Sabvoton Regen Settings

nelwyn

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Feb 5, 2023
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Hello! First post here, but I haven't really found an answer to my question anywhere else yet. I recently upgraded my bike to a 3000w 72V NBPower kit with 80a Sabvoton controller and NBPower 72V 20Ah 80a battery. I'm using regen with the E-brake setting only, but I wasn't sure what I should put for the amp setting. It seems like the higher the number the more the regen braking I get, but I'm wondering if it's safe to even be doing it that way or is there a limit to what I should be putting? My battery says it has a 5 amp max charge voltage, but I'm not sure if that only applies to a charger. I've been trying values between 20a-50a.
 
Is the battery common-port BMS? Meaning, the same wires on the BMS are used for charge and discharge? Or are there separate ports (separate wires for each port)?

What cells are in the battery? Knowing the cell brand and model, you can look up their max charge rates, then multiply by the number of parallel cells in each group (the xP number in the pack's "xSxP" number (such as 20s4p)).
 
nelwyn said:
I'm using regen with the E-brake setting only, but I wasn't sure what I should put for the amp setting. It seems like the higher the number the more the regen braking I get
Do you want your main benefit to be braking or regen, and what kind of conditions would you be riding in?

On braking vs. regen, lower is better for energy going back to the battery, since higher slows the bike too quickly to get any sustained benefit.
On conditions, setting it high with dry conditions with good traction may be fine, but if you're going around a downhill curve with a loose surface or when it's wet, you're back tire may wash out when the braking comes on abruptly.
 
Just to add what amberwolf and e-hp said, Sabvoton appears to be using phase current for regen setting and not DC current, this means that the regen current setting should be 2.5 or 3 times higher than what your cells/pack can handle. Let's say your battery can safely handle 10A charge current, the regen setting current should be 25A or 30A to get 10A of DC current but that's not totally accurate because motor RPM determines the regen current aswell.

In my case the way I tested my regen to make sure the charge current never surpasses my safe charge current is first figure out my max safe charge current of my pack which is 20A, then entered 60A into the regen current setting and went top speed of my bike then regened, I then observed my display which has a power out/power in measurement in watts, converted peak regen watt measurement into amps and made sure it was under 20A which in my case it's just under. This ensures that no matter what speed I go, my regen current will never exceed my safe charge current and it's very unlikely for me to end up in a scenario where I will be going max speed down a hill for me to exceed that.

It is possible and some people do run higher regen current setting that their pack is rated for because peak regen current only lasts a split second before the bike starts slowing down and your regen current drops so you're not going to do much harm if for example your pack is rated for 10A charge current but you send 15A for a split second.
 
amberwolf said:
Is the battery common-port BMS? Meaning, the same wires on the BMS are used for charge and discharge? Or are there separate ports (separate wires for each port)?

What cells are in the battery? Knowing the cell brand and model, you can look up their max charge rates, then multiply by the number of parallel cells in each group (the xP number in the pack's "xSxP" number (such as 20s4p)).

There are separate wires (XT-90 for power and XT-60 for charging). I'm not sure of the cells, but I think they are some kind of 18650.

Do you want your main benefit to be braking or regen, and what kind of conditions would you be riding in?

Probably regen since it's not a particularly large battery. I'm just riding on the street mainly and sometimes the sidewalk.


Just to add what amberwolf and e-hp said, Sabvoton appears to be using phase current for regen setting and not DC current, this means that the regen current setting should be 2.5 or 3 times higher than what your cells/pack can handle. Let's say your battery can safely handle 10A charge current, the regen setting current should be 25A or 30A to get 10A of DC current but that's not totally accurate because motor RPM determines the regen current aswell.

According to the Amazon listing, it has a 5A max charge current but I assume that means continuous and coming from a charger. So it sounds like I should be safe around 15-20A although I probably won't get much braking like that.
 
nelwyn said:
Probably regen since it's not a particularly large battery. I'm just riding on the street mainly and sometimes the sidewalk.
If you don't have long steep hills that you descend at the beginning of your ride (e.g. you live at the top of a big hill), then I'd just adjust the settings to have the braking effect that works best for you. If you do a lot of stops and starts, even on flat ground you'll notice some improvement since you use the most power when starting from a stop, but with regen you offset some so of that when coming to a stop.
 
Electric bikes thats Im! at . Its a new frontier. To be part of the electric vehical community , its great .
Thank You Endless Sphere for being here too.
 
nelwyn said:
There are separate wires (XT-90 for power and XT-60 for charging). I'm not sure of the cells, but I think they are some kind of 18650.
To know if it's common-port or not, you'd need to know if the BMS actually has separate "P" and "C" ports or just one that both of those wires go to. (separate wires doesnt' really say). Not knowing if the BMS is common or separate, or what FETs it has to know what kind of current limit they may have, or what the BMS specs are, exceeding the only limit you do know (5A) could damage the BMS, even if it's momentary.

Not knowing what specific cells you have, there's no way to know what is a safe charge current. With cheap cells, it could be as low as 100mA each. Meaning, if it's a 4p (4 cells in parallel in each group) it could be only 500mA charge rate that is safe (regardless of what the pack itself says it's rated for).


Given the lack of information about the pack, it's probably safest to assume the max charge current they state of 5A is really the max safe limit--I'd stick with all charge current lower than that, just so you don't damage anything and cause yourself problems with the battery.

If you go higher than that, not knowing anything else about it, you risk damaging either cells or BMS. (and damage to the BMS usually means eventual damage to the cells as it typically gets damaged in a way that prevents it from shutting off charge or discharge or both whenever there is a cell either low or high in voltage). Cell damage can lead to fires.
 
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