Parallel diy 48v lfp batteries

[LakeHouse]

If all the bms can do is wide open or nothing, why are there settings for charge/discharge?

For open-loop: So the BMS knows when to switch from 'wide open' to 'nothing'.

For closed-loop: So the BMS can tell the charger how much current to give it. And also, in a separate setting, the same as for open-loop.

 

[timselectric]

I feel like a wildman...

0.2V for me.

That's not wild at all.
I don't recommend more than 0.5v
But have personally done it at 5.0v
Again, I'm not recommending that.
But it was exhilarating.

 

[rhino]

So again, I return to questioning if any common JK, JBD or DALY BMS has the ability to regulate current as stated. It is my understanding that this is a very rare feature and the BMS is simply an on/off switch when it comes to the current exceeding spec.

The JK Inverter BMS has a 10A current limiter. I'm not exactly sure how it enabled. Otherwise there are settings for charge and discharge amps that will turn the charge or discharge off if they are exceeded. Not regulate it.

 

[Kornbread]

Guess I'll have to record the next time another off-voltage pack is hooked up.

 

[ScrodusGargleRotten]

The JK Inverter BMS has a 10A current limiter. I'm not exactly sure how it enabled. Otherwise there are settings for charge and discharge amps that will turn the charge or discharge off if they are exceeded. Not regulate it.

I think it is only enabled immediately after turning on and only for a second or two.

 

[sunshine_eggo]

Although I have not verified it with an amp probe, in the app, I've watched the current stop and maintain at 30amps when connecting a battery pack, that was a little off voltage wise, to the main pack. Set the bms to charge at 30amps, and it did. If all the bms can do is wide open or nothing,

If your delta was less than 0.2V, then 2X 16S batteries in parallel are limited to 31A in parallel.

why are there settings for charge/discharge?

For the same reasons there are settings for HVD and LVD. One may wish to reduce the current limit in either direction due to cell limitations.

The JK Inverter BMS has a 10A current limiter. I'm not exactly sure how it enabled. Otherwise there are settings for charge and discharge amps that will turn the charge or discharge off if they are exceeded. Not regulate it.

Based on that wording, it only applies to charging, and it only applies when the charge protection value is exceeded.

I have seen something similar to this on a brand of batteries owned by @guybarth. They have in internal mechanism that increases resistance until the apparent voltage hits absorption, and the charger tapers current naturally. They would do this any time the charge current exceeded 15A.