Fire History

[Tawpie]

1 hour ago, supercurio said:

sent to either Begode

That's the very last black hole I'd send it to… a qualified tech with a schematic (or a knack for reverse engineering a board to recreate its schematic) would be enough to see if something is 'broken'. Once the schematic is in hand, most any analog EE should be able to evaluate it. I'm guessing it consists of a few off the shelf charge control chips with resistor-divider networks to feed voltage to the control chips. Control chip output is routed to a series FET to switch off charge input. "Balancing" is accomplished through a bunch of comparators driving FETs that engage the bleed resistors... and that's about it.

But figuring out if it was broken (it surely was broken) should be very easy for a tech.

Edited May 27, 2022 by Tawpie

[Mike Sacristan]

I believe the notion of cell abuse is based on the LGM50T being called a 7.3A cell. All tests I have seen show it to be a nicely working 10A cell which performs almost identically to the Samsung 50e. Even at 15A.

The updated spec sheet shows 14.4A at +10 to +25C. Then dropping off to 7.3A as they get warmer (or colder). It is hard to find proper tests with all the data we would want but it looks like there is a span of +25C before it goes down to 7.3A. These temps are easy to achieve at continuous load. Sure this would stress the cells performance-wise but the same would happen on a Master with Samsung 50e. The spec sheet for the newer LGM50LT show similar 14.4A / 7.3A.

I have abused my Nikola and MSX much more than I have my EXN. The EXN is just prone to taking knocks on the edge of the shell where the BMS is. The same thing happened to my friend Thomas when his EXN fell from a plant pot that he was using as an EUC stand. Tipped and fell from a height of 20cm. There could have been damage before that though... all we know is that it was the last straw that broke the camel's back.

I have seen plenty of the MSP HT riders abuse their wheels. They take the abuse until they don't. In comparison to them I baby my EXN. 

I will check with Sergei is the BMS is lying around somewhere. Sending it to someone for examination would be worth a shot.

I was relying on the balancing to equalise any errors and figured it would be worth a shot. As this is the "hope" that we live by day to day.  

 

[alcatraz]

14 hours ago, GoGeorgeGo said:

I think one of the main correlations is with pack size. In terms of how many parallel cells you have. Most fires have been wheels with 4 or less parallel groups or wheels with shoddy wiring issues. 

Having more parallel cells reduces the stress on the packs, since each group is responsible for less output and less input. Just my theory though im not an electrical engineer

Bingo!

There's another way to see it. The pack is relatively low-current for the wheel's power draw.

An 1800Wh pack is commonly 4P and if it uses low-current cells like M50T it has about: 4x10A = 40A current. That's under ideal conditions. 40A is not a lot.

The insane new RS134 that's on the way has only 3P and can do ~110km/h. You'd think those wheels would all go up in smoke but not necessarily. 3P is fine if high current cells are use. For example 3x30A = 90A.

Apparently at high temp (50-60degC) these M50T low-current cells have even less than 10A output so there's thermal runaway when you pull relatively normal currents after the batteries have heated up.

You could probably get in trouble with an EX.N 2700Wh if you torque it. Oppositely there are 4P packs that are run gently and will work fine.

(Personally I wouldn't use other low-current cells like 50E if I were heavy or pushing the wheel.)

[alcatraz]

A few randomly placed high voltage alarms like this one should be sufficient to catch a bad bms I think.

 

(I'm aware that this is a LOW voltage alarm (useless), but there might be a high voltage alarm out there somewhere.)

 

[Funky]

You guys are talking about - that batteries don't "like" heat. Lets say people are riding 32-35+C in summer. Add the heat that batteries make.. Maybe there's something also?

Also charging in summer 32-35+C temps..

Edited May 28, 2022 by Funky

[goatman]

some batteries like heat, if the lg m50lt doesnt like heat and it gets hot then it will get damaged and the cell resistance will increase and then it will run hotter faster and pretty soon you have a heater cell

p42a liked 103f/39c which i used 13 amps to get it there and then gradually decreased the amps to the 3.2v cut off give it a 2 minute break and charge it up while its nice and warm

what some think is abusive others like 

even my lead acids like 30c to deliver their rated capacity

but when you start talking about these storage batteries, they like low C rates and controlled environments like in your house not out in the hot sun or freezing cold

i like light and fast that can be quickly recharged and can take the "abuse" even if those packs dont last as long as a pack with twice the capacity and needs to be replaced twice as often, you only used half the cells as a big pack.

in Mikes video Sergei was mentioning to replace the packs every year, pretty pricey

run a cell the way its designed to run and you can charge it twice a day for a year straight (730 cycles) before thinking about replacing it

[Funky]

As i ride very rarely. And when i do, i charge mine wheel once each 3-4days.. I don't plan replacing batteries sooner than 5 years. Or only when i get problems..

Or if i don't have any problems in those 5 years. Buying completely new euc, when time comes. I'm sure there will be "new" light ~20kg wheels made in that time period. With "real" smart BMS and all goodies..

I at least hope, at some point they will stop making those "monster" wheels.. Start updating/refreshing lighter wheels. < As most people buy those. (Talking about people who don't make youtube videos, chat on forums. Who simply buy wheel and ride.)

Edited May 28, 2022 by Funky

[techyiam]

10 minutes ago, Funky said:

at least hope, at some point they will stop making those "monster" wheels.. Start updating/refreshing lighter wheels. < As most people buy those. (Talking about people who don't make youtube videos, chat on forums. Who simply buy wheel and ride.)

Around these parts, and along the routes that I take, the euc's that I have seen in the wild have been Shermans, EX.Ns, V11s, V12s, RS-19s. I have seen maybe one other T3, and 1 or 2 S18s. I rarely come across euc's that weighs less than 50 lbs.

[yoos]

4 minutes ago, techyiam said:

Around these parts, and along the routes that I take, the euc's that I have seen in the wild have been Shermans, EX.Ns, V11s, V12s, RS-19s. I have seen maybe one other T3, and 1 or 2 S18s. I rarely come across euc's that weighs less than 50 lbs.

Funny how this mimics the car preferences -- in the Old World people ride small, compact cars while America likes large pickups and muscle cars  

[Begodecrashtestdummy]

37 minutes ago, yoos said:

Funny how this mimics the car preferences -- in the Old World people ride small, compact cars while America likes large pickups and muscle cars  

Yep we like to go fast and show off 🤣🤘🏻 

 

Edited May 28, 2022 by Dosingpsychedelics

[techyiam]

18 hours ago, yoos said:

Funny how this mimics the car preferences -- in the Old World people ride small, compact cars while America likes large pickups and muscle cars  

I have been told that in the US where gas prices are much lower and land is more expansive than in Europe, people tend to buy bigger vehicles. However, I don't see any reason why this would hold true for personal transportation devices like euc's. But then I don't have the stats either.

 

Edited May 29, 2022 by techyiam

[Funky]

1 hour ago, techyiam said:

Around these parts, and along the routes that I take, the euc's that I have seen in the wild have been Shermans, EX.Ns, V11s, V12s, RS-19s. I have seen maybe one other T3, and 1 or 2 S18s. I rarely come across euc's that weighs less than 50 lbs.

Sure i would love those wheels to, i'm sure anyone would love bigger, better things. We mostly have apartment building here. 

If i didn't live in 3rd floor apartment. I would not need to carry it in train daily. (We got those old trains, where you walk upwards..) And i needed the "speed" (We ride on sidewalks with people..) And i needed the range of 40+km.  Heck if i didn't need the portability. I would love to have 20" euc, bigger tire the better.

I was talking about people who used these thing as real "last mileage" devices.

I haven't seen many riders here, once i saw a guy in shop with euc - and he had one of those small v8, ks16, ks14 type wheel. And once i saw 4 guys riding 2 commander, 2 shermans on highway < That was surprising to see.  Doh they where going side lane.  (We don't ride with cars here.. And mostly on sidewalks, as we don't even have bike lanes. Only in bigger cities and rarely.) To me euc is the same as regular bike.

Heck our cities are even small 3x3kms (Most). Main big city here is ~14x14km size.

Edited May 28, 2022 by Funky

[techyiam]

59 minutes ago, Funky said:

Sure i would love those wheels to, i'm sure anyone would love bigger, better things. We mostly have apartment building here. 

If i didn't live in 3rd floor apartment. I would not need to carry it in train daily. (We got those old trains, where you walk upwards..) And i needed the "speed" (We ride on sidewalks with people..) And i needed the range of 40+km.  Heck if i didn't need the portability. I would love to have 20" euc, bigger tire the better.

I was talking about people who used these thing as real "last mileage" devices.

I haven't seen many riders here, once i saw a guy in shop with euc - and he had one of those small v8, ks16, ks14 type wheel. And once i saw 4 guys riding 2 commander, 2 shermans on highway < That was surprising to see.  Doh they where going side lane.  (We don't ride with cars here.. And mostly on sidewalks, as we don't even have bike lanes. Only in bigger cities and rarely.) To me euc is the same as regular bike.

That makes sense. I won't likely see people who are using euc's as last mile devices. And our bicycle routes include many side streets that are that not well maintained. And I only need to go up 5 small steps. For me, I won't consider using last mile devices because I would rather ride my motorcycle instead, or simply just drive. But after discovering euc's, and realizing how efficient and fun these things are, and how wasteful ICE vehicles are, I can't let myself drive ICE vehicles, if I can help it.

[Paul A]

European cities/towns may be many centuries old.  They grew in size organically, not largely planned/designed from the start, before invention of cars.

Residential and commercial use are mixed together, necessarily in walking proximity.  Narrow streets were adequate for walking, horse and carriage.  

Large. public plazas, town squares, promenades, public transport, are pedestrian centric.

 

US cities in instances are planned/designed from the start for cars.  Residential and commercial can be separated by great distances.

 

Small cars are needed for some towns with old, narrow streets.

Edited May 29, 2022 by Paul A
Typo

[yoos]

12 hours ago, techyiam said:

I have told that in the US where gas prices are much lower and land is more expansive than in Europe, people tend to buy bigger vehicles. However, I don't see any reason why this would hold true for personal transportation devices like euc's. But then I don't have the stats either.

That and what Paul A is saying: more compact towns and cities in good old Europe. There are lanes where literally only a small car will get through. The same goes for parking: a large car sometimes simply won't fit or will require a ton of microscopic back-and-forth maneuvering to park into an opening.

Generally speaking, as a convenient commuting tool the EUC shines the most as a last mile or general 5-10km trip superportable vehicle (i.e. easy to carry, trolley and stow, no parking required). And this scenario is best served by the relatively affordable 15-20kg sub 45kph cohort of EUCs (no suprise it's also the best selling category) In other scenarios it's the ingenuity and fun of the EUC that makes people use them instead of say bicycles, scooter, motorcycles, cars and public transport. It takes an enthusiast to fully embrace the "EUC life".

[Funky]

Well our roads in city aren't so close to houses, etc.. like in that photo. xD We got roads where 2 cars could pass each other more or less.(People/cars share the path front of houses) We simply don't need those big euc here. City to next city we got highway and normally next closest city is 20-25km away. <(So we really can't ride there..)  And as i said, we got cities pretty small. Heck i could ride whole outer court of my city on 18xl and i still would have 50% battery left.  

[yoos]

Sorry for having derailed this thread a bit. To get back to proneness to fire, I wonder if it is best to have individual packs with 1p each or a single pack with maximum amount of parallels? E.g. the infamous begode packs are 900Wh packs 24s2p. Within that pack there is a series of 24 pieces, and each piece is 2 cells in parallel (both in terms of spatial location and in terms of electric circuitry). A standard Nik+ packs two such packs. What would be safer -- a single 24s4p pack with cells packed in groups of four, or four packs 24p1s each?

On first glance the one-big-pack setup is better because having more cells in each group averages out variances in capacity, requiring less balancing. It is also arguably easier and cheaper to waterproof, protect and equip with a BMS one single pack compared to several smaller ones. [Though, of course, for weight and shape balancing reasons the battery is usually split between two sides of the wheel]. 

[techyiam]

15 hours ago, Paul A said:

European cities/towns may be many centuries old.  They grew in size organically, not largely planned/designed from the start, before invention of cars.

Residential and commercial use are mixed together, necessarily in walking proximity.  Narrow streets were adequate for walking, horse and carriage.  

Large. public plazas, town squares, promenades, public transport, are pedestrian centric.

 

US cities in instances are planned/designed from the start for cars.  Residential and commercial can be separated by great distances.

 

Small cars are needed for some towns with old, narrow streets.

Forget electric or any other form of motive power. Those use cases require good old human power: in-line skates, kick scooters, skate boards, walking, jogging, and etc.

[techyiam]

6 hours ago, Funky said:

Well our roads in city aren't so close to houses, etc.. like in that photo. xD We got roads where 2 cars could pass each other more or less.(People/cars share the path front of houses) We simply don't need those big euc here. City to next city we got highway and normally next closest city is 20-25km away. <(So we really can't ride there..)  And as i said, we got cities pretty small. Heck i could ride whole outer court of my city on 18xl and i still would have 50% battery left.  

Sounds like for your use case, should you want more comfort, a S18 with Molicel would do well, assuming you are handy, and can make the stock suspension to work well.

Edited May 29, 2022 by techyiam

[RayRay]

5 hours ago, yoos said:

What would be safer -- a single 24s4p pack with cells packed in groups of four, or four packs 24p1s each?

Wait a minute, I re-read the above and this wouldn't work. One cell in series is only a few volts and you've connected them all in parallel. Unfortunately, you can't power an EUC with 3.7 volts, (but the fire risk would probably be the same for the same amount of batteries).

----------------------------------------------------------------------------------------------------------------------

I'm not sure it makes a difference, since you still need to fit these packs in the same space and then wire them together (to make four parallel packs). The problem is we're trying to cram more and more batteries into a relatively small space; making the end result more combustible. (If one cell ignites, then they will likely all ignite in short order.) 

When riding, having more packs is safer in general because you can deliver more power to maintain balance (maybe). However, when it comes to fires, they tend to spread quickly (even to the other side) because there is so much fuel. My understanding is basic and I'm speaking in generalities, but these fires come down to poor wiring/electronics in dangerous situations (i.e. lots and lots of batteries sitting next to one another). 

Edited May 29, 2022 by RayRay

[yoos]

1 hour ago, RayRay said:

Wait a minute, I re-read the above and this wouldn't work. One cell in series is only a few volts and you've connected them all in parallel. Unfortunately, you can't power an EUC with 3.7 volts, (but the fire risk would probably be the same for the same amount of batteries).

Sorry, my mistake, I meant 4 packs of 24s1p [not 24p1s which was misspelt]. Voltage should be the same, the difference is whether we have 4 parallel packs or one pack where each element of the series has 4 parallel cells.

[FlyingWigs]

1 hour ago, yoos said:

Sorry, my mistake, I meant 4 packs of 24s1p [not 24p1s which was misspelt]. Voltage should be the same, the difference is whether we have 4 parallel packs or one pack where each element of the series has 4 parallel cells.

Shouldn't make much of a difference, the individual cells will still have the same loads.

Again, why I liked the idea of the 2700wh nik, it's 6p so the cells should stay within mfr specs. 

[Begodecrashtestdummy]

On 5/28/2022 at 4:25 PM, Funky said:

As i ride very rarely. And when i do, i charge mine wheel once each 3-4days.. I don't plan replacing batteries sooner than 5 years. Or only when i get problems..

Or if i don't have any problems in those 5 years. Buying completely new euc, when time comes. I'm sure there will be "new" light ~20kg wheels made in that time period. With "real" smart BMS and all goodies..

I at least hope, at some point they will stop making those "monster" wheels.. Start updating/refreshing lighter wheels. < As most people buy those. (Talking about people who don't make youtube videos, chat on forums. Who simply buy wheel and ride.)

Sheesh you charge once ever 3 to 4 days .i charge my wheel twice a day  lol 😂 I just got my wheel and  I’ve put on over 700km on it already 🤘🏻😎🤘🏻I’m already gunna start saving for another wheel aswell hopefully battery technology makes huge advances in the next few years 

[Funky]

8 hours ago, Dosingpsychedelics said:

Sheesh you charge once ever 3 to 4 days .i charge my wheel twice a day  lol 😂 I just got my wheel and  I’ve put on over 700km on it already 🤘🏻😎🤘🏻I’m already gunna start saving for another wheel aswell hopefully battery technology makes huge advances in the next few years 

When i ride, i normally ride ~6km daily, slowly ~20-25kph speeds.. As i don't gear up at those rides.(Only wrist guards) Job/train/home. For fun rides i go ~25km rides.

To me euc is nothing special.  Same here, i will be thinking of buying something new, when "solid state" batteries become a thing.  

I'm thinking about building new PC now. Than buying new euc. Can't waith Ryzen7000, RTX4000 release. ~4k$ budget. Also getting new 32" 1440p screen. <3 My FX-8120 cpu and GTX660 gpu is starting to show AGE.  

Edited May 30, 2022 by Funky

[alcatraz]

On 5/29/2022 at 7:49 PM, yoos said:

What would be safer -- a single 24s4p pack with cells packed in groups of four, or four packs 24p1s each?

Depends on the type of failure. 

If a cell internally short circuits 4x 24s1p is safer. Because 3 neighboring cells aren't going to dump their charge into the short. Instead the 3x 24s1p packs are going to dump 1/24 of their voltage/charge into the remaining 23s1p pack.

If a nickel strip open circuits (severs) then 4x 24s1p would also be safer.

With 4x 24p1s you need four BMS'. That's the problem. More places a failure can occur during charging etc. Those four BMS' need to communicate between eachother to not overcharge healthy cells when some cells start to deteriorate.

If we didn't run "the wrong cells" in our wheels, it would be less likely that they would deteriorate which puts a lot less pressure on the BMS(s). But any cell would eventually (10+years?) show problems. Then only a great BMS would keep things operational/safe. 

Personally I think probably the easiest solution is to use only one really good BMS. The single BMS should be user replaceable with a standard wire harness. You run a diagnostic on it, get a green light and ride. No matter if the pack is 20y old you can trust it because the trusted BMS gives you a green light.