Strange problem: Replacing a battery w/ a DC power supply

[ShiftCTRL]

TL;DR Summary

12V DC transformer in place of a 12V battery, the unit stops working.

Hey everyone,

So I'm trying to figure out what could be causing this problem:

I have a DEWENWILS Wireless Remote Wall Switch which takes a 12V battery 60 mAh(23A battery), when I replace the battery with a 12V 500 mA DC power supply, the unit stops working properly. I'm able to use the Power Off button, but the Power On refuses to work. I've been at this for a while and can't seem to figure out why this is so? Could the difference in mA be the culprit?

If I put the battery back in, everything works fine again. If I replace the batter with transformer... same problem.

Any help would be greatly appreciated - thanks!

P.S. I forgot to mention i

 

[anorlunda]

Welcome to PF.

You sound very confused. Transformers are AC devices not DC. Do you mean a DC power supply? If yes, then they are rated in volts and amps, not mah. mah is a way to rate a battery.

You say you are replacing a 12V 23A battery with a 12V 0.5A power supply? That wouldn't make sense either.

Give us more details about the old battery and the new stuff, possibly photos of the components and their nameplates, and tell us what you are trying to accomplish.

 

[ShiftCTRL]

Welcome to PF.

You sound very confused. Transformers are AC devices not DC. Do you mean a DC power supply? If yes, then they are rated in volts and amps, not mah. mah is a way to rate a battery.

You say you are replacing a 12V 23A battery with a 12V 0.5A power supply? That wouldn't make sense either.

Give us more details about the old battery and the new stuff, possibly photos of the components and their nameplates, and tell us what you are trying to accomplish.

Apologies for all the typos - I'm on no sleep... Yes, DC power supply and I meant to write mA (0.5A). The 23A battery is the model of the battery (which is 12V 60 mAh).

Basically I would like to replace the battery in the wireless remote with a DC power supply.

I don't have any pics with me right now, but I'll be sure to add it later.

 

[Baluncore]

Basically I would like to replace the battery in the wireless remote with a DC power supply.

Have you got the correct DC polarity to the original battery connections ?
How do you know that your power supply is producing about 12 V DC ?

 

[ShiftCTRL]

Have you got the correct DC polarity to the original battery connections ?
How do you know that your power supply is producing about 12 V DC ?

The polarity is correct and (aside from the power supply being labeled) we also tested it. We also tried/tested a bunch of other 12V power supplies that we had without any luck.

 

[Tom.G]

Size 23A battery (A23 size):
cylindrical (inch dimensions) 0.4dia. 1.1long, (slightly skinnier than a size N cell)
12V alkaline, 60 mAHr to 1/2 voltage
typical load 0.48mA

Please measure the supply voltage when connected to the device. It may be too high with such a light load.

Cheers,
Tom

 

[ShiftCTRL]

Size 23A battery (A23 size):
cylindrical (inch dimensions) 0.4dia. 1.1long, (slightly skinnier than a size N cell)
12V alkaline, 60 mAHr to 1/2 voltage
typical load 0.48mA

Please measure the supply voltage when connected to the device. It may be too high with such a light load.

Cheers,
Tom

Thanks for the advice Tom, I'll make sure to do that in the morning and report back.

 

[russ_watters]

Please measure the supply voltage when connected to the device. It may be too high with such a light load.

I was even thinking the opposite could be a problem: charged battery voltage is way above nameplate, so a power supply at nameplate voltage could be at the bottom of the acceptable range. Either way a voltage mismatch is a possibility.

 

[Asymptotic]

Size 23A battery (A23 size):
cylindrical (inch dimensions) 0.4dia. 1.1long, (slightly skinnier than a size N cell)
12V alkaline, 60 mAHr to 1/2 voltage
typical load 0.48mA

Please measure the supply voltage when connected to the device. It may be too high with such a light load.

Cheers,
Tom

I believe Tom has it nailed.

Recently another poster had a question involving a 9V, 500 mA transformer-based unregulated DC supply so I have the specs for that on hand. It has a transformer, full wave bridge, and 1000 uF smoothing capacitor, and in that case delivers 9 VDC at 500 mA load with an unloaded voltage output of 13.67 VDC.

If your 12V power supply is similarly designed it'll be operating at somewhat more than 18 VDC when drawing only 0.48 mA.

 

[Dullard]

That is a strange problem. The replies suggest that everyone missed the fact that the 'OFF' command works and the 'ON' command doesn't. The problem almost has to be:

The wall-wart that you're using is of the transformer 'battery charger' type. There is rectification, but no filtering - the output is a rectified sine. As the device is intended to operate from a battery, there is little/no input capacitance present. You are (effectively) powering the unit for (estimating) 4 milliseconds and then powering it down for 4 milliseconds. The 'OFF' command is apparently short enough to get out in that time. I would not be surprised if the outlet required (just for example) 3 receipts of an ON command, and only 1 (or 2) of an OFF command to 'execute.'

Getting a better power supply is still the right answer.

 

[anorlunda]

Summary:: 12V DC transformer in place of a 12V battery, the unit stops working.

I'm able to use the Power Off button, but the Power On refuses to work.

I couldn't process that statement either because it makes no sense. If the device is off and can not be turned on, then how would you know that the power off button works?

 

[Dullard]

It's 2 devices:
An RF wireless remote control (the article under discussion) and the outlet that it controls.

 

[zoki85]

That is a strange problem. The replies suggest that everyone missed the fact that the 'OFF' command works and the 'ON' command doesn't. The problem almost has to be:

The wall-wart that you're using is of the transformer 'battery charger' type. There is rectification, but no filtering - the output is a rectified sine.

But...

The polarity is correct and (aside from the power supply being labeled) we also tested it. We also tried/tested a bunch of other 12V power supplies that we had without any luck.

 

[Dullard]

I'm assuming (perhaps incorrectly) that he just went back to his bag of stray wall warts and got a similar device. The 'unfiltered' variety used to be very common (not sure these days). I am otherwise befuddled as to possible causes for 1 command to work and another not to.

 

[ShiftCTRL]

I couldn't process that statement either because it makes no sense. If the device is off and can not be turned on, then how would you know that the power off button works?

I'm able to turn on the unit by plugging the battery back in.

 

[ShiftCTRL]

Hi everyone, I finally got some time to take a few pics of the transmitter and two of the power supplies I've used.

 

[ShiftCTRL]

Size 23A battery (A23 size):
cylindrical (inch dimensions) 0.4dia. 1.1long, (slightly skinnier than a size N cell)
12V alkaline, 60 mAHr to 1/2 voltage
typical load 0.48mA

Please measure the supply voltage when connected to the device. It may be too high with such a light load.

Cheers,
Tom

Hi Tom, I just checked the power supply I used most of the times in my test and indeed it's reading 17.8 volts when connected to the board. However the other power supply with the variable voltage power supply is tuned to supply ~12VDC to the board.

I have to go to the site where this unit needs to be installed to double check using the variable voltage power supply and then report back.

 

[ShiftCTRL]

Hi Tom, I just checked the power supply I used most of the times in my test and indeed it's reading 17.8 volts when connected to the board. However the other power supply with the variable voltage power supply is tuned to supply ~12VDC to the board.

I have to go to the site where this unit needs to be installed to double check using the variable voltage power supply and then report back.

Sorry for the late report back. The Variable power supply didn't work either. We ended up buying a bunch of power supply units to see if anything would work and as it turns out only one did... the one with slightly less than 12VDC and 100 mA. Anything above 100 mA wouldn't work.

At any rate, I'm glad it's working - thank you all for your help!