CR500rider

Lets see how long this will stay up here http://www.rccrawler.com/forum/showthread.php?t=273524

rc18junky

One thing you need to realize is no lipo cell are made in the USA there all from china. maxamps is getting them from the same factory's all lipo makers are getting them. My hope is maxamps for what they charge is doing a better job screening the cell they receive. Making sure there better quality cell then others. I do trust as Americans and not using slaves labor as in china there building them with pride and insuring a quality product

chuckk2

Last I saw was that Revotrix was making it's own cells in Singapore.

Maxximize

I haven't really tried anything else, but I like my Maxamps Life packs. They came with a build sheet, initialed by someone for each station they passed through. The cells were within .01 volts of each other on both packs when I got them, and they still balance out within .01 volts. It is my understanding that they are built when you order them, and the cells are cherry picked. Performance is very consistent from fully charged until the packs are dead. Granted I'm driving a bone stock brushed Mini Revo (Titan 550) so there isn't a huge amperage draw here, but I'd bet it's around 15-20 amps or so under load. So far so good, I'll keep using them. I believe you get what you pay for when it comes to electronics.

Maj_Overdrive

My Feedback: (11)

Guys, there's no screening or cherry picking going on. Most cells are made in China by a number of different companies. Enerland is the only company I know of that makes the cells and also sells completed packs, as Polyquest packs, but I'm sure there are others that do the same.

Either way way here's how the packs you buy from the lhs, tower, Hobbyking etc are made. Someone who wants to sell packs gets in touch with a lipo company in China. The lipo company says we have cells in these capacities and in grades A, B and C. The cells are given these grades based on a few rudimentary tests after being manufactured based on internal resistance, low load charging and discharging performance etc. You need to remember these are quick, low load tests not full blown high load cell matching like in the NiMh days when paying extra for that Trinity pack with matched Panasonic cells was well worth the extra dough. Only a small sample of lipo cells from each batch get more extensive and higher load testing that would even come close to what you could call matching, screening or cherry picking. So even picking grade A isn't that much of a guarantee. Maybe the factory has a AAA grade option where they test a greater number of cells per batch to try and ensure a more accurate sample but it's still not a guarantee. Either way more times than not one factory's cells are in more than one company's packs. Even Enerland's cells end up in packs other than their own Polyquest brand.

So the guy who wants to sell packs picks a factory, then picks the grade. Now they can have them shipped to the US for assembly and sticker slapping here. Or they can have them assembled by the same factory there, maybe another factory there and have them shipped wherever with stickers already slapped on.

I honestly hate lipo conversations though. The whole industry is a sham, especially when it comes to C ratings. There isn't a lipo pack out there that can discharge anywhere close to its discharge rating without sustaining damage. BigSquid had a video years ago of a 3s pack being discharged by a pair of automotive battery testers which made for an amp draw (I forget exact number) right at the packs constant, not burst C rating. Either way the pack's voltage dropped from 12.6v (fully charged) to about 9v instantly when the test started which would've triggered the lipo cutoff in the esc. How can you give a pack a constant c rating that would trigger the cutoff when you try and draw a load equal to the constant c rating? Oh and btw they let the test continue and the pack was on fire in about 3 minutes. This was 5-7 years ago and things have only got progressively worse with inflated c ratings. I can't find that big squid video anymore but there are others on youtube showing the same thing with these inflated c ratings. I forget whether it was SMC or SPC but one of them actually wrote a letter on Facebook calling out other manufacturers for inflating ratings because they get their cells from the same place as other sticker slappers and they had to inflate their own ratings to keep up.

Go ahead and think you're getting better because your company charges more and/or says they do more. The reality is the equipment to test and prove that you're really getting more costs more than their annual advertising budget. And if they had that equipment they'd be posting discharge graphs from it (and not the Eagletree stuff they used to post back in the day) to prove what their packs are truly capable of. No company will do that because it would disprove their own ratings (if you're a current customer would you want to see how much they've been lying to you?) and it would make them look bad compared to the competition's inflated ratings. Well at least to the morons who don't like concrete data and would rather believe cheap marketing hype than the expensive testing equipment. So I'm pretty confident none of the companies selling packs would actually buy that equipment and if they do have feel free to tell us the make and model. The factory that makes the cells usually (not always) does have that equipment, but like I said only a small sample from each huge batch get more extensive testing on equipment like this. And the factory may not even take the time to test a sample from every batch and instead just down grade the batch to B or C rating.

One of these days I'm going to win lotto and I'm going to buy the equipment necessary. Then I'm going to shame the entire lipo pack industry with real numbers on a website and post it on all the forums. Until then I hope someone starts regulating the industry with a realistic c rating system, one that keeps the cells above the cutoff voltage and preferably doesn't cause fires in 3-4 minutes. End rant.

Maj_Overdrive

My Feedback: (11)

Oh and by testing equipment I don't mean stuff like the Competition Electronics Turbo 35 GFX in the original post of this thread. Nice job bringing back a dead thread btw. The GFX is a nice piece of equipment and gives good results but isn't as laboratory spec as I was thinking. A proper setup to do high load, constant amp draw testing has a load center that costs way more than the GFX. I don't even want to think about what the measuring and recording side costs.

Edit: I actually used to have the same Turbo 35 GFX in the original post (got it in a lot for cheap and sent it in to be upgraded for lipo) and have used it to test some lipos. Between it being way more than I needed and the sickening results I achieved testing lipos I sold it. Thought selling it would improve how I felt about lipos if I couldn't tell how bad they were lying to me but come to think of it I actually haven't bought a lipo since I sold it. And now I'm due for some new packs... Maybe I'll just quit rc

Maxximize

Yea I think C rating on batteries is actually very similar to horsepower and kv ratings on nitro engines and motors respectively. And RPM ratings on mass produced brushed motors fit in there as well. Some could be measuring no load RPM/kv and using more volts than the others are, so you never know what you're getting. Same with nitro engines. They make flywheel dynos, sure. But they aren't made to adhere to any specific standard. It's not like the automotive industry where manufacturers are forced to dyno all of their engines using the same net horsepower figures, and the process is standardized by the SAE requiring them to dyno all the engines sold in the US exactly the same way. Cold cranking amps on car batteries are similarly rated by a standard and almost always supply the rated power. Imagine buying a battery for your RV or worse yet your bass boat that was rated like RC batteries are only to discover that it can start the engine, only if everything else is turned off because it can't hit the required amps. It's a shame the RC industry isn't like the automotive industry in that manner. I agree with you, though. I too hate convos about power plants and batteries/nitro fuel for RC usually. They just never seem to go anywhere and people never actually answer anything, just argue their ideas are right and everyone else is wrong. I take to finding stuff out on my own these days when it comes to engines, motors, fuel, and batteries. I bought the ones for the Revo because they are the only smaller LiFe packs that will fit in it and have larger gauge wire for use with ground vehicles instead of RX/TX packs with 20ga wire on them.

Now, what I meant by cherry picking is that they receive the bulk shipment of cells from China, and test them once they are at the assembly shop and pick the best of the bunch, possibly just canning the weaker cells and the ones that won't take a full charge. This is what I think you pay for with high end batteries that usually cost more. Also, when dealing with Maxamps you have support that is based in the US, so if you have issues you can get meaningful help, another thing that adds to the cost. I've heard all too many times of cheap no name packs that arrive with horribly out of balance cells, and ones that have cells that simply never will balance out properly. For cheaper packs, it seems to be a lottery of sorts. That said, I just got 2 Zippy Flightmax 2S 2100mah 30C LiFe packs for use in my newly built Lunchbox that ran $15 each, $9 less than the 1050mah packs for the Revo. So far, they have been perfect. Balancing out just as well as my Maxamps 2S packs for the Revo. One major difference though is that the Zippy ones cannot be charged as fast. They have a max charge rate of 2C, while the Maxamps ones are good for 15C. I can't hit that with my charger, but I do charge them at roughly 6C (max for my charger is 6 amps) and they take the same mah as a 1C charge and are fully charged from dead (2.8-3.0v per cell) in about 10 to 12 minutes. I'm a little more careful with the Zippy packs and only charge them at 3.5-4 amps at the highest. But usually give them a 1C charge if I'm not in a hurry. I do always balance charge every time though, even though I don't think you have to with LiFe.

All that said, I have seen videos of 4S? LiPo RC batteries being used to start cars, so they must have a decent burst rating of at least a few hundred amps and be able to hold at least 12-13 volts, or that would never happen. That is however, just as you said, a burst test scenario and not at all a sustained test. I'd bet if the car's starter was left on for 20 seconds it would cause the battery to grenade. I wonder if one could build their own device to pull heavy amounts of constant amperage and test batteries with a good multi meter?

Maj_Overdrive

My Feedback: (11)

Full disclosure. Brands I've had, ran, and/or tested on my GFX: MaxAmps, Polyquest, Turnigy, Hyperion, Venom. I've never owned a MaxAmps lipo, I tested a friends nearly new pack though. Not going to get into the results but MaxAmps only beat one pack and basically tied another. And I had bought an 8cell NiMh from them that they wouldn't take back when they shipped it to me missing a battery bar. Had to remove the shrink wrap and solder on a battery bar myself to use it. Not exactly the warrantee and customer service those drinking the koolaid usually talk about.

I don't know the details of every companies operation. Maybe there is cherry picking going on. Maybe they do take the time to charge every cell they receive, then discharge it recording the results. Maybe they do chuck, discard, recycle, resell, return or give away the cells they reject. The time it would take to do that testing would require higher prices whether the testing equipment was basic or more advanced. But all their advertising in magazines and websites requires more money too. Just look at Traxxas and their price increases. Sure they've come out with some new features for their vehicles, but the vehicles are largely the same while their prices have increased a lot the last 5 years or so. The thing that has changed more than their vehicles is their advertising. Multi page ads in magazines, at xmas time those magazine ads grow to basically a catalog, their sponsorship of multiple drag racing cars, the monster trucks. All that stuff wasn't around 5 years ago when their prices were lower. A LST used to cost way more than a Maxx or Revo 5yrs ago, now the gap has closed. Losi still does the same amount of advertising they did 5yrs ago but Traxxas has increased theirs and raised their prices to compensate. Sure MaxAmps USA labor costs more and so does their warrantee but there's other factors too.

What anyone believes is worth it for them is up to them. Not gonna judge or try and change anyone's minds. If you like brand X, they've been good to you and you can afford them then by all means go for it. MaxAmps has been at the center of this kind of debate forever and unless they go out of business the debate will rage on. Because Internet.

Maj_Overdrive

My Feedback: (11)

Back to ratings for a second though. Yeah there needs to a standard for rating batteries. Whether it's holding a certain voltage under a certain load, temperature or whatever. Then you could compare apples to apples instead of varying degrees of bs.

I dont think Kv is as suspect. Kv is always rated unloaded. Kv will vary slightly but this is due mostly to manufacturing tolerances, variances in how the motor is wound, exact magnet strength, etc. Now power ratings, peak wattage, etc that is more suspect. What's acceptable? Sure the windings can handle 2000watts going through them but the motor will be 250f in 20 seconds killing the magnets. Even Castle admits that the 90% efficiency it has for some of its motors is only at a power level the motor cannot reliably sustain continuously.

Which brings us to why lipos (and esc's) survive even though they shouldn't. Google some Castle esc datalogs and it becomes clear. Motor draw is nowhere near constant with only peaks approaching or meeting the rating of most packs. Obviously these peaks don't last long and average draw is much lower. An esc and battery may be 150amp rated but neither would survive long trying to sustain that level of current. But they can take it when the peak amp draw is 150amps while average amp draw is more like 80amps. But even that average draw of 80amps is just an average of a single application of throttle that lasts what, a few seconds? Then you release the throttle for a turn or stop the vehicle completely.

So so you mash the throttle from a stop, amps rise fast, hit a peak of 150amps for a split second to get the vehicle moving. Once it's moving amps drop down to around 100amps, fluctuating as the vehicle finds, loses then finds traction again, until tapering off little more. Then you release throttle or brake before doing it again. And taking off from a stop cause the highest spikes in amp draw, if you're already moving amp draw isn't as high. So while on the throttle average amp draw is more like 80amps which the esc can dissipate and the battery is more able to handle. Over the course of a whole pack though average amp draw is even lower, maybe 30amps, due to the breaks in acceleration while turning and braking. This is why boats and planes are harder on lipos, they have a more constant draw that's also higher due to the amount of drag on them.

Testing. Constant amp draw like you mentioned is key. The Big Squid video I mentioned was a simple test but amp draw was not constant. It was 2 automotive battery testers, the kind with the coils and the sweeping analog gauge, a multimeter to measure voltage and another to measure current by inductance. I forget the exact number of amps it drew but I believe it was 60amps and was definitely right at the packs constant c rating. Either way at the start of the test amp draw was 60amps, but amp draw wasn't constant and dropped as the packs voltage dropped. The load needs to vary to keep amp draw constant. The load center required to maintain a constant amp draw is a specialty item and not a cheap one, and why I used the term "laboratory spec".

Maxximize

Yea I think that brands of batteries are kind of like cars, some have better luck with one or the other. Though they are in different vehicles, I notice no real difference in performance in the trucks between my Maxamps and Zippy LiFe packs except the Maxamps ones can charge much faster. They both perform similarly to the 6S NiMH packs I run in those trucks, but do have more punch of course. Although the 1050 packs in the Revo do provide slightly more speed than the 1200mah NiMH does. I think that has to do with the NiMH getting hit so hard at full throttle that it runs lower in voltage under load than the LiFe packs do. The Titan 12T does seem to be a power hog. In the Tamiya with it's silver can, it's much harder to notice and I run a 4200mah NiMH in that one to boot.

Man that sucks about the NiMH pack! I haven't had to claim a warranty for my packs yet, but I had a few questions about them and the response time was quick and clear. I'm happy with that for now, and hope to not have to claim a warranty on them. I would actually try for these though in hopes of getting a new one. If one of my Zippy packs died I'd just toss it and buy a new one haha. Either way, we all use what works for us I suppose. I've always subscribed to the you get what you pay for idea. Recently I went against that rule with a Flysky radio system and Zippy batteries, which has worked well.

That's what I've always thought with ESC and motor ratings. Efficiency, wattage, and amperage isn't really very accurate. I think of it as a "Our number is bigger so our motor is better" kind of thing.