"We take a close look at a battery management board from a four-pack of lithium cells pulled from a Mitsubishi i-Miev electric car flooded in Super-Storm Sandy."
The Automatic Mode of my DIY ESS is now fully Functional !
- If my solar system(*) generates more power than my usage, the ESS will switch from GTI Mode to Charger Mode and start switching ON chargers one by one to reach a Net usage close to 0W
- If the used power is greater than the solar array generated power, or if it is cloudy/dark, the ESS will switch to GTI Mode and start switching ON Grid Tie Inverters (GTI) one by one to reach a Net usage close to 0W
* (simulated for now using a small 900W heater on the generation line , since I am still waiting for my contractor to install the solar inverter)
This week end I added this Forced Charge Mode fonction to my LiFePO4 ESS to manualy force the charge at low rate hours - at night - and re-use this energy during the day when energy is more expensive ...
To enter FCM, depress at least 2 seconds the pushbutton, and to quit this mode, same thing, and the ESS will go back to fully automatic mode ...
Update: After connecting the 4 chargers leads, it is now actually charging the battery pack; check this out
Friday night, after checking that all the cells were at 2.75V (same as the morning), I started the charge process, screwing the leads of my 300W 24V LiFePO4 charger directly onto the battery pack terminals.
Here are some pictures of the charge steps at different hours: Note the voltage changes and the time on the clock in the back
I cheked the cells voltages every once in a while and they remained perfectly together all the way
I stopped the charging during the night for security reasons, and restarted it int he morning
Then I decided to test one of the three small low cost chargers I received this week, clamping the leads onto the battery pack terminals
and AC power, it just starts, with a red led and the small fan cranks up slowly, but remains pretty quiet
and it pushes roughly 100W into the pack
I then tried the two other chargers
got rid of the US AC plugs and leads connectors
clamped them on the pack terminals in parallel with the 300W charger leads
and hook together the AC side wires and plugged them in using a French AC plug (no earth/ground on these chargers because they are all plastic)
286W are used when all 3 small chargers are switched on
Now I switched the 300W back on, we are at 605W used and pushed intot the battery pack
Volatge is going up 0.1V
And the target pack voltage is reached at 28V, equals 3.5V per cell, as Jack Rickard recommands in his charging advices and I do not want to stress the new CALB cells for this first charge
Here, the chargers have been switched off, and I started the Grid Tie Mode, and the voltage immediatly drops ...
This is the amount of energy used to almost fully charged the 8 CALB CA180FI cells
Control Board with all GTI relays closed/on
And this is the generation graph for this first fully charged day
Parked at my usual spot at Mairie de Paris for a walk and ice cream in Marais, and to my surprise there was a new Autolib Station right after the charging station and a disable parking spot
