Carbon Monoxide and Propane Gas Alarms

I think there is safety code that require those sensors to be hardwired in RV.
Just like for years new houses can't have battery-operated smoke detectors and even those hardwired in some jurisdictions have to be interconnected.
One more time- the freestanding CO detector I bought has 10 years battery. Once the battery dies- it goes to garbage. I tell you exactly in about 8 years how it works.

News Flash: whether the CO/propane alarms are 12 volt hard wired or AA/9 volt battery units, you still have to replace them every 5-7 years because what dies is the detector, not the battery.

But I hear ya, the battery units are cheaper. RV manufacturers put in the more expensive units in spite* of the cost for two reasons: (1) they are more reliable, and (2) because they are more reliable, they are mandated by law. Not that the latter applies to YOU when you go to replace them.

*You know they use every trick in the book to make the RV the cheapest way possible, right?

I replaced our no longer made CCI lp detector with an MTI Industries unit thats pretty close match (mounts in cut wall):$47
amazon link https://www.amazon.com/gp/product/B003D32OK0

non replacable battery...5 year life span

Replaced old Atwood carbon monoxide alarm with a Kidde KN-COPP-B-LPN unit with digital display, replaceable batteries: about $20.
A lot smaller than the Atwood but covered screw holes
Amazon link...https://www.amazon.com/gp/product/B004Y6V5CI


Our smoke alarm failed and here in CA can no longer buy simple units with replaceable battery, so had one shipped to friend out of state...

Be sure to mark the install date on the back of the detector.

I like having my propane sensor wired in. I bought mine on Amazon for about $50. According to the link, it’s $49.60 now.

https://www.amazon.com/dp/B000AMBHG4/ref=cm_sw_r_oth_tau_5KR2EbECWSA6E

As of today you have probably a million options.
For propane, I bought USB-powered sensor per other member recommendation. I remember it being in $20 range and doing more than propane.
For CO I bought stand alone sensor, with 10 years batteries build-in and I use it at home or in RV depends where I spend my time. I keep it in cupholder in my TC and it went off once when my wife was frying bacon without turning hood fan on. It also shows temperature. AVAILABLE AT WALMART. You still might want cheap smoke detector regardless.
IMHO we should have CO2 and combustion gases detectors in our RV, but seems you can't buy them. About 25 years ago I could buy 1 who was cigarette lighter plug-in. When I can't vote for its efficiency, it had about 5 sensors on it and is MIA as of today.

This is what have..Top is smoke alsrm and the bottom is the Carbon monoxide detector..

My class C came with a Carbon Monoxide alarm with a 9v battery, the propane alarm is wired, I replaced them both at different times, now i'll admit that at my age, my memory isn't what it was, but i know both of them together wasn't any where near what you're talking about.
I could go out and look it up, IF I felt like going out in this pouring rain. ;)

I just checked. The replacement unit I bought a couple of years ago currently costs $35. I have an additional battery powered CO detector that cost in the range of $15-20.

I hear you, I replaced both of mine last spring with direct 12v replacement units that pretty much matched the factory detectors.