
Maxamps buys a CBA with amp and doesn't know how to use it.
Bait and switch the older "20C" cells without anyone being able to locate a graph of the older 20 C cells. Point to the neweer graphs instead (better cells)
Market the latest cells in a hurry , test them afterwords.
Hurry to get a graph out on the net , oops.
Replace graph , oops.
Realise the "pack" will not make the rating.
Replace the graph with single cell and forced cooling at less than the rating
Conclude that "it will go even more"

I'd like to see some cycle life and some real temp at end and after end of one 35 C discharge test.

There are plenty of other tricks to use when marketing battery numbers , I wil look for them.