Off grid 48 volt battery for AED unit ?

[SurpriseAZ]

Seeking design advice about how to power off grid AED cabinet for remote area where grid power is not available. ( Automatic External defibrillator )
Unit has internal communications, heating probe blanket and cell service card to report back to 911 system. Total use is 80watts.

Advocates For Health – Better Access to AEDs

advocates4health.org

We would like to power from solar panels on the to battery. Need to be able to keep online for as long as possible without sunshine. Cold weather is a factor because location is Minnesota and other northern locations. The southern locations have cooling units to maintain even temperatures.

200 w solar is thinking
Size of battery ? 200AH
Cabinet has limits for space. Small foot print is challenge. 8’w by 18” tall but not deeper than 10”. We plan to insulate the battery storage area.

Any tips or connection to company or person to aid the project is requested.

Thanks,

 

[DIYrich]

What is your limit on Panels? That is likely to be your limiting factor. For 80w continuous you need at least a 2kWh battery for 24hr. Probably twice that for inverter, unless you can run everything direct from battery. Winter you will need more power (panels) to heat battery. You could use lead acid battery to minimize temp problems, but that means you need even more power for self discharge.

 

[Rednecktek]

Cabinet has limits for space. Small foot print is challenge. 8’w by 18” tall but not deeper than 10”. We plan to insulate the battery storage area.

Ok, physics is NOT your friend here, I would give up on 48v and go with 12v instead and a couple high density "mini" batteries. Especially with such a low load of 80w, 48v systems are going to start with more standby consumption than load.

At least you have room above the batteries for mounting the inverter, SCC, shunt, etc. I just don't see a 16 cell pre-built existing that will fit in there. Even if you did a DIY, you'd have to use some tiny cells or get real creative on the stacking.

Just for giggles, convert those measurements into metric and hit up Docan or SFK or any of the sites that sell cells and see what size cells you could phisically fit in different directions, that'll get you an idea of what capacity batteries you could fit.

 

[50ShadesOfDirt]

It sounds like this AED unit:
- needs to always be running (it is monitored, and reports back to 911)
- these things cost 1000's of dollars, and need to be "protected" (protection system needs $$$)
- you need something foolproof, because it's an AED

We don't know enough about where the AED cabinet lives, and what resources are available around it. Is it just a cabinet hanging off a tree, on a job-site and will be moved later, etc.? Some of these answers might further direct the solution (as in, I might put everything on a trailer of some kind).

So, I'd put in a bulletproof inverter-charger and battery-bank, a site-sized propane tank, and a propane fuel-gen (small, but appropriately sized), and enough smart gear to decide when the battery-bank is low, and start recharging it from sources that can never go down, regardless of weather and such. If a trailer *is the right answer*, then solar panels can be easily integrated.

When all is said and done, this AED cabinet has its bullet-proof support system, and perhaps other things around it can benefit from the spending and the available power.

Without knowing all the constraints, choices, and other requirements, I'd say use a portable solar gen, sized right, and fed with whatever will keep it going thru MN conditions year-round. I currently like this portable solar-gen that allows you to use your own battery-bank (vs it being integrated, and/or having to buy some vendors' idea of a battery-bank or expansion capabilities):

amazon.com/ECO-WORTHY-Portable-Controller-Traveling-Household/dp/B0DB1VGGJ9

But, without answering all the design q's, don't yet know what's appropriate for the design.

Hope this helps ...

 

[SurpriseAZ]

What is your limit on Panels? That is likely to be your limiting factor. For 80w continuous you need at least a 2kWh battery for 24hr. Probably twice that for inverter, unless you can run everything direct from battery. Winter you will need more power (panels) to heat battery. You could use lead acid battery to minimize temp problems, but that means you need even more power for self discharge.

This is 100% DC unit. No need for inverter. AED unit is kept in a insulated bag that is also DC powered now. Power use is hard to track because of the thermostat of the warm bag. @ .19 per kw hour in Minnesota the power use for entire month is 15kw in June to 47kw in Jan. That is TOTAL for entire month.
When this type of unit can have AC power it has a AC to DC 24 volt converter. $ 1.96 per month total. Fees and taxes run bill higher. But that is not the issue. Remote locations is the goal.

 

[SurpriseAZ]

It sounds like this AED unit:
- needs to always be running (it is monitored, and reports back to 911)
- these things cost 1000's of dollars, and need to be "protected" (protection system needs $$$)
- you need something foolproof, because it's an AED

We don't know enough about where the AED cabinet lives, and what resources are available around it. Is it just a cabinet hanging off a tree, on a job-site and will be moved later, etc.? Some of these answers might further direct the solution (as in, I might put everything on a trailer of some kind).

So, I'd put in a bulletproof inverter-charger and battery-bank, a site-sized propane tank, and a propane fuel-gen (small, but appropriately sized), and enough smart gear to decide when the battery-bank is low, and start recharging it from sources that can never go down, regardless of weather and such. If a trailer *is the right answer*, then solar panels can be easily integrated.

When all is said and done, this AED cabinet has its bullet-proof support system, and perhaps other things around it can benefit from the spending and the available power.

Without knowing all the constraints, choices, and other requirements, I'd say use a portable solar gen, sized right, and fed with whatever will keep it going thru MN conditions year-round. I currently like this portable solar-gen that allows you to use your own battery-bank (vs it being integrated, and/or having to buy some vendors' idea of a battery-bank or expansion capabilities):

amazon.com/ECO-WORTHY-Portable-Controller-Traveling-Household/dp/B0DB1VGGJ9

But, without answering all the design q's, don't yet know what's appropriate for the design.

Hope this helps ...

This is 100% DC unit. No need for inverter. AED unit is kept in a insulated bag that is also DC powered now. Cabinet is secure and provides all weather protections now. Power use is hard to track because of the thermostat of the warm bag. @ .19 per kw hour in Minnesota the power use for entire month is 15kw in June to 47kw in Jan. That is TOTAL for entire month.
When this type of unit can have AC power it has a AC to DC 24 volt converter. $ 1.96 per month total. Fees and taxes run bill higher. But that is not the issue. Remote locations is the goal.