I wanted to post this in battery builders, but this isn’t about building. More about how you handle packs afterward.
I recently consolidated most of my packs and cells into a single container to move from one spot to another after an extended work absence.
Packs are at storage voltages (3.8 and 3.7v) and balanced. No packs with a history of impact, questionable puff (lipos) or excessive discharge are in mix. I got rid of them prior to storage.
I will be stuck with this pelican case of doom for about a week of not having a real house and garage with appropriate storage. The case will be inside an AC cooled room when not in car.
The good:
+The biggest and oldest lipos are in fireproof bags.
+the case has padding
+fire extinguisher is next to case containing cells
+case is in climate controlled indoor area near a patio door (overnight location)
+zero intention of leaving them in the car without direct supervision
+12s series packs disconnected to 6s packs when possible
The bad:
-all packs are in very close proximity
-30ah of brand new factory lipos are not in fire bags, still in Amazon box
-case is flammable (but airtight, Pelican case)
-mains leads and balance leads are randomly tucked in with cells
-batteries in a car, in SoCal.
-How do you move batteries from point A to point B?
-Comment on my battery care sins if not confessed above.
For context (and maybe bragging rights), I have 6.4kwh of lithium batteries in a single pelican case. (A hybrid Prius has about 8kwh, the newest Tesla model y is rocking 75 to 80 kWh)
Something to possibly consider…
Storage voltages of 3.7V, 3.8V, and other high voltages like that, are fine for long term storage but leaves a great deal of energy in the cells.
Discharging down to about 30% state-of-charge is the standard used by manufacturers now and it removes a great deal of the energy that would be available to cause a fire and/or ignite other cells in case of a short-circuit or physical damage to a cell.
If the cells/packs are not being stored for long periods without being checked then discharging them down to a much lower voltage can remove a lot of risk.
For standard li-ion chemistry this is about 3.35V or so. For LiPo’s you would have to check a low current discharge graph for the cells you have to see what voltage 30% is. The lower the voltage the better though, as long as the cells do not drop down below about 3.0V in storage.
Other thoughts…
Keeping the packs separate helps prevent spread of a thermal runaway situation but is not convenient.
Protecting each pack individually can help protect them from vibration/shock/physical damage as well as short-circuiting.
A fire extinguisher cannot help with a thermal runaway event but can put out any fires the cells cause once the thermal runaway has stopped.
In sweden petrol is taxed at 60%. Cause you know, why the fuck not, 1 kWh was 7kr(0.7usd) this morning as well x) Atleast saleries are following the inflation (not)
you should try it!
