Batteries - turret001/OffGrid GitHub Wiki
Batteries keep the house running at night. Draining them past their damage floor wears them out for good, so the controller protects them.
The floor and the way back
| Rack | Floor | Power back on, at least at |
|---|---|---|
| Improvised Battery Crate | 30% | 35% |
| Battery Bank | 15% | 25% |
| Sealed Battery Cabinet | 8% | 25% |
What happens at night
- The batteries run the house until they reach the floor.
- The controller cuts the house off that same minute. The screen says
LOW BATTandLOAD SHED BACK AT N%. Batteries sitting at the floor do not wear. A backup generator on Auto starts before that happens, at START AT. - When the sun is back, the batteries charge. Power returns by itself once they can run what is switched on for about half an in-game hour: never below the minimum above, at most 95%.
- Switching appliances off while the house is dark lowers N, so power comes back sooner.
Grades at a glance
| Improvised crate | Battery Bank | Sealed cabinet | |
|---|---|---|---|
| Damage floor | 30% | 15% | 8% |
| Wear per hour below the floor | 2.2% | 1.0% | 0.35% |
| Round trip (energy kept) | 72% | 86% | 94% |
| Capacity left at -10 C, outdoors | 42% | 55% | 74% |
| Can be equalised | yes | yes | no |
Equalise
Equalising is the only way to get lost battery health back. Everything else in the system takes it away.
Why a battery loses health
Every time a lead-acid battery is discharged, a little lead sulphate is left behind on its plates. Normal charging clears most of it. What stays turns hard, and the battery holds less for good. Draining a bank past its damage floor speeds that up enormously, which is what the floor is there to prevent.
What an equalisation charge does
It is a deliberate overcharge, held above the normal full voltage for hours. That breaks the hardened sulphate back down and stirs up acid that has settled to the bottom of the cell. Real off-grid systems do this every month or two as routine maintenance. Your controller does the same thing, on the same principle.
How to run one
Right-click the controller, Off-Grid › Start an equalisation charge. The row only appears when there is something to fix, and the charge switches itself off when there is not, so it is not a setting to remember.
Three things have to be true for it to make progress:
- a rack that can be equalised, which means a crate or a Battery Bank, not a sealed cabinet
- that rack below full health
- surplus sun, meaning more than the bank and the house can use
It costs you nothing but sunshine
An equalisation charge runs on power that was about to be wasted. When your bank is full and the panels are still making more, that extra normally goes nowhere. Equalising is somewhere for it to go.
So in July, when a good array throws away kilowatt hours a day, recovery is free. In January there is no spare sun and nothing happens. It never takes power away from the house.
How long it takes
About 2% health per hour of genuine surplus. Recovering a badly worn bank from its floor back to full is roughly 37 hours of spare sun, which is a summer project rather than a button. Watch the EQUAL lamp on the OG-1200, and the EQ figure on the STATUS page for what today's charge has put back.
It brings every eligible rack on the system all the way to full, not just the worst one.
Why sealed cabinets cannot
Overcharging splits water into hydrogen and oxygen. A crate or a Battery Bank vents that off harmlessly. A sealed cabinet cannot vent, so the same charge would build pressure, blow its safety valves and dry the cells out for good. Off-Grid refuses rather than offering you a way to destroy the best rack in the game.
That is the real trade in the top grade. A sealed cabinet keeps 94% of what you put in and runs down to 8%, but when it finally wears, it stays worn. A Battery Bank is less efficient and nurses back.
Cold, and where you keep the bank
A cold battery holds less. Not permanently, and it is not damage: warm it back up and the capacity comes back. The Info card shows an amber Takes charge up to line whenever the cold is costing you something.
Since 2.11.1 the mod uses the air where the rack actually stands, not the weather outside, so where you put a bank matters.
| Where the rack is | At -10 C outside, a Battery Bank holds |
|---|---|
| Out in the weather | about 55% of its rating |
| In any room | about 80% |
| Beside a lit fire | more again |
Above 15 C there is no penalty at all, so none of this matters in summer. Below that the gap widens the colder it gets, which is exactly when you need the capacity.
Two things worth knowing:
- Cold limits what the bank will take in, not what is already in it. A cold night does not drain a full bank.
- The damage floor is unaffected. It is a share of the bank's normal rating, so it does not move around with the weather and the controller will not flap on and off as the temperature drifts.
So the short version: put the bank indoors. A shed counts. A room with a fire in it counts for more.
Breaker trip
Old versions latched off when the bank ran flat. If a controller still says BREAKER TRIP, use Off-Grid › Reset the breaker once.