EG4 LL (V2) 48V - Top Balance Process

[WattAboutThat]

I am in the planning stages of a new system install, and need some guidance from those of you with experience.

This is a completely Off Grid install.
No electric on site.


It is my understanding that prior to putting batteries in the rack and connecting them all to the bus bar that i am required to Top Balance each individual rack battery to the same or close to the same voltage or level of charge.

I currently do not have a separate 48V charger,

Questions:

1) Do I need to Top Charge these rack batteries,
or will the individual BMS’s balance them over time?

2) How do I charge them individually if I only have an inverter (18kPV)?

3) Do I need a separate 48V LiFePO4 charger to charge each battery prior to connecting to the bus, by taking them to a location that has grid power?

if yes,
4) What charger is recommend to use in Top Balancing these batteries?


On a separate issue regarding wiring rack bus bar to inverter:

5) Does one of the battery rack bus bars need to be inverted so that one wire, for example red positive, is at top of rack, and other wire, for example black negative, is at the bottom of the rack, in order to create equal resistance between inverter and all rack batteries, so that each battery charges and is drained equally?

6) If I have multiple battery racks, each connected to a common bus, and then that bus connected to the inverters (for example 2 or more inverters), do I need to do anything special to wire the racks’ bus’ to the common external bus, in order for them to charge and discharge equally?

7) Does having multiple battery racks require a different method of daisy chaining the communications wires across the racks?
Or do I connect all communications wires to all batteries as if they were in one rack?

8) And does length of communications cable between any two racks, since longer than cables between batteries within the same rack, affect functionality?

Assume these are EG4 LL (V2) 48V batteries in EG4 racks, each battery has 6 dip switches for battery addressing, and assume there are Two (2) or more racks, each containing Six (6) of the batteries.

Thank you for your assistance and feedback

 

[robby]

I am in the planning stages of a new system install, and need some guidance from those of you with experience.

This is a completely Off Grid install.
No electric on site.


It is my understanding that prior to putting batteries in the rack and connecting them all to the bus bar that i am required to Top Balance each individual rack battery to the same or close to the same voltage or level of charge.

I currently do not have a separate 48V charger,

Questions:

1) Do I need to Top Charge these rack batteries,
or will the individual BMS’s balance them over time?

You need to charge them to an equal voltage level on all packs before connecting them altogether.
the easiest way is to fully charge them one at a time.

2) How do I charge them individually if I only have an inverter (18kPV)?

Set your charge rate in the inverter to roughly 25 Amps and connect the first batteryand let PV charge it.
Then repeat for the next one until all of them are charged.

3) Do I need a separate 48V LiFePO4 charger to charge each battery prior to connecting to the bus, by taking them to a location that has grid power?

No your inverter should be able to do it.

if yes,
4) What charger is recommend to use in Top Balancing these batteries?

See above post.

On a separate issue regarding wiring rack bus bar to inverter:

5) Does one of the battery rack bus bars need to be inverted so that one wire, for example red positive, is at top of rack, and other wire, for example black negative, is at the bottom of the rack, in order to create equal resistance between inverter and all rack batteries, so that each battery charges and is drained equally?

That’s the second best way. The best is to have big positive and negative bus bars that each battery can connect to.
this looks usings it’s own short cable.

6) If I have multiple battery racks, each connected to a common bus, and then that bus connected to the inverters (for example 2 or more inverters), do I need to do anything special to wire the racks’ bus’ to the common external bus, in order for them to charge and discharge equally?

7) Does having multiple battery racks require a different method of daisy chaining the communications wires across the racks?
Or do I connect all communications wires to all batteries as if they were in one rack?

8) And does length of communications cable between any two racks, since longer than cables between batteries within the same rack, affect functionality?

Assume these are EG4 LL (V2) 48V batteries in EG4 racks, each battery has 6 dip switches for battery addressing, and assume there are Two (2) or more racks, each containing Six (6) of the batteries.

Thank you for your assistance and feedback

 

[Redflyer]

Similar to the original post.

I have six EG4 LifePower batteries that I 'synced' before adding to the single server rack cage. I had them with a tenth of a percentage on charge. Over time, one has become a weak sister and drops to 20% before the other 5. I get the red alert light on that one battery. Of course, it's also slower to recharge....just from starting at a lower point maybe?

This is what I was thinking of doing for my next move..

Just charge the whole rack up to 100% via PV. I do have a 48v charger, but don't really want to mess with the bus bar when everything is up and running. I guess I could turn off every battery and hook it up that way? A quick disconnect for each battery would be pretty cool...but that's not how this works.

Thanks.