Bafang SOC incorrect readings / Limited Battery use. Help!

Patchogue

10 mW
Joined
Jan 1, 2018
Messages
23
I'm having an issue of when my battery is at 46V the SOC reading is down to 7% (flat) and it doesn't allow me to use the rest of the battery. I upgraded the firmware to the file from Tomblarom, the flashing was completed with success, the system runs but no luck. I set the Min Volt Cut down to 41V or 40V or 38V and nothing. It's all the same.

Anyone having this issue? Is there a way for the bafang controller to learn the full battery capacity? I'm using a 58.8V 21Ah battery. No errors or anything. It just doesn't seem to allow me to use the battery at any voltage below 46V / 45V.

I used a spare battery with 58.8V 16Ah and it was exactly the same.

Any help it would be much appreciated.

Cheers
 
42v is 0% SOC or 3v per cell. 46v is 3.28. There is not much left in the battery. Don't even think it would be 7%. With voltage sag close to BMS cut off 2.8v-2.9v.

Don't under stand why the need to shorten the battery life.
 
Yes, you are right about those values. But I'm not here to discuss battery health or why I would like to use my battery this way.

Although I don't know much about the Low Voltage Limit settings of Bafang. I assume that if you put 40 Low Voltage Cut Off that it would change the percentage reading, maybe my assumption is wrong.
I just got curious when I read this post:

https://www.endless-sphere.com/forums/viewtopic.php?f=28&t=100064&p=1678415#p1672160

How did he get that voltage with a SOC like that? Even when I change for battery type to 48V or 36V, the SOC remains the same.
 
A person would want the software to do as configured. Sounds like the upgrade fixes the throttle/pas issue and get few more watts out of the battery. Don't think "Delphis1982" who has posted twice on the forum was able to get another 1,200 watts out of his battery by using the upgrade.
I'm sure everyone can get more if they remove there BMS and run the cells down to 2.5v. Still will not be more than 75w.

by Patchogue » Sep 25 2021 12:21pm

Yes, you are right about those values. But I'm not here to discuss battery health or why I would like to use my battery this way.

Although I don't know much about the Low Voltage Limit settings of Bafang. I assume that if you put 40 Low Voltage Cut Off that it would change the percentage reading, maybe my assumption is wrong.
I just got curious when I read this post:

https://www.endless-sphere.com/forums/v ... 5#p1672160

How did he get that voltage with a SOC like that? Even when I change for battery type to 48V or 36V, the SOC remains the same.
 
Just because he posted twice it doesn't mean he doesn't understand a lot about certain things. Should I expect to believe that you are a genius because you posted almost 2000 times?
As he mentioned in his post "But I don't recommend to go lower than 43V for daily use. I just did it once for testing."
I'm sorry but in reality he can get another 1200 watts if he wants... he didn't mentioned how big his battery is. Assuming in a conventional way that normally people usually don't run more than a 21Ah battery, at 43V he could pull 900W theoretically. Should be less under the load from the road and wind.

This is not about removing BMS's and run cells down to 2.5V.... I could discuss with you battery usage but this conversation here is not about that.
I already mentioned that this is not about on how I want to run the battery and battery health and you keep on wanting to talk about that.... I only posted a hand full of times here and it doesn't mean I don't know about batteries.
If you are selling ebikes to normal customers, you should say something like that "A person would want the software to do as configured."
It's not what I'm trying to get here... I other wise I wouldn't be posting at the famous endless sphere forum, home of wacky scientists.

As I said, I don't know much about the Bafang configurations and SOC readings. This is about the topic of setting the program Low Voltage Limit at 40V and being shut at 46V. Without much voltage sag, just with the wheel in the air at assist 1. If was trying to get a big load as Delphis mentioned, of course the voltage sag wouldn't allow and it would go straight to the BMS cut off limit.
My BMS cut off limit is around 2.8V / 3.0V per cell. I would like to know if the Bafang can be adjusted to get that low at the controller side of things. Lets imagine that I use the battery from full to 80% most of the times and if one day I had an "emergency" and had to run it a bit more how could I do that.. that's all I'm trying to figure it out.
 
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