I like to view it from the perspective of being a tour de france bike racer before 1990 when they didn’t wear helmets. If the total time of all the riders from any of the tours of more recent date, when better records are kept, is added and put in relationship with the amount of long lasting head injuries that occurred, there’s a ratio revealing a likelihood that’s unknown to me but I like to believe it tells of the greater importance of being good at falling.
I wear a helmet if I go out of the city on a bike but on the board I almost always put it on. too many weird things happen on a board. literally two days ago almost fell off someone else’s crazy powerful board without a helmet just trying it going down the street.
In a weird unexplained bike accident I had I experienced a very scary fading out for a 20 minute period but I luckily started to recognize faces and shook it off and have been said to be as good as ever if not better now! If I had been wearing a helmet I wouldve been just as injured as I hit my cheek bone only. If there had happened to have been a car behind me and I’d been run over my helmet wouldve likely been no help of course.
Yeah absolutes are tough. Not an apple guy either.
Let me rephrase - your tolerance for risk is much higher than mine. I always balance charge my lipos. If i had some 18650 packs i might not, but for Lipo - i always balance charge.
Safety is more important to me, and i would not feel comfortable suggesting to anyone that they don’t balance charge lipos. That seems like suggesting negligence… Someone will do this, with damaged cells, or already mis-mashed and different charge levels… it’s a BAD IDEA AND RISKY. So please, balance charge your lipos until you know what you are doing and can make an informed decision and accept that risk for yourself.
I’m not particularly safety minded, I almost always forget my helmet unless my kid is with me…Then I remember because I make him wear his.
I do get particularly pissed off by burning up money and that is ABSOLUTELY what you will do if you continually do NOT balance charge. You might not have a fire from a vented cell, bit you will eventually get a bad cell. Then you have useless battery and have to buy another. All of which could have been avoided with the use of a BMS, or in my case, a balance charger.
More importantly, saying you don’t need a BMS to new builders makes you an asshole or an idiot. Don’t be that guy. I guerentee some 15 year old will see this post and figure he can save 30 bucks, and $30 is a lot to a 15 year old, and burn up a battery, get pissed and quit.
Is making an inane statement that cannot be justified or proven under any definitiin of normal conditions worth causing some kid to quit skating?
The more people on boards the lower the cost of components, the less often cops will screw with us, the more prolific shops will be that sell estate components.
I’ve been using 4 5400mAh 4S Multistar packs in a 2S2P configuration… Some of the cells charge to 4.21, others only to 4.17. After riding, the difference is even more dramatic… Even a 0.2V difference in some cases. If you buy 1000 cells off eBay and match them up based on internal resistance (don’t quote me on that), then you may get away without balancing or balance charging, but you definitely shouldn’t tell a newbie that they don’t need safety features…No offense, but people don’t seem to know much of anything about LiPos when they’re just starting into an RC hobby or EVs…
My friend bought a HobbyZone Champ a couple of years ago, and was confused about why the small lipos wouldn’t hold a charge after sitting full for a month or two- case and point. Yes, you can say that you know what your doing because you’ve blown up a few packs of your own, but everyone ought to use LiPo safe-bags and anything else that would seem even remotely necessary, regardless of experience.
Check out this or this.
I started this and ask in the thread and Im 15 on my first build, just like you all say that you shouldnt try to save a couple bucks on bms but since Im on a limited budget and on my first build what other components can I save on?
15? doesn’t matter. you can figure it out if you want to at any age. it takes responsibility either way and wiring up a bms is fraught with dangers as well. I’m sure you’ll figure it out and do the responsible thing either way, there are different paths to chose and a bms is not the land of instant safety even after you get it running. expect failure! electric skateboards are failing left and right, look around and you’ll see.
What motor? More specs on the batteries, too. I run 8s packs, but it’s really a total of 16 cells- 4s packs in 2S2P, for example.
On the BMS side, you may need to match the configuration, but I don’t really know. I haven’t messed with BMS’s too much, I just make sure my packs are at 3.8v before I leave them lying around. Maybe soon, though
Fair enough. I think the issue is your experience and willingness to chance damaging known-good cells is higher than most. And more concerning - suggesting to folks that definitely do not have your experience and common sense when emulating your setup - who might use a mix of cells - good and bad, because “i don’t need to balance” - could lead to catastrophic issues. That is where i think we get our feathers ruffled and over-react. I’d hate for someone to lose their board, let alone more, because they took something i said as gospel and didn’t question or take precautions.
BMS adds a fair bit of complexity. I’d get your dad’s help to get it setup correctly. You need to do a ton more research - keyword search BMS and start reading.
Having not setup a single board with BMS (my marbel has it, but i’ve not built one w/ it) - there is another wrinkle - pay attention to both Charging Amps, and Discharge Amps. Folks have wired less expensive BMS’ssss as charging only and bypassed for discharging direct from the batteries to avoid the small/cheap BMS limited discharge.
A space cell 10s3p has 60A discharge capability. I’ve measured on dual motors 8s a peak of 45A using VESC’s. It will depend on your batteries’ discharge ability (look at the C rating of lipos, or discharge in amps of an 18650 cell (25r’s claim 20A iirc) - then you get into increased Amp delivery/capacity in parallel…
Higher voltage is more efficient - so less amps. A 6s setup will pull more amps for the same load/speed vs 8s i got 45A peak.
It’s a lot of info - takes a while to get the hang of it all. I don’t claim to be an expert by any stretch, but love learning new stuff every day!
I’ll just leave this here. I have a dozen or so more ammo cans full of swollen or exploded LiPos, but by all means @RogerD, keep advicing strangers to not use a BMS.
Then you must be exceptionally careless. I dont’ have one single “dangerous” cell. And putting slightly puffed batteries in an ammo case kind of explains to me where exactly you are coming from, so to speak. Some people are over obsessed with safety
Roger - losing respect for you quickly. (i know i know - i’m sure it hurts… )
You are saying someone is careless vs poor quality/inexpensive cells that just fail… that’s ignorant. It’s called MTBF. happens.
“over obsessed with safety” - by not using “slightly” puffed cells? Dude - really?!?
Newbies - please use common sense. Don’t listen to Roger here. WIll you burn your house down - likely not, but you definitely might fry your board. And all we all need is another news article about some board catching fire/smoking on public transport… so we have further restrictions using these for transportation/last-mile/fun!
Balance to start - if you get comfortable and feel confident later to not balance - at least learn enough to make this an informed choice vs following some random guy on a forum who isn’t seeming very credible…
Don’t take my word - do research. Inform yourself. Check other forums and look for someone who has a reputation for being knowledgeable/helpful and ask them!
When you own hundreds of Lipos and thousands of Liions that go on half a million dollar aircraft, yeah you tend to be a little ocd about which cells you fly.
You also tend to see a lot more duds when you buy this many.
The ones in the picture are also not “slightly puffed”, they also have shrapnel embedded in them. We keep them in ammo boxes because again, we have tens of half a million dollar aircraft sitting in our workshop and losing even a single aircraft because of carelessness is not an option. If a cell combusts a few years down the line, it won’t matter because we took the appropriate steps to be safe.
I value my life more than these airplanes. If you dont then thats up to you but dont go telling kids its ok as that is idiotic. (I’m not calling you an idiot, I am calling your actions idiotic)
so you fly drones for the military? guess. they use lipos? and then again maybe while a lipo gets a bad rep it’s really the li-ion that are the more dangerous as they shoot off like rockets sometimes when they go up. All this talk makes me want to blow some up honestly. for science. want to know what would happen if it were hooked to the the ac outlet in my house. not “a plug and leave to charge setup”
I’m calling him an idiot. Not because he said something stupid, but because he keeps saying it regardless of proof to to contrary.
My father law has this saying that makes me want to punch him in his old ass fake teeth… “It’s ok to be a dumbass, but there’s no requirement that you open your mouth and prove it”. It rings particularly true in this case.
i think people are giving Roger unwarranted hostility. If you look in the ebike world, which has been spinning long before esk8, it’s pretty common practice to no balance all the time when charging and they dont use a bms. Many people bulk charge lipo if you look on endless-sphere. It’s fair to say it’s more dangerous, maybe, but maybe not and it depends on the person. It depends on even your charger as I’ve heard of cheap balancing chargers setting peoples stuff on fire. In my mind the most important thing when charging lipo or li-ion is that you’re there to deal with anything if it goes wrong. Even if you burn up your house or your neighbors house at least youre there to get them out of it. Of course putting out the fire is even better but a house is replace able and it’s the lives that are all that matter.
here’s the harbor freight new lithium saw teardown. no bms! no way to even balance if you wanted to! danger direct from the store and you’d have no idea
http://www.etotheipiplusone.net/?p=4187
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