Offgrid: Solar Charge Controller Load output issues

Manish

Hello Community,

My first post.

I have built a small off grid system to power LED lights during the night to provide some additional lighting on my street. I have the following: 

100W standard poly solar panel

12V 26AH SEALED VOLT DEEP CYCLE RECHARGEABLE BATTERY

12V/24V PWM Solar Charge Controller 30A (also have a different brand 10A PWM charge controller as a spare)

14AWG running from my Solar panel to my charge controller

16AWG running from my charge controller to my battery

16AWG running from my charge controller load terminals to my load

My problem is from my charge controller to my load

At first, I had a 300W inverter running off the load, the inverter wont work and I thought 300W was too much so I got a 100W inverter. Same issue, load wont power the 100W inverter. I changed the charge controller and same results.

I tried to bypass the inverter altogether and got a 12v 12W DC LED bulb and hooked it to the load terminal - does not work. Same bulb direct to battery works, tried swapping the charge controller but still does no work.

During some trials and errors, I swapped the 16AWG wire from charge controller to battery with a much thinner wire (don't know the AWG, it was a laptop charger wire) and the inverter that was hooked to load terminal worked but I am suspecting my panel wont be able to charge my battery adequately with this wire). I don't want to hook my DC light directly to battery as I want the advantage of cut off when the voltage drops to protect my deep cycle battery + my charge controller has a dusk to dawn load feature. Plz advise on where I am going wrong.

Thank you all in advance.

Estragon

One thought is the voltage may be too high on the load output for the inverter. Using a thinner wire may have caused enough voltage drop to put voltage into a range acceptible to the inverter.

A pwm controller typically works to charge a battery by pulsing current at panel voltage, which may be ~18v. As the battery voltage rises while charging, the pulses are spaced out further, but still at 18v. Some LED lights are okay with wide voltage ranges, some are picky.

It may be that you need to use the load terminal to drive a relay, which controls a connection from the battery to the inverter.

littleharbor2

The load output on these small controllers is intended to control lighting circuits and is usually triggered by darkness. You need to program it for always on if you want it to power daytime loads. BTW these load outputs aren't intended for powering an inverter. Connect inverters directly to your battery. Sounds like you are running too small of wire as well. Why are you running smaller wire on the CC output?

Manish

littleharbor2 said:

The load output on these small controllers is intended to control lighting circuits and is usually triggered by darkness. You need to program it for always on if you want it to power daytime loads. BTW these load outputs aren't intended for powering an inverter. Connect inverters directly to your battery. Sounds like you are running too small of wire as well. Why are you running smaller wire on the CC output?

Tried setting always on and on darkness, also ditched the inverter altogether and plugged a 12v 12W LED DC light to load and still no go.

Manish

Estragon said:

One thought is the voltage may be too high on the load output for the inverter. Using a thinner wire may have caused enough voltage drop to put voltage into a range acceptible to the inverter.

A pwm controller typically works to charge a battery by pulsing current at panel voltage, which may be ~18v. As the battery voltage rises while charging, the pulses are spaced out further, but still at 18v. Some LED lights are okay with wide voltage ranges, some are picky.

It may be that you need to use the load terminal to drive a relay, which controls a connection from the battery to the inverter.

I have configured the controller such that it only kicks in during dusk to dawn (when the panel is not generating current), I also suspect what you are, the smaller wire maybe adjusting the voltage but this is a serious flaw with charge controllers, remember I have two different controllers and both are behaving the same.

I am not too familiar with the relay suggestion, how will it work? Will I plug a relay from my load to battery and then to my actual load (LED lights?), will it give the full discharge protection?  

littleharbor2

Manish said:

littleharbor2 said:

The load output on these small controllers is intended to control lighting circuits and is usually triggered by darkness. You need to program it for always on if you want it to power daytime loads. BTW these load outputs aren't intended for powering an inverter. Connect inverters directly to your battery. Sounds like you are running too small of wire as well. Why are you running smaller wire on the CC output?

Tried setting always on and on darkness, also ditched the inverter altogether and plugged a 12v 12W LED DC light to load and still no go.

You could have the polarity reversed. Try and determine correct polarity. 

Can you test the terminals with a digital volt meter? You could verify that your settings have been set and are getting voltage before you make any load connections.

Estragon

If the panels are producing zero current, the voltage issue may not be the problem. Still, using a relay is likely the better way to control. As Mcgivor noted, load terminals on small controllers have limitations.

The relay connects between the battery and the load, using wire and fusing or breaker appropriate for the load.

The relay control circuit would connect to the load terminals on the controller, so when the controller puts voltage on the load terminals the relay (normally open) closes and completes the battery to inverter circuit.

A 300w inverter could draw upwards of 30a or more. A 16ga wire is way too small for that. Even a 100w inverter should probably be 14ga or heavier.