Motor assistance with low battery level

[luigi61]

I have a Turbo Levo 2018 with Brose 1.3 and the 504 Wh battery (actually at 96% of health status)
I noticed that the motor assistance cuts off when the battery level reaches the 8%.
No difference between eco, trial and turbo: at 8% my motor doesn't give any assistance to the biker.
The connection with the app (Levo or Mission Control) is working but without motor assistance.
Do you think it's normal? What is your experience?

 

[Nifty 56]

That doesn't sound right to me. I've got 2 mates with Levos and never had that problem. Maybe someone knows more?

 

[jeffintheusa]

Just last night I ran my battery down at the conclusion of a ride. What I found was that the assistance was significantly reduced once I got below 9%. I have a 2019. I was not using Smart Control and so I think it just gives you a tiny amount of assistance to ensure the battery doesn't discharge to the point of damaging it. When I got to 6% there was such a small level of assistance that I only felt it on the flat sections. Climbs felt like there was no assistance at all.

I'm also interested to hear other peoples experience. For example, if you're using smart mode is the result different below 10%?

 

[Clint600f]

This is from the manual..............

13
8.3. CHARGE LEVEL DISPLAY
The charge level of the battery is permanently displayed during your ride. The number of LEDs glowing will indicate the
remaining battery charge.
When the battery charge reaches 20%, the last two LEDs will glow red
(fig.8)
.
At 10% battery charge remaining, the system will start to reduce the amount of support. At 1%, the system switches
off the motor support.

 

[Mabman]

You will get the most amount of power out of an electric motor when a 36v battery is fully charged to between 41.4 - 42.5 depending on the voltage of the cells used.. As you use power you draw down the voltage and available power will decrease but not become real noticeable until the last 20% or so of charge. It's just a factor of eBike life and will never change no matter how battery technology progresses.

Fuel operated motors of course do not suffer the same effect.

 

[MattyB]

You will get the most amount of power out of an electric motor when a 36v battery is fully charged to between 41.4 - 42.5 depending on the voltage of the cells used.. As you use power you draw down the voltage and available power will decrease but not become real noticeable until the last 20% or so of charge. It's just a factor of eBike life and will never change no matter how battery technology progresses.

Fuel operated motors of course do not suffer the same effect.

All true, but I don’t think it is the key factor here. It seems far more likely that the BMS has been configured to ensure the cycle life and capacity of the pack is protected however the rider uses it, and that mean reducing the assistance significantly as soon as the pack reaches 10% capacity remaining. That 10% is also highly likely to be a conservative number; I suspect at “10%” it is nearer 20% remaining, and “fully flat” according to the BMS nearer to 10-15% actual capacity remaining.

 

[Mabman]

All true, but I don’t think it is the key factor here. It seems far more likely that the BMS has been configured to ensure the cycle life and capacity of the pack is protected however the rider uses it, and that mean reducing the assistance significantly as soon as the pack reaches 10% capacity remaining. That 10% is also highly likely to be a conservative number; I suspect at “10%” it is nearer 20% remaining, and “fully flat” according to the BMS nearer to 10-15% actual capacity remaining.

Agreed that the BMS is there to regulate the lowest point in voltage so to preserve the integrity of the pack and is set by the manufacturer. It's main purpose is to completely shut off the battery once it's threshold has been met and on a 36v battery that is around 28v minimum. It also shuts down the charging process and regulates that in order to make sure the individual cells are balanced properly at the end of a full charge cycle. It really doesn't have the effect you are describing to my knowledge.

As I have said in other posts the whole percentage thing is too nebulous and there should be a real time readout of voltage status and ah's and wh's used on displays instead of the funky bar deals and trying to figure out what each bar represents because they will not all disappear equally due to the fact that voltage will drop more precipitately the closer it gets to the LVC.

This is the display I use for my hub motor bikes and not only does it supply these numbers as well as other useful data it also is the brains of the outfit and can be accessed for programming via a cable or by manipulating the buttons. The top screen is what I have going most of the time and the upper right shows ah's used, speed and temp while under way.



As for instance I have a lvc of 44v and a 520wh battery so I had a few more miles to go. I know that more modern ones will calculate the remaining distance but I don't mind doing some simple math along the way. Also there are plenty of Apps that do similar functions and more like GPS readings that make profiles for elevation and route maps but none that I have found that are as exact as this one feeding directly off the controller.

However this is not to say that one can't just get used to how their display reads over the course of riding it no matter how little info it provides. My mtb the display only tracks mileage as it is a 48v setup and I use a 52v battery so the battery bar deal shows full bars until it doesn't and I better hope I'm close to the barn....

 

[JanCapek]

I think it should be also noted, that voltage of the battery fluctuate under different levels of load. I was checking this with my Ebike Diagnostics app and the voltage can drop by more than 2 Volts if I pedalled hard on my Levo.

Related to this is second thing - temperature. For most of us, its quite cold outside nowadays, so battery can drop quicker under lowest voltage limit if it is almost discharged and under load.

So I don't think its big issue that assistance cuts off completely even before battery percentage drops to zero. But of course, we may not care about this and battery percentage indicator might be more clever...