I need advice with making a 12vcd backup for an electronic wood stove thermometer I just bought. The unit operates off of an a/c adapter that outputs 12vcd: Here are the specs: My ideal would be to find an off-the-shelf supply with built-in battery backup, but I don't know what amp hr to look for in the battery mode. Absent that, I could manually switch over to a battery supply should the power fail. I could hook (8) alkaline batteries in series, but don't know how to estimate how many hours I'd likely get out of them (meaning it might not be worth it.) I know how to solder. Manually switching over would be no great inconvenience, because I only really need to remotely monitor temps overnight (during the day I've got stove top thermometers), and the power rarely goes out here. But I wanna be ready. Thanks
How much current does the unit draw? The adaptor is usually overrated. Hooking the eight 1.5 volt batteries in series decreases the amps eight times and increases the volts 8 times. Look at the unit main unit and see what current it draws and let me know. Also, I am guessing you just want to power the main unit, not the remote. One alkaline AA battery has 2400 mah or milliamp hours. Divide that by 8 and we have 300 mah which means an 8 series pack could power a 300 milliamp draw for one hour or a 30 milliamp draw for 10 hours. 1 amp equals 1000 mills. According to what I found online it uses <2 watts. Since volts times amps equals watts and we know 12 volts that would be .16 amps or 160 milliamps. Your 8 pack of AA alkalines would give you 1.87 hours. Since it is indicated that it uses a tad less than 2 watts (the < symbol), you might get 2 hours depending on how low a voltage your device can operate. This supply would give you 10 times that of an eight-pack of series AA. So 18-20 hours and it could be recharged. Amazon.com: TalentCell Rechargeable 12V 3000mAh Lithium ion Battery Pack for LED Strip, CCTV Camera and More, DC 12V/5V USB Dual Output External Battery Power Bank with Charger, Black : Electronics The DC5521 plug included with this pack is 2.1mm. I am assuming the polarity is the same but I would check it out before plugging in. Some use the outside as the positive and other the inside. If not the same, a reverse polarity plug adaptor can be purchased. .
Thank you, Faye. I should have tagged you, since I figured you would be the one to rescue me. My last electronics class was in the 1970s (Intro to Tubes and Transistors.) A few questions: 1-Where did you get the figure of 2w power draw? The specs I pasted say <0.5W, and there is nothing on the product itself. Wouldn't than mean 8 hours of AA power and not 2 hours? 2-Do D cell batteries have a higher ma output(would they last longer?) 3-The specs on that battery you linked say "Voltage range of the 12V output port is 12.6-9V, it is not constant, compatible with most 12 volt devices." I assume you have no way of knowing if my thermometer will work at the low end of this. 4-I plan on powering both the thermometer and the remote. But since they will be in different rooms, they would not be drawing on the same supply. Is that what you were asking? I have an email in to these guys asking if the settings are retained during a power outage, meaning if I have to go through the set-up process on both units every time I switch to a different power source during outages, batteries may not be worth messing with. (They've been real responsive to my pre-sales questions.) Here's a sample of how to set one parameter: This is obviously not ready for sale at Walmart. Here are a couple of info links: Product page Manual page Thanks again for the assist!
Not sure if I am rescuing you or confusing myself. Apparently, the <2 watts I found on the Amazon ad was a mistake. I somehow overlooked the .5 watts you posted as input draw per unit. So that would be a 40 mill draw and give 7.5 hours on the AA 8 pack. A high-quality alkaline D cell is about 8000 mah so 8 in series would deliver 1000 mah or 1000ma (1 amp) for one hour. With the 40 milliamp draw that would be 25 hours if I figured this all correctly. The battery supply I linked above would be good for 75 hours. That would be 3 days. If you have frequent and long outages, that might be the best selection since it is rechargeable. Thanks for the opportunity to do knowledge recall and fight off dementia. My electronics knowledge is also vintage. I quit with the takeover of ICs and boolean algebra. I understand transistors, but vacuum tubes are my love.
I believe I have a better option for you with an uninterruptible power supply found here. https://www.amazon.com/Battery-Backup-Uninterruptible-Security-10000mAh/dp/B07W8MCBMS/ref=sr_1_12?keywords=backup+battery+12v&qid=1637425665&sr=8-12&th=1 You should be able to leave it plugged in and run your wireless thermometer from it directly. It looks like the cables supplied with the uninterruptible power supply should be able to make the hookup but not sure. You would have to buy two of course since you need to power the remote also. With the above, you won't be using the power supplies that came with the thermometer. Power handling capabilities of the power supply is adequate. With this system, you won't have to manually switch from house current to battery. The thermometer won't lose power during an outage. It's like the same deal with those power outage generators. What say you Faye? Check it out.
A lot less money for sure and also plenty of uninterrupted power. It appears a 2.1mm adaptor plug is included. This would be nice for a Wi-Fi backup and charging cell phones during outages. Nice find Edward.
I appreciate the help. I took electronics just as transistors came into being, but transitioned to accounting when I ran out of electronics classes I could take at night. I kept our old TV sets running by making use of the U-Test-Em kiosks. I still have one of my old tube floor radios (although I gave away my Zeniths with the cat-eye tuner.) I used to listen to BBC broadcasts some evenings in lieu of watching the telly. My reason for buying this wireless thermometer is because I exclusively heat with wood and the guy sold me on a soap stone stove. The upside is it holds (and radiates) heat after the fire has gone out. The downside is that it is sensitive to over-firing (max surface temp NTE 600°F.) This is never an issue until I fully load the firebox for an overnight burn (which is the only time I fully load it), meaning I'm asleep and cannot monitor the thing. The firebox is only 2ft³, so just one or two sticks of wood with a higher-than-average BTU in that jam-packed small space can get the thing real hot real fast. I've had it get real hot (hit 600°F) twice in the past 11 years, and just happened to sense something was wrong as I lay in bed so got up and looked. And these newer stoves cannot be completely choked off...there is a permanent air inlet built in from the back (I don't know if this is a pollution thing or a combustible gas thing or what.) So you cannot close off the air supply. This project is for safety and for my peace of mind. I'll set the alarm for 525°F or so. There are no fire hydrants out in the sticks (I'm surprised property here gets insured in the first place.) At a minimum, the stove would be expensive (and inconvenient) to replace. If the house goes up, it's time to break out the coat hangers & marshmallows and wax philosophical. We do not get frequent or extended power outages here. So my anticipated use for battery backup is likely less than once a year , and even then only overnight. An 8 pak of D batteries is gonna be over halfway to the cost of that rechargeable power supply, and the D batteries will need to be replaced, and I'd still have to put a case together, and I'd still have to physically unplug/plug stuff to swap over when needed. So that power supply looks like the best option. I'm gonna send the mfr another email and see what they think. I just got back from Lowes, where I bought stuff to use for the heat sensor. It's magnetic to stick to cast iron, and the center plunger is strongly spring-loaded, so cannot "just sit" on top of the non-metallic stove...the spring pushes it over. (That Keeper note is theirs, not mine. It a retainer that ships with the unit.) Their only option were this cast iron surface (or pipe) sensor and a stove pipe sensor...I need to monitor the soap stone surface temp. I got some stuff to make it work. Thanks for the assist!
Thanks, @Ed Wilson What do you mean "a lot less money for sure," Faye? It looks like Ed's unit is $20 more than the one you found...at least on first glance.
You probably found this already, but if not here it is from the manufacturer of the thermometer. https://www.auberins.com/index.php?main_page=product_info&cPath=17&products_id=441 The old iron coal stoves were known to hold the heat overnight as well.
Thanks, Ed. That's the site I bought the stuff from. I started out chatting with the guy on one of the formal Selling/Buying sites, and ended up going directly to their site because I wanted to buy 2 types of sensors, and they did not offer that option anywhere but buying direct. They were real responsive...shipped the same day and got back to me quickly with my pre-sale questions. I've not received a reply to my recent inquiry, but they may not work on the weekends. Did you see the pic of the setup flow chart I posted? I gotta laugh. Reminds me of my first dot matrix printer where I had to learn hexadecimal commands in order to apply underline, bold and italics to my printed text. It's so primitive.
That flow chart is a handful. Maybe setup isn't as bad as the flow chart looks. I was wondering why you didn't buy the AT200CHIM which is a single unit and cheaper. The piezo buzzer option is as loud as a smoke alarm.
The AT200CHIM is a local thermometer only...it does not transmit to a monitor. I bought the AT210-A thermometer along with the AT210-B monitor specifically so I could put the monitor next to my bed and see stove's temperature while I'm in bed (without having to get up and walk to the living room.) Each monitor can receive signals from up to (10) different transmitters, so if you have a wood boiler outside, you can sit inside and monitor the temp of the stack, the temp of the firebox, the temp of the water, etc. with a single monitor. Since these are 12VDC, the manufacturer says that an outside thermometer/transmitter can be powered by a car battery (which is made for the elements) to avoid running an a/c extension cord. I looked at those buzzers, but I don't see what you're really getting. They attach to the monitors with 6' cords, so it's not as though you can put them far away (like down in the basement or something like that), and the piezo buzzer is only 3db louder than the internal one. There are no settings for the alarm volume in either transmitter or monitor, and you can only temporarily mute each Alarm Event after the alarm goes off...then it resets when the alarm condition clears. Knowing this, I'll just set a high alarm [over-firing] and leave the low alarm [needs more wood] off...I'd rather be chilly than give myself a heart attack!!! And the temp is always displayed...I wake up at least a couple of times during the night, so will glance over to see where it's at.
So I got the thing set up. 50% relied on instructions and 50% relied on ArcherKit experience to decipher how to access menus. It's so primitive. I'm not certain of its accuracy yet. The unit says 185 and my regular thermometers read 250, although it displayed room temp fine when I initially hooked it up. I got 2 input sensors: a magnetic one for stovetop contact, and a ring attachment for external stovepipe attachment. It should have come set for the magnetic one I specified as part of the kit. Sensor Type is a menu item, but they don't provide a cross-reference, so I can't verify this. There are 3 Sensor Types you can buy and 10 different Klingon symbols on the settings. I'll have to play with it.
The reference that this setup could be powered by a car battery is what made me question the current draw. I think the option that Ed linked would be best because of the quick auto switchover. I thought it was $126. I give up as I think my mind and eyes are playing mean tricks on me. I was trying to find where I saw 2 watts and can't find it again. It must be time for me to toss my antique broadcast and audio sheepskin in the G can and go play dolls with the girls. SIGH!
I think the car battery suggestion for outdoor applications is merely for convenience, not because of any needed Cold Cranking Amps. I gotta play with this today. When taken off of the stove, the room temp reads fine. When on the stove at higher temperatures (≥200°F) it's off by 100°F and more. I don't know if this is a sensor issue or if the setting code is wrong. The sensor is the one I attached a pic of above, and is designed to a cast iron stove, not soap stone. But that should not matter. And I can't try the other sensor I bought because I don't know it's code. I'll have to wait until tomorrow to talk with their tech support. Right now I have the sensor and a stove thermometer on a cast iron griddle on my stove so I can gather some data. So far I love the concept. I could keep an eye on the temp all night long...I just had to add 100°to the readout.