Made a travel battery related post in my other build thread.
TLDR at the moment it’s looking like I can make a 20S3P travel battery, using 12x 5s1p modules that are each 80Wh and have their own 3d printed enclosure. They would be wired up in a 4s3p config for this board. It’s gonna be a very tight fit, but it probably should be possible to make it fit.
Also this pack structure would require that I don’t have a BMS in the board due to space constraints. I don’t mind that, but definitely something to keep in my mind and plan around.
I’ll probably build my offroad board’s 20S1P battery this way, so that I can test if it’s worth commiting further to this modular idea. If the construction and the cells both work well, and the pack fits, then I would have the battery situation sorted assuming I can make it to esk8con.
You could always toss the individual 4s3p packs onto a hobby charger that can charge and balance the cells at the same time. Then you could skip the BMS all together.
The individual packs would be 5s1p. I’m going to make a harness for a BMS so that I can balance them all at once but hobby chargers would also work. They are so much extra effort though
Cologne update as I forgot to do one. Day one was on the raceboard. Was a pretty fun track. @TZDKB also tried out my board and also got a video of chasing me down.
And I’ve also got a selfie stick view from a couple laps - I wasn’t able to push the board as much or put down my puck with the camera though, but still looks fast.
If you watch Tilo’s chase video, you will see that I put down my hand a lot heelside. I don’t normally do that on outdoor tracks, but on this track, where the loss of grip is especially sudden due to the slick surface, I felt much more in control and more confident pushing grip limit with getting so low and sometimes even putting my hand down. That said, it’s a very exhausting way to ride, and on usual surfaces probably not faster.
Regarding the tires on this track. I found that the linnpowers worked very well, but needed a good 3 laps of carving going up in intensity before they got up to temperature and started feeling good. At higher pressures I could have heated them up a bit quicker, but I don’t think it would have been quick enough to be usable in a race scenario. When we run a race, we usually have half a lap or so to warm up the tires. Cold they felt like I was riding on ice. This is very similar surface to Waldshut, but there was a lot more rubber laid down on the track. Also probably similar surface to what the Aussies run indoor sometimes.
I had a lot of rubber pickup as well, and the tires were sometimes flinging rubber into my face.
for 2 year already , i use spindtend J version at 18s with 100A battery current and 225 phase each side, yes i use lipo , so no bms and my pack can push more then my vesc for sure but i never have heating problem with my custom aluminium plate i made , btw if you need more power , if you feel you need more power your 80A bms is the problem , also you use 2 vesc so its only 40A battery per side , i can’t read 400pages so i am not sure if you figure it out why your molicel pack not performing like you want , but can handle 180A continous and your bms limiting it to 80A , i know you don’t want to heating up the battery pack but burst is only for 1-2 second you never gonna break something ,
I’ve seen way too many spintends blow up, I don’t trust them anymore, especially not for pushing it this hard. There’s much less blown makerx D100S then spintends out there.
I’m running 520 phase amps for acceleration, 580 for braking, 180 battery amps for both acceleration and brakes.
Regarding the battery, the BMS is only wired up for charging. I went so overkill on the BMS because I wanted to be able to charge at 45A - but ended up getting P42A instead of the originally planned P45B so I can’t charge above 30A.
For discharge I use the full 180 amps, which is about 13kW and that’s not enough. I’ll be building a new pack with tabless cells and copper connections eventually, specced for 270A at 20S, that will be 17-19kW depending on sag.
To expand upon this since I think its important information for esk8 builders to know:
The vast majority of builders today use a charge only BMS because the protections of a discharge BMS can often sacrifice the riders safety to protect the board battery.
Discharge BMS’s do offer the benefit of cutting off discharge in case you forget your board on and can protect your pack from a slow death by idle discharge, but their primary function ends up being to cut off power to your board at the worst possible time (max throttle, high load) which generally ends in streetface.
(You can also find much smaller 10-40a BMS’s to use for charging only than 60-300a BMS’s for discharge as well)
sorry i didn’t zoom the picture of is battery pack i was not really reading the post
my first bms was in 2007 with lifepo4 if i remembering
but i still prefer lipo for simplicity of changing my pack to 12s-18svoltage and capacity in a minute, also lipo i safer for high temperature vs molicel , also i can remove pack if something fail , for me adding more electronics mean more chance to fail , yes i am old school but only thing i need is a lipo pack+fuse+ wrist seadoo style kill switch . no fancy stuff no apps ! i my enduro ebike is also running on lipo with 25kw
i yes like manualy balance my each of my 16Ah lipo pack x8 , this is so old shool for you guys but like i say i never have any problem because i am the bms !
lipos are cool but you don’t get the range of li-ion. Tucker and Reggie are both running bms on their raceboards (that are set up with lipos) with good success
very nice build !, i plan to go 4wd also for better braking performance (face plant performance! ,) but i am bit concern about the wh/km, as i am not racing like you but only cruising for long distances ,
also my M1-AT with straight cut is geared 5.2 at 18s , and its already loud and need to wear earplug + motorbike helmet to help so not sure if you will do the move or not thanks
range ? my pack can be connected in 2 minute without any tool , with theses configuration :
12S : 400, 800,1600w/h,
18S: 1200, 2400w/h
not so bad, and i charge them at 40A
even less of a reason to run lipo in my opinion.
can run a smaller charger, just have to plug it in once, don’t have to manually balance anything (although you could just run a bms with your lipos)
my last pack could also charge at 40a in theory but i never had a reason to nor the ability to for that matter. 20-25a was plenty.
i also don’t know of any reason where changing the configuration of my pack would provide any benefit for me but i’d love to hear your reasoning behind it.
doesn’t apply to you as you’ve previously stated but the high output lipos that are used for racing don’t have the range of li-ion builds on similar platforms.
I can’t give you any number on how much the wh/km will go up. This board can consume quite a lot of power when it’s pushed. I took it on my 15 km commute once, keeping 30-40 mph / 50-65 km/h for most of it and the battery was very close to empty by the end.
It’s also definitely going to get louder than 2wd.
ok , i ordered 4.6 from kevin will get them tomorow and will see if the sound is quieter ,
i really love your setup maybe next year i will go with molicel but i don’t want to spend time to build pack , maybe purchase a use race pack will a great idea . I really like your stuff i hope you send more videos, i just saw your GT2E remote in the last video and it was my first ek8 remote in 2016 and yes its best and the failsafe work really well also
It’s a kinda janky way, but that was the easiest way I could think of just buying a proper solution.
I made a circle out of 50mm thick nickel that fits over the tire. I made them so the fit over the exway venator 165 mm, but I plan to use linnpower slicks - the venator is the plan B.
Each of them is 7 Ohm, meaning at 12V, each power supply powering 2 wheels so 6 heating pads, there’s around 10A per PSU. My power supplies are 12.5A so I might also wire up a PC fan in parallel and ziptie it onto the PSU if the setup works decently.
This is some kind of kinda toxic chemical that I apply onto the tire tread, and it’s going to get the tire to grip more and drop durometer. The linnpowers measure 67-68A from the factory, the 9x3.5 CSTs measure 72A. I’m going to apply some coats to both - that should make them grip more, and hopefullllly make them perform better for the race. If this experiment goes sideways I’ll have the exway venators to fall back on.
,) but i am bit concern about the wh/km, as i am not racing like you but only cruising for long distances ,
. Was on my list of things to try. Interested to hear how it goes