The BMMS can do it's thing and cut off the supply. I'm failing to see why the battery being a victim of fire is a pre-requisite for dedicated ventilation to the outside - we normally want to close off such ventilation systems under fire conditions to avoid fuelling said fire.

If vent is required, the required flow rate should be readily available (by calculation or a minimum standard, etc) IMO. 

Wow, really interesting video. Ive never installed a Lithium ion battery in a dwelling.

Im shocked that we allow the sale of electric light vehicles using batteries based on Lithium ion chemistry. 

For some balance you should watch the following video which includes tests on LifePO4 batteries. The battery chemistry of most leading domestic ESS providers.

https://youtu.be/Qzt9RZ0FQyM?si=4qcPtXdFwJIazArL

Im shocked that we allow the sale of electric light vehicles using batteries based on Lithium ion chemistry. 

New things don't necessarily have to be totally safe - no worse than what they replace will often do.

Given the risks of carrying tens of litres of petrol around (and many instances of ICE engine fires from just driving along the motorway - no need for any impact damage) and the likes of the Liverpool multi-storey car park fire (started by an ICE Landrover apparently), in a way society could "afford" quite a few serious incidents and sill be in a better position.

  - Andy.

gkenyon said:

Chris Pearson said:

On a more practical note, does it matter electrically where the battery is sited please? (I had thought that it would make sense to keep all the DC bits together.)

'Electrically' is a strange word to use, because it does matter that overcurrent protection is provided very close to the battery (wherever the battery is sited), and further that we don't have wires floating around outside enclosures that have no overcurrent protection.

Yes, keeping DC together is a great idea, but in practice there are other issues that might take precedence.

I used the word, "electrically" to differentiate from the fire risk and whether the location is able to support the weight, etc.

I had assumed that the DC equipment would be co-located to avoid the added complexity (and cost) of converting the DC to AC and back to DC again for the battery.

In my own house, the intake is in a detached garage, which feeds the house's main DB. There is a distribution circuit to a small DB on the second floor adjacent to the only bit of roof which would be suitable for PV panels. This would seem to be more than adequate for a 4 kW array.

The battery could not go next to the house's DB because it is in a passageway and leaving aside considerations of escape routes, it would take up too much space.

That leaves the garage where there is plenty of space. (However, I wouldn't be too happy if a battery fire spread to my Rolls-Royce!)

I thought that voltage drop might just be relevant, but apart from that, does it matter where a battery might be situated please?

pww235 said:

pre-requisite for dedicated ventilation to the outside

Toxic chemical production. It's not Lithium chemistries either ... many battery chemistries have the problem.

Agreed, this could be cables too ... although in most homes people will be out before cables start burning, the Data guys already have made some decisions on ICT cabling in BS 6701 that haven't happened in BS 7671 (at least as yet).

pww235 said:

we normally want to close off such ventilation systems under fire conditions to avoid fuelling said fire

Hence distance from windows, doors etc. ... the building still needs to comply with other fire regs after changes are made to the electrical installation.

pww235 said:

the required flow rate should be readily available (by calculation or a minimum standard, etc) IM

OK, possibly something to ask the manufacturer.

All good questions ... but the Public Consultation period is the time to make suggestions and provide reasons why provisions in a standard ought to change or be more permissive.

Just to note that, with BS 7671, the relevant Public Consultation period that matters isn't necessarily the one just before the next Edition is published, but the ones on standards that start IEC 60364-xxx and BS HD 60364-xxx, because with the UK being a member of CENELEC, we have to adopt the technical intent of the EU-wide agreed standard. We can make things more onerous, or make minor changes to wording to make things easier to interpret, but if we want to drop or relax a provision, this usually needs to be done before the CENELEC standard is published (that then makes its way into BS 7671 at the next Edition). See pages 15 and 16 of BS 7671:2018+A2:2022 for a list of the standards we (have to) adopt from CELENEC.

pww235 said:

we normally want to close off such ventilation systems under fire conditions to avoid fuelling said fire.

I guess it’s to vent the toxic gases like Hydrogen Flouride that are emitted if cells are punctured or in TR. Though ironically in an “cold roof” attic space a LifePO4 battery would be well ventilated by natural airflow. Also ironically, the battery is less likely to suffer impact damage in this less frequented space.

Also i was under the impression that the recommendation was to stop incoming air and cooking canopy extracts under fire alarm conditions, but to maintain top of stairwell ventilation to aid smoke clearance.

DA said:

ironically in an “cold roof” attic space

ironically, not all year round !

DA said:

battery would be well ventilated by natural airflow

Independent of battery chemistry, but venitlation as someone said, possibly too close to windows with some heavier than air gases and vapoirt - not all flammable?

DA said:

Also ironically, the battery is less likely to suffer impact damage in this less frequented space.

A fair point, and something to consider before locating a battery near a garage door, for example. And of course relevant to all battery chemistries, but there are other locations that can be "less frequented" ?

DA said:

For some balance you should watch the following video which includes tests on LifePO4 batteries. The battery chemistry of most leading domestic ESS providers.

In making that statement, you appear to believe that LifePO4 was ignored in the development of the PAS, and requires some "special treatment", yet I have posted above the "not in loft" being the contentious issue is actually independent of battery chemistry.

I'm not sure how many times I must repeat that, and I guess people will hear and see exactly what they want to?

Should we not consider the installation of batteries within fire-resistant, dedicated outdoor enclosures? Also within the enclosure include for integrated climate control system for optimal operating conditions.

AMK said:

Should we not consider the installation of batteries within fire-resistant, dedicated outdoor enclosures?

That is, effectively the preference of PAS 63100 - outdoor (enclosure or outbuilding).

When one wishes to build an attached garage to a dwelling, even one that is in practice too narrow, and will only store household tools, building control get involved and require windows to be removed, plumbing and so forth to be fire-stopped, and if you are building a habitable room above it then fire resistant ceiling materials. In effect the garage is to be built as if not only is there a car within it, but that the car will be on fire. It is not totally clear why such an approach does not extend to the construction of kitchens, as there are far more domestic fires started there, but that is an aside.

It strikes me a similar designed in approach will eventually be needed for battery systems, at least larger ones. The problem is there will a great many existing properties, where such an addition is simply not possible.

I am currently in a South American country with far fewer heath and safety scruples as the UK, and as the water supply is intermittent, it is common to have a tank on the roof for the inevitable water cut.

Maybe a similar approach could be adopted in the UK for the sort of thing we are considering. Perhaps the more 'uptown' version,.

In the UK such a thing would almost always need planning consent, but here it does not.

The 3 lines in the foreground under my window are 13.8kV between phases for those curious. Did I mention the lack of an H and S culture. ?!

Mike

Mike