Thankful for battery backup during power outage

[TRzzz]

In the wake of the recent hurricanes and the power outages they caused, I want to post an encouragement to anyone who relies on their CPAP but doesn't have a source of backup power that will cover you for several days to consider buying or building a backup power assembly. Where I live in eastern Georgia, we thankfully only lost power for a few hours this time, but three winters ago we lost power for a day and a half after an ice storm, and the torture of being unable to sleep without a CPAP motivated me to find a solution.



My setup consists of a 55Ah battery inside a plastic "field box" or ammunition box. On the outside of the box is a standard automotive power port as well as two USB ports for charging phones. Also mounted on the box is a voltmeter and ammeter to monitor the flow of electricity and the status of the battery's charge. These meters aren't necessary to the whole operation, but they provide useful information. To maintain the battery charge I use a CTEK MUS 4.3 charger. My CPAP is a Resmed S9 Autoset, so I also use Resmed's power adaptor with an automotive power plug. This adaptor is unfortunately about as expensive as the battery, but using it obviates the need for a power inverter, thus increasing the number of hours the battery can be used before a recharge is needed.

If you are keen to create your own setup, search on the message board for the two words choosing and battery and you'll find some excellent info from Capn Loki. You can also glean ideas from videos on YouTube showing how others have assembled a backup power box.

If you don't want to or are unable to create your own, perhaps you can find a friend to do the assembly for you. Otherwise, you can find some backup battery packages on eBay that contain the essentials to get you going. You'll pay a 40% to 50% markup, however, so you can save some money by sourcing the parts on your own.

My assembly, including the Resmed power adaptor, cost around $200 to build. The charger is an additional $60-$70. I consider the power box to be a form of insurance, and stretching the cost out over the life of the battery amounts to only a few bucks a month for peace of mind.

[Guest]

Excellent. I like it.
With all that has been going on I couldn't agree more.
I have several jump starters I use including a 100A deep cycle in a Minn Kota power center box. While I like the options Minn Kota offers the 100A battery weighs a hefty 65# which may not be practical for some/most. Which is why I mostly use the jump starters saving the 100A for long term outages. I have only used it to test things out so far.

But that also makes me want to build a smaller 45/55A sized battery source.

Is that an on/off switch I see?
Can you list the parts you used? I am mainly interested in the volt, ammeter & USB part numbers and sources.

TY

[JimW159]

Have you found any heat buildup in the case? Do you vent it or use a fan? As a comparison, what size of Pelican case would accommodate your setup?
edit: do you see any problem using the case as a platform for the S9 when in use?

[TRzzz]

Full parts list
Atlas 55Ah battery
https://www.apexbattery.com/apex-apx12- ... 15362.html
Sealed lead acid AGM batteries are available from many sources online. I chose this one based on a combination of cost and a weight I could easily carry (40 lbs).

Cabela's Green Dry-Storage Ammunition Box
http://www.cabelas.com/product/Cabelas- ... 705904.uts
Many companies sell a box similar to this one. I chose an ammo box rather than a standard battery box as it has a smaller footprint. Standard battery boxes are constructed with ventilation in mind, but since AGM batteries don't require ventilation you have a wider range of possibilities. This box is perfect as it is barely tall enough to fit the battery yet has enough room inside for the the components and wiring.

Voltmeter, ammeter, and switch.
These are available from a variety of sellers on Amazon and eBay They look more or less identical, and I wouldn't be surprised to learn they are all made at one factory on the other side of the world. Display colors are blue, red, or green. Here are some examples.
Voltmeter
https://www.amazon.com/dp/B010HM43RQ
Ammeter
https://www.amazon.com/dp/B016WNAHCE
Switch
https://www.amazon.com/gp/product/B017KP67GI
Wire connector for the switch (not required but makes installation much easier)
https://www.amazon.com/gp/product/B01H5C0X2K
Voltmeter, USB charger ports, and 12V power port in one package (saves a few bucks)
https://www.amazon.com/gp/product/B01BXTX11Q
Fuse holder (I use two, one to connect the battery to the switch, the other to connect the battery to the charging port)
https://www.amazon.com/dp/B003CEXZTE

Misc parts from the auto parts store: 14ga wire, spade connectors.
Special tools: 3/4" hole saw for the switch, 1-1/8" hole saw for the meters.

To connect the various wires together I installed two junction blocks (aka bus bar, NOS found on eBay), one for positive and one for negative, but you can also use wire connectors.

For charging convenience I installed a charger port on the other side of the box. The port you install will depend on what model charger you use. You can save some money and assembly hassle by attaching your charger to the battery terminals with alligator clips.

[TRzzz]

Have you found any heat buildup in the case? Do you vent it or use a fan?

SLA AGM batteries generate no heat or meaningful fumes, so ventilation and cooling aren't needed.

As a comparison, what size of Pelican case would accommodate your setup?

For a 55Ah battery, the closest Pelican model would be the 1430. Since AGM batteries don't have liquid acid sloshing around, the battery can be stored on its side, making the Pelican iM2100 an option as well. Pelican makes terrific cases, as is reflected in their high price tags, the 1430 being north of $90. In contrast, the Cabela box is usually $14.99 but is on sale right now for $8.99. While not as rugged as a Pelican, it does have a rubber seal inside the lid to help protect against moisture. If your needs don't require carrying the battery into messy outdoor environments, the Cabela box will do fine. Here's a similar box at Lowes that also has some nifty storage pouches:
https://www.lowes.com/pd/Kobalt-Zerust- ... x/50396626

edit: do you see any problem using the case as a platform for the S9 when in use?

It can act as a platform for your CPAP, however tug too much on the hose and it will fall off. Velcro would be an interesting enhancement.

[parzad]

Here's a similar box at Lowes that also has some nifty storage pouches:
lowes com/pd/Kobalt-Zerust-15-75-in-Black-Plastic-Lockable-Tool-Box/50396626

Here's a copy of a review from the Lowes site at the above link about this box.

I recently bought 8 of these tool boxes because they had good reviews and I liked the fact that they had the external storage pouch with them. When I received the tool boxes their were no external pouches. I tried to get the store to find them and they said they no longer came with them. This was a total bummer for me. I feel like this was deceptive advertising on the part of Lowe's. I think I will get a refund on my outstanding order. Poor business practice.

I wish I read it before I bought mine. While it mentions the box doesn't come with the pouches in the pictures. it also does NOT have a lock if that is needed or wanted. It is more like a large plastic "ammo box". Appears to be a nice box just not described or pictured correctly.

[parzad]

it also does NOT have a lock if that is needed or wanted.

My mistake, it does have a hole for a lock on the aluminum clasp, in the lower RH corner, it is hard to see but it is there.
I received the Cabelas Ammo box today. The two boxes are the same size. There are other minor differences ie. the clasp is plastic, it doesn't have the loops on the sides for the pouches that no one knows where to get, etc.

The big difference is the price. The Kobalt is $19.98. The Cabelas box is on sale for $8.99 (as of this writing) (Original Price: $14.99) plus tax and shipping if that applies. If you order enuff the shipping goes down so mine costs $11.46 ea. Wonder if this sale price means it will soon be discontinued.

The Lowes box will be going back.

btw - Cabelas offers a measly 5% Military Discount while Lowes is 10%. For me 5% does not even cover the taxes.
fwiw - For Lowes you will soon have to get their MyLowes card to receive Military Discount.

[parzad]

@TRzzz, how did you mount or secure the battery inside the box? What did you use? TIA

[TRzzz]

@TRzzz, how did you mount or secure the battery inside the box? What did you use? TIA

My original thinking was to use a strip of velcro on the floor of the box and on the bottom of the battery, but I decided to go cheap and repurpose the cardboard and styrofoam packing material in the box the battery came in, squeezing them around the battery. Yeah, this is a chintzy solution, but it works. Due to the height of the battery terminals (sticking up just above the top of the box), the battery can only fit in the box one way, and that coupled with the packing materials means it isn't going anywhere.

As long as we're discussing it, here's how the various parts are connected inside the box.

[parzad]

Due to the height of the battery terminals (sticking up just above the top of the box), the battery can only fit in the box one way,

Does this mean the cover will not close? This is a 55ah battery right?

afaik the ammeter needs to go in series (in line) in order to measure current else it won't work. I'm not so sure about the way it shows the switch either.

[CapnLoki]

afaik the ammeter needs to go in series (in line) in order to measure current else it won't work. I'm not so sure about the way it shows the switch either.

It looks like the amp-meter is in series on the ground side. The high side is probably only to power the meter display. If this is a shunt meter, its common to put the shunt on the ground side and measure the voltage drop over a small calibrated resistance.

[chunkyfrog]

Small tip: with the BassPro takeover, Cabela's has been phasing out house brand items.
--presumably to replace with BassPro nameplated merch.
Good opportunity to score some deals!
The LaVista store is a short hop away, and we have already snagged some sweet bargains.
Even cooler--brand new Costco right next door!

[Guest]

It looks like the amp-meter is in series on the ground side.

Ok good call. I still don't understand how that switch is sposed to work.

[TRzzz]

Due to the height of the battery terminals (sticking up just above the top of the box), the battery can only fit in the box one way,

Does this mean the cover will not close? This is a 55ah battery right?

The underside of the cover has maybe 3/4" clearance above the side of the box, so it does indeed close. This 55AH battery is a near perfect fit.

afaik the ammeter needs to go in series (in line) in order to measure current else it won't work. I'm not so sure about the way it shows the switch either.

I am a novice when it comes to electrical things, so I don't know if there is more than one way to connect it all together, but the way I have it works.

[D.H.]

My backup CPAP - in the envet of a power failure is my old Everest-3 CPAP. I replaced it last year after the battery pack burned out.

However, I was able to get a replacement battery pack on E-bay. I really need to use my new one for compliance, but it's good to have that on-hand.