MaxAmps Voltage Drop Graph

[lincpimp]

Originally Posted by MacII

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.

[Sammus]

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.

[jhautz]

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.

[lutach]

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.

[lutach]

Originally Posted by jhautz

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.

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".

[johnrobholmes]

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.

[johnrobholmes]

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

[glassdoctor]

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.

[glassdoctor]

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

[glassdoctor]

Originally Posted by Blunten

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.

[Cain]

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.