ASK Cub Reporter, 12.06.2012, Version- Another Week of Questions vs My Weak Answers
*Handling – 7/10 -* The NeXXt is not the worst driving vehicle we’ve ever tested, but it was pretty darn close.
It’s gets a passing grade even though it’s one of the worst vehicles you’ve ever driven? I think your scale is a bit off.
Cubby- Yo what’s up Jason, thanks for the email and be sure to shoot Brian your snail mail for some of our uber stickers to paste your rig with.
I’ve explained this before, but I’ll post it up again for those readers that may have missed it. Since we’ve gone to the 1-10 rating system we rarely use 6’s or below. For the most part we use 7-10 as sort of a grade system, such as 9-10 being a type of “A” and being superior, an 8-9 being a sort of “B” and being “above average”, etc. Starting in 2013 we will be going to the grade system. Instead of a 1-10, we’ll simply be going by grades, A through F, which in theory should be easier for readers to relate to, and easier for us reviewers to stay consistent with. High hopes, I know.
As far as the NeXXt goes we gave it a 7 out of 10 for handling even though IMO it was one of the worst rc vehicles I’ve driven in the last 30 years. However.. we use multiple testers, and not all felt the same way I did. While I did not enjoy the NeXXt bouncing around like a basketball with 50 psi of air in it, other testers thought that was a blast. Iron Mike couldn’t get enough wheel time with the NeXXt, and each time he got to drive it he would plow straight into the roughest section of track he could find just to get it bouncing all over the place. What was fun to Iron Mike was pure hell to me, and that’s why we use a multitude of testers in pretty much everything we review here. Each and every one of our readers is different, enjoying different handling styles, etc. We attempt to get a broad spectrum of input from our testers because we already know you guys have very diverse tastes, then we attempt to state as many of our opinions as possible to get you guys in the ballpark with whether or not you would enjoy the product.
There it is, and there ya are Jason. If you don’t dig a buggy that bounces around uncontrollably, the NeXXt is NOT for you, but if you are as brain damaged as Iron Mike, you might laugh yourself silly every moment you are pulling trigger on it.
Oh and.. I’m wayyyy too lazy to check, but I would doubt that we’ve issued too many handling scores lower than the one we gave to the NeXXt, if you have some free time research that for me and LMK.
Young bashers vs. new battery tech
I have a truck/battery tech question that I’m seeking expert advice on and believe you can best answer. The forums are filled with so-so or partial answers so I’d like your take on the matter. I’ve been out of the hobby for over 20 years and battery tech has evolved quite a bit.
My kids (4&6 yrs old) have been begging for R/C vehicles and this year Santa is coming to the rescue. The younger one wants a Gravedigger 30th anniversary RTR and the other a HPI Blitz RTR. Both come with LiPo cutoff and brushed motors. While shopping for a charger, I came to the following conclusions. Overnight chargers will not cut it and good NiMh chargers can only handle one battery at a time. I’d need two chargers to keep up with two kids, and we’d still spend most of the day charging. In cutting to the chase, why not just go LiPo, where I can balance charge in parallel – with one potent charger (liking the i-charger 400W). I am eying up the Turnigy Nano-Tech 2S2P 5800 mah batteries which are no more expensive than NiMh and they can provide the desired run times of around 20-30 min. Charging at a 2C rate safely at 5A, I should be able to charge two batteries in a more reasonable amount of time. I’m not interested in speed at this time, but can’t see sinking one dime into NiMh battery tech.
Q1: In keeping with the brushed motors for the time being, are we going to fry motors or ESC’s with this brushed /5800 LiPo set-up sooner than brushed/5000mah NiMh?
Q2: Assuming heat in the motors/ESC is what kills them – and for my newbie kids, top speed is irrelevant, what gearing should I go with?
Q3: Is there another battery tech that is better for my application such as A123’s LiFe – the rumor being it offers lower voltage and is less damaging than the LiPo?
Love the reviews – keep em coming. They led me (and my son) to the Blitz RTR. Also, the 30th anniversary Gravedigger, with 2.4 Ghz resolved my issue with Traxxas putting crap Radios with their basic RTR packages.
Thanks in advance,
Cubby- Wow, a lot to chew on in your email Ed, but thanks for taking the time to write in.
First- to your direct questions.
Q1- Are you going to fry more motors when using a 2S Lipo or when using a 6 cell Ni-Mh? Answer- I have never buckled down and done a somewhat scientific study on that one. The Lipo will maintain a higher voltage under load, thus making your motor faster, but it is much lighter. The Ni-Mh is putting out less voltage/slower, but it’s heavier to hall around. I’ve done impromptu testing on this subject, but it always yielded spotty results for me- sometimes the motor driven off a Lipo lasted longer, sometimes it was the motor being powered by the Ni-Mh. If I had a spare 100 hours or so I’d doing more testing on this for ya, but I don’t, so I’m not going to give you a solid answer on this one.
Q2- What gearing should you go with? I am a big fan of gearing via temp gauge. Your kids may never get the stock motors hotter than 100 F with bone stock gearing due to their driving styles, in that case you could elect to leave gearing stock. Or you may choose to drop a few teeth on the pinion to knock a few mph off the top end (making them easier to drive) and get longer run-times. Whatever you do gearing wise, pick up a cheap temp gauge from your LHS and use it. Below 120 is awesome for motor life, 120-160 is less than optimal, and hotter than that and you start ruining electronics. But… IMO more important than gearing is properly seating the brushes on those RTR brushed motors. Out of the box most RTR brushed motors arc like mad because the brushes are not seated properly to the comm, thus causing lots of extra heat, wasted energy, and short lifespans. Yes, water dipping a RTR motor is time consuming, it might take up to an hour per motor in the water to seat the brushes, but it is well worth it if you are wanting to get the maximum life (and power, and run-time) out of a motor.
Q3- Is there better battery tech out there for your application than A123 LiFe cells? The A123’s have one major downfall, their form factor. They are a PITA to fit properly in most of our vehicles. And yes, 2 cell LiFe vs 2S Lipo, the LiFe are about 1 volt less under load, meaning your truck will feel significantly slower unless you gear up. But… when you gear up you pull more amperage to make the power, making more heat. Lastly, A123 filed for bankruptcy a couple of months ago, and they haven’t been supporting the rc hobby the last couple of years, so I would not recommend you buy them at this time.
My recommendation to you is… wait for it… no, seriously wait for it… Ni-Mh.
I have a 5 yr old son that is getting his first ever rc truck for Christmas this year. In theory I plan on him doing most of his own charging (we’ll see how well that goes.. LOL) so he’s getting a new ECX Torment and four 1800 mah Ni-Mh packs with an old school Dynamite twin peak charger. I’ve water dipped the motor and made sure the slipper is a bit on the loose side so when he pins it WFO against a wall it burns up the slipper and not something else. I’m going Ni-Mh for this reason- you can do stupid stuff to a Ni-Mh and not get into much trouble, that is not the case with Lipo. For years I was paid to burn Lipo’s up, I know first hand how they react in a thermal runaway, and while the chance is small it might happen, I don’t want my 5 year old anywhere near a Lipo fire.
That’s it for this week ya bunch of lunatics, submit your questions, answers, and anything else in that demented brain of yours to Cubby at BigSquidRC.com. If your email makes the big time on our front page you’ll get free stickers, and if I pick yours as letter of the month you’ll be dialed with an uber new BSRC t-shirt.
YOUR Cub Reporter