Mppt charge controller error

[Willbiker]

Hi everyone

I have a 40 year old caravan which is only 10 foot long and space is precious and pay load is limited. So I decided to mount 2x 200w panels on the roof rack of my tow van and mount a leisure battery and 2 mppt controllers in a heavy duty storage box. This way I can store all the heavy equipment in the tow vehicle and also unplug the pannels and remove the box should I need to use the van when away..

Anyway... my 2 controllers are connected in parallel to the battery however one of them, after a while, has a flashing battery charge bar. I replaced the controller only to find the new one does it too! What do you think the issues is?

I have attached some pictures. Ignore the second battery, this is not yet connected up.

Any help would be greatly appreciated!

 

[snoobler]

First, those aren't MPPT charge controllers. They are PWM charge controllers made by "MPPT Solar." They are essentially a scam. There's no such thing as a $23 MPPT controller.

Second, when paralleling charge controllers, after the bulk charging phase, it's common for the stronger charge controller to output more and the weaker one to drop to float before the other is finished charging.

If your "flashing battery charge bar" indicates "full battery," then that's probably what's happening. If not, they're basically junk, and anything could be going wrong.

 

[Willbiker]

Thanks for the reply. I was not aware of this scam!! I will look to upgrade them eventually. The battery level shows empty when flashing. It may just be down to them being shite!

 

[MisterSandals]

How are your panels setup? Is it one panel to each SCC?
What happens if you switch the 2 SCC’s?
What happens if you only run a single SCC?

 

[Willbiker]

Each controller has 1 panel connected to it. I have switched the panels over with no change. I havent tried runing just the problematic controller so I will give this a go. Thanks!

 

[MisterSandals]

One more thing to check is the voltage from panel(s) to the SCC at the terminal. I recall my cheapie PWM controllers only showing battery voltage when panel voltage not sufficient. The panel voltage needs to be a few volts above charge voltage.
Is one panel partially shaded? Even the shadow of your hand on panel will significantly lower panel output.

 

[Willbiker]

Thanks I will try this. Nope no shade at all.