Hi from New Zealand

Hi Everyone,

So Im just starting out on my journey to build a DIY powerwall/bank under a bus Im converting to a tiny home, so Ive been watching of the the YouTube channels and working my way through reading this forum.

I have lots of questions so.

Im looking for a good/bag/ugly list of battery manufacturers, for example Im seeing that a lot of Sanyo batters end up being heaters, and one of the two Sony factors, but keen to see everyones own experiences.

Im also interested in understanding why people dont protect each cell opting for BMS per parallel bank and fusing each cell, is this because in a default situation parallel batteries will self balance, but how does that protect against an internal cell failure

Lastly what materials have people consider to isolate/seperate cells from fire if there is a thermal runaway, what about the battery box what are people looking at to contain the fire.

Some ideas are using old PC (computer) cases, ammo boxes, steel cabinets, steel shelves, cement board ("villaboard") lining, etc.
Someone even used an old vending machine.
Risk of fire is reduced by good cell checking, particularly for IR, not using cells that have been low voltage for a long time.
Also good fusing of cells & battery packs + using a BMS.

It is very unusual for a cell to catch fire. Mind if they do you cannot extinguish it, only contain it. Weeding out heaters and self discharging cells in the early stage is key. I also recommend using an infared thermometer to check your cells regularly.

Many people use the Batrium for battery monitoring. This will help you to easily identify if a cell develops a problem with self discharge, which is usually the source of heat for a thermal runaway event.

Cells do have built in protection, and will usually vent, as a result of internal pressure build up, instead of heating to a point where they catch fire. You can read more about battery protection here.

The best option with large packs, made from second hand cells, is to isolate them from anything they may set fire to in the event of a catastrophic failure. Secondly, there is no substitute for close monitoring. Both manual, and automated.