Setting Low voltage cutoff for 52v system on BBS02

Tmiller

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Just finished my build with a BBS02 with a 52v battery. I have been programming and tweaking the settings. I purchased from a vendor who set up some programming before I got it. Was asked for Agressive/moderate riding and chose moderate. I assume the voltage for the cutoff was matched to the 52 volt battery. As I was using the programming tool and did a read of the stock settings to save to my PC, I noticed that the low voltage cutoff was set to 43. I changed it to 46 for a 52 volt system. When I went to write the settings, I got an error stating that the field was out of range. It would not accept anything larger than 43, This is where I have the setting now.

Thoughts?
 

HumanPerson

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set it to 41 or 40
i havent checked but i believe mine is set to 38, i ride it down to 40v before i even think about charging it.
 

Tmiller

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I have a chart that shows a 52 volt battery dead at 45 volts. How can a setting of 38 work without causing a massive under voltage of the 52 volt battery?
 

HumanPerson

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i guess i may be confused
are you asking what the low voltage cut off is? there are a few variables there but for the most part
a 52v ebike battery low voltage shut off is anywhere from 41v down to 35v, depending on the
battery composition and the bms ..etc..etc..etc..
 

HumanPerson

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It really all depends upon the battery cell chemestry, like the chemical composition, along with the BMS, if that makes sense.
It's weird really
 

HumanPerson

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and the brand i'd think....seems like the cheap ones are hit and miss but some of the samsung and panasonic are good...or so others say.
very strange these batteries
 

Vinz

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Good topic - I was just wondering the same thing. Thinking of getting a 52v battery for my BBS02.
I currently run a 48v battery, and the motor controller came set for a low battery cutoff of 41v, which is the recommended setting.
Using a simple ratio, the cutoff for a 52v battery would be 44.46v. But if your BBS02 came pre-set at 43v, that's where I would leave it too.
So, I don't know if I'll be able to change the 41v setting. I also wonder what effect the display might have. My 860C display can be set for a 48v or a 52v battery, It might only effect the display's battery status indicator, and not the controller setting.

UPDATE
I use the Speeed (not an error) app on my Android phone to program the controller. The highest value available for the low voltage cutoff is 43v. So that answers that question. Since the app works with the 02 and HD, it should be 43v for both.
 

RayT63

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I am using an EGO 56v (14s) battery pack. The battery adapter manufacturer recommends not draining this battery below 46v, and that sounds reasonable for my application. However, Penov's May 2016 software, or my BBS02 controller won't accept a value higher than 43v. Regardless of what other battery packs claim, I'd like the controller to help me stop draining my battery at 46v. Is there another software package out there that will allow me to set 46v for the low battery cutoff? Thanks much.
 

m@Robertson

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On your typical 18650 or 21700 cell in an ebike, LI-NMC or a close offshoot is usually the chemistry. A 43v cutoff on a 52v pack translates to 3.072v, or the equivalent of roughly a 6% charge. The standard range for cells like this is generally 4.2v fully charged and 3.00v fully discharged. Considering, as was pointed out above, that heavy depth of discharge is a bad thing, 43v is a pretty low value to force a stop, and really you shouldn't go that low if you can avoid it to preserve battery life. Personally, I try and not go lower than 46 but if I am pushing my luck I will see sags down into the 45's as I'm limping home.

If the controller doesn't shut down at a place you like, you'll have to do it via a programmable BMS that you specified when you built the battery pack, or had it custom built... which means almost nobody has that option available, I'm afraid.

That means you just have to be aware of your charge state as you run the pack down. Myself, I always use displays that show numeric real time voltage.

 

RayT63

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On your typical 18650 or 21700 cell in an ebike, LI-NMC or a close offshoot is usually the chemistry. A 43v cutoff on a 52v pack translates to 3.072v, or the equivalent of roughly a 6% charge. The standard range for cells like this is generally 4.2v fully charged and 3.00v fully discharged. Considering, as was pointed out above, that heavy depth of discharge is a bad thing, 43v is a pretty low value to force a stop, and really you shouldn't go that low if you can avoid it to preserve battery life. Personally, I try and not go lower than 46 but if I am pushing my luck I will see sags down into the 45's as I'm limping home.

If the controller doesn't shut down at a place you like, you'll have to do it via a programmable BMS that you specified when you built the battery pack, or had it custom built... which means almost nobody has that option available, I'm afraid.

That means you just have to be aware of your charge state as you run the pack down. Myself, I always use displays that show numeric real time voltage.

Thanks for the reply and charts. I don't believe my battery has a BMS that will cut out at any point. Being able to leverage a tool battery lowered my build cost considerably. I'll look into a BMS cutoff that I could wire between the battery and the motor. If this build hooks me, I might have to reconsider a dedicated battery, purpose built for ebikes.

I think the EGO tools stop when voltage drops to a certain point. I was hoping to have the Bafang controller also help protect the battery for me. The programming software that I have has a drop down menu that goes to 46 volts for the cutoff, but I get an error with that value as well as 45 and 44. Fortunately, my display has a voltage reading that I will watch to preserve my battery. I'm afraid that if I do draw the battery down too low, the EGO charger might refuse to charge it.
 
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