Stark Varg charging/starting issue

[Erwin P]

I rode my Stark to 3% yesterday and put it on the charger later that evening. Did not start charging, nor was i able to start the bike.
As long as i held the power button i got a red light, turns of after releasing the button.
Later that evening i tried a few other times over the hours and evetually it started charging.

So this morning i had a look and the bike was charged a 100%, blue light, everything as supposed.

However i turned it of to stop the charging and have a little ride. It wouldn't turn on. Same red light as long as i hold the button.
I took the problem from yesterday was an empty battery and thus no power to start the bike. But i've seen a 100% now so plenty of power to do anything.

Any of you had this problem?
I mailed Stark, but they mostly take 2 days to respond and i have a training tomorrow and a race saturday so i hope for quicker answers.

 

[fsfs]

I rode my Stark to 3% yesterday and put it on the charger later that evening. Did not start charging, nor was i able to start the bike.
As long as i held the power button i got a red light, turns of after releasing the button.
Later that evening i tried a few other times over the hours and evetually it started charging.

So this morning i had a look and the bike was charged a 100%, blue light, everything as supposed.

However i turned it of to stop the charging and have a little ride. It wouldn't turn on. Same red light as long as i hold the button.
I took the problem from yesterday was an empty battery and thus no power to start the bike. But i've seen a 100% now so plenty of power to do anything.

Any of you had this problem?
I mailed Stark, but they mostly take 2 days to respond and i have a training tomorrow and a race saturday so i hope for quicker answers.

This is a simplification of the turn-on process:

1. You press the button and the VCU and BMS is powered on using the 18650 cell inside the VCU.
2. The BMS measures the cells voltages (100 of them) and sends them to the VCU. The VCU sums them to get the battery voltage.
3. The VCU tells the BMS to perform precharge. The BMS turns on the precharge circuit and measures the DC link voltage (which it continually sends to the VCU).



Consider Vin (blue) to be the battery voltage calculated in step 2.
Consider Vc (red) to be the DC link voltage -- voltage on the big capacitor in the inverter.
After a certain time the DC link voltage should be very very near the battery voltage.
The DC link voltage is measured with an analog circuit that does have a bit of measurement error.

4. After a certain time (t) the two voltages are compared inside the VCU. If they are within tolerance the main relays are closed and the bike is on.

My guess is that in your case the measurement error is basically equal to the tolerance, so trying to turn it on is basically a coin-toss.

Unfortunately, the LED remains red -- it does not flash some sort of fault code.

Stark would do well to calibrate the DC link voltage measurement circuit for each unit produced.

Another possibility for them is to have a small voltage tolerance value in factory, and double this tolerance before shipping the bike (simple software change). As it is now, bikes where the measurement error is basically equal to the tolerance will make it through QC where they actually should not. Having the LED color/flash pattern indicate the fault would also be helpful.

I am not 100% sure this is the problem in your case, but it is my best guess.

 

[Erwin P]

Stark thinks the battery and they supply a new one.

Stark did very well on their part in this case.

They emailed today so o could schedule a meeting tomorrow. After i told them i have an important training tomorrow and a race the day after they scheduled someone free so i could have the converange call today.
After some testing the conclusion was the battery.
As they knew i had the race they directly called the closest dealer to tell him he could take a battery out of a bike and they would send him the new one.
So i took out my battery and on my way now.

 

[fsfs]

Stark thinks the battery and they supply a new one.

Stark did very well on their part in this case.

They emailed today so o could schedule a meeting tomorrow. After i told them i have an important training tomorrow and a race the day after they scheduled someone free so i could have the converange call today.
After some testing the conclusion was the battery.
As they knew i had the race they directly called the closest dealer to tell him he could take a battery out of a bike and they would send him the new one.
So i took out my battery and on my way now.

Replacing the battery replaces the BMS and the analog measurement circuit. Sure, that is one way of fixing it, but an expensive one.

 

[Erwin P]

I think they will refurbish this one though for sales in the future.

As long as it doesn't cost me anything i'm fine with it.

 

[Theo]

As they knew i had the race they directly called the closest dealer to tell him he could take a battery out of a bike and they would send him the new one.

Well, this is how winners behave when they face problems!
Those Vargs may not be as relaible as they should be yet and sometimes we may feel like we were a little bit part of their research and development, but I believe in what they do, I want them to succeed and I think they will.
Go Stark!