ASK Cub Reporter, A Weekly Q & A Session- Version 12.09.2010
You have questions, we have answers, you have issues, we’ve got your tissues.
“To whom it may concern; you may want to revise your test results & testing methods in the 4s lipo shootout…
Capacity test: You put the turnigy lipo in last place because it had the lowest mah capacity; that’s utterly ridiculous. That’s like scoring a Ferrari higher because its faster than your mustang. If you actually scored that test on rated capacity vs actual tested capacity, the turnigy would come out in 1st place because it held 80mah more than its rating; the lipo in first place held 60mah less than it was rated for- your testing criteria/ methodology is seriously flawed, making that test pretty much worthless and entirely misleading. Once again you have failed to test like with like, resulting in totally skewed results that are largely subjective.
Top-speed test: Another horribly flawed test. This time you compared lipos with different mah & discharge ratings and decided it was totally reasonable that the highest rated pack should come in first place, even though the rather lower spec turnigy was only 1mph slower. Given that the thunderpower lipo is capable of producing 344.5 amps continuous ( well, until the wires melt anyway… ) and the turnigy only 180 amps, its safe to say the turnigy actually gave the best result based on its specs vs performance. As it happens though, the MMM system is recommended for use with lipos capable of producing at least 120amps, so all those batts are more than adequate; if you really wanted to see how well the pack could power the buggy then you should have been geared for perhaps 50-60mph on 4s lipo, to really put a load on the packs and see which ones couldn’t supply the current that’s being demanded, thus a slower speed ( and higher lipo temps ) would have been observed. Poor testing methodology once again..
(this is gonna be a long one.. click through to read the whole thing)
Voltage under load test: I don’t even know where to start- your commentary on the turnigy pack is hilarious quite frankly; you compare lipos of massively varying mah capacity and C rating, and put the pack with the smallest of both last in the results table; well duhhh…. Lets do some basic math shall we. The pack with the highest mah capacity will run for the longest length of time, assuming the discharge ratings were all the same & were accurate ( this is the #1 reason why all your tests are so horribly flawed- you cannot compare packs with different specs and group them in the same results table without accounting for the difference specs that will skew the results ). However, if the mah
capacity of all the packs was the same, then the packs with the highest C rating would last the longest, since these packs will suffer less voltage sag under load resulting in a longer discharge time before they reach 3.0v per cell; I have grouped the lipos you tested in order of their power output, collectively in terms of maximum continuous current and total power rating in watt/ hours:
Thunder Power RC 5300mah 65c = 344.5amps & 89.04 watt / hrs
Team Checkpoint 5400mah 35c = 189amps & 90.72 watt / hrs
Venom Group RC 5000mah 50c = 250amps & 84 watt/ hrs
ACE Acepow Electronics 5000mah 40c = 200amps & 84 watt/ hrs
Turnigy 4500mah 40c = 180amps & 75.6 watt/ hrs
Well, wadda ya know, the order is almost exactly the same as the test results, who’d have seen that one coming? Oh yeah, that would be anyone with a calculator & 2 ounces of common sense. It seems however that the Ace lipo did better than expected- I suspect this is down to some inflated specs on the part of venom, otherwise the packs performed exactly as they should have done according to their ratings. It boggles the mind that you were surprised the lowest rated pack ( runtime and C rating ) came last in the test, and the highest rated pack came first; these are the sort of observations that I would expect a 10 year-old to make, not a bunch of so-called experts who give advice to people based on some horrifically flawed understanding of raw data.
Weight comparison: You have go to be kidding me?! You score packs with different mah capacity & energy densities based on weight, and again, wadda you know, the smallest and lowest spec pack wins the weight contest! What kind of jokers are you? That’s like saying a 500g weight is lighter than a 600g weight, so the 500g weight wins the contest. The results are barely worth looking at because, one last time now, you cannot compare lipos of different specs and then group them in the same table- the mah capacities atleast should all be matching, then you might be able to draw some conclusions / results about their energy density & C rating vs their weight ( highest C rating being the heaviest is the logical conclusion is the way I see it.. ). As it is, the results table you arrived at is a no-brainer pretty much- the turnigy is the smallest pack so therefore the lightest, Venom & Ace seem to have traded places once again due to some over-rated specs most likely in the venom department, checkpoint is heaviest due to having the largest mah capacity- the more lipo material you have to store energy, the larger and heavier the pack has to be…
As for the actual driving test results, no surprize really about the results there, though it was nice to see the Ace lipos getting great results as Iâ€™ve been recommending those to people as a state-side
alternative to the Turnigy lipos.
Overall I have to say I am deeply disappointed with how poorly carried out your testing is, and how ridiculous the results were due to a total lack of common-sense when interpreting the results. I would strongly recommend in future that you either consult someone who has some proper electrical knowledge whom can assist you in turning the raw data into a results chart that has even the slightest bit of meaning or relevance, and I would also strongly suggest that you only compare LIKE WITH LIKE to reduce the horribly skewed test results you are producing with out accounting for different specs between each pack.
Yours Faithfully, Neil W.”
Cubby– What’s up Neil? A little passionate about your batteries eh? Join the club.
First off, there is no need for us to “revise” our testing at all. This 4S Lipo shootout was done specifically to show where you gain (or lose) performance in batteries of different capacities and “C” ratings. Perhaps you would have preferred they all have been the same rated capacity and “C”, but that was not the criteria of the last shootout. Alas, we have already done a shootout like that, just look back at our Lipo Shootout 2 if you want to see packs of similar capacities go at it head to head.
So why would us crazy guys at BigSquidRC even consider using packs of different capacities and “C” ratings? Yes, certainly, we could have requested specific mah packs from the manufactures, but we did not. We do our shootouts based on what the readers want. The bulk of the emails looking for the next shootout were requesting we do a best of 4S, and that’s exactly what we did.
So why would our readers even want to see batteries of different capacities battle each other? Well, have you ever seen a track that ONLY allowed 4S 5000 mah “40C” packs to race? Ever see a bash spot that only allowed 4S 4500 mah “20C” packs? No you haven’t, nor have I. The bulk of our readers walk in to a hobby shop and see a vast array of capacities and “C” ratings, they simply want to know what the highs and lows of each pack are, and more importantly, which one is the best for their individual needs.
We compared different capacities and “C” ratings against each other in the shootout because, like it or not, they WILL be competing against each other on tracks and bash spots across the world. At the end of the day, just like the masses, we at BigSquid drive our cars/trucks, and don’t care what the sticker says, we care more about having longer run times, higher top speeds, with more power than the next guy.
Maybe the next shootout will all be the same capacities, maybe not. It’s really up to what our readers want to see. This isn’t about us, it’s about you guys. I’ve got Neil down for a vote for “same capacities and C ratings”, all you guys gotta do is email us and let us know what YOU want to see next.
So is it fair that we even allowed smaller capacity packs to go up against larger ones in our shootout? Is it fair that lower “C” rated packs went against higher ones? The results speak for themselves. Neither the highest capacity nor the highest “C” rated pack won the 4S shootout, and the same can be said for our Lipo Shootout 2. In our first shootout the winner gave up roughly 3000 mah to two of the tested packs, but it was tied for highest “C” of the field at 40C. Btw, the pack that finished last in the first shootout was also a 40C.
Couple more notes on our 4S Shootout-
Capacity- Neil would liked to have seen the pack that went over it’s rated capacity the most be declared the winner, but the masses want to know which one simply has the longest runtime, so that’s how we gave out the win in that category. BigSquid has an enormous reader base because we cater to the non-hard core types, the guys that simply want to know which of these packs will make their car run the longest. Fortunately for everyone, we listed and posted a graph of the results of our capacity test, so anyone can look at that info to determine a “winner” with whatever criteria you care to use.
Also of note in capacity- In the industry, it’s not a good thing to be far under, OR far over the stated capacity. Being under capacity gives the end consumer less runtime, and can also be a sign of poor cell design and/or QC. Being far over capacity also creates issues, the first issue being that most cell manufactures will “promise” a potential buyer (battery reseller) specifications plus or minus 3 percent (sometimes more like 5 or 8%). Meaning, if “Happy Flower” battery company is trying to sell a pack to “American Battery Company”, they’ll promise that their 100 mah pack will have no less than 97 mah, and no more than 103 mah, trying to impress them with good cell design and quality control. If “American Battery Company” buys a thousand of these cells and they vary wildly from 80-120 mah, then “American Battery Company” knows that “Happy Flowers” quality control stinks. If the QC stinks on capacity, it’s going to stink on other performance parameters as well.
Then there is another issue with being over capacity, called “understating” a pack (a couple of companies have gotten into some pretty good trouble because of this). This is something manufactures and sometimes resellers do to try and make their packs look more impressive. Every buy a pack labeled at 5000 mah that actually put out over 6000? That is well beyond a QC issue, that is just outright lying. Want to impress a battery noob? Take a 5000 and label it as only being a 4000 mah. It’ll have lots of runtime compared to another companies 4000, and typically maintain higher voltage. In the industry, when looking at cells of the same capacity you want to see as close to rated capacity as possible, and see it over a large range of samples. A cell/pack that puts out well over (or under) rated capacity is frowned upon.
Top Speed- Perhaps some readers think that the highest capacity and highest “C” rated pack will always be faster. That is simply not so. That’s why we actually test these things. For example, look at our first Lipo shootout where the SMC 5000 20C pack pulled 54 mph, and the SMC 5200 40C only pulled 51. In the previous two shootouts we had trucks set-up for higher top speeds to really differentiate the packs, but in the last shootout we took a different approach using a buggy set-up for standard track racing as a change of pace just to see what the differences might be. This lower load resulted in all the packs being bunched tightly together. The TP was able to nudge out one extra mph, a very impressive achievement indeed considering how the test was set-up.
Voltage Under Load- Some readers might think that the battery with the highest mah and “C” rating will inherently win. Once again, not so, that’s why we actually test these packs. It’s entirely possible a kick-ass 4500 20C COULD beat a 5000 30C, and some people don’t seem to realize that. For example- even in our 4S shootout the Ace 40C pack produced higher voltage than the Venom 50C pack. If a higher “C” pack always puts out more voltage, then the Venom should have done better than the Ace, and it clearly did not. For an even clearer example, take our first shootout where the Thunder Power 5400 25C averaged 7.12 volts under 30 amps and the SMC 8000 28C only averaged 7.10 volts. We never assume any pack is better than another, regardless of what its sticker says, we TEST them to separate the great, from the good, from the downright awful.
Weight- Some readers might also believe that the highest capacity and “C” rate pack will always be heavier. Not so. Do I really need to state examples? Sure! Take our first shootout where the SMC 5000 was lighter than the Speed Power 4000. Or in the second shootout where the JGB 5200 35C was lighter than the Common Sense 5000 40C. Sometimes packs will fall right into line with assumption, but not always, that’s where our hard work comes in handy for you guys looking at buying new packs.
I read your lastest battery shootout and the Gens Ace pack won…… Gens Ace won no doubt because they sponsor your web-page… your shootout batterys should neever come from your web-page sponsors…. maybe that way the best pack will win….
Cubby – Yo Dwight, nice to see you can still type, even with your severe brain damage.
But seriously, my pay (or anybodies pay at BigSquid) does not vary based on who wins our shootouts. Personally, I really didn’t care who won, my one and only concern was to conduct the tests the best we could and let the chips fall where they may. And as a group, all the BigSquid guys pride themselves on being unbiased. That does not, and really can not come across just from reading our shootout over the internet, but if you are willing to travel to the Chicago metro area, feel free to come watch our next one (and that goes for anyone out there). The more witnesses the better.
Thunder Power won our first shootout, and they’ve never been an advertiser of ours. Hyperion won the second shootout, and they’ve never been a advertiser either. Yes, Ace won our last shootout, and yes, they’ve been a advertiser of ours for quite some time, but they also competed in our second shootout and did not win. If we were only handing out wins to advertisers, don’t you think we would have done it during the first two shootouts as well?
In closing, our last two shootouts have been carried out in public at local tracks. There were plenty of non-BigSquid bystanders around, all very curious about the results and our testing procedures themselves. We do all the tests in public so that if anyone ever wants to call us out, we’ve got people other than BigSquid contributors to explain exactly the integrity of our testing. We take our testing VERY seriously, as we feel most of the mags do a poor job, and we just want to crush their biased methods.
That concludes yet another ridiculously long, yet epic, episode of “ASK Cub Reporter”. Send us your questions, hate mail, love letters, crude jokes, and chrome spokes to Cubby at BigSquidRC dot com!
YOUR Cub Reporter