I don't want to buy a gas generator!

[oneandahalflegs]

Hey, Need to know how crazy I am. First two things, 1. I have ALS, am wheelchair bound, and am ventilator dependent 24/7. 2. I am a mechanical engineer that does not like to let anyone else work on my shit,.... I have had to give up on that one.

My trach was installed last September. we have been working towards making my house better prepared for emergencies. Doctors, nurses, and other ALS patients scream GAS GENERATOR.

What I want to know is it possible and sensible to build a battery bank with inverter blabla to replace that generator. If an event where to last more than 4 days we would be out of there. Don't necessarily need solar, but need to understand the math. battery bank sitting charged for months is,.... crazy?

Here is some of the data I've gathered so far. not sure we need everything here. Would think we would separate circuits like a generator hook up.

Would love to hear your thoughts.

	watts
	min.	max	volts	amps
heater		800	120	6.7
hot water	2	76	120	0.6
fridge		360	120	3.0
well pump		5000	220	22.7
outlets in addition	0	500	120	4.2
sump pump		200	120	1.7
septic pump		200	120	1.7

 

[Supervstech]

A powerwall is exactly what you are describing.

Basically, a smart ups for the house.

If you have time of day demand rate electrical costs, it can even save money on the power bill.

Now solar is even better, as it charges from the sun instead of the utilities, but, yes. It is done.

 

[DThames]

"I am a mechanical engineer that does not like to let anyone else work on my shit ", that has to be awful, on top of your physical problems. The starting load on the well pump will cause a battery/inverter system to be oversized just to handle that pump. Solar charging can't be depended on if you have clouds. Output on a cloudy day can be 5% or less of normal, easily. I don't think you will be able to do better than a generator with high power loads and with the need for prolonged power in a power out emergency. They have generators that will run on natural gas and propane, are self starting, can test themselves on a timed cycle, and can be wired into the house as a permanent system. If you just don't want to have a generator running with the noise and such, a battery/inverter system with emergency generator charging would be a possible solution.

I am working on an emergency system, planning to use a generator only for high loads and charging if the sun doesn't cooperate. I have been giving this sort of thing thought for a while.

I am curious about the low watt number for the hot water. My electric water heater is a power hog.

 

[SCClockDr]

Hey, Need to know how crazy I am. First two things, 1. I have ALS, am wheelchair bound, and am ventilator dependent 24/7. 2. I am a mechanical engineer that does not like to let anyone else work on my shit,.... I have had to give up on that one.

My trach was installed last September. we have been working towards making my house better prepared for emergencies. Doctors, nurses, and other ALS patients scream GAS GENERATOR.

What I want to know is it possible and sensible to build a battery bank with inverter blabla to replace that generator. If an event where to last more than 4 days we would be out of there. Don't necessarily need solar, but need to understand the math. battery bank sitting charged for months is,.... crazy?

Here is some of the data I've gathered so far. not sure we need everything here. Would think we would separate circuits like a generator hook up.

Would love to hear your thoughts.

	watts
	min.	max	volts	amps
heater		800	120	6.7
hot water	2	76	120	0.6
fridge		360	120	3.0
well pump		5000	220	22.7
outlets in addition	0	500	120	4.2
sump pump		200	120	1.7
septic pump		200	120	1.7

You stated you have ALS, I see no life support numbers. That is the number you need to exceed, the others do not matter if life support falls short. "Out of there" may not be an option if TSHTF. (Quake, major storm, etc.)
Location might provide some insight to your dilemma as well.
What you describe would require a minimum of 2 backups were it me. So a fossil fuel generator (diesel or propane) with an abundance of fuel storage seems reasonable.

 

[oneandahalflegs]

"I am a mechanical engineer that does not like to let anyone else work on my shit ", that has to be awful, on top of your physical problems. The starting load on the well pump will cause a battery/inverter system to be oversized just to handle that pump. Solar charging can't be depended on if you have clouds. Output on a cloudy day can be 5% or less of normal, easily. I don't think you will be able to do better than a generator with high power loads and with the need for prolonged power in a power out emergency. They have generators that will run on natural gas and propane, are self starting, can test themselves on a timed cycle, and can be wired into the house as a permanent system. If you just don't want to have a generator running with the noise and such, a battery/inverter system with emergency generator charging would be a possible solution.

I am working on an emergency system, planning to use a generator only for high loads and charging if the sun doesn't cooperate. I have been giving this sort of thing thought for a while.

I am curious about the low watt number for the hot water. My electric water heater is a power hog.

Good points. hmm, maybe well pump could be separated from this plan to reduce battery requirements. Pump could be generator only. this might allow for smaller generator and battery.??? Getting complicated. the biggest issue with generator is that my wife gets stuck with it. Tools and machines are not her skill set.

Rinnai tankless running on propane.

 

[kernel]

Many inverter systems actually have a disclaimer against use for medical life support systems.
That being said, there is no reason a system cannot be designed with reasonable redundancy, build two. Or three.

Two is one, one is none. Two sets of power electronics and batterys along with a smaller mobile system.
A generator backup really could be a(the) third option or redundancy, but im with you on not wanting them around.

 

[oneandahalflegs]

You stated you have ALS, I see no life support numbers. That is the number you need to exceed, the others do not matter if life support falls short. "Out of there" may not be an option if TSHTF. (Quake, major storm, etc.)
Location might provide some insight to your dilemma as well.
What you describe would require a minimum of 2 backups were it me. So a fossil fuel generator (diesel or propane) with an abundance of fuel storage seems reasonable.

Ventilator requires 70watt at 120Vac to run and charge it's internal lipo batteries. Assume this is part of the addition outlets requirement. worst case the vent can be run on 12 VDC (not charging batteries) then requires 15 watts. I have a Jackery 500 that should provide some serious cushion for this purpose. the internal battery for the vent should provide 6 hours of run time.

I am in South East Pennsylvania. Storms that knock out power are our concern.

I do have a 300 gal tank of propane that I would love to have a generator connection to... expensive.

 

[SCClockDr]

I do have a 300 gal tank of propane that I would love to have a generator connection to... expensive

Not as expensive as the alternative.
I'd bullet proof your life support backups first.
A small Honda EU2200Si or EU3300Si converted to propane would do nicely. The 3300 is electric start and can be made automatic.
Genrac etc. whole house generators are indeed expensive.

 

[kernel]

A house ups system (battery backup) and two smaller ancilliary systems sized for lighting, comms, and life support are pragmatic. Alont with an electric start honda as suggested above no problems in most storm situations. Weeks of backup on very little fuel.

If you have batteries and sun exposure, a pv module makes sense and can extend your autonomy and provide generator run time avoidance. it does not have be a full blown resi system to do much more than offset day use and power electronics consumption.

If you have a way to power everything you would use, over the duration you are designing for and measure that, you would be in the best position to decide on a path.

These charts can work but nothing beats direct measurement and sage derate for desired performance and endurance.

 

[SolarQueen]

Your chart is missing a critical column. Time running. For example, sure your well pump draws 5000W, but for how long throughout the day? Maybe a half hour? Watts x hours = watt hours, which is what you need to determine the battery bank size, and the solar if you go that route. 5000W x .5 hours = 2500Wh. Your fridge probably only actually runs 12 hours a day. Add time to each item, and the feasibility will be more clear.

 

[FilterGuy]

Hey, Need to know how crazy I am. First two things, 1. I have ALS, am wheelchair bound, and am ventilator dependent 24/7. 2. I am a mechanical engineer that does not like to let anyone else work on my shit,.... I have had to give up on that one.

My trach was installed last September. we have been working towards making my house better prepared for emergencies. Doctors, nurses, and other ALS patients scream GAS GENERATOR.

What I want to know is it possible and sensible to build a battery bank with inverter blabla to replace that generator. If an event where to last more than 4 days we would be out of there. Don't necessarily need solar, but need to understand the math. battery bank sitting charged for months is,.... crazy?

Here is some of the data I've gathered so far. not sure we need everything here. Would think we would separate circuits like a generator hook up.

Would love to hear your thoughts.

	watts
	min.	max	volts	amps
heater		800	120	6.7
hot water	2	76	120	0.6
fridge		360	120	3.0
well pump		5000	220	22.7
outlets in addition	0	500	120	4.2
sump pump		200	120	1.7
septic pump		200	120	1.7

Check out this planning tool:
https://diysolarforum.com/threads/energy-audit-and-system-sizing-spreadsheet.3552/

 

[FilterGuy]

Note: The spreadsheet does not try to do anything special for things like a well pump that has a really high turn on surge. You may want to do some side calculations to see if the inverter and battery bank need to be bigger to handle the surge.

 

[oneandahalflegs]

Your chart is missing a critical column. Time running. For example, sure your well pump draws 5000W, but for how long throughout the day? Maybe a half hour? Watts x hours = watt hours, which is what you need to determine the battery bank size, and the solar if you go that route. 5000W x .5 hours = 2500Wh. Your fridge probably only actually runs 12 hours a day. Add time to each item, and the feasibility will be more clear.

Understood, and how do others measure this duration,?

 

[FilterGuy]

Understood, and how do others measure this duration,?

For things like lights and other things that are manually controlled, you just pay attention for a few days and you can then make a pretty good estimate.

For things like refrigerators that turn on and off by themselves, I have put a Kill-o-watt on it and measure the whr consumed over a set period of time.
I can then calculate the duty cycle.

Example with random numbers:
Watts used while on: 6
Watt-hours over a 6 hour period: 18
Watt-hours/day = 18 Hrs* (24Hr/day/6hr) = 72Whr/day
Hours on/day = 72Whr/day/6watts = 12 hrs/day

 

[oneandahalflegs]

For things like lights and other things that are manually controlled, you just pay attention for a few days and you can then make a pretty good estimate.

For things like refrigerators that turn on and off by themselves, I have put a Kill-o-watt on it and measure the whr consumed over a set period of time.
I can then calculate the duty cycle.

Example with random numbers:
Watts used while on: 6
Watt-hours over a 6 hour period: 18
Watt-hours/day = 18 Hrs* (24Hr/day/6hr) = 72Whr/day
Hours on/day = 72Whr/day/6watts = 12 hrs/day

I have kilawatt,. my not so willing assistant just went back to college,. I need real data from well pump.

 

[DThames]

Good points. hmm, maybe well pump could be separated from this plan to reduce battery requirements. Pump could be generator only. this might allow for smaller generator and battery.??? Getting complicated. the biggest issue with generator is that my wife gets stuck with it. Tools and machines are not her skill set.

Rinnai tankless running on propane.

Because we have a slow producing well, we put in a 1000 gallon concrete sand filter many years ago. A well pump pumps water into the filter (was on a timer at 2 minutes per hour) as needed but this might be short of high short term demand. So the filter is a buffer. It happens to hold enough water to last us for 2 or 3 days if the power is out. We have a pump in the filter to pump into a pressure tank, as normal. Pumping from a holding tank to a pressure tank doesn't need to be as large of a pump as to pump from the well. So some storage might take the size of the well pump out of the equation, if that might be an option.

 

[SCClockDr]

A Shure flow RV water pump can do that transfer (filter > pressure tank) with 12 volts DC.

 

[kernel]

Yes kill-a-watt and clever multi outlet strip use will allow measurment of groups of devices or whole rooms.

Lights are easier to estimate than most other intermittent loads.

A proper whole house and individual circuit measuring monitor could be set up for a few hundred dollars. (Ct array)

Or if you need, you could hire an energy auditor to measure just electrical usage. They will likely attach an array of current transducers to a portable data logger eith network access or just leave it for a time and pick up the data.

A clamp on current meter can be used to measure surge and continuous load of individual circuits or the mains and added to the spreadsheet. An electrician would provide this service at a reasonable cost.

If you have a dmm and clamp on ammeter you can turn on breakers to what you would have in critical loads and measure that at the service conductors to measure true overlapping loads as they would occur in backup use.

Ultimately if budget allows, you could take your utility billing details and figure out a target kilowatt hour budget based on full on use for a certain number of days and you have a close number from possibly years of billing.

Looks like an ad, its not. Energy detective. Cool tool.

TED-The-Energy-Detective.com - The Energy Detective Home Energy Monitoring

Monitor your energy consumption with The Energy Detective's TED5000 Home energy monitor.

www.theenergydetective.com

 

[SCClockDr]

On a nuclear submarine when the reactor scrams the entire boat "rigs for reduced electrical" lots of stuff gets turned off to preserve power so the engineers have enough power to restart the reactor.
It would be wise to audit your electrical needs and develop a list of prioritized loads & label them.

 

[oneandahalflegs]

Yes kill-a-watt and clever multi outlet strip use will allow measurment of groups of devices or whole rooms.

Lights are easier to estimate than most other intermittent loads.

A proper whole house and individual circuit measuring monitor could be set up for a few hundred dollars. (Ct array)

Or if you need, you could hire an energy auditor to measure just electrical usage. They will likely attach an array of current transducers to a portable data logger eith network access or just leave it for a time and pick up the data.

A clamp on current meter can be used to measure surge and continuous load of individual circuits or the mains and added to the spreadsheet. An electrician would provide this service at a reasonable cost.

If you have a dmm and clamp on ammeter you can turn on breakers to what you would have in critical loads and measure that at the service conductors to measure true overlapping loads as they would occur in backup use.

Ultimately if budget allows, you could take your utility billing details and figure out a target kilowatt hour budget based on full on use for a certain number of days and you have a close number from possibly years of billing.

Looks like an ad, its not. Energy detective. Cool tool.

TED-The-Energy-Detective.com - The Energy Detective Home Energy Monitoring

Monitor your energy consumption with The Energy Detective's TED5000 Home energy monitor.

www.theenergydetective.com

Never tease a data geek with a tool like that....