Any particular reason why you didn't go lower than 10V with your adjustable adapter? It will help find a practicable solution if you could find out how low you can go before the gizmo starts sulking.
Would you be satisfied with using dry (non-rechargeable) batteries as the backup and replace them from time to time? Using non-rechargeables could greatly simplify things.
Your adapter output reads about 17V when it's marked as a 12V adapter.
Another unknown factor is the amount of current drawn by the device. The 1A rating of the adaptor gives some indication but not a precise one because such ratings are usually round-figure ratings and are usually higher than the actual load current drawn by the device it supplies.
That and the load current will help decide what type of backup battery will be suitable.Yeah, I wasn't sure if I was going to break it, but I'll try lower voltages if it'll help.
OK. Then you have to accept that you have to have some way of charging the battery. This means either incorporating a charger in the backup system or moving the battery back and forth between the gizmo and a separate charger.Not really. I'd kinda like the rechargeable batteries.
17V is the peak value of 12V RMS. The filter capacitor in the adapter charges up to the peak voltage when it's unloaded, and the voltage drops when it's loaded. By how much it varies between loaded and unloaded conditions depends on a number of factors like the load current, filter cap and transformer characteristics.Are you sure the reading on my DMM and the voltage rating on the power adapter are the same unit of voltage? I remember something vague about a root-mean-square function from school, and if I divide 17 by the root mean square value for a sine function I get 12.
See above.Sounds like another test that I should do. I'll post the results of my tests probably as an edit to this post or something.
There is one important thing I did forget to mention: there's at least one setting on my device that has the word "power" in it's description, so the amps probably varies but likely not by much.
You can recharge your battery pack conveniently, while connected to device A, if you install the right kind of switch and the right diode and the right resistance. All this will be tricky and you'll have to do some testing.
whether to open device A and rework circuitry, or else break up the wires which carry wall power so you can attach the Y device externally.
whether you want to select power source via manual switch, or else use a jack with internal automatic switching,
what to house the batteries in, and whether they will be inside device A, attached to the outside, or at the end of a length of cable.
I'd prefer automatic switching
On second though I probably can't fit the batteries inside the device. 8 AAs won't fit and a C battery also won't fit. I can probably construct my own battery pack casing out of something and some electrical tape. I also have heat shrink tubing available.
On the other hand, you spoke about installing a switch to select battery power or wall power.
However if you do not want to run wires inside your device then you must tap into the DC lines from the wall adapter. It will involve soldering wires to a plug, soldering more wires to a jack.
Sp all I need to do is get some rechargeable batteries and diodes whose voltages add up (or at least very close) to the output voltage of the power adapter? And I can find the voltage of a battery by charging it normally and then measuring the voltage with my DMM, correct?
Three more questions: 1) Is it safe to leave this plugged in or is there a risk of overcharging? 2)will the device work if the batteries are not charged but it's plugged into the wall? 3) would it be possible to extend the battery life by putting more batteries in parallel?
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