Getting power to / in the camper. Sizing things up right.

[dbhost]

I have a bit of a pickle here I am hoping folks can help me out with.

Right now my electrical going into the house is 300w solar suitcase into a charge controller / DC to DC charger, the other side is coming from a high output alternator.

Truck battery is just s simple group 65 AGM battery 950cca and it runs the truck / winch / lighting just fine.

I at present have a group 27 deep cycle flooded battery I am using for a house battery.

I have 4 items that need to have power but not all at the same time.

#1. Alpicool APLT60 63quart 12v fridge 45w draw. This cycles on and off but needs power 24x7x365
#2. Z2 Travel CPAP, Max power draw 35w, typical 20w. Only needs to be powered while I am trying to sleep. So 8hrs / night, but typically overnight so no fresh solar.
#3 Asus ROG Strix G17 laptop. Transformer charging 240w, USB C charging 100w.
#4. Samsung Galaxy Note 9. I have a spare and mine works great so I see no need to upgrade for a good long while. I actually have a little 50w multi USB charger I can charge phone and cameras on, so this might not be an issue.

I know I can get 3-4 days of CPAP run time off the group 27 battery as I set it up during the Texas ice storm / power outage of Feb 21... But not sure about with the fridge.

I am considering since it reportedly fits in the tray, I am going to use a Ford E Series cutaway cab and chassis frame mount battery box for the house battery, but I am considering using a Group 31 AGM battery as my DC to DC charger is not rated for LifePo4, and standard lithium batteries give me the heebie jeebies.

My question is, would a group 31 https://www.autozone.com/miscellane...fz-RWTUBQVXyuDoCEmAaAl2BEALw_wcB&gclsrc=aw.ds 875cca do what I am trying to do?

Should I just chuck this idea and go with a Jackery, and if so, what size?

Sorry, battery sizing is a pain to figure out...

 

[DiploStrat]

This may help: https://cookfb.files.wordpress.com/2016/09/plan-electrical-system.pdf

Instant gratification: Put your B2B to a gel profile and get a "drop in" lithium iron battery. Simply no reason to use lead acid these days.

But you really need to sit down and do a careful plan. (Or come to OEXPO East and attend my planning session.)

 

[dbhost]

So IF I am reading this right. My only devices intended are...

#1. Fridge. Run 24x7 typical draw 45w when cycling, but cycles on / off depending on situation. Figure average 25w / hr. 2.5amp / hours
#2. CPAP only used overnight. Except on ramp up, pulls 2.0 amp / hours
#3. Laptop. Can and should be kept topped up with solar. 100w USB C, have this...
#4. Phones, camera etc... I have a 65W mini panel / USB charger rig that was given to me as a gift. This will simply be run on the side.

Should solar be too tough to obtain decently, I do have a 1KW Sportsman inverter gas generator, and the alternator on the truck...

I am thinking, correctly or not, a Group 31 deep cycle / AGM battery at 135 Amp Hours should be sufficient for storage capacity FOR NOW. Down the road a second, I would need to figure the wiring out, and a heavier duty charge controller / DC to DC charger will likely be in order but I doubt I will hit that kind of energy usage unless I go with AC, which I plan on running exclusively off of the generator.

 

[ExpoMike]

Note, lead acid batteries are only good for 50% of their rated capacity. Going lower will start to damage the cells and shorten the lifespan of the battery. A 135AH battery is really only good for a max of about 67AH. This is where LifePO4 batteries come into play. You can easily use 80% of the rating of the battery and can cycle down to 5% without doing damage. Another advantage is they keep the voltage consistent through the capacity, where lead acid ones start to taper off voltage, which increases amp draw of devices and hence draws quicker. It's a big investment up front but given they should last 8-10 years, in the long run, they cost less.

On a different note, how do you like the Z2 Travel CPAP?

 

[dbhost]

Note, lead acid batteries are only good for 50% of their rated capacity. Going lower will start to damage the cells and shorten the lifespan of the battery. A 135AH battery is really only good for a max of about 67AH. This is where LifePO4 batteries come into play. You can easily use 80% of the rating of the battery and can cycle down to 5% without doing damage. Another advantage is they keep the voltage consistent through the capacity, where lead acid ones start to taper off voltage, which increases amp draw of devices and hence draws quicker. It's a big investment up front but given they should last 8-10 years, in the long run, they cost less.

On a different note, how do you like the Z2 Travel CPAP?

I have had the Z2 for about 5 years now. I bought it with year end FSA money that had to be spent so I bought a travel CPAP. Great health investment, allows me to travel again.

Aside from the mask / tubing it is about the size of 2 decks of cards, so nice and compact, and it holds pressure pretty well. It uses moisture rebreather so it does not need a humidifier, but to be blunt, I have to sleep with a bottle of water next to the bed. I will get up once in the night, take a big swish of water to hydrate my mouth / throat and I am good the rest of the night.

It is no noisier than say my regular home unit, so yeah, pretty good. And of course 12v connectivity is a huge bonus.

On the LifePO4 battery rig, my charge controller / DC to DC charger is an AtemPower 20 amp unit and not compatible with LifePO4 batteries. I have a friend that has a hookup for batteries, or so he claims, I am all for LifePO4 but not straight Li Iion as the Lithium Ion batteries are showing a tendency to become battery flambe and I don't want that under my truck...

I have no qualms using a different controller but it should not be much, if any bigger than the AtemPower unit, again truck shell camper, not a lot of room, and it should not be stupid expensive. So let's try to stay under $250.00 for a 20 or so Amp unit...

Which leads me to another stupid question. Is it bad to run say a bigger charge controller, say a 30 or 40 amp with solar panels that are rated for 20 amps? Not sure how they get 20 amps, I am figuring since it is a 300w panel they must be talking about at 24v...

 

[dbhost]

Here is the Solar panel rig.

https://amzn.to/3dS3hBk

The charge controller will do LifePO4, but...

The DC to DC charger I have is this...

https://amzn.to/3dG3IyR

When I search for DC to DC charger or MPPT charge controller, I don't see support for LifePO4... Thus my quandry....

Of course if there is a safe way to connect say the solar charge controller, and do some other way to connect alternator to secondary battery for LifePO4 charging, I am all ears...

 

[ExpoMike]

Though I haven't installed it yet (build out is taking way longer), I did a lot of research and bought this unit which is a DC/DC controller with solar, was well received by those who have used them. They allow for LiFePO4 charging as you can set your own charge profile.

KISAE Controller

This will allow up to 50 amps (adjustable in 5 amp steps). Will take 12 or 24v panels (I have 24v ones).

 

[dbhost]

Just checked out the AtemPower web site, they claim support for LifePO4 batteries. Reviewers on Amazon claim otherwise. I don't know enough about LifePO4 to know one way or another... I know there is a LiIon charging profile available and I believe that is wht the charge controller MFG wants us to use...