LiFePO4 ESS update: After bottom balancing for several days, back to charging

LiFePO4 Battery Energy Storage System (ESS or BESS) update

I have been bottom balancing my cells for 5 days now and they are all really close to 2.70V, which is a fully discharged cell

I have been using my bottom balancing device based on a programmable dual relay voltmeter and it is really usefull for this matter
The voltage of the groups of 4 cells tend go back up after leaving them for few yours, not much but they were sometimes back to 2.75V, so I would repeat the process over and over, for all groups

Something important I noticed was after the first night, some groups of cells already bottom balanced in the evening at 2.70V went down to 2.55V or 2.60V when checked the next morning ! After few minutes I realized it could be caused by only one thing: the digital voltmeter that is always ON and connected to the pack through the DC-DC converter: The cells being very low, their tiny consumption, over time, was making the voltage drop quite a bit (we are on the steep part of the discharge curve). I had to push some energy - using a small 12V charger - into these groups of cells to reach 2.70V again.

Since my new LiFePO4 24V 10A charger is still in transit in China, I decided to use the 48V one and it should not be a problem because I am limiting the pack voltage to 29.2V via programmable voltmeter second relay and the automotive relay placed on the charger line

Pack voltage down to 21.6V = 8 x 2.70V

Charger switched ON, and voltage going up already, ampmeter showing 3.5A

Afer few minutes, voltage os going up pretty fast; here 22.3V = 2,78V per cell

LiFePO4 ESPSS - Edging 0W usage & Trying to match it

Energy Storage & Power Supply System update: trying to cancel phantom loads by launching only the small GTI (N°1) that outputs 65W:

Trying to adjust GTIs power supply to match power usage:




After plugging in Wattson to my MacBook the next morning, this is what it looks like Holmes software:

Here is the Energy usage & generation graphs, and as you can see the green line (generation) is following the blue bars

And here is the same period, but showing Power this time: Same thing for the behavior  

ESPSS Charger Security Relay Update

Last night I wired another relay for the charger line, that will be activated by switching to Charger Mode (C), and deactivated if the charger does not stop like it should in case it fails (rare but I heard it could happen)  and the pack voltage goes higher than 29,2V (8 cells x 3,65V). Also the Ampmeter will now be used to monitor the Amps going from the charger to the battery pack.

LiFePO4 Energy Storage & Power Supply System update

The System has worked fine, several nights in a row

My pack voltage is slowly dropping of course but I am not wasting energy anymore, adjusting to my usage constantly

Last night I wired another relay that will be triggered by switching to Charger Mode, and switched off if the charger does not stop like it should, in case it fails and the pack voltage goes higher than 29,2V

LiFePO4 Energy Storage Storage Sytem - Automatic Cutt Off - Video

In this video shot last week, I show you the automatic cut off of my LiFePO4 Battery Bank / Energy Storage System: At the end of the discharge cycle, reaching 48V, one of the two relays of the programmable dual relay voltmeter will open, which will in turn open the Tyco Kilovac contactor, cutting power to the Grid Tie Inverter and thus stopping the power being fed back into my home grid.
My system is now almost fully atomated...

LiFePO4 Battery Bank / Solar Energy Storage System

In these 3 videos, I will present you the LiFePO4 Battery Bank / Solar Energy Storage System I am currently working on

Video 1/3:

Video 2/3:


Video 3/3: