Cpap Power For Boondocking

Thanks Randy!

I’m pretty sure you’re talking about Rotus8’s thread linked in the first post:
Auxiliary Battery For Refrigerator

But thanks for that reminder - I’d forgotten that one of the bits discussed there was an isolator. That would be an alternative to marine-style battery switching. I’m adding a small edit to Post #16, above.

AlCat, that’s to you - the linked post that started with Rotus8’s aux battery in a TV has lots of good info on a practical and tested approach to wiring the CI batt and an aux/pony batt to the tow vehicle.

 

Yup, that's the thread, sorry, didn't see it was already posted. One of my favorite mods to date.

Randy

 

I finally dug up my figurin's from a few years ago. My best number was a draw of 0.85a, = 6.8ah for 8 hours sleep per night.

So that would mean I need 34Ah of discharge for 5 nights with no margin (and no humidifier). Plus 20% margin = 41Ah, or, plus 50% margin = 51Ah. There are reasons to be conservative, not only the importance of good sleep is to a sleep apnea sufferer, but also that capacity goes down with temperature, and, all batteries will lose some capacity over time.

Conservatively, that means for no more than a 50% draw down, a 100Ah (sealed) lead-acid at $165 is the most economical approach for 5 nights. No additions for gennies or solar panels. Leave home with it fully charged, and no muss or fuss. Leave the CI batt for lights, water pump, fan, phone/tablet charging.

Like this one:
https://www.amazon.com/dp/B00S1RT58...olid=1LKMP5AQM58AS&psc=0&ref_=lv_ov_lig_dp_it

That's a 60 lb. battery, it's not going to be able to be put into the cabinet like AlCat does with little 1-night (lithium?) batteries. And, it will take some additional $ to set it up, but it's definitely the price/value leader the way I see it right now.

A lithium battery, on the other hand, can be drawn down pretty much all the way. So, the equivalent would be a 50Ah lithium that only weighs 15 or 20 lbs. That looks to be somewhere between $400 and $700 bare battery.

Hmm....

 

Continuing down the economy/value path to lots of power, Costco has a Battery Tender 3a smart charger for $40 with free shipping. It appears that it is available to non-members as well via web, and may be in some retail warehouses.

Can't seem to include the link, if you're interested search Battery-Tender-Power-Plus-3-Amp-Charger or 100241973 at costco.com.

Edit: Maybe this will work
www.costco.com/Battery-Tender-Power-Plus-3-Amp-Charger.product.100241973.html

This is for conventional flooded or sealed / AGM lead-acid batteries.

3a isn’t the highest charging rate, but it’s far from the lowest. Mid-range at a lowest-capacity price.

The Battery Minder 2012-agm is a 2a charger that includes a desulphation phase for $90. There are multiple models for different battery types, as flooded/gel/agm should have different charging profiles.

A great higher capacity charger with desulphation is the CTEK Multi US 7002, 7a, for $120. Settable for different battery types. I installed one of these in my last camper.

I guess I should have included this in the first post: I’m a bit of a saver, and mostly aim for managing costs and higher value. Does that make any sense? Somehow a CI 550 worked in my personal equation... maybe I’m getting soft!

 

Curious if the CTEK could be used as a replacement for the stock charger under the trailer. Are there controls that have to be accessed?

 

Here’s what it says on this page.
The MULTI US 7002 is prepared to charge and maintain, no matter the weather, temperature or situation. The MULTI US 7002 is extremely robust and water and dust resistant (IP65 classification). The MULTI US 7002 is certified for use between -4°F and +122°F.

I had to look up IP ratings:
IP Rating Chart | DSMT.com

Having used the 7002, you’d select the mode appropriate to your battery just once, when you set it up. It also lights a series of LEDs that wouldn’t be easily visible, that tell you what stage of the charging cycle it’s in. But, you can pretty much tell the same thing from the plug-in voltmeter. It does have a “power supply” mode, that turns off the intelligence so you can power up the trailer without a battery. If you needed it, you’d hit the mode button for that, and see the LED switch to the right mode. Then, later, get back to the right mode for your battery.

It’s certainly a great charger! I don’t know if it’s worth the upgrade from the stock 5a or 6a charger. You do get desulphation that BatteryTender and Marinco don’t have. An abused battery needs that, and from what I’ve read, may recover a lot of capacity. OTOH, if you don’t draw down the batt over 50%, and leave the trailer plugged in over the winter, you might only gain the 1 to 2a charging advantage of the CTEK.

 

A quick update:
Research continued, and led me to a new line of Victron AGM batts, called the "Super Cycle". They are different than conventional AGM chemistries, and they've done testing that validates battery life even with severe (over 50%, up to 100%) draw downs.

Above, I'd computed 34ah as the expected draw for my CPAP for 5 nights. This doesn't take into account decreased performance factors like cold weather, as the battery ages, or coverage for over 5 nights. The new target was 50ah. Adding that safety margin and including no more than 50% draw down led me to 100ah as desired battery capacity, to be dedicated to CPAP use.

Enter the Victron Super Cycle 60ah AGM #BAT412060081, tested to yield over 300 cycles at 100% draw down. To be clear, I'm *not* planning to routinely draw down 100% of capacity. But, the difference in price, size, and weight of a 60ah that could routinely handle 34ah draws, and which life would not be very impacted by occasional deeper draws, made it the one. 33 lbs. instead of 60-ish, and small enough to fit in the 550 forward interior cabinet (no new wiring!). Also small enough to pull into the house in case of power outage.

I ordered it this morning, as well as a Victron Blue Smart 10a IP65 charger (10a!!!), that can be monitored and configured with a smartphone... and will post back when I've had a chance to use them, and to evaluate the supplier. Sourcing this stuff was a little challenging. Apparently Amazon doesn't quite have everything ;-)

 

Seth: re the Victron AGM batts, why not (also) put one in the teardrop's battery compartment?

I'm still trying to solve the fridge problem as well as the CPAP problem

Would this battery be compatible with the TD's trickle charger?

 

Al / Cathy,

The Victron Super-Cycle would be good to look at as a replacement primary battery battery for the TD. With its deep-discharge capability and high capacity, I think it would compare well to the stock 76 a/h batt.

I haven't looked at that and speced it as a) our current house battery is still good, and b) I did want redundant systems. If I lose the Victron, I still have the house batt, and vice-versa.

This is, so far, all theoretical, as I'm still awaiting delivery of the Victron... need to check into that! I hope my experience will be as expected from the specs!

Yes, the Victron is an AGM, and reasonably close in best charging profile to the stock batt - the stock charger (which isn't a trickle charger!) should be fine with a Victron AGM. A smart charger like the Battery Tender or the later charger (?) delivers, um, was it 4a for the "bulk" part of the cycle, then maintains at a trickle. That's different than a trickle charger...

 

Very interested in the Victron battery, sounds like it performs like a lithium (i.e., deep discharge) at a fraction of the cost. Iwonder what the largest Victron there is that will fit in the stock battery compartment. I have also been wondering if the VTech charger that other folks have been discussing could replace the CI stock charger?

 

I think the 100 AH Victron would fit, but I'd need to measure again...and again

 

I'm thinking a 100 AH Victron to replace the TD battery, and the 60 AH Victron at the head of the bed (not coneected to TD) for CPAP use......

 

I’ll measure too, when I get a chance. This weekend?

The Victron Super Cycle (be aware, they have more conventional AGM batts, too) does have a deep discharge profile more like a Lithium. But not the same. For true deep-discharge performance and longevity, lithium is still best, I think. But, you’re right, that lithium ion is at something like 7x to 10x the cost of an AGM. The Victron Super Cycle is considerably less than a 2x premium over AGM.

Per the specs, the new Victrons seem to have a considerable deep-discharge advantage over conventional AGM, but service life will be limited by regular deep pull downs. Just not as much as a conventional AGM. For me, I had a hard look at how many nights I’ll actually get out over an 8 or 10 year battery life. Not enough! With my current availability for camping, 20 nights is a *big* year. With the Victron testing out at 300 cycles of deep discharge, that keeps up with my anticipated usage over a 10-year service life.

The big deal for me, I hope, will be the smaller batt in the forward cabinet, made possible by Super Cycle’s better accomodation of occasional deep use.

If the 100ah fits the compartment for the TD house battery, that’s a pretty substantial upgrade for maybe $300. A 50% draw gets you 50ah (instead of 38 or so for the standard batt). And, drawing down 60% isn’t much of a hiccup - 60ah!

I’ll certainly post back when I’ve got some real hands-on. Hope this really works!

 

OR
100 AH Victron in the TD (used for fridge and for cpap)
and 100 (or maybe 60) AH Victron in the tow vehicle, used when fridge is in the tow vehicle and tow vehicle isn't driving....

or maybe just one LiFePo4 battery in the TD and call it a day. Battleborn's 100 AH is about an inch too big, though....

 

Urk. I just called the seller - they are saying that the (60ah) battery isn't yet in the country; that it will be August 15. Tabling this for now, but I'll be contacting other sellers to see if the 60 is ashore on the west coast.

 

Battleborn has a 50ah LiFePo4

50Ah 12V LiFePO4 Deep Cycle Battery - Battle Born Batteries

but August 15 is right around the corner

 

I've used this one and it works great with a native 12v cpap.

No humidifier it goes several nights. Fully charged from AC it goes 2 nights with humidifier, charged about 90% from DC it goes one full night with a decent reserve but not quite two nights. Couple cool things about it. The meter on the front shows both the charge rate and the discharge rate. It can also charge while being used, so you can plug in one side to solar and both use it and charge it. Also, it has an attachment to let it be used as an emergency car jump starter.

Oh yeah, and a built in inverter good enough to run the laptop off!

 

Link is bad

is this it?
Amazon.com: Suaoki 400Wh/120,000mAh Portable Solar Generator Lithium ion Power Source Power Supply with Quiet 300W DC/AC Inverter, 12V Car, DC/AC/USB Outputs, Charged by Solar Panel/AC Outlet/Cars: Garden & Outdoor'

 

I don't use a CPAP but do have the above unit. It's pretty nice in terms of flexibility in power delivery (120AC, 12V and several USB outlets). It fits well in the front cabinet (at the head of the bed). It will tell you power output or input (in watts) at any given moment. I also got a 100W folding solar panel which typically will deliver around 75 watts when I've charged this way. I haven't really used it this way but I think it could be used to charge the house battery via the AC output. I also haven't used it to power the "house grid" but was told by Cary that one could turn off the house battery and plug into a 12V outlet and power the trailer this way. There is a lot of flexibility with this unit.

 

Yes, that's it.