ASK Cub Reporter, 01.24.2013, Version- You Have Questions, I Have Questionable Answers

Cubby,
After reading some information on rctech I am confused as to which is the best way to break-in a lipo battery, can you clear this up?
Charley D.

Cubby– Yo hey what’s up Charley, and thanks for taking the time to write in.

What is the best way to “break-in” a Lipo? Actually, I think I have a better question than yours, how about “Do I actually need to break in a Lipo?”.

Doing battery tests take a lot of time, seriously. For example, lets say I wanted to truly see if there is a need to “break-in” a Lipo. IMO, that would take at least a sample size of 10, meaning I’d be doing some sort of break in method on 10 packs, while also testing control packs that were not broken in, just run normally for comparison. Lets say during the break-in process you are only using 1 or 2C charge rates, so that’s between 35-70 minutes charge time per pack, and lets say you are only discharging at 2-5C (12-30 minutes per pack) during the break in process. And lets say we test them out to 100 cycles to measure long term effects. You can do the math here, even if using 5 chargers (and dischargers) you are looking at hundreds of hours here.

Now I’ve seen a bunch of rocket surgeons who absolutely cry up and down that you must “break-in” a Lipo pack. But… out of all those guys, I’ve yet to see any of them show scientific proof that indeed it results in higher voltage, longer run-times, or longer cycle life. Some of them may post a few discharge graphs here or there, but only of small sample sizes (like 2), and they never show graphs of their “broken in” packs compared to control samples. Oh and they never show this data out to a bunch of cycles, like 100+. As stated earlier, it takes a lot of time to do these things, so I certainly don’t blame them for not doing extensive testing, however they shouldn’t be shoving the “you gotta break-in your Lipo” propaganda down peoples throats unless they honestly know it’s worth the time and effort.

What I do know from first hand experience is this- your Lipo’s are only good for a certain amount of cycles, the more cycles you use “breaking them in”, the fewer you will have for actual driving.

So… to get down to your original question, “what is the best way to break-in a Lipo?”. I personally wouldn’t waste my time until it has been proven to be worth it. But… if I had a gun to my head and was forced to break some in, I’d recommend three cycles at a 1C charge and 2C discharge. This method wouldn’t waste much time, it wouldn’t put much strain on the pack, and well, I’m just making this up, so why not.

But seriously, some day when I come up with a couple hundred hours to play with, I’m firing up the CBA and truly finding out if “breaking in” a Lipo is worth it.

Cubby-
So “Santa” brought my youngest son a new Kyosho DBX VE 2.0 this Christmas. And, after being away from RC for 20 years I have been plunged back into the hobby head first trying to learn about brushless, lipo, etc… Along with the technology advances this ride has 3 gear difs, which of course you know (saw the review), and I have been battling trying to get him a set up that will drive through
the corners.

My question pertains to gear dif set ups as I believe this will be the key to making this thing work. What are the typical effects of stiffer/looser difs in both front and rear of 4wd buggies? I noticed in the review you only added dif oil to the center, why? I have been given a couple of different ideas and feel a little confused about it. Also, with the center dif is there any great effect to the front or rear by heavier or lighter there? Thanks for the help!!

Mark S.

Cubby– Yo hey what’s up Mark, be sure and shoot Brian your snail mail so he can totally hook ya up with an uber BSRC sticker pack. Oh and hey, hope you are having a blast with your new K-car, the DBX is an animal no doubt.

Why did we put oil in the center diff of our Kyosho DBX buggy? Putting oil in the center diff ensures more power makes it to the unloaded end of the buggy. For example, if there is no oil in the center diff, every time you punch the throttle the buggy will tend to lift the front end, and once the front tires leave terra-firma all the power would get transfered to them, which of course does no good because they are in the air. Putting oil in the center diff helps to transfer more power to the rear wheels that are still on the ground where it can actually be used.

There is of course a major downside to running too heavy of center diff oil- jumping. Lets say you were to lock the center diff in your Kyosho. When jumping your buggy would be extra sensitive to throttle and brake inputs, making it harder to jump. A vehicle with a properly set-up center diff is easier to jump than anything else, easier than any 2wd, and easier than a 4wd with no center diff.

About oil in the front and rear diffs- to really boil it down for bashing, the heavier the oil you use, the less “traction” that end will have. For example, lets say you are having massive over-steer and you are looking to tame the steering down a bit- you would put heavier oil in the front. Lets say the rear of your buggy is sliding all over the place and you would like to have it more planted- install lighter oil.

As far as a set-up that will be easier for your son to drive- that depends a lot on his driving style. Many new drivers put too much steering input into the transmitter, resulting in them over-steering and darting all over the place. Taking out some steering, whether it be with heavier front diff oil, heavier front springs, or simply turning down the amount of steering on the transmitter (or a combo of all of the above), can help these drivers. However, some new drivers have a hard time steering because they never lift off the gas and push going into corners. Taking out steering won’t help these drivers, only learning some throttle control will.

That’s it for this week folks, submit your questions, answers, and whatever else is oozing from those sic brains of yours to Cubby at BigSquidRC dot com. If your email makes the big time you get free stickers, if I deem yours as “letter of the month” we’ll totally hook ya up with one of the new BSRC t-shirts.

YOUR Cub Reporter