ASK Cubby, Verion- It’s Thursday So Listen Up

“LiPos

Dear Cubby,

I have a question about safe liPos. There are a range of liPo’s on the market and they vary in price, but is there a safer one? I have been bashing for about 2 years and never used any liPo bigger than an 11.1. A track was just built down the street from me for 1/8 truggies and buggies, so I dropped a rent payment on one. I don’t plan on racing other than the other guys at the track so I don’t need the best, but I do want something that is safe. So should I save up and get a $250 Max Amp or a $70 Fantom? I don’t want to burn down the truggy or the house.

Thanks,

Lipo impaired Dan”

Cubby- Yo hey “LiPo Impaired Dan”, thanks a lot for the letter. I like letters that get right to the point and are about something that a lot of people would like to hear a response about.

So… you want me to tell you which one is the safest LiPo on the market. I can not do that. Years ago I worked for a battery manufacturer (read- designer & importer, they were all made overseas) and all I did for 60-80 hours a week was test Lithium based cells. Sometimes that testing was running single cells on a West Mountain CBA to check output performance. Sometimes it was going outside into the parking lot and doing safety testing. The safety testing I did ranged from dead shorting a cell, to physically damaging a cell, to overcharging them. So yes, I got paid see which Lithium based cells were the “safest” and which were the most “dangerous”. I have not done that job in over a decade, therefore, I have very little clue on what cells are the best and worst on the market today.

However, if there is one thing that I always am, that would be verbose, so here are a few of my thoughts on the subject.

1. A LOT of Lithium packs are sold now days, yet it is still rare to see one go into thermal runaway. Sure, I see cells that have vented internally (puffed) all the time, but it is quite rare to see one actually “go up”, and when I do, I would say that 100% of the time it was caused by user error. What are some of these errors? Improper charging is the big one. Some idiots like to over charge their LiPo at high amp rates to get an output voltage increase, but this can have a gruesome ending. Physical cell damage is the second big one. For example I’ve seen guys accidentally cut a LiPo pack with a hobby knife while working on their truck which sets off the pack. Or I’ve seen bashers land hard and their pack goes flying out of their truck which can often dent an edge or taco the pack, also setting it off. If you charge (and discharge and store) your LiPo packs properly and make sure you don’t physically damage them, it is highly unlikely you will ever have an issue.

2. Bigger packs store more energy than smaller ones, but they aren’t prone to “going off” more easily. For example, a huge 6S 6500mAh pack has a lot more energy (and potential for damage) than a small 1S 400mAh cell, but you won’t have a problem with either unless you do something really stupid (like charging a LiPo in NiMH mode or driving a nail through the center).

3. When I did do testing years ago, I noticed no correlation between price and safety. It was really pretty random. Some of the cheapest packs seemed relatively safe, as did some of the most expensive. Same thing went for the most dangerous, some of the cheapest packs tested very poorly for safety, as did some of the most expensive. The only way to know which is the safest is to test them all and nobody I know has the time or money to do that.

4. LiFe cells did tend to be the safest back in the day, but you’ll suffer a voltage penalty when using them. However… if you are running 8th scale buggy, perhaps you can run 6S LiFe and you’ll end up (roughly) with the voltage of a normal 5S LiPo pack. Or run a 5S LiFe for “roughly” the voltage as a LiPo 4S.

Boiling it down- if you don’t do anything stupid, safety will NOT be an issue when using Lithium based batteries of any of the popular brands.

“like your BigSquidRC

Friend,

Really love your BigSquidRC. The story is just like a legend! i can image the feeling of a boy got his first nitro truck, must not less than the feeling that i got my first beautiful dress! I love RC, and i hope that there is a chance for us to cooperate!

Looking forward to your response!

Best regards,

Liffish H.”

Cubby- What… In… The… Freak…

So ya… I get plenty of crazy letters here at Big Squid. This one might be one of the strangest. Sure, endless rants on how bad ROAR sucks and how messed up “racers” are can make for fun reading, but this letter from “Liffish” just makes me scoot back in the chair and scratch my head.

So here is your response Liffish… Ok… So I am guessing English isn’t your first (or second, or third) language. I have never worn a dress, so I have no clue as to how the first one you put on might have felt, but yes, I agree with you in the fact that rc does kick ass.

So there is your response, I think you owe me a sticker pack for taking the precious time out of my day to read your email. Just say’n…

There it is folks, this week’s ASK Cubby is a flip’n WRAP! Normally I say here that I hope anyone and everyone shoots me an email, this week it can be anyone and everyone except for Liffish. Any which way, my email is thecubreportrc at gmail dot com. Write me, love me, cherish the thought that I might actually read your email.

YOUR Cub Reporter