02 April, 2021

Off Grid power pack for CPAP users. Future expansion.

 I assume for those that have watched my videos, or know me personally know that I am on CPAP therapy. I am also an avid outdoors enthusiast. And have found the 12v portable power packs typically pre designed and sold for use with CPAPs being $350.00 + and having extremely low run times of one night or less effective use before the battery is drained. 

As you no doubt have heard, or even experienced personally, Texas suffered from an extended power outage in Mid February 2021. 

In my experience, I was prepared, or so I thought. I had an Everstart 1100 amp peak jump starter / power pack. I had used it for a max of 2 nights while camping off grid. However during the power outage, and family members thinking this was going to be short enough they were charging phones on it. I didn't even get one hour of CPAP time on it.

I needed a solution. NOW, and I needed one with capacity. Plus I needed to be able to extend my run time off grid for more than 2 days.

While they were open prior to them being forced to close, I was able to run into my local O'Reilly auto parts and grab a group 27 Deep Cycle battery, on what charge they had it with, some crimp on alligator clips, and a 12V power outlet socket. I quickly grafted together a simple rig that had the alligator clips holding on to the positive and negative posts powering the port. This was a quick and dirty way to provide power to my CPAP for the duration of power outage. I did test with my multimeter, starting voltage was at 12.9v, ending voltage after 4 nights of usage of my Z2 CPAP (no humidifier) was at 12.4v. No more than 8 hours night use. The battery was the trick, but was not a permanent solution.

And I need a solution for camping, not just emergency prep, it needs to be portable.

To begin with, I know I needed weather protected ports. I wanted 2 12V ports that were switched. I found panels that provided that, AND a voltometer. HOWEVER, the switches wouldn't quite handle both 12v ports I wanted, so what was the solution? After reviewing, I am going with 2 of the 3 in 1 panels. They provide on / off switch, 12v outlet, 2 USB charge ports, with voltometers. There seem to be a LOT of brand names with the same thing. I opted for the Deyooxi branded one, seems like the same thing in all with the same features.

I am fusing these using inline marine grade ATO fuse holders I already had in my toolbox grafted inline and tied together as a harness. I needed fuses, if I needed new holders I would have ordered the ATO / ATC 12 gauge marine sealed holders and fuse kit from Amazon. ATM fuses are available and smaller, but the fuse holders have insufficient wire for this project. you want 12 or 14 ga, not 16 or 18 ga.

I needed crimp connectors, for butt splices and ring terminals, I wanted heat shrink models. I opted for the 300pc box from Amazon. It works, but quaility is spotty. But all of the options seemed iffy. I will link it here, but use at your own discretion. Metal thickness left me wondering how cheap they could get.

Now I have the stuff to put together, but I need a housing for it all. 

I need a battery box, with enough space for a group 27 battery, AND the connectors in question. The only model I have found is the NOCO Group 27 battery box model HM327BKS.

Lastly, and since I can't find a fair deal on this online I am going to tell you about it. You will need a roll of electrical tape. Walmart has 3/4" x 60' rolls of electrical tape for $0.57 roll. 

So the build and costs are like this.

Battery $99.00 + tax / core charge.

Battery box. $12.99

2 @ Deyooxi 3 in 1 output / switch kits. $16.99 each, $33.98 for both.

Fuse holders / fuses. $12.99

Heat shrink terminals / crimps. $16.22

Electrical Tape. $0.57

That gives me a total for this project of $175.75

Any added length to your wires is going to be out of your inventory and /or buy wire. Again 14 ga wire or better to handle the amperage.

The process I used was.

Disassemble one of the Deyooki sets, use panel for sizing. Attach using masking tape to allow for positioning and holding while marking goes on. Select appropriate sized forstner drill bit, and mark hole centers on 3 device holes. Move to second side, repeat.

Next using sacrificial board line up starter holes and complete drilling device holes using forstner bit.

Assemble devices to panel, panel and devices to box on one side using second 3 in 1 and a guide.Secure using provided backing nuts. Reattach wiring using second 3 in 1 as guide for where wires go. Temporarily attach wires to battery and test function. Disconnect, repeat process for second 3 in 1.

Remove inline glass fuse holder for 3 in 1 power lead, graft in ATO fuse holder loaded with 15 amp fuse using 5/16" ring connector and butt slice, careful to keep length apropriate. Shrink heat shrink tubing on connectors.

Replace ground side ring connectors with 5/16" ring connectors. 

Tape wrap grounds together, and positives together to split off to battery terminals, bringing them together quickly but not too tight. Wrap all wires as a bundled loom until they split out to each side, wrap wires as loom per side. This step protects the wires and keeps them from being just loose and messy in the box.

Make terminal connections for grounds, and positives to the appropriate posts. Not previously mentioned, but assumed you had 5/16" -18 nuts to secure on the threaded posts. Slip positive side ring terminals over positive post, and run nut down / secure, repeat process on negative side. 

Test function on both sides.

Expanding the art.

At some point down the road I am going to want to add a DC / DC charger, and terminal mount AC to DC charger (auto style battery charger with ring terminal attachment). To make this happen I do not want the charging side and the load side to be on the same post. I opted for lead top post to threaded stud marine terminal ends for $1.99 each. 

I am not aware of online sources for this, but I HIGHLY recommend getting the NOCO terminal anti corrosion spray which I got from Walmart Auto Department for something like $3.00, it included a pair of the anti corrosion terminal pads, and a small can or anti corrosion terminal spray. This should be in your auto maintenance took box / supplies to begin with... 

For the time being I am going to use my Black and Decker 25 amp (at 12v) output auto battery charger (max 4 amp at 110v AC) being powered by my Harbor Freight Tailgator 900w peak generator. This is NOT my ideal long term.


I am wanting to eventually build in a 4 battery bank for a long term overlanding rig.. But for the mean time.

I have not opted yet for a specific make or model, but I am looking into a DC to DC charger / charge controller. There are models on the market I am researching that will allow me to charge from both my vehicle alternator, AND solar power. I am not well versed enough in this to speak wisely at this point though...

My pending choice for generator is a 2000 watt peak Aipower SUA2000IV however that is beyond my budget at this time.

With my long term desire for a proper 4 bank battery setup, I am wanting again, long term, to use the NOCO 4 bank onboard charger.

At the point of the 4 bank system, I will want to add a 2KW pure sine wave inverter to produce clean 110v power. I have not selected a specific make or model. The idea is to power laptops, and some misc 110v devices while I try to provide most power via 12V.

As you hopefully can see, I am trying to design my system so that it works for now, and most pieces can be repurposed in the future when a large upgrade in my off grid activity abilities will be made.

No comments:

Post a Comment