Hurricane preparedness

[gnappi]

I have a decent 8500 watt genset that has worked out for the last 12 years for me after storms and losing our power. The issue was and likely will be keeping the Genset running and / or getting gasoline. What I use it for is my refrigerator, and two 6000 BTU window AC units.

What I'd like to find out is whether or not given my current and easily expandable system is reasonable to think I can duplicate my genset duties. So I bought a Killawatt meter and ran my two appliances to get my expected loads.

My refrigerator 1.15Amps with compressor and fan running. It runs infrequently and in standby drops to zero. Even if Genset is running I unplug it overnight

Two 6000 BTU window AC units @ 2.8Amps each After a hurricane they run continuously with exception on cooler nights I run AC fans.
Minor conveniences like two small LCD TV's @ less than a half amp each and some LED lighting.

NOTE, the system is NOT grid tied.

My current system panels are 575 watts (space left to expand to 775W total) with a 60A MPPT controller.
Battery system is 12 volts (2x100Ah Marine deep cycle, easily expandable to needs)
I have one 5000/10000 watt 12 volt inverter and one 12 volt 1000w inverter

Have parts / pieces to add ground mounted panels at 300 watts of panels (easily expandable another 400 watts to 700w total) with 60A MPPT controller.

So, given I'm stuck with 12 volts (cast in stone, 24v/48v ain't happening) and no place for additional panels but ample space for batteries, what would I need to sustain some level of comfort at night with my two AC units running 24/7.

 

[MisterSandals]

My refrigerator 1.15Amps with compressor and fan running. It runs infrequently and in standby drops to zero. Even if Genset is running I unplug it overnight

Two 6000 BTU window AC units @ 2.8Amps each After a hurricane they run continuously with exception on cooler nights I run AC fans.
Minor conveniences like two small LCD TV's @ less than a half amp each and some LED lighting.

Can you quantify how many minutes per hour your refrigerator runs? This would let us calculate watt hours per day.

Same for your other AC units and lights; we need usage as watt hours per day.

 

[MichaelK]

My current system panels are 575 watts (space left to expand to 775W total) with a 60A MPPT controller.
Battery system is 12 volts (2x100Ah Marine deep cycle, easily expandable to needs)
I have one 5000/10000 watt 12 volt inverter and one 12 volt 1000w inverter

Have parts / pieces to add ground mounted panels at 300 watts of panels (easily expandable another 400 watts to 700w total) with 60A MPPT controller.

So, given I'm stuck with 12 volts (cast in stone, 24v/48v ain't happening) and no place for additional panels but ample space for batteries, what would I need to sustain some level of comfort at night with my two AC units running 24/7.

This is not going to work at 12V. Sorry, but you need a reality check here. I have a 48V system with 4500W of panels, and I'm running one air-conditioner in addition to my frig.

You can basically forget about running two air-conditioners on less than 600W of panels. It ain't gonna happen!

 

[gnappi]

As I said, I can easily add 200 watts to the existing wall mounted (south facing) panels making that 775 and the ground setup at currently 300w I could easily add another 400 watts. That would give me 1475 watts. I would think that during the day this might keep whatever batteries I have topped off?

Anyway, the refrigerator runs two or three times an hour for ~5 minutes each time, Killawatt says 134 watts and 320watts for the AC units.

 

[MichaelK]

Amperage is impractically high for 12V. 1475W/13V charging = 113A. Have you priced a controller that can handle >100A? They are not cheap! Please explain your slavish adherence to 12V? This would be so much easier to accomplish with a higher voltage system.

 

[gnappi]

Amperage is impractically high for 12V. 1475W/13V charging = 113A. Have you priced a controller that can handle >100A? They are not cheap! Please explain your slavish adherence to 12V? This would be so much easier to accomplish with a higher voltage system.

Not slavish, my inverters would be costly to replace, now if someone would offer to upgrade me for free, I'd not be tied to 12 volts, as it is, not today.

Maybe I was unclear... As I said, I have TWO 60A Mppt controllers, I'd not need anything larger there.

I "GET" that running at 24/48 volts this would be easier to accomplish, but that wasn't my question. Adding the panels I mentioned at 12 volts is readily and inexpensively done, as are 12 volt deep cycle marine batteries.

 

[time2roll]

Are the air units on 240 or 120 volts? 2.8 amps seems low for 120 volts.

 

[mrdavvv]

They need to be 240.

Or he has a seer 30 system

 

[time2roll]

So maybe 150 amps continuous at 12 volts. That is 3600 amp hours for each 24 hours. I think you need 56 cells at the common 280 Ah to make 14 batteries in parallel or combine the cells in parallel for fewer but larger batteries. Yes a few things may have a duty cycle but other items you may want don't seem to be listed. That should buy you enough time to hunt for additional gasoline. Solar can probably maintain the batteries but I am not sure how much sun you will get in the days that follow the big storm. Going to be a power deficit either way.

That is my back of the napkin plan. Best of luck.

 

[eXodus]

I have a decent 8500 watt genset that has worked out for the last 12 years for me after storms and losing our power. The issue was and likely will be keeping the Genset running and / or getting gasoline. What I use it for is my refrigerator, and two 6000 BTU window AC units.

My current system panels are 575 watts (space left to expand to 775W total) with a 60A MPPT controller.
Battery system is 12 volts (2x100Ah Marine deep cycle, easily expandable to needs)
I have one 5000/10000 watt 12 volt inverter and one 12 volt 1000w inverter

Have parts / pieces to add ground mounted panels at 300 watts of panels (easily expandable another 400 watts to 700w total) with 60A MPPT controller.

So, given I'm stuck with 12 volts (cast in stone, 24v/48v ain't happening) and no place for additional panels but ample space for batteries, what would I need to sustain some level of comfort at night with my two AC units running 24/7.

Hello Fellow Hurricane Prepper.

Questions:
What are the brands/model of your MPPTs? Are you sure they can only do 12V ? Many of those are 12/24v (usually in Chinese fineprint)

Can you section of the house/cabin to only run only one of the Window A/C Units?
I'm currently installing folding doors for just this scenario. It's a hurricane, we all sit in one room together, no need to Air condition more then hat.

For nice times, yes full A/C everywhere but just a once in 3 year power outage? Doors are really cheap. Even a curtain would do for sectioning of the space.

 

[gnappi]

Thanks all, and yes the CC's (Asian ) can do 12/24/36/48 volts. The AC units are high seer 110 volts. Suprisingly, the little units keep the house at a live able level. The ceilings are "cathedral" style which helps, and the attic ventilator (on its own solar panel) also helps.

Timetoroll, I'm trying to wrap my mind around the 150 amps continuous comment? I'm solar math impaired help me understand that?

 

[Supervstech]

150A at 12V is 1800W... your stated loads are 940W plus surge starting loads. I’m not sure why he stated 150A either.
looks like he napkin figured about 30% high... not far off though.
Cut down usage, and you could drop below 400W... for emergency backup, ac being the priority, a single unit... and spot use of the tv’s

 

[Diysolar123]

well, as a fellow "in the hurricane zone" planner I divide things up and do not try to go for a single solution to meet all needs.
fridge/freezer need a big startup rush of current, and then settle down nicely. For those a a solar system works great as their total daily demand is not that bad I use 2/0 awg wire from battery to the inverter.
For AC, well, they really suck the power and for that while solar can definitely meet the need, it takes a LOT of solar panels.
Sometime when the hurrican leaves its clear skies and solar is nice, other times, well, its overcast for several days and that leaves solar useless.

I just use a propane/gas generator which can help top off the batteries and run the AC as needed.
You can easily store propane for, well indefinitely in large tanks; gasoline can also be stored long term IF the container is full and air tight (swap out the fuel every couple years)! I have a couple of the 100lb propane tanks, easy to store and the limit of what you can easily move around to get refilled (about 150lbs full, I use my harbor freight engine lift to move it!!).

as to your max current draw at 12v... its just a simple math problem.
total wattage / 12v == the amps; now take that and plan on a 2x "surge" for wire sizing. Depending on the motor, sometimes the surge is 3-4x!!

 

[gnappi]

Yeah, being in Florida since the mid 70's I get the aftermath sky condition issue, sometimes blazingly clear and hot, other times overcast. But luckily overcast days are not as hot and are more tolerable with just a fan.

So, fourteen 100 Ah batteries is close to the number I'd need? I'm guessing my night time run time will be minimal, maybe not worth the time, perhaps a propane mod to the genset is a good idea too.

 

[eXodus]

Yeah, being in Florida since the mid 70's I get the aftermath sky condition issue, sometimes blazingly clear and hot, other times overcast. But luckily overcast days are not as hot and are more tolerable with just a fan.

So, fourteen 100 Ah batteries is close to the number I'd need? I'm guessing my night time run time will be minimal, maybe not worth the time, perhaps a propane mod to the genset is a good idea too.

what you need is to run that generator more efficient.

That generators probably needs a gallon or so per hour. ? No matter if you got any load to it connected or not.

I got a 5500w Generator and I'm planning to install battery chargers for about 5000w. So that when I fire up that generator it charges my batteries full first. I'm going to have about 10kwh in batteries. What I need for about a day without any sun.

So worst case I fire up the generator - two hours every day to recharge the battery bank. My generator needs about 3/4 of a gallon for one hour.

When I would run the generator for A/C units - it would run 24h a day - so 15-20 gallons a day. Going down to 2 gallons a day - that's 90% reduction in runtime - without any solar. For batteries + inverter.

 

[time2roll]

The stated loads were 1500 watts continuous until the A/C was clarified to be at 120 volts. So make it 100 amps continuous and 2400 Ah of battery is needed for 24 hours. You can buy a few less cells or get more run time. Your call.

 

[MichaelK]

So, fourteen 100 Ah batteries is close to the number I'd need? I'm guessing my night time run time will be minimal, maybe not worth the time, perhaps a propane mod to the genset is a good idea too.

This just seems like the height of foolishness to me! You have the money to go out and buy 14 batteries, but you don't have the money to upgrade your inverter? I don't think anyone can successfully run a 12V bank paralleled with 14 batteries without ruining some/all of them. Just do the math here. 100Ah X 12V X 14 batteries = 16800Wh of storage. A little bit less than my 48V single string set of L-16 batteries. I'm running 8 L-16s in series to get 377Ah X 48V X 1 string = 18096Wh.

Even if you insist on keeping your 100Ah 12V batteries, they could be wired into three 4-batteries strings that would be MUCH easier to keep balanced. 14 batteries in parallel is a problem just waiting to happen. Keep in mind that you will also save a LOT of money on expensive copper wire, because you don't have to design everything to carry hundreds of amps of current, and there will be far fewer connections.

 

[time2roll]

As stated OP could almost run everything on the 1000 watt inverter. Max probably 2000 watts is very doable on 12 volts. That 5000 watt 12v inverter is a joke. Wire it and fuse it for 2000 watts and see what goes.

 

[OnTheRoadAgain]

Running an 8000kw genset "might" be excessive and run through a lot of fuel.
At least one of those AC units AND the fridge should be able to start up and run on a 2200watt fuel sipper.

I have a decent 8500 watt genset that has worked out for the last 12 years for me after storms and losing our power. The issue was and likely will be keeping the Genset running and / or getting gasoline. What I use it for is my refrigerator, and two 6000 BTU window AC units.

What I'd like to find out is whether or not given my current and easily expandable system is reasonable to think I can duplicate my genset duties. So I bought a Killawatt meter and ran my two appliances to get my expected loads.

My refrigerator 1.15Amps with compressor and fan running. It runs infrequently and in standby drops to zero. Even if Genset is running I unplug it overnight

Two 6000 BTU window AC units @ 2.8Amps each After a hurricane they run continuously with exception on cooler nights I run AC fans.
Minor conveniences like two small LCD TV's @ less than a half amp each and some LED lighting.

NOTE, the system is NOT grid tied.

My current system panels are 575 watts (space left to expand to 775W total) with a 60A MPPT controller.
Battery system is 12 volts (2x100Ah Marine deep cycle, easily expandable to needs)
I have one 5000/10000 watt 12 volt inverter and one 12 volt 1000w inverter

Have parts / pieces to add ground mounted panels at 300 watts of panels (easily expandable another 400 watts to 700w total) with 60A MPPT controller.

So, given I'm stuck with 12 volts (cast in stone, 24v/48v ain't happening) and no place for additional panels but ample space for batteries, what would I need to sustain some level of comfort at night with my two AC units running 24/7.

Hello,
I didn't read the entire thread so if this has already been suggested then please forgive me but........

Have you considered (or do you have) a smaller gasoline generator?
An 8kw generator uses an awful lot of fuel.

I have 4 generators. Two 2000watt inverter generators, one 3500watt inverter generator and one 6500watt non inverter generator.
I find I can run one 5000watt window AC unit AND my refrigerator off of one of these 2000watt generators for nearly a day and a half on ONE gallon.

It might be beneficial to you to add a 2000watt inverter generator. Good ones like Pulsar can be had for around $300. Dirt cheap.

Not sure if this would even work for you but it works well for me and many others. The golden ticket for generators is utilizing as little fuel for as much comfort and utility as you can squeeze out of available supplies.

Of course, solar is even better if you have it.