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Topic: Looking for pcb charger 220v to 12v (Read 125 times) previous topic - next topic

heinburgh

Hello forum,

For my remote projects I found a very handy little solar charge controller on ebay that charges my 12v 7ah batteries. When I remove the plastic cover the pcb fits into my project boxes very nicely and takes up very little space.

https://www.ebay.co.uk/itm/6v-New-Solar-Pwm-Charge-Regulator-Controller-F2-3a-Auto-Panel-12v-Battery-Kit/123030372130?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Now I have a project to set up where 220v mains is available, so I'm looking for something similar to charge the same batteries from mains, but all I can find are bulky things built into the power plugs. Does anyone know of a good source for what I'm looking for?

Thanks,
Hein

MorganS

Anything that plugs into mains is subject to safety approvals. If it was easy to get it out of the case and access the hot terminals then it would not pass that safety check.

It is usually best to use a wall-wart type supply and have a 12V wire going to your device. A standard DC barrell connector is good for this.
"The problem is in the code you didn't post."

heinburgh

It is usually best to use a wall-wart type supply and have a 12V wire going to your device. A standard DC barrell connector is good for this.
I agree. But the device needs a backup battery, power cuts happen often in Africa.

I remember taking one of these small chargers out of my gate motor box a few years ago when I converted it to solar, was a small thing with a tiny transformer with very little else on it. Surely this would be available to buy SOMEWHERE.

MorganS

"The problem is in the code you didn't post."

heinburgh

I have not calculated that (and now I prepare for the mocking that I will surely receive from the experienced old boys for that...)

I run a MEGA with sim808, 320 x 480 tft screen, two small cpu fans, few LED's. The sim808 has gps which comes on every 5 minutes, then it goes to sleep, but from the forum here I learnt that even if the GPS is switched off, the antenna still draws current. Then I have a temp sensor, pressure sensor and halls effect sensor, which is given power every five minutes and reading taken. After readings the data is sent to the web with sim808. Every 60 sec the sim808 checks in to see if there are new settings.

I have an identical setup running on a 20W solar panel and 6V, 4Ah battery - which is not enough. The battery drops to 5V every morning at around 2am. So I'm going with 12v from here on with 30amp solar panel, which is max for my charge controller.

MorganS

So a 4Ah battery lasts about 8 hours? Then your average power consumption is 0.5A. With the sim808 on a low duty cycle, it could be drawing large currents, which the power supply would have to supply. However, you said it's just charging the battery, so the battery can provide the peak currents (many amps as required.) Add extra capacity on the charger so that it can charge the battery as well as run the circuit. Maybe 1A.

For a reliable solar system, you need to consider a long run of cloudy days. Usually you would want to have enough battery for 5 days of zero solar generation. Sometimes more, if it's on a remote site and you need it to keep running for a week while you hike up the mountain to fix whatever broke on the solar cells.

So look at eBay or Mouser or Digi-Key for power supplies that make 1.0A at 12V from 220V. There must be a few available in the form-factor you desire.
"The problem is in the code you didn't post."

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