Solar Power solution to allow Defibrillator equipment to be accessible?

[aandncaravan]

I know that the Forums are not meant for this type of thing, but there are many Solar aware people on this Forum and this is Community based that benefits the Public.

 

We have just had the request below to provide a Solar solution to allow Defibrillator equipment to be accessible to the public even when low temperatures threaten it's usability.

There are a lot of very good technical minds on here that might enjoy helping create a solution? I would imagine the money available for such a project is likely to be 10p, so bearing that in mind ................

 

"Hello We are a Community Council, in the Scottish Borders, who have adopted phone boxes in our area and furnished these with G5 AED Defibrillator equipment which are stored within insulated cabinets. Unfortunately the phone boxes get too cold in the winter and the equipment has had to be brought indoors. We are looking for a Solar solution to either :

(a) heat our phone boxes or

(b) heat a storage cabinet in which the AED is stored. I can send a document with full details of the current position if you can provide me with an email address. If you have a solution that could work for our dilemma we would be delighted to hear from you".

 

 

This only arrived at 18:30 tonight so not had much time to think. My initial reply was,

 

Hello Sheila, We would need to know more about the Insulated storage cabinets so we could work out the level of heat loss through the insulation.

Once we know how much heat/energy is required to maintain a stable temperature inside the cabinet we can look at whether Solar can be a viable solution?

Solar is unlikely to provide a solution powerful enough to heat an entire Phone Box?

 

If you consider that in Summer in the Sahara a 100watt Solar panel can generate a fair quantity of power as the sun is high in the sky and the Solar day runs from 04:00 to 22:00.

 

But in mid winter in Scotland the amount of power would be very small.

For example the Solar day in Glasgow in mid December doesn't start until about 10:00 (it is dark until around 09:00). The Sun drops 14:00 and it gets dark again at 16:00.

In Winter the sun is low in the sky, and it is often cloudy, so the power generated between 10:30 and 14:30 in mid Winter will be little.

 

When Snow shades the panels, it is likely to be Zero output? So when it is most cold you have the least energy to play with.

 

If the cabinets are extremely efficient the small amount of power from the sun may be enough? Need to know all the details, like the insulation material, it's thickness, the volume of air inside and the space occupied by the defibrillator, etc

 

Angling the Panels so they slope will help prevent Snow settling and improve the Solar Gain but may make them prone to damage from high winds by creating a Sail effect?

A Pyramid shape on top of the Phone Box might provide low wind resistance, good 'Snow settling' resistance and improve the Solar gain by presenting a much larger surface area?

Maybe all four sides of the Phone box could be a Solar Panel, even the Door? A small LED light operated only when the Door is opened would stop it being too dark?

 

Let me know what details you have on the cabinet and see where we go?

Kind regards,

Allan".

 

 

Different?

 

 

[Tracker]

Great project, well beyond my amateur knowledge, but wouldn't a wind powered generator be a better idea?

[aandncaravan]

Wind power might be a better solution as you probably have close on 24 hour power, and overnight is when the heat is needed the most. However, the project brief is to provide a Solar Solution, so can we assume they have already debated this and rejected it?

[colin]

We have a defib in a red 'small pane' telephone box hundred yards down the road, ours has planning constraints, i.e. it's listed and within a conservation area, in this case adding anything on top would not be allowed.

How about fixed verticaly to top of side (or door) ?, as you say the level of insulation would be critical, but if you can cook a chicken in a heavily insulated box with a 60w bulb then there's some hope.

[colin]

aandncaravan - 2016-07-08 9:32 PM

 

Wind power might be a better solution as you probably have close on 24 hour power, and overnight is when the heat is needed the most. However, the project brief is to provide a Solar Solution, so can we assume they have already debated this and rejected it?

 

It is very common to see low power consumption set ups like speeding indicators and radio reporting of reservoir levels which are powered by wind and solar, it may be the person tasked just hasn't thought of it.

[Solwaybuggier]

Maybe AEDs differ, but I used to be in our local First Responder group. Our defibrillator was kept in an outside box with insulation. I know it can get pretty cold in the Borders though.

Given the no of defibs which are stored outside across the country, I wonder whether the enquirer shouldn't really be encouraged to seek advice from Ambulance trusts/Heartstart projects etc, rather than reinvent the wheel via you?

Sorry if this sounds negative!

[747]

I would assume that there would have been a 240 volt supply to at least some of the phone boxes. If so, a simple solution would be to install a light bulb in the box to maintain a heat level. Even 12 volt Halogen bulbs give off heat, so 12 volt solar (or even 24 volt) If a timer or even a thermostatic switch was included, it could work automatically.

 

ps, I have used the light bulb trick to keep welding electrodes dry in humid climates.

[aandncaravan]

Solwaybuggier - 2016-07-09 7:27 AM

 

Maybe AEDs differ, but I used to be in our local First Responder group. Our defibrillator was kept in an outside box with insulation. I know it can get pretty cold in the Borders though.

Given the no of defibs which are stored outside across the country, I wonder whether the enquirer shouldn't really be encouraged to seek advice from Ambulance trusts/Heartstart projects etc, rather than reinvent the wheel via you?

Sorry if this sounds negative!

 

From what I understand the unit itself is not directly damaged by the low temperatures, Tech specs say it should be used/long term stored in the temperature range 0 to 50 degrees.

I understand that the battery loses some efficiency at temperatures less than this, and below -15 battery damage can occur?

The units generally use a Lithium Sulphur dioxide battery and the specs for this say,

"In addition, the forms of this vented battery that contain acetonitrile can produce small amounts of very poisonous hydrogen cyanide when subjected to extreme temperatures.

Another consideration: Especially after long storage and/or being subjected to low temperatures, the voltage may dip suddenly....".

 

The unit itself has a built in temperature sensor flagging up when the unit is outside the temperature range 0 to 50 degrees.

 

Apparently the use of these boxes has been greater in very low 'snow on the ground' temperatures, than at other times.

The snow creates conditions that triggers extra exertion, higher Heart rate, etc. Maybe Farmers trying to get in Sheep, people walking distances after getting stuck in the Snow, just general stress of driving in the snow, etc. ??

 

So, apparently, the use of the box, so theory goes, is when the battery will deliver the least energy and is the most hazardous, hence the project to keep it above 10 degrees centigrade.

 

It seems that this Community run project is the first of it's kind to consider this aspect.

 

I have asked the question on Wind Power and Mains power.

 

[Solwaybuggier]

aandncaravan - 2016-07-10 12:20 PM

 

It seems that this Community run project is the first of it's kind to consider this aspect.

 

 

It may well be the first "community-run phone box incorporating defibs" project - but around the country there hundreds, maybe thousands, of Community First Responder (CFR) groups who use shared defibs. Some have indoor storage, but many use outside cabinets for storing the defibs, so they are accessible to all CFR volunteers. Quite agree this may be suboptimal - but I'm just wondering whether the enquirers might not do better seeing first how others have tackled the problem of the effect of cold on AED batteries? Either via Ambulance Trusts, or British Heart Foundation?

[aandncaravan]

They have responded today to say they have already dismissed Wind power and Mains power as an option. No idea why, but they have.

They were quick to point out, quite correctly, that the project we have been asked to assess, is to look at if we can use Solar Power to address the low temperature issue, nothing else.

 

However, I have asked if there is a problem with these cabinets in the rest of the County and there isn't. Just with the Telephone boxes.

The installation of these de-fibs usually involves mounting them on the wall of a building. The brick wall behind and the sheltered nature of the building means that the temperatures rarely drop below freezing inside the defib box, even on an unheated building in sub Zero temperatures.

 

A phone box in a isolated highland location has an internal temperature at night that is close to the external temperature, it can also be several degrees lower than a Town.

.

But in anycase, questioning any other part of the project is outside our brief.

 

 

 

 

 

[747]

The only way I can think of generating heat by solar goes back to my original suggestion. Fit the defib in an enclosure fitted with a couple of 10 watt, 12 or 24 volt Halogen bulbs, coupled to a thermostatic switch.