Varg Down on power - Thermal Limiting

[rayivers]

I added this post looking at various cooling options to the 'Battery Cooling' thread in Electric Powertrain.

 

[mbw479]

Yeah there is lots of people around the world much faster than me, I can't be the only one having this problem. Great bike, alot of fun to ride but when it comes to a race bike it's more of a toy than a tool.

I did some flat track practice on mine this weekend, at 60hp it started to limit output after about 7-8 laps......they need a warning on the dash to let you know when this happens because it comes on slow, then eventually the bike get really slow.... its a bit confusing when it starts.

 

[Beagle]

I did some flat track practice on mine this weekend, at 60hp it started to limit output after about 7-8 laps......they need a warning on the dash to let you know when this happens because it comes on slow, then eventually the bike get really slow.... its a bit confusing when it starts.

That and Supermoto on long tracks when you can keep it pinned for long will be terrible for this. I wonder if they have a way to address this for the incoming Supermoto Varg?

 

[willy]

I did some flat track practice on mine this weekend, at 60hp it started to limit output after about 7-8 laps......they need a warning on the dash to let you know when this happens because it comes on slow, then eventually the bike get really slow.... its a bit confusing when it starts.

How long did it take to do 7-8 laps?

 

[mbw479]

How long did it take to do 7-8 laps?

5-6 minutes

 

[willy]

5-6 minutes

Wow, so it goes to show its not just sand riding but anything where it is getting put through its paces. How long is a flat track race?

 

[mbw479]

Wow, so it goes to show its not just sand riding but anything where it is getting put through its paces. How long is a flat track race?

Thats on hard packed deco too......Around here a flat track race is normally 4 laps, max 4 minutes so it will be fine. Different events can be much longer though. There is an event I do every year that is a barrel race with barrels 700M apart, the race takes 4 minutes, the varg would not be able to do it. Thats is 8 times holding it flat out between barrels, I am sure it would overheat before the race finished.

 

[NZEV]

I have a different power issue, I'm riding motos on a sand track. The stark is thermal limiting itself at 7 minutes and by 10 mins is going so slow. The battery is getting hot and putting itself into a limp mode. After a month of testing and lots of emails back and forth with stark. stark admits this is what happens when it's ridden on sand under heavy load, but according to stark the product is not defective because I'm not using it for its intended purpose as they looked at my bikes ride data and said, I'm going from 0% to 100% throttle constantly which they say causes the battery to overheat. I'm no Sebastian tortelli but I was inside the the top 15 mx1 NZ, and their is no way I can get the stark to to a 20 min moto flat out. It just can't handle the jandal.

Is it limiting due battery overtemp or IGBT (inverter) overtemp?

 

[mbw479]

Is it limiting due battery overtemp or IGBT (inverter) overtemp?

IGBT, by feel it is hot…..

 

[Beagle]

Technically it's perfectly doable to go liquid cooled for intense use as Ducati did with its 150 hp MotoE with 18 kWh battery (made of 1152 "21700" cells).

Maybe the extra weight would be worth it for road legal Supermoto ?

 

[willy]

Is it limiting due battery overtemp or IGBT (inverter) overtemp?

I don't know, whys that?

 

[Theo]

That may be a bit of an extreme case use (sand and national pro level) but they do advertise it for competition.

They do indeed advertise it for competition, I won't question that. On the other hand, they have also written in the manual that the recommended operational temperature range is up to 25°C/77°F. I did notice that before buying the bike but I bought it anyways because I'm way slower than professionals and because I dislike the typical summer warmth, so it wouldn't be too bad to skip some rides in the hottest weeks of the year anyways, besides I can always find some fresher air in the mountains where I can rent downhill bicycles.

At least now the limitation is pretty clear, I'm just surprised not to have seen anyone else reporting it?
I guess the other guys riding sand must have been slower than you

Actually Josh Hill did discuss such issue in this video, from 3:00 to 4:05; notice that he also talked about the recovery cooling the bike down. He also answered my comment about it; the comment is highlighted.
link to YouTube video with highlighted comment

 

[Beagle]

Actually Josh Hill did discuss such issue in this video, from 3:00 to 4:05; notice that he also talked about the recovery cooling the bike down. He also answered my comment about it; the comment is highlighted.
link to YouTube video with highlighted comment

Good catch, missed that, so that could be an issue for pros, and some specific terrain/use like sand, Supermoto, flat track.
AFAIK it wasn't an issue racing and winning AX UK, we'll see how it goes in France SX tour with Bogle and Zaragoza !

For the Alta boys, did they change anything regarding thermal limitation between their early and final bikes?

 

[Theo]

AFAIK it wasn't an issue racing and winning AX UK

I don't recall the source of the following piece of information; I think I've heard A. Wass saying it in an interview, but for that championship they used Vargs with what looks like the same battery case but with fewer cells inside because their capacity was enough and their combined weight smaller. Now that you've made me thinking about it, I think that maybe there was more room between the cells and heat didn't accumulate so much.

 

[willy]

Good catch, missed that, so that could be an issue for pros, and some specific terrain/use like sand, Supermoto, flat track.
AFAIK it wasn't an issue racing and winning AX UK, we'll see how it goes in France SX tour with Bogle and Zaragoza !

For the Alta boys, did they change anything regarding thermal limitation between their early and final bikes?

SX would be much easier on the stark, as the tracks are tighter and it's more about momentum and rhythm, usually on a hard pack track, so it's not being held wide the whole time and as long as the races aren't more than 12 mins. plus the help of the factory stark team doing everything to keep it cool and I would imagine the factory bike would have a much higher thermal limit programed in than our production bikes. Bogle will probably do the france sx ok, but if bogle was doing a outdoor national it wouldn't have a chance.

 

[mbw479]

I don't recall the source of the following piece of information; I think I've heard A. Wass saying it in an interview, but for that championship they used Vargs with what looks like the same battery case but with fewer cells inside because their capacity was enough and their combined weight smaller. Now that you've made me thinking about it, I think that maybe there was more room between the cells and heat didn't accumulate so much.

They need all the cells to get the operating voltage up as they are connected in series.

 

[Beagle]

I don't recall the source of the following piece of information; I think I've heard A. Wass saying it in an interview, but for that championship they used Vargs with what looks like the same battery case but with fewer cells inside because their capacity was enough and their combined weight smaller. Now that you've made me thinking about it, I think that maybe there was more room between the cells and heat didn't accumulate so much.

SX tour are typically 10 min races, 4 rounds outdoor then 6 nights indoor (3 double night events including Paris SX of course).

Some french riders are doing 25 min outdoors but regional level, not elite.

Edit: Thomas Do said he had a lighter battery for the last 2 rounds in SX tour. Important detail he was racing SX2 capped at 48 hp. The battery pack consists of 4 parallel sets of 100 battery cells in series. They can remove 1 set to save 7 kg, maintain the same voltage, rear wheel torque would be reduced to 704 Nm and maximum power reduced to 60 hp (thanks to Last2Stroke).

No clue if they did that in AX UK nor if they'd do that in SX1.

 

[Philip]

Edit: Thomas Do said he had a lighter battery for the last 2 rounds in SX tour. Important detail he was racing SX2 capped at 48 hp. The battery pack consists of 4 parallel sets of 100 battery cells in series. They can remove 1 set to save 7 kg, maintain the same voltage, rear wheel torque would be reduced to 704 Nm and maximum power reduced to 60 hp (thanks to Last2Stroke).

If Stark offers such a package from the factory, let's name it Stark Varg Lite, I bet it would have its fans.

In fact, they should offer a spare battery with a reduced cell count for $2.5K.

 

[Travelingmike]

Got about 12 hrs on Stark. Riding at PC( hangtown), 55 Y/o intermediate othg, 84 deg. I was doing run up for a triple I had been doing , battery at 45%. I run 48 hp. For the first time I turned throttle- expecting normal awesome response. I turned it to full- I never do this, realizing response was lacking. I cased the end of triple- thankfully no wreck. First time slow/ lack of response on my Varg- a bit unnerving. I do some top up charging with 120v generator. Is this thermal limiting? I sent message to Stark. Another guy was on track- pro level on a Varg- no issues. Thoughts? I charge minimal- so fan on while charging probably not an issue. Bike did feel hot.

 

[mbw479]

Got about 12 hrs on Stark. Riding at PC( hangtown), 55 Y/o intermediate othg, 84 deg. I was doing run up for a triple I had been doing , battery at 45%. I run 48 hp. For the first time I turned throttle- expecting normal awesome response. I turned it to full- I never do this, realizing response was lacking. I cased the end of triple- thankfully no wreck. First time slow/ lack of response on my Varg- a bit unnerving. I do some top up charging with 120v generator. Is this thermal limiting? I sent message to Stark. Another guy was on track- pro level on a Varg- no issues. Thoughts? I charge minimal- so fan on while charging probably not an issue. Bike did feel hot.

It takes a fair bit of wide-open throttle to thermal limit the Varg, I have done it twice in 30hrs of riding.

The first time I was doing top speed runs on a beach, I held it flat out for 800M (1/2 mile) then turned around and did it again immediately, on the 4th run it thermal limited.

The second time was on a flat track with 2 long straights about 250-300M, it thermal limited on about the 10th lap.

It would be very hard to do on a mx track especially if the track was rough.