Noob question. EG4 batteries parallel topping off necessary?

[Danny1987]

Hello Solar Forum,

I have a Growatt 12k with four EG4 batteries in parallel, 48volt system. Same cable lengths and wire gauge from battery to busbars. Equal state of charge on all batteries prior to installation.
After some testing/discharging grid power was connected to recharge the batteries.

Two of the batteries charged within approximately 2 hours. The other two are still charging (SOC diode flashing). All batteries are communicating via ethernet cable and charging on preprogrammed Growatt LI setting.

Should all batteries be charging at the same rate since they’re in parallel?

Does Growatt and EG4 BMS work together to fully charge each battery evenly?

Thanks in advance.

 

[timselectric]

If this is the first charge, this is fine.
Everything will even out.
It may even take a few cycles.
The batteries all communicate to the master battery. And it passes the information on to the inverter.
But, the batteries still have a little bit of individuality.
For internal cell balancing. As long as none are lagging way behind. Don't worry about it.

 

[Danny1987]

Thank you for the clear explanation how it all works!

 

[Don B. Cilly]

Just out of curiosity, did you parallel them "properly" or did you make the classic rookie mistake of connecting one battery's positive and negative to loads/charge - and the others "behind" it?
-

 

[timselectric]

I have a Growatt 12k with four EG4 batteries in parallel, 48volt system. Same cable lengths and wire gauge from battery to busbars.

 

[Danny1987]

Just out of curiosity, did you parallel them "properly" or did you make the classic rookie mistake of connecting one battery's positive and negative to loads/charge - and the others "behind" it?
-

The batteries are connected to bus bars using 4 foot, 2/0 awg cables, same for both neg and pos. Currently in this configuration:

Oooo oooO

 

[Don B. Cilly]

But are you drawing/charging from the positive and negative of the same battery, or the positive of one and the negative of the one furthest away from it?
-

 

[timselectric]

But are you drawing/charging from the positive and negative of the same battery, or the positive of one and the negative of the one furthest away from it?
-

Equally, from the bus bars.
They all have the same length and size cables.

 

[Don B. Cilly]

That still doesn't answer my question...
-

 

[timselectric]

That still doesn't answer my question...
-

4 batteries, with equal length and size cables.
Ran to bus bars. (Probably mounted on the wall, under the inverter)
Inverter is feed from the bus bar.

sorry, I don't know how else to explain it.

 

[Danny1987]

But are you drawing/charging from the positive and negative of the same battery, or the positive of one and the negative of the one furthest away from it?
-

Not same battery. Positive from 1st and negative from 4th(furthest).

 

[Danny1987]

4 batteries, with equal length and size cables.
Ran to bus bars. (Probably mounted on the wall, under the inverter)
Inverter is feed from the bus bar.

sorry, I don't know how else to explain it.

Exactly the setup.

 

[timselectric]

Deleted post

 

[Don B. Cilly]

Not same battery. Positive from 1st and negative from 4th(furthest).

That answers my question :·)
I just asked because I've seen it so often lately... and obviously it would pretty much guarantee that your batteries would go out of balance.

 

[Gabe7979]

I have heard that GROWATT 5000ES or any GROWATT inverter will communicate through the BMS connection only with GROWATT batteries , other LI batteries need to connect through the RS485 connection and the battery type need to be USER2 and not LI. Anyone have any input to that. Thanks

 

[Danny1987]

I have heard that GROWATT 5000ES or any GROWATT inverter will communicate through the BMS connection only with GROWATT batteries , other LI batteries need to connect through the RS485 connection and the battery type need to be USER2 and not LI. Anyone have any input to that. Thanks

My EG4’s and Growatt 12k inverter communicate via the BMS port, LI setting. Not sure if EG4’s are produced by growatt or not.

 

[LithiumCanuck]

Is it better to charge EG4 batteries individually before connecting them in parallel or it doesn’t matter and we can parallel them immediately when we get them out of the boxes?

 

[timselectric]

As long as the voltage is very close. The SOC doesn't matter.

 

[timselectric]

Close being .5 volts