diy solar

diy solar

A few questions to get a small system up and running TIA

LLLL

New Member
Joined
Feb 2, 2020
Messages
44

I have two EG4-LifePower4 48v Lithium Batteries, and one Growatt 3kW Stackable Off-Grid Inverter (the 2nd inverter in the photo is for future expansion). I have Bus bars to arrive soon in the mail.

20220701_085411.jpg

My questions are:

Do I need to Top Balance the batteries?
If yes, what is the best way to do this?
(I have a EG4 Battery Charger - 48V 18A)



Then this question:
Even though this is an Off-grid system, I have easy access to 120v 20amps of power – Is it a good idea to keep the charger connected to the bus bar so to always have the batteries topped off?
(I was told not to do this as the as it would hinder the batteries from cycling normally)
 
Do I need to Top Balance the batteries?
No.

(I have a EG4 Battery Charger - 48V 18A)

The Growatt all-in-one units include an ac2dc charger.
Then this question:
Even though this is an Off-grid system, I have easy access to 120v 20amps of power – Is it a good idea to keep the charger connected to the bus bar so to always have the batteries topped off?
(I was told not to do this as the as it would hinder the batteries from cycling normally)
Depends on how these units handle the neutral to ground bond.
Especially since it appears you will be using them in parallel.
 
Last edited:
The only way to determine if you need a top balance is to monitor individual cells as the charging voltage passes through 54.4V (3.4V per cell) this is where the charging curve starts to turn up from horizontal to vertical. Since these are new batteries I'm NOT suggesting you need go through all that trouble. That said, it probably would be a good idea to use the EG4 charger set to something like 54.8-55.2V for a 24hr cycle, this will give the BMS some time to balance.
You don't need to keep the charger turned on, LFP chemistry doesn't need float.
 
Thanks, BentleyJ -

Do I understand this "EG4 charger set to something like 54.8-55.2V for a 24hr cycle, this will give the BMS some time to balance" that I hook up the charger to the bus bar and let it do it's balancing over a 24 hour period?

Also, the charger doesn't have adjustments to set it to "54.8-55.2V" is there any change in approach knowing this?

I'd like to keep the charger turned on, all the time, any down side you see to doing so?
 
I have not read the EG4 manual so I cannot speak to its specifications but if the charger does not have user settings so a reasonable float voltage (53.6V) can be set then absolutely you should not use it to float charge your batteries.
 
Depends on how these units handle the neutral to ground bond.
Especially since it appears you will be using them in parallel.
Thanks, Smooth Joey,
My intention is to have the neutral and ground separate. Grounding to a ground rod.
Will this work for having the charger always connected to the grid?
 
Thanks, Smooth Joey,
My intention is to have the neutral and ground separate. Grounding to a ground rod.
Its a bad idea.

Will this work for having the charger always connected to the grid?
Do you realize that you will have 3 ac2dc chargers in your setup?
 
Back
Top