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Old 02-11-2020, 01:02 PM
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Real life experiences with inverters and batteries (non-RV)?


Short version: Power was out for more than two days while I was away on business. We have gas logs and gas water heater, so no problem there. Plenty of flashlights and batteries for my wife to use. Friends offered to come get her and have her stay with them, but she was concerned about leaving the kids. Biggest problems were keeping a charge on her cell and the fact that her CPAP wouldn't work. She was also concerned about the food in the fridge.

In my post-event guilt, I've addressed several of the issues, including getting a 12 VDC to 24 VDC converter to run her CPAP from a 12 VDC source. Now, I just happen to have a 1200-watt inverter sitting around. I know I can run it off the car using clamps and 4 AWG cables to the battery terminals, but she is not going to go out and hook that up by herself. Therefore, I'd like to have a decent rechargeable battery in the house. I could use it either with a lighter adapter so she can run her CPAP, or I could leave the inverter connected to it so she could have (limited) AC. In either case, it would be inside the house in a conditioned environment while charging and discharging.

What kind of real-life experience does anyone have with doing this? There are obviously some gray areas.

1. I'd like the SLA deep-cycle battery to be large enough to be useful, but small enough she can move it if she needs to. Maybe 35 AH? 55 AH? 75 AH? 100 AH (about 60 pounds!)? Remember, I don't currently have a battery (except in my car) on which to do any testing.

2. I know the inverter can run my side-by-side refrigerator, but I don't know how much power it draws. I'm guessing 400 to 700 watts. Can I cycle the fridge for an hour, leave it off for a couple hours, and then cycle it again for an hour safely to preserve battery power?

3. Would I be OK using my big car battery charger (in deep-cycle AGM mode) to put an initial charge on, say, a 55 AH battery and then use an inexpensive battery maintainer to keep it topped off? Is this a problem with a deep-cycle battery?

Ideally, I just want to spend $125 - $175 on a single battery and leave it at that. People who seem knowledgeable about inverter/battery systems almost always start out by saying, "In my RV..." and the info isn't always directly comparable to what I'm trying to do.

Or, should I forget the whole idea and have a Pop-Tart?

PS - "Kids" = dogs.

Last edited by ZonexandScout; 02-11-2020 at 01:04 PM.
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Old 02-11-2020, 02:15 PM
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Charging a cell phone and operating a CPAP machine is probably ok. Once you add in the fridge, you're toast. The CPAP and phone charger will probably run for a few days on a 12 volt battery with an inverter. A fridge uses roughly twice as much energy per day as a 12 volt battery will contain though, so you'll be completely dead in about half a day.

Trying to cycle the fridge won't work. You will either just make the fridge stay on for longer while it is plugged in (so that it ends up using about the same amount of energy) or you'll unplug it while it's still cooling, which will use less power but also will not keep your food cold enough, which kinda defeats the purpose of running the fridge.

Add in air conditioning and your power requirements go up significantly from that.

Have a pop-tart.

Or buy a generator.
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Old 02-11-2020, 02:41 PM
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Quote:
Originally Posted by ZonexandScout View Post
2. I know the inverter can run my side-by-side refrigerator, but I don't know how much power it draws. I'm guessing 400 to 700 watts. Can I cycle the fridge for an hour, leave it off for a couple hours, and then cycle it again for an hour safely to preserve battery power?
Think about this for a second: If it were possible to cycle the fridge, leave it off for a few hours and save electricity while still maintaining temperature- wouldn't this be the default setting from the fridge manufacturer?
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Old 02-11-2020, 02:53 PM
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YamatoTwinkie, I get your meaning, but I'm assuming that I'm keeping the fridge closed while the power is out. After all, refrigerators DO cycle on and off. My intention would be to allow it to cycle for a period in an effort to retard the eventual thawing of frozen foods. Every few extra hours can mean I don't have to toss $$$ of food out.
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Old 02-11-2020, 03:00 PM
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engineer_comp_geek, thanks for the input! A generator is out of the question, for both financial and operator (i.e., my spouse) reasons. I was hoping that a 100 AH battery might give me as much as 4 hours of operating time. Spread over a few days, that might make a difference. I have no illusions about operating a fridge continuously on a battery.

The CPAP is actually a challenge since it operates pretty much continuously, though at a much lower current draw. Plus, it's at the other end of the house and my spouse is unlikely to carry a bigger battery that far.
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Old 02-11-2020, 04:03 PM
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For my CPAP, I have a Duracell Ultra DURG12-31J-A. It's certified for medical devices, unspillable (Gel) and has 31AH. It weighs around 20-25 lbs. as near as I can guess.

My CPAP has a 12VDC connector, and I bought a good car 12V female connector to wire to the battery itself. I have used it all night just to test, and it works fine. According to the draw of my CPAP, it should be good for 3 nights, but I haven't tried it. Obviously I can't use the reservoir heater, but I never do when camping out. I keep it on my bedside table, and take the charger up there once a month (I have "charging day" once per month and take care of everything including car power packs).

Last edited by pullin; 02-11-2020 at 04:04 PM.
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Old 02-11-2020, 04:06 PM
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Sorry, missed the edit window. It cost $120.00 (before tax, I think).
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Old 02-11-2020, 05:28 PM
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Quote:
Originally Posted by pullin View Post
For my CPAP, I have a Duracell Ultra DURG12-31J-A. It's certified for medical devices, unspillable (Gel) and has 31AH. It weighs around 20-25 lbs. as near as I can guess.

My CPAP has a 12VDC connector, and I bought a good car 12V female connector to wire to the battery itself. I have used it all night just to test, and it works fine. According to the draw of my CPAP, it should be good for 3 nights, but I haven't tried it. Obviously I can't use the reservoir heater, but I never do when camping out. I keep it on my bedside table, and take the charger up there once a month (I have "charging day" once per month and take care of everything including car power packs).
Very helpful! Thanks! I was thinking that a 35 AH battery might do the trick for a couple nights and that it would be light enough for her to carry from the charger in the utility room to the bedroom.
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Old 02-13-2020, 04:47 PM
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Originally Posted by ZonexandScout View Post
YamatoTwinkie, I get your meaning, but I'm assuming that I'm keeping the fridge closed while the power is out. After all, refrigerators DO cycle on and off. My intention would be to allow it to cycle for a period in an effort to retard the eventual thawing of frozen foods. Every few extra hours can mean I don't have to toss $$$ of food out.
Refrigerators don't just cycle for giggles. The cycles are in response to a thermostat setting, where internal temperature has increased above the setpoint. By unplugging it, all you're doing is allowing internal temperature to exceed the threshold, which may or may not be above food safe temperatures depending on how long you leave it unplugged.

You could accomplish the same thing with less effort (and risk of spoilage) by just raising the fridge thermostat setting.
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Old 02-14-2020, 08:56 AM
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I doubt the extra battery capacity to run the fridge would pay for itself. What is the total value of the food in your freezer? If you have something vital in your freezer or fridge (like medication), you can get a small 12v fridge. Also, being thawed and re-frozen does not make food inedible, as long as it does not warm up above 40f or so. You can also stock up on ice and use it to keep the fridge cool.

Last edited by scr4; 02-14-2020 at 09:00 AM.
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Old 02-14-2020, 09:54 AM
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Well, while batteries aren't cheap, I already have the inverter sitting around, along with battery cables. I know I can run the fridge on the inverter if I connect it to my car battery while the car is idling. I'm thinking that I would be looking at a battery cost of $175 to $350. At any one time, I have at least $300 worth of food in the fridge (not including the time and trouble of cleaning it out and restocking).

I'd have no problem spending $500 on a small inverter/generator, if only my wife could start it and get it hooked up.

I was just hoping somebody would come along and say something like, "Yeah. I've got 200 AH of batteries and run my fridge for 30 minutes every eight hours. I can maintain decent temperatures for 3 days." (I doubt it would work for three days.)
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Old 02-14-2020, 10:58 PM
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You have an inverter, but otherwise my suggestion would be something like this "powerbox":
https://www.canadiantire.ca/en/pdp/m...-0112028p.html

This is from a Canadian retailer, but they're actually made by a US company who rebrands them for sale in Canada. With a little digging, I found the US brand online a few years ago to compare prices. They're identical, except the plastic handles are a different colours.

We have an off-grid cottage and I used one of these every weekend for about 3 years. It worked well until it didn't. The biggest negative is that the units aren't repairable - the batteries cells are sealed so once they go, they can't be repaired or replaced (easily). I have a friend with a cpap and he bought one to use for camping etc. Works great for 2 or maybe 3 nights of cpap, but longer than that, you need to charge it somehow.

It sounds like you don't want to do a generator, but that would be my recommendation. Once my power pack died, I got smallest Honda (which will do your fridge). IMHO, it would be complete peace of mind.

It's only the size of a large briefcase & very easy to start: Switch to start position, flip choke to on, pull starter cable, flip off choke. It's so easy, I would literally send my 9 year old daughter to do it. Plug your extension cord in and you're good to go. Unless your wife is really physically incapacitated then it shouldn't be an issue.

https://powerequipment.honda.com/gen...models/eu2200i

The Honda's are more expensive, but mine is now 10 years old and still starts as easy as the day I bought it.
  #13  
Old 02-15-2020, 09:18 AM
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Thanks, GMANCANADA, but it really is a hard fact that my wife (67 YO with neuropathy, needs a cane to walk) is not going to start a genny, run the cables, or refuel it. I've tried to get her to hook the inverter to one of our cars and she says (nicely), "Ain't gonna happen."

I think the extent of her potential involvement would be to turn on a pre-connected inverter and run a short extension cord from the utility room to the adjacent kitchen.

Side story: When the power had been out for more than four hours, my wife took her flashlight and went around the house turning off and disconnecting all the electrical equipment, multiple outlets, and anything she could find. She had heard that the electrical system surges could damage equipment when power was restored. Having to figure out everything she turned off and disconnected took me nearly two days. In fact, it was about two hours after the power was restored that I discovered she had also disconnected the fridge and it was still unplugged.

Thanks again to everyone who has responded. In a perfect world, I'd have a small inverter/generator in the shed and be able to pull it out, hook it up, and get it going when required. When I'm OOT, it's not an option.
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Old Yesterday, 05:10 AM
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If you can afford it, consider getting an auto start generator. Sounds like you don't have near enough money to get one to run the whole house, so push button, not automatic when the power goes off.

It still needs a battery: the battery needs to be big enough to start the generator. Start it every 4-6 months, check the gas and battery.

Last edited by Melbourne; Yesterday at 05:11 AM.
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