Also no offence from me. I am also only interested in the facts. i want to avoid that another myth is created because of misunderstandings. because there are already enough of them.
I have also build a Android app to watch the live recordings to understand the VESC much better.
Your mentioned that the battery is going from 80% to 20 % at 80 amps. Please tell us the voltage for that because percentage values don#t make sense. Because i am quite sure that the voltage sag you are talking about is absolutely normal.
I will be recording more video soon to highlight this, but my battery sags from 48.6 volts down to 42.2,which is not a good amount of sag. As a result, When I get down to 46 volts with no load, I have to stop riding, as I will sag it down to 38 volts or less at that point on a steep hill. Min I should go is 38.8, max is 50.4 volts. Evolve’s new Carbon GT has this issue. The reason, this is their first board with li-ion. They always used lipos before, and never had this issue. Before, when I used to use lipos, I never sagged like this. Chaka has talked a lot about sag in the 18650 thread, and recommended going up to a 12s6p (which is what he uses) to resolve the sagging issues I have. Jason is aware of them too, this is one reason why he doesn’t run cells close to their max discharge ratings. Some sag will always exist, but it’s ideal to get the sag as low as possible (preferably < %5)
Bear in mind, the numbers I give in there are based off of readings from my built in volt meters and was before the app. Now that I have the app, I can see better and determine these things when I’m not going 25 mph and trying not to fall, lol. So I know now my sagging is actually much worse.
This poll confirmed to me that the sagging I’m seeing is not normal.
I don’t know why your against percentages… I get that batteries don’t discharge linearly, like percentages are calculated, but they are pretty close.
Also, regardless of whether this kind of sag is normal or not, the point is that you can’t run these cells that close to their max con rating without a lot of sagging, so again, the VESC-X solves nothing here, since the battery is the limiting factor.
Why is a sag from 48,6V to 42,2V (3,52 V each cell) not a good amount of sag? It#s just normal and what the battery is made for.
When the battery is at 46V (aorund 30 - 40 % battery left) with no load then a sag to 38V (3,17 V each cell). Which is still or because the battery is rated to 2.5V minimum under load. So you still can go full throttle and have fun.
BTW: insead of not doing full throttle you could also set the VESC settings for battery cutoff start and end right because then the VESC is doing that for you. I let mine start to reduce the power at 3.2V and stop powering at 3.0 V. But that is because i run laptop batteries which are only rated for a max power output of 5 A and continuous at 2.5 A. So i overpower them drastically. And instead of my batteries the samsung 25R are build to do that.
But even mine still do absolutely fine and don’t get hot. Because the battery temperature would predict the limit of the cells and even if i drive hard i use max amps for maybe 10 % of the time. On average i hardly ever use max amps. For example if you go full throttle all the time on the flat you don’t even get close to the max amps. Up a hill with your gearing, weight and speed you might do that.
And we don’t draw constantly the max amps so we are absolutely fine. I would even say it would be fine to draw max 100 amps from a 4P setup of those cells because they can stand the burst.
I’m not saying it’s not normal, but it’s just not desirable nor good. And there’s solutions to solve this issue, which are good lipos or higher p li-ions. @Jinra and @chaka are better people than me to talk about the details of voltage sag.
What lipos are you using btw?
The best lipos I used were the zippy flightmax 8000 mAh cells, and they sagged very little.
Don’t know the brand of my lipos? On my laptop cells I have a huge voltage sag. From 50 Vdown down to 32 V (not recommended) under heavy load (80 A) but they still do fine and the board is doing well and powers out 2500 watts which is enough for my weight of 80 kilos with clothes on. And I can bomb up my hills with 42 km/h. But I don’t know about the hills in San Francisco but I can imagine that they are a completely different level.
But you could drive longer on your cells because you could go lower with the volt level under load. I am simply saying the cells are doing absolutely normal and they are not a bottle neck.
Regardless of whether they are doing what they should or not (since we seem to differ largely in opinion here), how can they not be a bottle neck? Your not going to be able to pull higher amps from those cells than the current VESC v4.12 can already do continuously, so the VESC-X does nothing to increase performance here…
Why shouldn’t you pull 80 continously from them when they are build for that. You said you only can do 40A or 50A from that pack and I simply say that this is not the case. Anyway, we should stop here.
Sometimes there is a reason why you want to have higher amps. One - two thing I can point out are better heat management, better quality material (last longer), doesn’t get damaged easily. Just same reason why boeing 737 is a huge success although they fitted in way bigger engine that they don’t need, because only using 20% of the load increases it’s life expectancy.
Because you get more sag… Ask @onloop why he puts a 40 amp fuse on his space cell, when the batteries cells are rated to 80 amps?
The closer you get to your rated max amp (assuming the rated max amp is valid and confirmed by people like Mooch), the more sag you get… This is a fact, which any person whose researched batteries extensively on this forum can back up. Ask chaka, ask jinra, ask onloop, and many others. They will tell you the same thing.
I’m sorry, and I mean no offense, but I’m done wasting my time arguing about it. You can either accept it as a reality or not.
But most likely, Jason will keep the 40a fuse on the battery pack for the the Raptor 2, which as I have already shown with diagrams even, will make the vesc-x a useless improvement in a dual drive raptor 2 in terms of it’s increased continuous amp rating.
Assuming the 40amp fuse as the amp limit we can figure what will be the max power of this board while integrating voltage sag. At full charge ten amp draw from a typical Li-ion with a 20 amp rating will be at 3.8 volts at full let’s say X the 40 amps = …
The most powerful direct drive board can do 1520 watts max before dropping precipitously within seconds from voltage sag. No?
By the way. I drive my 80 A max board with a 40 A fuse. Not recommended but on more than 1000 km i never had a problem. I guess my car fuse needs way more than 40A to blow. But Enertion might use other fuses.
So @Hummie now i am curious. Just tell me what we will see in the future of you. More P batteries, A123 or Lipo’s.
From looking at all these claims and reading the true figures it does look that it’s not going to be much better than raptor 1 and not worth the extra money. Feel sorry for anyone who has paid more than $1000 as personally don’t think it’s worth much more.
i have no plans but am surprised we all let the important fact slip through that the motor and esc typically isn’t near their peak abilities with these Li-ion battery packs. The real power limit is the batteries and power is so important
Didn’t evoheyax switch from the batteries to the fuse as bottle neck? But now really let us stop here. Otherwise we kill this thread with bitching around. @evoheyax impressive board btw. (seriousely)
Ok now that we have a thread that is just for RV2 my interest with the new board is going to be how reliable it will be. The vids that are coming out against the V1 Id like to see powering on numerous laps up and down hills for say 20mins. Rather than just a power lap on veladrome or once up a hill. Ok it will need to be sped up.