Maxamps not up to snuff?

[Mightytaco]

I have to say im a little disappointed in these maxamps 6000 packs i have. I finally got a data logger and the results suprised me! My peak amp draw on my test run with my 1/8th scale was 98amps but the voltage dropped to 10.5 volts at a couple of points! Anyone else have similar issues with theirs? i thought these were good up to a 20c discharge. Could i have a bad pack?

My setup:
Motor 8xl
Gearing: 14/46
Batts: 2x 2cell 6000mah packs in series.
controller: MGM 16018 in "race mode"

[lincpimp]

The 6000 packs are 3000 cells in parallel, and I can say that the 3000 cells I had puffed under less than a 50 amp load. I would say that the 6000 packs are good to 90 amps, but no more. IMO they are closer to 15c cells than 20c. The 4000 cells can handle their rated current as can the 5000, so i think that Maxamps are being optimistic with the 3000 ratings.

In my experience, MaxAmps over rates their packs. Also, I've heard that there 6000mAh are not that great at all. I've used their 4000mAh and they perform like garbage for being a 20c pack, their more like a 10c pack. Since them Ive gone to TrueRc packs and have not looked back, they perform awesome, greater than advertised. You should really look into some Flightpower lipos(more or less top of the line lipo); they are top notch and are worth every penny, even if they are a little more expensive than others.

Hope this helps!

Bye

[lincpimp]

I still wish that I bought the trakpower packs over my 5k maxamps packs. They were the same price to me, and I like the hard case idea, since I seem to destroy shrink by looking at it! Oh well, the 5k packs are doing fine, and may be a true 20c pack. I reserve the use of my 4k packs to 10th scale anyway.

[johnrobholmes]

From my experience and talks with industry folk, Maxamps has one thing going for them: a lot of advertising. The average user has no way of testing the actual discharge rate, so there are many many companies that fudge numbers. Kokam and Neu are some of the few that are honest. I have never dealt with flightpower packs directly, but from the runs I have seen with them they seem to keep the voltage under load.

[Finnster]

Originally Posted by johnrobholmes

From my experience and talks with industry folk, Maxamps has one thing going for them: a lot of advertising. The average user has no way of testing the actual discharge rate, so there are many many companies that fudge numbers. Kokam and Neu are some of the few that are honest. I have never dealt with flightpower packs directly, but from the runs I have seen with them they seem to keep the voltage under load.

I am going to refrain from blasting them, as they are a guest here. But I would largely agree with the above statement in regards to many companies. I can't say every MA pack holds up to its rating, they seem a bit hit and miss, and generally they seem to take the "optimistic" rating. That's why I always go w/ TrueRC packs, they tend to underrate all their packs, plus they are considerably cheaper for what amts to the same quality of pack for the most part. Its my understanding both cells originate from the same factory ;)
I think a more realistic rating for the majority of their packs would be 15C.

[johnrobholmes]

Another point to consider, what is a true 20C pack? I see many graphs of a 2200mah 20C pack that doesn't hold 2200mah at the said discharge rate. The mah of the pack is usually derived from a 1C discharge. What is the cutoff voltage of the test too? There are no clearly defined rules for the variables tested, and average voltage isn't given for the discharge rate either.

[neweuser]

Because I'm not a full blown racer, I happen to like my 4s and 5s MA packs. I get nice run times, and have not had any issues with them. I own 4s 8000, 5s 8000 and a 2100 for my rc18t, and love them all.

Of course, I have not tried the Flight Powers, which could be why. The reason is runtime. I cannot find a flight power pack that goes to 8000mah

[Finnster]

Originally Posted by johnrobholmes

Another point to consider, what is a true 20C pack? I see many graphs of a 2200mah 20C pack that doesn't hold 2200mah at the said discharge rate. The mah of the pack is usually derived from a 1C discharge. What is the cutoff voltage of the test too? There are no clearly defined rules for the variables tested, and average voltage isn't given for the discharge rate either.

Well discharge capacity does depend on the discharge rate, that's no secret. Ie higher discharge = lower capacity. In all fairness, there are not any std rules in rating batt packs. Its kinda like cars and HP, up to a certain point you can prolly get away w/ saying anything, b/c test condits are so variable, & if you lowball it people w/ just buy the other guy's car.

Generally tho I've seen 3.5V/cell as the limit to discharge rate. IOW, a 2S1P 2.1AH 20C batt should hold 7V @ 42A continuously. If its doing 6.5V, its not 20C

The nice thing about MA is they do have std size lipos (44mm wide) and in a large range of caps. TRC's tend to be 50mm and don't fit in NIMH batt trays. They are much more affordable than FPs tho too.

[johnrobholmes]

Now there is the Elite brand too, they fit in battery trays.

I have in the past destroyed a number of the 6Ah packs under conditions that they should have been ok in. I like the maxamps packs overall because of the bang for the buck factor, but when compared to other "better" packs, they don't stand up.

I recently had a short lived interest in parking lot drag racing and I could really see (according to our Bushnell radar gun) a difference when switching from a 5S 5Ah maxamps pack to a Neu 4900 (I think it is) 5S pack. The difference was worth a couple to a few mph over 132 feet of running. To me, that's substantial.

Lately, I've found myself going with the Neu and Flightpower packs for applications that need them and the truerc packs for applications that don't require so much battery.

Originally Posted by neweuser

Because I'm not a full blown racer, I happen to like my 4s and 5s MA packs. I get nice run times, and have not had any issues with them. I own 4s 8000, 5s 8000 and a 2100 for my rc18t, and love them all.

Of course, I have not tried the Flight Powers, which could be why. The reason is runtime. I cannot find a flight power pack that goes to 8000mah

A 5000 MAH 25C flight power pack would easily last as long as the 8k, or darn close

I also have to say, my flight power and TrakPower packs FLIPPING RULE!!!!!!

[Serum]

I've seen various discharge graphs of these 6k packs, and they simple are not up the task. Surprised to hear this story is still continues for this particular cells. Contact Austin about this; he will do anything to keep the customer happy.

[Mightytaco]

Thanks for the replies guys. Before i had the logger i was wondering if i was hitting the amperage "fuse" of the mgm controller. Here is part of one of my test runs a few days ago.

Graph

[DrKnow65]

Dropped this post in the maxamps factory thread but I'd like some second opinions from the brushless crowd.

OK, long winded message so put on the ole' reading glasses and grab a cup-o-joe.

Just recieved my 8000HV pack last week for my brushless XXXT project and decided to charge them up this moorning (I am posting the some 12 hours later). Soldered on the deans connectors, shuffled the wires in the balance connector to fir my B6 balance charger and proceeded to spend 4 hours balance charging the new pack at 4amps (1/2C).

Charger goes beep and the pack is done right? So I let the cells settle down half an hour and get out my trusty fluke meter to verify the cells are balanced and within voltage range... This is where it gets off track . The cells show a .03v difference... I thought .03-.05v difference is when you decide to re-balance the pack?!?! Checked on the RCM and other forums and this seems to be concensses.

So I call MA support and ask the kid if this is ok for a brand new pack -I understand balancing is important because the paperwork sais to do it. His responce is that it is borderline if it's ok or not. I ask him what I should do, if I should discharge them on the charger and try again or what? He sais not to discharge them on the charger but it's ok to run them for a bit in the car?!?!?! What??? so then he backs up and starts to explane he's the only one there untill monday and I propable shouldn't do anything until someone who might know what to do comes in... I can't use my new pack till monday?!?!

So back to the forums I go. I find some info about discharging the cells to balanced level and then charging them agan as the 300ma shunt in the charger might not be enough to overcome the difference in cells at a higher charge rate. Makes sense. So I discharge the cells to 3.8volts at 1amp individually via the balance connector and then let them sit the 15min to stabalize (another 4 hour ordeal) test the cells and we are at 3.84vots each (perfect). The charger did take almost 300mah more out of one than the other but I figured they were not the same to begin with.

Back to the balance charger at 4amps and another 3 hours. BEEP, check the voltage again .04volts different. Kind of saw this coming as the charge voltage came up a little quicker on one than the other. Now it's night and I'm a little upset. I rigged up a car headlight to load the battery (4.5amps) and checked the voltage at the balance plug to see if mabey it's more balanced under a bit of a load, started at .04v difference and now it's up to .05v difference after 15 minutes.

So MaxAmps people, and anyone else who wants to drop an opinion (gonna copy this post for another thread in brushless).

1.Are these cells acceptable at the voltage difference they display?
2.Would they be considered "matched" at this difference?
3.Would a difference like this affect life span/failure potential?
4.Would quick charging these cells (non-balanced) exagurate the difference?