Golden Motor regenerative braking with Ping battery

[jtmjtm2001]

I'm about done with Crystalyte controllers and in the market for an alternative. I'm leaning towards the Golden Motor BAC-0201 48V/1000W. I'm planning to use the controller with my 5304 motor and Ping 30ah 48v. The question is will the battery handle regenerative braking? Thank you. John Morris

 

[Link]

It's not gonna like it. Ping's don't really take well to regen, and I'm not even sure that the BMS even allows it.

Then again, the 30Ah size is just so huge it might not have a problem if the BMS does work with regen.

 

[jtmjtm2001]

Thank you for the info. I think I'll get the standard version (non regenerative). John Morris

 

[ZapPat]

It's not gonna like it. Ping's don't really take well to regen, and I'm not even sure that the BMS even allows it.

Then again, the 30Ah size is just so huge it might not have a problem if the BMS does work with regen.

Link, FYI Ping's new batteries are made of cells that supposedly can take up to 1C charge, which is good enough for a fair amount of regen such as a regular ebike would see.

As you mention, we're not too sure of the BMS liking this or not, since it would have to be OK with monitoring negative current (or at least ignoring it). I have sent an email to ping about just this, and will post what I learn. If I don't find out what I need from him, I'll cut open the shrink wrap on the BMS and study the circuit.

I just got my 20Ah ping two days ago and it's just great so far, but I have yet to demand more than about 25A from it... more tests coming soon! I'll just say that so far these packs seem to have equal or superior internal resistance than all the recent headway cells that have been tested!!!

 

[dogman dan]

I feel my credit card whispering Piiiiing, Piiiiing. I'm sure happy with my Ping 1.0 but if the bms on the 2.0 is still the same one, it will not like charging over 5 amps. Regen is really cool on heavy vehicles the go up and down a hill all day, like strip mine trucks, since the economy of scale makes even small gains into huge money. But on an Ebike, especially with a good ping giving it enough range to kill your hubmotor, I can't see it being worth it exept for the bragging rights. It will be cool if the new bms will let us get even more amps out of the new cells. It won't be long I think before 2008 lifepo4 looks like horse and buggy stuff compared to what will be coming out in the future.

 

[Link]

I just got my 20Ah ping two days ago and it's just great so far, but I have yet to demand more than about 25A from it... more tests coming soon! I'll just say that so far these packs seem to have equal or superior internal resistance than all the recent headway cells that have been tested!!!

I've had no problems drawing 40A from my older 20Ah duct-tape pack. Doesn't even sag below 47V. The new cells should be excellent.

 

[ZapPat]

I'm sure happy with my Ping 1.0 but if the bms on the 2.0 is still the same one, it will not like charging over 5 amps.

What happens to your BMS when you charge over 5 amps? it gets hot or what? At two amps mine doesn't even change temperature. I have a nice 6amp vicor DC converter I'm going to use to charge my Ping pack tonight, so I'll see what happens.

BTW, does anyone know if balancing only happens when the first cells hit full charge? If this is so, then I should set my DC converter to at least 3.7V*16 = 59.2V, and leave it how long to be sure everything is equalized?

 

[fechter]

When charging from the charger, the current is going through a separate wire to the BMS. During regen, this part of the circuit is not going to be active, so there will be no limit on regen current other than what the cells themselves can take. Regen current will be passing through the LVC cutout and overcurrent protection FETs, but since the body diodes will conduct during regen, these won't be able to cut the current. The body diodes will be throwing off some heat, so depending on how many FETs are in parallel, you can calculate the maximum current based on heat dissipation for these parts.

 

[ZapPat]

When charging from the charger, the current is going through a separate wire to the BMS. During regen, this part of the circuit is not going to be active, so there will be no limit on regen current other than what the cells themselves can take. Regen current will be passing through the LVC cutout and overcurrent protection FETs, but since the body diodes will conduct during regen, these won't be able to cut the current. The body diodes will be throwing off some heat, so depending on how many FETs are in parallel, you can calculate the maximum current based on heat dissipation for these parts.

Thanks Fechter, that gives me a good idea how the BMS works!

And I guess this means we would want a regen-ready BMS to have it work actively in both positive and negative current drain (meaning it could turn the protection FET on during regen to reduce the diode's energy loss and heating during regen). One more thing to add to my "regen system wish list"