Small gauge wire from battery

[Bobduck]

It seems like the wiring from the battery is undersized. On my 528RWS, It is only 8 gauge. How difficult would replacing this wire be? Has anyone else done this? Or am I worrying too much about nothing?

[SeaDog]

Are you experiencing overheating of the wiring or is the circuit breaker for the converter tripping or fuses popping if not you may be worrying about something that is not a problem.

[Bobduck]

I haven’t even taken it out yet due to weather here in Montana. Just going through it and getting familiar with everything. Tidying up and making it ours. Installed a battery monitor (Victron shunt) and installed a 12v port for my cpap. I just don’t want to experience any troubles when we do hit the road.

[Bobduck]

After further research I found that 8 AWG will handle a lot of current at battery voltage so we were right, I was worrying about something for nothing. Thanks SeaDog for making me rethink this. And thank you for your service. I am also retired (USAF) 1971-1993.

[DustyRoads]

Originally Posted by Bobduck

After further research I found that 8 AWG will handle a lot of current at battery voltage so we were right, I was worrying about something for nothing. Thanks SeaDog for making me rethink this. And thank you for your service. I am also retired (USAF) 1971-1993.

What I did is use a low gage between 2 6volt batteries, to the battery shut off then to the battery monitor shunt. I believe it is either 4 or 6 gage, 8 would have been fine too.
Good luck and have fun camping.

[Daniel.mullins4]

Originally Posted by DustyRoads

What I did is use a low gage between 2 6volt batteries, to the battery shut off then to the battery monitor shunt. I believe it is either 4 or 6 gage, 8 would have been fine too.
Good luck and have fun camping.

just had this issue this week with camping buddy on CPAP, we plugged CPAP to 200 watt inverter with existing cigarette lighter plug in RV, CPAP would start and then shutdown, he purchased a 500 watt inverter and same thing, we then clamped 500 watt inverter direct to battery with 110v extension cord and CAPAP ran continuous, the 12v DC wire size on existing RV cigarette lighter plug was the culprit.

[Tom 2424]

If you can get by with running the CPAP without the humidifier, it should draw a LOT less current and give you fewer problems. In fact, my unit won't let the heater come on when running on 12V power.

[DustyRoads]

Originally Posted by Daniel.mullins4

just had this issue this week with camping buddy on CPAP, we plugged CPAP to 200 watt inverter with existing cigarette lighter plug in RV, CPAP would start and then shutdown, he purchased a 500 watt inverter and same thing, we then clamped 500 watt inverter direct to battery with 110v extension cord and CAPAP ran continuous, the 12v DC wire size on existing RV cigarette lighter plug was the culprit.

Were you trying to run with humidifier? If so I agree with Tom2424. I also agree the wire running to existing cigarette lighter outlet is not the correct gage. My thinking for my CPAP I will run a dedicated line directly to battery for an inverter to use. My new CPAP requires 24 volts.

[Outsider]

BobDuck and all,


I'm VERY interested in this conversation. I'm NOT a newbie but we just got our New-to-us GeoPro G19FD which has factory installed solar (100W panel on the roof and a GoPower charge/controller). I am pretty up to date on my understanding of solar as I designed and installed a better system than this on my last small Coachmen 16B. I'll be adding 2 Duracell GC2 batteries soon. We also just got our first CPAP unit at our house Friday (wire's) and will be carrying it with us. We boon dock/dry camp a good bit.


I'd love to know more details on how and where you added the DC port for the CPAP, also details on the DC cord/adapter you use for the unit.



Anyone my PM me please if you'd rather. Thanks for your help.

[TitanMike]

Originally Posted by Daniel.mullins4

just had this issue this week with camping buddy on CPAP, we plugged CPAP to 200 watt inverter with existing cigarette lighter plug in RV, CPAP would start and then shutdown, he purchased a 500 watt inverter and same thing, we then clamped 500 watt inverter direct to battery with 110v extension cord and CAPAP ran continuous, the 12v DC wire size on existing RV cigarette lighter plug was the culprit.

The cigarette lighter power outlets are usually rated for a maximum of 20 amp.

A 500 watt Inverter can easily draw 40 amp at rated load.

Max output from these outlets is AT BEST only 240 watts (20 amp @ 12 volts.

[rbq]

If your CPAP is a Resmed 24 volt unit, they make a 12 to 24 volt converter with battery clips or will plug into 12 volt plug. Found that I can get 3-4 nights on a 12 volt battery with the hose heater and humidifier turned off. For many years I had an AGM battery that fit in the compartment below my bed. I also ran the wires for a 12 volt plug over to the converter so I could use house 12 volt if boondocking. Used both successfully. Just recently I got a good deal on a 100AH Lifepo4 battery to replace the failing AGM that I will use for the CPAP. Haven't had a chance to use that yet, but should work well.

[Tom 2424]

If possible, you are much better off running your CPAP straight off of its 12V power cord, if it comes with one (I have 2 CPAPs, one can draw from 12V directly, the other cannot and must be used with an inverter).

Not surprisingly, it takes a good deal more power to take 12V, step it up to 120V with an inverter, only to have your CPAP power brick step it back down to 12V.

As an FYI, when planning for boondocking I ran a direct measurement of current draw for my DeVilbiss CPAP on its 12V cord and it draws 2.5 amps (at an intermediate pressure setting). No humidifier running. However, if you fill the water tank, you will be able to get slight humidification just from the air flowing across the water even without the (energy hogging) heater/humidifier running.

[TitanMike]

Originally Posted by Bobduck

It seems like the wiring from the battery is undersized. On my 528RWS, It is only 8 gauge. How difficult would replacing this wire be? Has anyone else done this? Or am I worrying too much about nothing?

No on same trailer but I upgraded the #8 wire on mine to #4 awg.

Not a terribly difficult job depending on whether or not the bottom is covered. I had to drop the bottom cover on each end to route the new wire. If you do this you also want to replace the ground cable at the battery with same size wire as your "upgrade" as well as the ground wire at the converter end.

I did this to improve battery charging times.

If you aren't concerned with slower charge time due to the converter switching from bulk (fast) rate to absorption (slower) rate due to voltage drop, I wouldn't worry too much. A #8 awg wire will carry 40 amp which is more than enough for lights, water pump, furnace, etc. It's only an issue when batteries are low and the converter is trying to charge at it's full output rate then voltage drop in the wire makes the converter think the batteries are almost charged.

Large wire has less voltage drop and the converter will stay in bulk mode longer resulting in quicker charging. Important when boondocking and running a generator. Not so much when at a shore power source that can run all night without bothering neighbors.

[Daniel.mullins4]

We did turn off the humidifier, we first tried the 200 watt inverter on cigarette lighter plug and same thing blower starts then shutdown, must be the surge wattage. Funny thing, he purchased the 12v DC plug to lighter plug and forgot at home, he did try that in the trailer at home and it worked fine. I asked “why didn’t you just leave that adapter cord in the trailer” that is another thread Things that go wrong while camping

[Outsider]

Anyone have any idea if the new 24VDC units actually draw less current over time than the previous 12VDC units. This is out first CPAP so I have nothing to compare to.


If we have to keep this 24VDC unit what setup would use the least amount of battery in the long run when dry camping? (12V to 24V adapter straight from the battery perhaps?) As I mentioned earlier we do about 50% boon docking/dry camping. I already plan to add 2 GC2 batteries and will probably have to boost my solar panel as well (have 100W on top from the factory and may add about a 200W portable with charge/controller to the side mount solar port).



Thanks.

[ependydad]

Originally Posted by Outsider

I'd love to know more details on how and where you added the DC port for the CPAP, also details on the DC cord/adapter you use for the unit.

I’ve slept with a CPAP for as long as I’ve been RVing. I know that the better way is to run it natively off of 12v but I typically have an inverter setup for a variety of things anyway and choose to just run off of that.

https://learntorv.com/cpap-boondocking/

[Tom 2424]

If you go to any site such as CPAP Exchange, or the manufacturers' web sites, you should be able to view the specs for any unit. I suspect that the current draw is lower at 24V (just like the reason large electric appliances use 240V instead of 120V), but the total power required should be similar.

So, for example, if you have a 12 to 24V transformer to feed your CPAP, it will draw at least twice the 12V current on the input side as it feeds at 24V on the output side. Usually, there's a slight conversion loss.

[chriscowles]

Originally Posted by Bobduck

I haven’t even taken it out yet due to weather here in Montana. Just going through it and getting familiar with everything. Tidying up and making it ours. Installed a battery monitor (Victron shunt) and installed a 12v port for my cpap. I just don’t want to experience any troubles when we do hit the road.

DW and I both use CPAP. We don't have heated hoses and don't use humidifiers when camping.

We have 12V DC adapter cords from the manufacturer. I added a 12V port near the bed, supplied by 12 gauge wire. It works well, even with a splitter to accommodate both adapter cords.

We use the CPAPs on 12V all the time, even when we have shore power. If there's a power failure or if our EMS cuts power due to a brownout, it doesn't disturb our sleep. The trailer batteries take over seamlessly.

[chriscowles]

Originally Posted by Outsider

Anyone have any idea if the new 24VDC units actually draw less current over time than the previous 12VDC units. This is out first CPAP so I have nothing to compare to.


If we have to keep this 24VDC unit what setup would use the least amount of battery in the long run when dry camping? (12V to 24V adapter straight from the battery perhaps?) As I mentioned earlier we do about 50% boon docking/dry camping. I already plan to add 2 GC2 batteries and will probably have to boost my solar panel as well (have 100W on top from the factory and may add about a 200W portable with charge/controller to the side mount solar port).



Thanks.

Resmed's 12V-24V adapter (linked below) provides up to 90W. Any 12V outlet in a trailer should be able to handle that. As others have said, shut off the heated hose and humidifier if you can live without it.

The converter will eat a little energy so that 90W may require 8-9 A/h. If you have a 200Ah lead-acid battery bank and start with it fully charged you can easily get more than 8 or 9 hours out of it before you need to recharge it. And that assumes you're using the maximum 90W, which you probably aren't.

https://www.cpap.com/productpage/res...ve-10-machines

[llamb]

Originally Posted by Bobduck

I haven’t even taken it out yet due to weather here in Montana. Just going through it and getting familiar with everything. Tidying up and making it ours. Installed a battery monitor (Victron shunt) and installed a 12v port for my cpap. I just don’t want to experience any troubles when we do hit the road.

So 8 AWG is enough to handle 40A at 10 ft (5ft total distance as the return counts towards total length) with a 3% voltage drop. You can go about 3x that length, but the voltage drop goes up to 10%. So the question is more about how long is the loop. How sensitive to the voltage is the end device. All of this factors into the will it work or not. and the am I going to burn things up equation.

https://www.bluesea.com/support/arti...r_a_DC_Circuit