9v Battery Eliminator (9v DC Adapter & Battery Eliminator) - Replace Your 9-Volt Batteries with Wall Power Supply

I've checked, and if the two-part plug-in substitute for a 9v battery is used as a kit there shouldn't be any polarity problem. The AC/DC converter plug prongs are reversible, because AC cycles back and forth, and for this purpose the converter doesn't care which prong the AC comes from. The DC polarity at the point of connection where the the adapter attaches instead of the 9V battery will always be right -- male pole positive. The seller explained to me that polarity can be wrong if an AC/DC adapter with a purposefully different DC polarity -- like for a guitar pedal -- is substituted for the converter that comes with the 2-part kit.

The 9 volt output on this battery eliminator is a generous 1/2 Amp (500 milliamps). A typical rating for a fresh 9 volt Alkaline battery is 550 milliamp hours; which means you can draw 550mA for 1 hour - or - 55mA for 10 hours (the same amount of total energy). In other words, this battery eliminator is capable of operating a device which is so power hungry (55mA) that it would use up a brand new 9 volt Alkaline battery in 10 hours. Ample power! Additional note: I found the in-line connector to be a welcome enhancement. It readily enables the separation of the device from the cord.... Hope readers find this useful info...

It does the job but..... The connector between the power supply and 9 VDc adapter slides apart too easily. Fixed with a little electrical tape. Power supply wall wort gets a little warmer than I like.Otherwise good deal.

I have a set of Bunker Hill (Harbor Freight) infrared sensors set up by my front and side doors (in windows, not outside). Anyway, seeing as there are plugs nearby them, I figured I would try a battery eliminator in one (trial run). I did check the polarity with my tester before use, it was correct. Works like a charm. I did make a little notch in the battery cover for the wire to pass through (looks better than leaving the cover off). I also made a loose knot in the wire, behind the cover (in case it got pulled accidently). I have recently ordered another for the other sensor. If I remember, I will update on longevity.Edit - I forget to mention the cord (on the one I received) is 44 inches long.Edit - I needed to extend the power cable on my second battery eliminator (didn't want to use an extension cord on the adapter). I purchased this https://smile.amazon.com/gp/product/B01MUH5QF4/ (white to match the window), works perfect.Edit - Feb 23, 2020. The two I bought are still working fine.If this review was helpful, please click 'Helpful' below (lets me know that I'm not wasting my time, by doing these). Thank you!

The product worked great! I was a little disappointed at first that the 9v adapter didn't seem to work with anything else that needed the same voltage and amperage. I was confused by this and then spotted this in the description:Please Note: Your Adapter Must Have a Comparable 5.5mm X 2.1mm DC Barrel Jack With Tip Center Positive PolarityThis was the issue: most of my peripherals call for "tip center negative polarity". So I ended up also getting a polarity inverter so I could more easily use this adapter with other things and also use other 9v adapter with this batter replacer.I hate buying and changing 9v batteries, so this was a perfect solution for me!

The convenience, and cost savings make this worth the $10 it cost. It keeps my digital thermometer running without a problem.There are two issues with it:1. The red LED on the power block is very bright. I'm not even sure why it needs a light. Easy to fix with a piece of electrical tape to cover it. It still has a little bit of a glow, but not bad.2. It emits a high pitch whistle sound. At this point even cheap power supplies run quiet, so this is not great. I may have just received a bad one, but I can live with unplugging it when not in use.

I bought this for my home studio that serves as my Virtual station for work. I bought this to eliminate the need for 9V batteries. This absolutely has not worked for me. I didn't return it with the hopes I might someday get it to work and it's a great concept, but for the boom stationary microphone I purchased it for, it is nothing like the electric options you get with a AA option. I would not buy this again.

works and saves batteries