MaxAmps Voltage Drop Graph
 

You may have seen me start testing some of my MaxAmps packs in a Li-Saver thread, but I thought I'd put the testing in it's own thread.

I have four 2s 6000mAh MaxAmps packs, none of which have more than 20 cycles. Since I've had them, they have always been used with an LVC and balance-charged with either a Hyperion 1210i + LBA10 or a Hyperion 0610iDUO w/ built in LBA10 balancers.

I tested them one by one in my Kyosho Kanai III with a MM/9XL/UBEC. I also tested a True R/C 2s 8000mAh pack just to compare it because it's rated roughly the same as the others. I tried to run for the same amount of time on the same terrain.

Keep in mind that the True R/C pack is new and the MA packs are used, but they haven't been abused, never been over 100F, never been run without an LVC, and can't have more than 20 cycles on them.

MaxAmps 2s 6k:
# 20C Constant(120 amps)
# 30C Sustained(180 amps)
# 50C Burst(300 amps)

True R/C 2s 8k:
Up to 120A continuous
160A Max burst

So, what are your thoughts?

http://i192.photobucket.com/albums/z...oltageDrop.png
PS. I'll be posting this in the Traxxas forum too, so you might see it twice if you frequent that place too.

Wow, I'm surprise the trueRC performed that well...

I have heard several people swear by the truerc packs, I guess it wasn't BS after all. Thanks for the graphs, that was good to see yet disappointing and great at the same time. All in all it makes me glad I am selling the last of my maxamps packs off.

So is this a chart of 10 full pack cycles, plotted to a line for each pack? We are seeing the average voltage over the discharge of the pack, or some other finite time period?


Good info, I like to see data like this.

It's the average voltage for every point that the pack hit a specific range of current.

It was nowhere near that scientific. I noticed that the Li-Saver LVC kept tripping on my Revo even when the packs were fresh off the charger. It did it with any combination of my four 2s 6k MaxAmps packs. I thought it was a problem with the LVC, until someone on here suggested that I test the packs to see if they were just dropping voltage that badly under load.

I tested each pack seperately in my Kyosho buggy for about 10 minutes each. Each pack was fresh off the charger when the test run began. I used the first 1000 mAh of each test for the graph. I tried my best to run the car the same for each test on the same "track" in front of my house. I basically did laps through my lawn and my neighbor's lawn across the street, stopping hard at the end of each lap and starting hard again at the beginning of each lap.

If I were trying for a lawsuit or something, I'm sure better tests could be performed. The only real test I need is the fact that I can't run these packs in my Revo without tripping the LVC on take-off.

Now I know, at least for myself, not to spend any more of my money on MA packs. I also had two 3s 5k packs of theirs puff a cell within the first 10 or so cycles each. I guess I can't sell these packs, so I'll just keep them around for smaller lighter vehicles. Maybe I'll run them in parallel if I can fit them in a different application.

I wish I had the time to do better testing, but this small test was proof enough for me.

I moved this thread to the General Electric section.

Interesting comparison! Did you use an Eagle Tree recording device? If so, could you post up graphs straight from the data?

I did use an Eagle Tree. I'll have to see if I kept the raw files for the actual ETree graphs. (They'd be on a different computer.) I can't read them very well which is why I make my own.

If I saved the raw files, I'll post the ETree graphs.

Thanks for moving the thread. I wasn't sure which section it belonged in.

here it comes aqwut.............

I told you so.. :)

Very interesting data. Thanks for posting.

So 2 packs aren't even living up to 10C.
1 Pack is barely doing 10C
The best pack out of the 4 is barely doing 15C?

The Best performing pack on the chart is made from 10C cells!

I realize you didn't want to destroy what is left of your packs.

But if you had your LVC set at 3.0 for this test. Then this explains the bottom of the graph.

If testing were done with No LVC, there's no telling where the bottom lines would be.

The True R/C packs are the 15C cells, but your point definitely remains just as valid. :yes:

I was running the MM LVC at 3v/cell. Yikes, right?

You know, I was just thinking back to some other problems I had 2 years ago when using MA packs, I was chalking it up to the BEC being a problem, but after these graphs, it looks to me like this could very well be the problem. This was using an old EVX with MA LVC's. I ended up using a receiver pack to fix the problem, but I still got odd behavior now and then.

Just couple thoughts:<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>
If you do the math than you find out that on individual cell level all packs have similar performance with reasonable standard deviation of given measurements.<o:p></o:p>
Keep in mind discharge rate and voltage drop do not have linear relation and these 2 packs(4 of one kind) have 8000/6000 mAmp difference in capacitance, thus in internal resistance.<o:p></o:p>
Not to mention startup voltage, and connectors material and condition, but that is setup conditions and I was doing math on normalized data to avoid complication to some extent.<o:p></o:p>
<o:p></o:p>
Bottom line, MaxAmps claims are inflated while batteries are not that bad, from this graph.<o:p></o:p>

And for the end-user the most important fact would be that True R/C 8000 mAmps packs are better than MaxAmps 6000 mAmps.

Good point Artur. I think MaxAmps should start getting better cells soon. There are plenty of places now that have awesome cells. If I was MaxAmps, I would just get some CBAs and pound through the cells they might be getting and post some real discharge for what they sell. They are a very well stablished company, especially if they are getting second quality cells at rock bottem prices and making a big profit on them. One example: I think I was the first one to actually use a large mAh pack, I had 2 12000mAh 3S packs and a lot of people thought it was pointless. The price back when I got them was $30 a cell. That was in 2003 http://www.rctech.net/forum/showthread.php?t=26840. Now MaxAmps should get rid of this packs they have with what seems to be low quality cells and get some cells that have proven themselfs.

Why change, you just explained their business philosophy.

I will attempt to make a point here:

I wonder how many maxamps lipos are sold to people doing MT nitro conversions? And how many are sold to people with rustlers and other electric 2wd 10th scale vehicles? While I can tell the difference, the benefit of better cells is not that obvious in the 10th scale 2wd segment. Lower weight and less traction produce less load, even with a powerful setup. I even compared a maxamps 4200 3s to a neuenergy 5000 3s in my crt.5 and did not see much difference. So their batteries are fine for that application, and that may be their main market right now.

Since they have opened the nitrokillers forum, it may be necessary for them to upgrade their cells, or else they will have to recommend the 8000 packs to everyone...

I don't have any MaxAmps products so I've not made any comments in any of the various threads about their stuff however I've got to say it's very disappointing to hear all the bad new about MaxAmps, mainly because they are the "flagship" LiPo vendor - if all you do is read the various RC car Mags. They get plenty of ink when the Mags do a conversion and they have a big advertising budget.

Based on my reading on this forum, I'd never buy a MaxAmps product but lots of uneducated folks will.

DM

Well, I think we can see where the big advertising budget comes from. They do have alot of ads in the mags. It would be nice if they stepped up with better cells, but I doubt it. If they can keep selling them to the uninformed, why change? I forsee that their nitrokillers forum may be their undoing, as people on there will find the better lipos as well. I wonder if Jason (admin over there) will just kick off everyone who starts to question maxamps products?

I also question their matching process, as all of my packs used to go out of balance quite a bit, and often required multiple charge cycles with the balancer to get everything equal. I often just charged at .5 amp all day just so I did not have to keep looking at them!

Also, most people changing from nimhs will be blown away by the power than even those lipos can provide. I did not understand the difference between the maxamps packs, and an enerland cell pack until I tried it. There really is no comparision, almost as much difference as the nimh to lipo change.

Do they heat up more too? A friend of mine is convinced (and I agree to an extent) the C ratings for lipo's are something that is mathematically derived from various battery specs (probably just the internal resistance), and even though a 20C constant battery is physically able to provide 20C continuous, it could get extremely hot, so it wouldn't actually be possible to take advantage of those maximum continuous discharge ratings under less than ideal conditions.

And where our opinions disagree: he thinks the temperature a pack might run at and their C ratings are totally unrelated, I can see how one might think that, and I nearly agree, but I also can't let go of the notion that surely a higher rated pack would run cooler at the same current draw? but then again, maybe the chemistry just physically allows it to deliver that current, but it will heat up over its maximum recommended temp unless submerged in flowing liquid nitrogen the whole time.

Very nice info here kungflow. I have proved this to myself in the past as well, although not a scientifically as you. I had a pair of 20C 4000mah 5s MaxAmps packs that I ran i parallel for 8000mah 5s. They puffed on me in only a matter of 20 cycles and always came out of my ruck hotter than the TrueRC 10C 8000mah 5s setup I have. The TrueRC 8000mah packs have hundereds of cycles on them now. The MaxAmps have been dead for over a year now. The MaxAmps should have been good for twice the current draw vs the TrueRC.

Havent bought MaxAmps since.

One thing some folks are saying about lipos is the fact when they are heated the IR drops. Some folks even heat their lipos before doing a run. All I can say is MaxAmps already made their big profits with less quality cells and now it's time to step up. They should have more than enough buying power and credit to do this. One concept they need to work out is the concept that I use and now I'm seeing Hobbycity and some others in Asia use. Make more profit from reasonable pricing. Make it higher to compensate for shipping, but don't go overboard. Like I said before I rather make $10 profit with 100000 units sold than make $50 profit with 10000 units sold. Plus the higher quantities will give them more credibility and manufacturers will want to sell to them and they can even get a more competitive price afterwards.

I still have my old TrueRC 4400mAh 11.1v packs and they are good. They are made from the 2200mAh cells. I put them in the BPP truck and they handled being abused a little. I guess the name says it all, "TrueRC".

Sammus- the heat of a lipo pack is quite the interesting subject. Let us take one of my crawlers for an example. It is almost all amp bursts with average amp draws of 2-3 amps. The bursts can be upwards of 60a or more.

With a vislero 2100 pack I never saw it get very warm and punch was pretty good. I figured it was enough battery since it didn't get warm. Well, sure enough it puffed up on me from the half second bursts I was asking of it. Rated 15C/20C, probably more like 12C/15C

Then I got two 1300 25C packs from innov8tive. I ran them in parallel for 2600 mah. Logic would say that this pack would run cooler right? More power available, should have an easy time coping. Well, that was wrong. It actually ran hotter, I got higher amp draws, and I also got better voltage under load and MORE punch. Go figure. The lower resistance cells were allowing even more power and within a few minutes were getting up to 120 to 130F.


Now most crawlers don't burst over 35a very often, but you can count on a few hits per run and 25a is a frequent occurrence even on small ledges. Take into account that maxamps has been pushing this battery on crawlers http://www.maxamps.com/proddetail.ph...le-Pack&cat=82 and you can see where my issue arises with them. I have recommended to JAM in person that it is not big enough for proper longevity. His response is that it doesn't heat up, therefore it is plenty of pack.

Hey Kulang- nitrokillers has a discharge graph "vault" in their forum, it would be a great place to put your graph. :D

I'm not sure this the right place to post this so I will post it anyways. I drag race my LSP last Sunday and this is the data from eagle tree. The battery was charged for each session. I was using maxamps 12 2200 mah, 25t/46t, 4.1in tires, neu 1515 2y. Max amps was 96.73 and watts was 3228. LVC was set at 3.1 volts. The lvc was not triggered in any of the runs. BTW, maxamps dont make these battery anymore, but they still sell the 1100 mah. There is about 20 cycles on the battery so far.

http://maxcapacitor.oplink.net/blunt...708voltamp.jpg
http://maxcapacitor.oplink.net/blunt...42708tnts1.jpg
http://maxcapacitor.oplink.net/blunt...42708tnts2.jpg
http://maxcapacitor.oplink.net/blunt...42708tnts3.jpg
http://maxcapacitor.oplink.net/blunt...42708tnts4.jpg

The first graph there shows a solid line (2-3 seconds constant) of 50+ amps and 40+ volts and peak of 70 amps and 36v =

samples show:
3.4v per cell @ 23c
3.33v per cell @ 24.5c
3.0v per cell @ 31c

Is this a "20c" pack? If so... it looks pretty good just pulling a couple points off the graph.

The last graph... shows a peak of 80+ amps (about 38c) and dips to just over 3.0v per cell... and the 96 amp (44c) does hit the 3.0/cell mark.

other peaks:
71 amps (32c) @ 3.1v per cell

These packs were 15c

Wow... that's even better.

These must be an old version? I think everything they sell now is listed as 20c. I'm guessing the pack temp was good (warm)

I bought these in Feb of 2007. These havnt overheat yet. The 1100 maxamps are selling right now use the same cells as the 2200.

any new news?

Just an FYI, I have been happy with my TrueRC 8000mah 15Cs in my E-revo, and was happy with my 6000mah 14.8V lipo in my EMBX5 from maxamps.