I am wrong about MaxAmps.
 

A small debate with Jason from MaxAmps have made me not want to bash about maxamps packs anymore... They are not the same cells as TrueRc nor I really thought they were using HeCell.. but they use China Based Tronics Electro Co. LTD cells.

Seems like the 20C continuous discharge rate is pretty accurate.. but I don't want to talk about the 25C discharge rate...

Depends on the cells used for the discharge, but that is the manufacturer I suspected for the past year or so based on form factor and weights. Straight from Jason's mouth? And all this time he kept telling me that maxamps makes them :D

It's nothing new true-rc packs are different? the sizes of the 4000 cells are different to begin with. They do offer the best bang for the buck though (TrueRC), it's about the same quality (voltage/current wise) for less than 1/2 the price.

Don't get me started on Jason, he really likes to back-pedal everything he says.

Unless their cells have become alot better in the last 6 months, they are not 20c cells. They may be able to produce that without puffing, but not while keeping the voltage over 3.5v per cell.

In any case, their prices are too close to hyperion, polyrc, polyquest, and flightpower. Neuenergy seem to be the cheapest enerland cell packs, and they easily outperform maxamps stuff.

Plus Truerc cells seem to be rated correctly, and that is my biggest issue with maxamps. They refuse to post data on their packs. They are just blowing smoke...

Thats ok, when large scale electric gets really popular and people are trying to run high draw setups in heavy vehicles, the truth will come out.

With the a123/enerland merger we are going to see a lot better pricing on enerland packs too.

That is interesting. Hopefully they do not drop the quality! Who bought out who?

I am pretty sure that a123 bought enerland,

http://enerland.com/pop/img/img5.gif


Every dealer that had a line into enerland now has a pipeline into a123 now. With the change comes changes in pricing and possibly management objectives but not manufacturing. a123 is ahead of everybody else with li-nanophosphate, and the Enerland manufacturing is the same for lipoly. a123 aren't going to buy a big dog just to screw up the quality name.

I sure hope not!

I was on another forum having a little debate with Jason... I tore up one of my 3 year old maxamp packs and did a search for the cells... a discharge graph of their 20C batteries weren't too bad.. until it saw the 25C discharge.. I was like, WOAOHH.. 25C, dropped below 3.0Volts, at about half capacity... But like I told him, for the $$$ maxamps wasn't for me.... WOw.. if A123 bought Enerland, that is crazy.... those are the only two batteries I'm using right now... I think prices went up for polyquest packs, only a few months ago they were about $50 cheaper from hobby-lobby...

Do you think we might be seeing prismatic a123 cells in the future then, would be nice....

That is normal for pushing a cell to hard continuously. What I see is a difference in the average voltage throughout the pack (at rated discharge). Tronics hang around 3.25v/cell whereas enerland is right at 3.4


Pink is the continuous rating.
http://enerland.com/upload/2100lpg.jpg

The Bottom two graphs would be a fair comparison..

25C continuous Rated pushed to 30C..
http://www.enerland.com/upload/3300XPSG.jpg

22C Continuous Rated Polyquest pushed to 25C..
http://www.enerland.com/upload/1200xpg.jpg

20C Continuous Rated Tronics pushed to 25C..
http://www.cn58.com/com/tronicshz/pic/1132208961.jpg

If we wanted to make an assumption, we could say that enerland under-rates their packs in comparison to tronics. We could also say that the given tronics battery might be better rated at 15C if amperage overhead is wanted.

What would be more useful to us is burst graph - How hard of a one second burst can they take.


Take a look at the 1200xp graph. The voltage actually rebounds on the green and pink lines. That is from the cell heating up as it goes through the cycle.

Yeah, there isn't any real hard evidence graphs out there that accurately shows the differences between each pack/cell type/chemistry. Because, for cars and trucks, burst performance is all that matters, right?

I am also very glad A123systems merged with Enerland. This should bring about almost revolutionary battery tech to RC market hopefully.

JHolmes... I saw a bunch of guys race and they kept their Lipos nice and warm.. I know that lipos do not perform too well when cold...

I really do hope A123 and Enerland comes with some new technology... Maybe something like the April fools Joke... GumLiPo..

Link to my thread about my MaxAmps packs.

Here's the summary:

http://i192.photobucket.com/albums/z...oltageDrop.png

Yeah, I saw your graph...

What cells are pack a,b,c and d?

All of them are 2s 6000mAh MaxAmps packs based on the link he has.

Yeah. noticed that later..

The 6000 mAh packs are poor, that's a fact; the 4000's and 5000's are better.

I've puffed 2 maxamps 5000's after very little usage, and being very well cared for. One burst into flames ruining both cells, the other puffed one cell only, and did not vent. That's a nice $220 down the toilet ;).

J.

Both of my 3s 5k packs puffed a cell within 10 cycles. Now one of them is a 2s 5k that I never use and the other one just sits in an Ammo can 'cause I'm too annoyed to "fix" my new pack.

But one thing is that MaxAmps is pretty good with their warranty... Send it back to them, I'm sure they'll take care of ya..

Probably not anymore after the badmouthing lol.

All my packs are out of warranty and I don't pay for the extra warranty period.

Austin (MaxAmps) heard about my testing and contacted me indirectly and wants to talk to me about it. I'm told he wants to send me a new pack to test as long as I post the results. I'm waiting to hear back from him now. I'll let you know what I find out.

Not to discredit Maxamps, but I think it might be difficult to successfully complete a test like that, since the pack Austin would send you might not necessarly be representative of other packs using the same cells that he sells.

Yeah I was thinking that, like when you see some dodgy takeaway shop claiming to win an award for the best pie or something, they just make one good one to give to the judge...

Do you think he would black shrink wrap a fp pack? That would be funny...

Out of the two guys, Austin is much easier to deal with then Jason. I never had any issues with him. Most of the packs I sent beack were thru Austin.

If I made a product and sold it for like 2000% profit, I would have some amazing warranty too :lol:. On the serious side though, they are probably making a nice profit to offer good warranty.

Their warranty is not that good. Not enough to justify lying about their products...

OOOHHH, I used the "L" word!

after my debate with Jason, and calling me a Liar, I know what he's all about... and I don't care...
These were the packs that I had a few years ago... I decide to open them up, to see what cells they were.. Of course now, they have the manufacturer put MaxAmps on their cells...
http://www.geocities.com/aqwut/MAXAMPS/Old.Maxamps.JPG

This is my story :rules:. I bought 2 4000mAh 3S packs from them to try it out. They shipped out the 2100mAh. I sent them back and they even paid for them. So what you're saying is that if you pay for the warranty, it's not good? If so, I think Max Amps should regroup real fast to avoid some pissed off clients.

I mean their 30 day no puff waranty. I would almost say that the 300 cycle warranty is mandatory. But that would up the price up even more, and then you might as well buy a better lipo. I can say that all of my packs that I had issues with had 10 cycles or less, most had 5 or less.

I would rather buy a product that does not fail and lives up to its advertised spec, than buy an over-rated item with a great warranty. I hate sending stuff back. Hell, I have had more luck buying used enerland cell packs off the plane guys on rcgroups that I have had with brand new maxamps packs.

I agree 100%. Max Amps, better do something fast. A lot of places have found some good sources for lipos and they are selling them at good prices.

Not for nothing, but I never had a problem with a MaxAmps pack when it was shipped fresh. For the first 20 - 25 cycles that packs were very strong (5k cells) and it's only after a while that they can't handle the draw.

If you do test with a newly shipped pack - cycle it hard about 15 times before comparing it with another pack.

Problem with all of the test and graphs we see is that you can be sure they have been run on a brand new pack at it's strongest.

My concern is longevity. When I have been running the pack for a year I want to know that it's still going to be a good qality pack.

I have been using TP and Apogee packs (the 900, 1320, and 2100 mAh ones) in my 1/18 scale buggies and currently have a few packs that are over 2 years old with no problems and no puffing.

I actually wanted to ask you guys for suggestions for making my testing better. It's pretty unscientific so far.

I like the fact that my tests are "real world" in an actual car on the ground, but that makes them hard to repeat pack to pack. I think I should do multiple runs per pack and test them within their first few cycles, then again like around 20 cycles like VintageMA suggested.

How long do you think I should run each test? I think that 10 minutes should be enough at 10 samples per second. How many times should I repeat each test per pack? An average of three sounds about right to me.

If Austin is willing to send me a pack for this, I definitely want to make the testing worthwhile. I'll probably take video of the testing as well so people can see the set-up and what-not.

Thoughts? Suggestions?

Run that pack till the lvc kicks in at 3v per cell. That way we can see what kind of capacity it has. Also some balancer info would be good. I would be interested to see how well the pack stays in balance during a full run. I had issues with my maxamps packs staying in balance during a run.

aqwut,

They claim that pack is 20C? Man, they are in deep crap. I just noticed the part number and the 15HR means they are 15C here is the discharge graph for it http://www.tronicshz.com/down/839.jpg. I actually spoke with the owner of Tronics regarding their LiFePO4 batteries and he is a class act. This is what he said in the last e-mail, "Tronics is not a new company, we do the high rate Li-polymer from 2003, is the first one suppliers in China. Including Polyquest, MaxAmps, CheapestPoly, and other big fright offers, we have so many good cooperation in the world". Now correct me if I'm wrong, but Polyquest is made by Enerland which is one if not the best lipo manufacturer out there. I have attached the discharge graph of a 25C rated cell and in my opinion it is only good for 15C discharge.

How do you monitor balancing during a run? Do you mean to just check to see if it's still in balance after the run?

Man, that will take forever to test each pack all the way to LVC in my buggy, especially if I need to repeat the tests. I need something with a higher amp draw that I can run on 2s. I have a VXL Stampede, but it is light enough that it doesn't seem to draw much current. I could use my bl-Revo or stock E-maxx, but they'd be boring as crap on 2s.

Ideas?

Just run it down to the lvc the first run and then after a dozen cycles. Would be interesting to see how the capacity changes after time.

Yeah, see if it is still in balance after the run, and then charge it at 1c and see if it can balance itself out during the charge. Alot of my packs needed charging at a lower rate, or filling up a bit, then blancing while off the charger, then charging again thru the balancer. It was a PITA, to say the least. My neuenergy, polyquest, fp, and polyrc do not need this, they will rarely go out of balance, and if they do it requires little balancing to get the right. I am a charger freak, check this out!

http://i206.photobucket.com/albums/b...p/DSCF1873.jpg