Cpap Power For Boondocking

Hi, all. First time poster, thought I might help someone. My CPAP usually lasts 5 nights and we're going on a 12-night trip. I've been thinking about solar and decided to make the leap. Did several hours of research - including this forum, thank you all for sharing your experiences - and then bought a Renogy 100W mono panel with 30A charge controller for $180, a pair of 30' 10 AWG extension cables with MC4 ends for $37, and a 7-round vehicle connection for $8 that I used to make a 7-round connection to the solar charging controller. (Wired the black 12v to the solar positive and the white ground to the solar negative. Go Power sells a 7-round connection for $39.) And then I bypassed the battery isolator. Total cost $225 for a 100W system without adding any wiring or holes to my teardrop. Might not be as portable as a suitcase model, but it's only one 40" x 27" panel to move around and was much less costly. And, having the charge controller nearer to the battery instead of being attached to the panel will reduce the voltage loss over the 30' extension. Now I just need to make sure my camping spot is within 30 feet of sun!

 

Pictures and or links are always nice too.

 

I started this thread back in April, and there has been progress! And some camping
This camper, our 4th, was new to us this spring.

* All bulbs in the cabin and galley have been replaced by LED, with roughly 1/10th the power consumption of conventional bulbs.

* Purchased a Yeti 35L cooler, it’s about right for a couple days, gets a little small after that. But it does work well. No power required.

* Have barely used the vent fan, and haven’t used the furnace at all. Summer in the NW!

* Have used the sink/water pump a fair amount, more than expected. I’d never had one that worked as well as this, it’s pretty handy.

* I have 10 nights in the CI, running CPAP off the house battery. I’ve not done more than 2 nights before some level of recharging by driving the TV. It draws down significantly in two nights. I might get a third night out of it, or maybe not. Note that this is the original 76ah battery in a 2012, and seems to have a little reduced capacity, I’ll probably replace it for 2019. Possibly with the Victron 100ah Super Cycle, which is a half-inch taller than the cleat at the back of the battery compartment - needs more measuring and figuring!

* I have 1 night running CPAP off a new, dedicated battery (it arrived last week, finally!).

Learning continued along the way, and continues still.

The new batt is small enough for the headboard cabinet in a 550, along with -either- its charger or the CPAP. It’s a 60ah Victron Super Cycle AGM, of a new design that can survive being drawn down to 100% DoD (depth of discharge, about 11.89v, but tested down to 10.8v). As I understand amp hour (ah) ratings, a conventional 60ah AGM would deliver about 30ah to 50% DoD as a general target. In theory, and as tested by Victron, I should be able to get 60ah out of it when needed, but a charge should be completed quickly after that.

(Which means that the conventional 76ah AGM in the CI would deliver about 38ah with good longevity.)

These Super Cycle AGMs are in short supply; I had to wait 6 weeks. I purchased a Victron charger at the same time. Recommended is that chargers’ capacity should be about ah/5, so, for 60ah a 12amp charger. I purchased a Victron Blue Smart 12v/10a charger, biggest I’ve owned, I can check the stage of charge cycle via bluetooth from a smartphone.

That batt & charger ran about $290 with free shipping from Jamestown Distributors. This was a special order; the batt and charger don’t appear on their website. Yes, the Victron line is oriented towards marine use.

Per theory, I’m using about 6.8ah/night on my CPAP, or about 34 per 5 night off-grid trip. That would seem to give me a significant margin, but with only 1 night out since I got the new rig, I don’t have enough experience to validate that. That’s the design goal, hope it works out that way! I really should do some serious monitoring, as Rotus8 recently posted. Another winter project!

Thanks for all the comments along the way - posters to this thread really helped me consider possibilities I’d not looked at before. Starting this, I was pretty sure I’d never want to deal with a second battery; that there was a new batt that should run 5 nights, with reserve capacity, that fits in the headboard cabinet and was affordable made all the difference!

P.S. It *really* helps to have a CPAP that accepts a 12v supply natively. Campers, you must request this whenever you’re up for a new device!

 

More than you ever thought there was to know about batteries for marine/rv applications, linked right here!

 

Which LED bulbs did you select to replace the native halogen bulbs?

 

Reelco 6-Pack G4 Dimmable LED Mini Bi-pin Base Light Bulb AC DC 12V 3Watts Warm White 3000K 20W G4 Halogen Bulb Replacement - - Amazon.com
These white bulbs have pretty good color, not crazy yellow or blue. They seem just a little brighter then the originals. They are dimmable, but, don’t get as dim as the halogen bulbs. They don’t seem to flicker.

LJY 2pcs Pack G4 3014 SMD 48-LED 3W LED Crystal Bulbs 360 Degrees Energy Saving Capsule Spotlight Lamps AC/DC 12V (Red) - - Amazon.com
I also put in 2 of these red bulbs. They’re listed as “not dimmable”, but they do dim a bit. Maybe to 60 or 65%?

IIRC, they are a little finicky to install, a little big, but they did fit, and it didn’t take long. Those are some pretty small screws holding together the fixtures - easy to drop and lose if you’re not careful. LEDs don’t heat up the cabin, and *should* have good longevity and durability. Then there’s the power savings...

 

This suggestion is probably not helpful, since you already have the cpap, but something to consider once it wears out. I have a mandibular device that does not require batteries and works by holding the jaw forward to keep the airway open. Works for me. Without it I would be a sick puppy and not be able to go RVing or backpacking. Basically gave me my life back!

 

Thanks! I've got one, too, but it isn't a real solution for me, it seems. But I keep it around to use in an emergency as it may provide some help.

 

I am wondering, did you analyze/measure whether the larger Victron Super Cycle AGM would fit in the TD's battery hatch?

Something else I am wondering about this (and other) batteries: Does it damage the battery if you discharge it and then recharge it, but only partially recharged? There are rare circumstances where I could recharge a battery completely after a few days of discharge, since I am only using solar, essentially, to recharge when we are on the road. Often the trips from one camp to another aren't long enough to give the battery any decent charge time from the tow vehicle.

 

I don't have the figures in front of me at work, but IIRC, the 100ah Victron Super Cycle is good in all dimensions but height. I've not really looked closely at the cleat that the battery slides under since taking those measurements, but, my working (untested!) assumption is that the cleat could be removed and reinstalled at the higher position.

I'm not clear on an answer to your second question, but will check the sources!

***Edit***
I meant to write, the Victron is about a half-inch taller than the stock 76 or 78ah batt.

 

Anyone know if there is a lithium battery that will fit in the battery compartment (2014)?

Thanks

 

Here are my sources:
My original battery in a 2012 Ultra 550 is the UPS12-300MR, specs here:
http://www.cdtechno.com//pdf/lit/12_1029_0915.pdf

The Victron 100ah Super Cycle is darn close to that size. It’s the BAT412110081, and you’d look on this spec for the 20 hour rate column, 100ah:
https://www.victronenergy.com/upload/documents/Datasheet-AGM-Super-Cycle-battery-EN.pdf

I’ve not found the scrap of paper I was doodling on, but my recollection is that per the specs, the Victron 100ah super cycle is an almost direct replacement for the stock 78ah, except it’s almost 1/2” higher.

One more potential issue is whether the terminals on the Victron line up with the CI wiring harness. Not a problem for anyone prepared for electrical work, but that might stop somebody else.

It would seem to have a substantial advantage over the stock batt, for just a little more money. Without hitting the books, I’d assume(!) that a lead-acid battery like the Super Cycle, that can be drawn down 100% sometimes and still have a very good longevity, is going to handle resting at half-charge better than a standard lead-acid AGM.

Gotta’ say though, after wrasslin’ with battery specs for the last 5 years or so, on our previous camper and this CI, I’ve reluctantly come to accept that it’s all relative. No matter what the specs say, our usage patterns are individual, as is how fast a TV can charge, or how much solar actually makes it to charge the batt. My takeaway is that specs are great for comparing one approach to another, but predicting actual performance (nights of CPAP use for me!) is very imprecise.

That’s one of the things that finally convinced me that the 2-battery system would be my next solution; that no matter what happened, I had a backup!

I myself am a bit on the fence about the next house battery. I have my dedicated CPAP batt, and the performance of the house batt seems to be down a bit. Buy the direct replacement? Easy and relatively inexpensive, about $160 online. Handles the typical camper pretty well! Spend $100+ more for higher capacity? McGyver it into place, fix wiring if needed?

Then there’s lithium ion. I’ve not speced one, but expect that would be somewhere in the $800-1200 range of cost. Victron is a great manufacturer of lithium too, but there are others.

 

I believe the Relion 12v 75AH LiFePO4 will fit.
12V 75Ah Lithium Battery for Renewable Energy, RV, EV and Marine Applications | RELiON

• Length: 10.2 in (260 mm)
• Width: 6.6 in (168 mm)
• Height: 8.6 in (218 mm)
• Weight: 23.6 lbs (10.7 kg)

These are $1,000

-Al

 

I had to do some long-delayed reading on battery chemistry:
Lithium iron phosphate battery - Wikipedia

Apparently I’ve been confusing LiFePO4 with LiPO chemistry. LiPO is relatively unstable, high output, used in drones, among other things. LiFePO4 does seem to have the characteristics for stability and power one would want.

One factoid I gleaned: Lithium, Li, LiFePO4 batteries have some limitations on max charging voltage, different than AGM / lead-acid batteries. So, you want a charger that can be set for Lithium/LiFePO4 chemistry. I’ve lost track of the stock charger info (was it BatteryTender 5a on older, Marinco something on newer CIs? Some info earlier in this thread). Are these chargers switchable to Li chemistries?

Potentially yet another electrical job, installing a new charger. But, please get charger recommendations from the battery manufacturer. The Relion specs linked by AlCat recommend a 37.5a charger. Say what? That’s a lot! My snazzy new charger is 10a, and it’s the most I’ve ever used!

 

Seth - I believe you need a different charger if you use different battery chemistry.

unrelated: I need to search the old battery threads to see what folks have concluded about placing a second battery beneath the sink. There is room there for a 75 ah battery.

-Al

 

I recently installed a 2nd battery under the sink (and bought a matching battery for the battery bay). I now have two 55ah AGM batteries running in parallel. We have an aux battery setup in the TV and rarely pull the fridge out and plug it into the TD, so 80+ usable AH's should last us quite a while. I also added the coulometer that rotus8 profiled a few months ago. I installed it near the fuse box cover on the removable battery panel/cover.

You could easily add a larger AGM dual battery setup (or LiFePO), leveraging the space under the sink. 110ah is all we needed.

 

Can I assume that since you can run a LiFePO4 battery down well below 50% without damaging it, that a 75AH lithium would be roughly equivalent to a 150AH AGM? Would the stock charger that came with our trailer work with a lithium battery?

 

stock charger does not work, afaik, with different battery chemistry
I think a 75 AH LiFePO4 would be more power than a 150AH AGM

 

Thanks Al. Is it possible to replace the stock charger in the same location with one that would work?

 

Hi. I'm not sure whether there is a charger that would fit in the same location. I haven't gone that far with my analysis. But I expect there is another spot where a charger can reside, if the current spot is too small.

I'm trying to recall if we have other members who have gone the LiIon route, so they'd know these answers.....