Heat Detection for Energy Storage Systems

[analog8484]

For a while they were not per the fire chief, but later he rescinded the order, so now they are. The people whose PowerWalls had had to be installed on an outside wall during the time the order was in force had their equipment fail to keep them in power during the Snowpocalypse outage because the batteries got too cold to operate.

Interesting. My understanding is that Powerwalls are rated to operate down to -20C ambient. The low temp during Texas outage was -19C (https://en.wikipedia.org/wiki/2021_...winter storm caused a,North Texas in 72 years.).

 

[ggunn]

Interesting. My understanding is that Powerwalls are rated to operate down to -20C ambient. The low temp during Texas outage was -19C (https://en.wikipedia.org/wiki/2021_Texas_power_crisis#:~:text=The winter storm caused a,North Texas in 72 years.).

Sorry, I didn't mean to imply that they all failed, but some of them did. In any cold snap, particularly where there are hills, some places get significantly colder than others.

 

[tallgirl]

For a while they were not per the fire chief, but later he rescinded the order, so now they are. The people whose PowerWalls had had to be installed on an outside wall during the time the order was in force had their equipment fail to keep them in power during the Snowpocalypse outage because the batteries got too cold to operate.

Was that limited to Lithium chemistries? I had multiple clients with lead acid batteries in garages or inside other structures in multiple states, and probably a few foreign countries as well.

 

[ggunn]

Was that limited to Lithium chemistries?

Yes.

 

[gadfly56]

Yes.

No one is worried about hydrogen generation with a large lead acid battery bank?

 

[ggunn]

No one is worried about hydrogen generation with a large lead acid battery bank?

That is a concern but the rules are different. Lead acid batteries in a garage are installed in sealed enclosures vented to the outside.

 

[tallgirl]

That is a concern but the rules are different. Lead acid batteries in a garage are installed in sealed enclosures vented to the outside.

Correct. The largest installation I worked on had hydrogen sensors which controlled a ventilation system. Smaller systems tend to use voltage controlled fans since hydrogen evolves at higher voltages.

 

[ggunn]

Correct. The largest installation I worked on had hydrogen sensors which controlled a ventilation system. Smaller systems tend to use voltage controlled fans since hydrogen evolves at higher voltages.

Explosion proof fans? Many residential systems I have seen simply rely on free flow ventilation from the top of the enclosure.

 

[tallgirl]

Explosion proof fans? Many residential systems I have seen simply rely on free flow ventilation from the top of the enclosure.

I don't know their various ratings. Presumably the hydrogen detectors in that large system activated the fans before there was an explosion risk.

In the case of the smaller systems that needed forced ventilation, there are plenty of inherently safe (brushless) fans.

 

[GoldDigger]

Sorry, I didn't mean to imply that they all failed, but some of them did. In any cold snap, particularly where there are hills, some places get significantly colder than others.

There is a distinction, not necessarily comforting to the owner, between a unit failing and a unit failing to act as anticipated in the system design or the sales brochure.
Low temperatures are known to reduce the power capacity of batteries. Li chemistry less so than many others. There is however a hard minimum temperature below which different Li chemistries are allowed to be charged, and that could indirectly reduce the available capacity of the battery bank at the time of a power failure.
Tesla car battery banks have temperature regulation mechanisms to both heat and cool the battery bank as needed. One of the heating mechanisms is to apply power pulses to the motor(s) which do not produce torque or consume much power but allow heating the batteries from internal resistance.
I do not know what sort of temperature control mechanism Powerwall batteries have.

 

[wwhitney]

I have been volunteered to canvas and (hopefully) find out how other California jurisdictions are handling this wide-open-to-interpretation “reasonable alternatives”. Storage System operating conditions for ambient temperature are usually well above the 100-degree F mentioned in the bulletin.

In this thread https://xenforo.mikeholt.com/thread...itch-into-smoke-circuit.2568977/#post-2768799 another user pointed to the Kidde Relay module https://www.kidde.com/home-safety/e...cessories/auxiliary-devices/sm120x/index.html

If you download the manual, you will see that this module can either activate a 120V device whenever the smoke alarms go off, or cause the smoke alarms to go off whenever a switch is closed (pull station or heat detector). See Figure 3.

So that means a complete solution for a garage which is too hot for the usual interconnected heat detectors is a 194F mechanical heat detector wired to the interconnected relay module, with the relay module outside the garage in conditioned space.

Cheers, Wayne

 

[mtnelect]

I remember reading a newspaper article about a house fire caused by a solar battery system a while back. I guess it is time to protect those systems.

 

[gadfly56]

In this thread https://xenforo.mikeholt.com/thread...itch-into-smoke-circuit.2568977/#post-2768799 another user pointed to the Kidde Relay module https://www.kidde.com/home-safety/e...cessories/auxiliary-devices/sm120x/index.html

If you download the manual, you will see that this module can either activate a 120V device whenever the smoke alarms go off, or cause the smoke alarms to go off whenever a switch is closed (pull station or heat detector). See Figure 3.

So that means a complete solution for a garage which is too hot for the usual interconnected heat detectors is a 194F mechanical heat detector wired to the interconnected relay module, with the relay module outside the garage in conditioned space.

Cheers, Wayne

That is an excellent solution, well-spotted!

 

[gadfly56]

I remember reading a newspaper article about a house fire caused by a solar battery system a while back. I guess it is time to protect those systems.

In the fire biz, "protect" is taken as synonymous with "put it out". It's doubtful that you can wrangle a fire protection system for a residential application that's going to be both affordable and useful. Taking a page from the explosives industry, protection is achieved via separation. Put the batteries in a separate building/enclosure where if it goes up, it won't take the house with it.

 

[jaggedben]

With the latest residential code updates, energy storage systems are basically required to have the same separation from dwelling areas as automobiles. Fire seperated room, or outside.

 

[gadfly56]

With the latest residential code updates, energy storage systems are basically required to have the same separation from dwelling areas as automobiles. Fire seperated room, or outside.

Just remember, the purpose of fire rated assemblies, especially in residential construction, is to provide sufficient time for the occupants to beat feet, not necessarily save the structure. While you could create a fire separation with an unlimited rating for all practical purposes, no one is going to throw around 2 foot concrete partition walls and ceilings in most residences. Most residential fire rated assemblies are one hour between an attached garage and the main dwelling. And that's for ordinary combustibles; I don't know what the difference in temperatures is between a lithium fire in a Powerwall mounted to the rated wall and a bunch of rags left over from a furniture finishing project.

 

[mtnelect]

I just keep in my mind reminding myself of "spontaneous combustion" images of cell phone batteries, solar lithium batteries and electric vehicle batteries, both usually kept at home. Which are hard or impossible to extinguish, like a road flare burning underwater.