Using a solar regulator with a laptop power supply

[inetdog]

Hi there,

I have one of those CMP12 solar regulators (12V 10A version) and it’s connected to a 12V 7AH SLA battery.

For the load, I have a 12V amplifier hooked up, which I use in the backyard for playing background music (and for parties).

Since it’s all sitting in the garage now, I thought I’d disconnect the solar panel from the regulator, and in its place, connect a DC power supply from a laptop (15V 4.5A) in order to charge the battery . No problem. After connecting the laptop power supply, the charging indicator began to flash and the battery was being charged.

Later on, I disconnected the laptop power supply, but this time, I plugged it in again while I had the amplifier (i.e. the load) already switched on and playing music. As soon as I connected the laptop power supply, the amplifier stopped playing music. I measured the voltage at the regulator’s load terminals and it showed only 1 or 2 volts from memory. As soon as I disconnected the laptop power supply from the regulator, the amplifier instantly kicked in again and started playing music.

I’m now wondering why this set up isn’t working. Could it be the laptop power supply is causing too much current to flow through the regulator (while the amplifier is drawing current at the same time)? If so, I would have thought the regulator being rated at 10A would be sufficient for this.

I then connected a universal power supply that lets you choose voltage from 12V up to 24V. The only voltage that worked was 12V. As soon as I bumped it up to 15V, the regulator would instantly cut off power to the load (i.e. the amplifier playing music).

Any ideas?

When you plug in the computer DC power supply, there is an inrush of current to charge the capacitors inside the supply. That, combined with the load to the amplifier, caused the solar regulator (or the DC power supply) to go into current limiting (foldback) mode. In that condition the voltage is dropped to a level where the current will not go over the set limit no matter how much the loads try to draw. The computer power supply will react to a lower input voltage by trying to draw more current. So the only way to get it working again is to disconnect and start over.

The "regulator" apparently also has a provision for cutting off the charging (and power to the load) if the voltage goes too high.

There is a lot that you have left out of your information, like just what terminals on the controller you have connected everything to, and what brand and model it is.

It will probably not work if you do not have a battery connected, and the amp and computer supply should be connected to the battery terminals, not to the Load output of the controller. Just make sure you do not pull the battery voltage down too low.

[pete_melb]

Hi there,

I have one of those CMP12 solar regulators (12V 10A version) and it’s connected to a 12V 7AH SLA battery.

For the load, I have a 12V amplifier hooked up, which I use in the backyard for playing background music (and for parties).

Since it’s all sitting in the garage now, I thought I’d disconnect the solar panel from the regulator, and in its place, connect a DC power supply from a laptop (15V 4.5A) in order to charge the battery . No problem. After connecting the laptop power supply, the charging indicator began to flash and the battery was being charged.

Later on, I disconnected the laptop power supply, but this time, I plugged it in again while I had the amplifier (i.e. the load) already switched on and playing music. As soon as I connected the laptop power supply, the amplifier stopped playing music. I measured the voltage at the regulator’s load terminals and it showed only 1 or 2 volts from memory. As soon as I disconnected the laptop power supply from the regulator, the amplifier instantly kicked in again and started playing music.

I’m now wondering why this set up isn’t working. Could it be the laptop power supply is causing too much current to flow through the regulator (while the amplifier is drawing current at the same time)? If so, I would have thought the regulator being rated at 10A would be sufficient for this.

I then connected a universal power supply that lets you choose voltage from 12V up to 24V. The only voltage that worked was 12V. As soon as I bumped it up to 15V, the regulator would instantly cut off power to the load (i.e. the amplifier playing music).

Any ideas?

BTW, not sure if this would have any impact, but I have a cigarette lighter socket connected in parallel with the load (although there is no device plugged into it). Also, in parallel with the battery, I have a momentary switch connected to a voltmeter, so I can push that switch button to see the battery's voltage at any given moment.

Thanks!
Pete