Design Help: Dual source DC battery pack with solar & AC power setup

[haiyan]

Background:
I am making a small dc battery pack system to power a tiny homeless shelter on wheels.

I rigged up a 50 watt solar panel from renogy, windynations p30l charge controller and a 12 volt 23 Amp AGM battery from attbat.
After wiring everything works fine.

Solar panel

http://www.amazon.com/gp/product/B00DVPPFDS?psc=1&redirect=true&ref_=oh_aui_detailpage_o04_s00

Charge Controller

http://www.amazon.com/gp/product/B00JMLPP12?psc=1&redirect=true&ref_=oh_aui_detailpage_o05_s00

Battery

I now wanted to have the option of adding regular AC source to charge the battery pack when there is no solar.
To test this I figured, I could use an old laptop adaptor @ 19.6 volts and 4 to 6 amps well under the 10 amps the charge controller is rated at.
So I have attached the laptop adaptor to the input ( where the solar panel input is on the charge controller) while keeping everthing else the same. I am expecting that it would start the battery charging process. however after a second or two the adaptor turns off (there is a blue light on the laptop adaptor that goes off) and the controller is not registering any input source.

Why is this happening? Shouldnt the charge controller be able to handle the 19.6 dc volts ( the output from the laptop adaptor) If I take the adaptor out of the ac wall socket and reconnect it the light on the adaptor goes on again but as soon as I connect it to the charge controller, it goes off again. And the charge controller doesnt register it as a solar source.


Any thoughts?
Thank you so much

[jflorey2]

To test this I figured, I could use an old laptop adaptor @ 19.6 volts and 4 to 6 amps well under the 10 amps the charge controller is rated at.
So I have attached the laptop adaptor to the input ( where the solar panel input is on the charge controller) while keeping everthing else the same. I am expecting that it would start the battery charging process. however after a second or two the adaptor turns off (there is a blue light on the laptop adaptor that goes off) and the controller is not registering any input source.

You are overloading the adapter. The battery will suck as much power as it can, depending on its state of charge. The laptop charger is trying for a few seconds to charge the battery at some current way over its rating, then its overcurrent circuit trips and shuts it down to protect it.

[SunEagle]

The solar charge controller will only work with pv panels wired to the input. It may work with a quality DC power source but that laptop charger is not like that.

The only other way to charge a battery from an AC source is to use a standard battery charger (sized for the type and AH rating of the battery) wired directly to the battery terminals.

[inetdog]

That charge controller (CC) is honestly marketed as a PWM CC. Because it operates by rapidly connecting the DC source directly to the battery and disconnecting it alternately (pulse width modulation) it will overload any DC power supply that does not have built in soft current limiting. That is why your laptop charger adapter is not working (not to mention that most laptops these days use a voltage well above 12V for their battery pack.)
An MPPT CC might or might not work, but it would be abusing the laptop charger to the point where it might not last very long.

[haiyan]

Thank you all for your input.

Based on everyones input I can go the simple route and get a 12 volt battery charger for AGM batteries but a good charger that will say charge a 340 watt battery at 12 volts costs over $50

It seems the problem ( after researching on Internet) is that the charge controller is requesting as much current possible from the laptop adaptor. In the solar panel this is limited by the sun and rating of the solar panel, however in an adaptor scenario, it can provide more current if needed and then is triggering its own safety overload.

Is there another way?I mean can I have some sort of circuit with a voltage regulator like lm350 that limits the current/voltage from the laptop power adapter. so that the charge controller doesnt succeed in overdrawing and shutting down the adapter? Has anyone tried anything like this? So it would send say 15 volts at 3 amps about 45 watts power.

Thanks again.

[jflorey2]

Is there another way?I mean can I have some sort of circuit with a voltage regulator like lm350 that limits the current/voltage from the laptop power adapter. so that the charge controller doesnt succeed in overdrawing and shutting down the adapter? Has anyone tried anything like this? So it would send say 15 volts at 3 amps about 45 watts power.

You could. But you'd be dissipating (3*(19-13))=18 watts, which means you will need a large heatsink. And you'll need to do a voltage plus current regulator, which the LM350 isn't designed to do on its own. (It can be done with an additional op amp though.) It would be a bit ugly.

[SunEagle]

Thank you all for your input.

Based on everyones input I can go the simple route and get a 12 volt battery charger for AGM batteries but a good charger that will say charge a 340 watt battery at 12 volts costs over $50

It seems the problem ( after researching on Internet) is that the charge controller is requesting as much current possible from the laptop adaptor. In the solar panel this is limited by the sun and rating of the solar panel, however in an adaptor scenario, it can provide more current if needed and then is triggering its own safety overload.

Is there another way?I mean can I have some sort of circuit with a voltage regulator like lm350 that limits the current/voltage from the laptop power adapter. so that the charge controller doesnt succeed in overdrawing and shutting down the adapter? Has anyone tried anything like this? So it would send say 15 volts at 3 amps about 45 watts power.

Thanks again.

You might find a way to get the charge controller to not work as hard as it wants to but in the end what you think you saved by not getting that battery charger will be spent on other devices as well as the high chance of the need to replace that laptop charger.

When it comes to solar / battery systems anyone that is looking to do it cheap or "free" is just fooling themselves. Solar technology works but it is not a low cost path to take.