Awesome new MPPT controller with bluetooth control for $99

[Cruiserdrew]

So in this screen shot, you can see you have to enable the charger. Check and make sure yours is turned on.

But I really believe once you investigate your low panel voltage you will find the answer. Please report back.

 

[Otter]

I *might* know your problem. First off your panel voltage is really low. It should be 16-18 volts. (Thats where the maximum power point is). So again look carefully at the panel, there's a problem somewhere. Measure the panel voltage not connected to the controller. Should be 22 volts.

But the problem-I seem to remember with this controller, there has to be at least a 3 volt difference between the battery and the panel for the panel to provide any real power. So with the panel at 14 volts and the battery at 12.5, it won't work. Something is up.

Are you certain the battery leads to to the battery input and the solar leads to the solar input? It's easy to confuse. Go back through everything. Here is what I would do:

-Disconnect the solar from the controller-measure the panel no-load voltage with a meter Should be 22ish volts
-Disconnect the controller from the battery. Measure battery voltage with a meter
-Reconnect the battery to the controller. Pull up the phone app, make sure the output is turned on and the firmware updated
-Reconnect the solar to the controller and see what happens.

If that fails, you'll need to go through your settings. I'll come back with a screenshot.

I checked the voltage of the panel disconnected from the controller, and I'm seeing a solid 19.7 volts. When I first connect the panel, app shows 18+ volts, then it drops to 13-15.

I do not have another panel available.

 

[Otter]

 

[Otter]

Showing 19 volts, but no Watts now

 

[Cruiserdrew]

Why don't you try a full manual set up. Maybe it doesn't like the AGM thing. Just do a full manual set up. And be sure the polarity is correct. It has to be something simple or the panel or the controller is defective.

Although I don't know why it would say absorb at 12.46 volts. It should say bulk.

Could you post a picture of how it's set up?

 

[Otter]

Why don't you try a full manual set up. Maybe it doesn't like the AGM thing. Just do a full manual set up. And be sure the polarity is correct. It has to be something simple or the panel or the controller is defective.

Although I don't know why it would say absorb at 12.46 volts. It should say bulk.

Could you post a picture of how it's set up?

I'll try the manual settings. Are you asking for a screenshot of the settings or an actual photo of my controller and panel?

 

[Otter]

Polarity is right. I've checked several times. With volts and no amps, I'm thinking a bad connection somewhere. Does that sound right?

 

[Cruiserdrew]

Controller, panel and wiring.

Yes-a bad connection at the panel could explain everything. You can open up the box on the rear of the panel and look in there too. Or it could be in the MC4 connectors. Really anywhere. If you were closer I'd come over and help trouble shoot with my panels and controllers.

A bad connection would really fit. As it starts to flow current, the high resistance connection causes a voltage drop hence the 14 volts you were seeing earlier today when it was trying to charge.

 

[Otter]

Controller, panel and wiring.

Yes-a bad connection at the panel could explain everything. You can open up the box on the rear of the panel and look in there too. Or it could be in the MC4 connectors. Really anywhere. If you were closer I'd come over and help trouble shoot with my panels and controllers.

So here's some pics. Sorry best I can do. Panel is on a roof rack. Working goes down the a pillar into engine bay and into the driver's foot well.

Solar wires into controller. Battery positive to controller positive. Controller ground to frame nearby. Was originally to battery negative post, but changed it about an hour ago to see if that would fix anything. In other news, my blue led sends too have quit working.

 

[Otter]

If you were closer I'd come over and help trouble shoot with my panels and controllers.

A bad connection would really fit. As it starts to flow current, the high resistance connection causes a voltage drop hence the 14 volts you were seeing earlier today when it was trying to charge.

I appreciate the offer.

Voltage was dropping but I was getting some amperage. Worst case I disconnectdisc the wires and run some straight connections to troubleshoot. See if I can figure out which one is bad.

 

[Otter]

I've direct wired all the connections now. Back to the voltage drop with low amps. Thinking it might be my panel. I'll call renogy tomorrow.

 

[lovetoski]

Awesome thread. I have the MPPT 75/15 enroute. Planning to install my Renology panels to my roof rack. I believe optimum performance is when the controller is as close as possible to the battery. I want this to be a permanent install, so under the hood is closest to the battery. Will this controller handle under hood heat?

 

[Cruiserdrew]

@lovetoski

I would not mount under the hood. Not so much because of the temperature, but because of the road spray and grit. It isn't really waterproof.

If you have fair sized wires from the battery to controller, it should be OK-like 8 ga or so.

Mine is running inside the cabin on the passenger side, 8 ga back to the battery and it's doing well there. Good luck!

 

[lovetoski]

Cool, makes sense. Thankyou. Inside it goes.

 

[Rob Faucett]

I use the 100/30 on 3 100 watt panels and love it. Works amazingly.

Whoa . . . what does 3 100 watt panels look like?

 

[Rob Faucett]

Apparently there is a new version of this controller, which is slightly more expensive but has Bluetooth integrated already, so cheaper in the end.

These versions are now called Smart Solar instead of Blue Solar, but overall are very comparable. It is interesting to swap them if you want to use Bluetooth and the VE.direct physical port at the same time.
And they expanded the range with a 100/20 model. Of course they have 100/30 and 100/50 already, but they don't come with a Load output port so for a different application.

If I roll with the 75/15 and put a 15 amp breaker ahead of the MPPT then don't need to worry about the panels generating more than that? Or does the MPPT have that breaker already?

 

[george_tlc]

If I roll with the 75/15 and put a 15 amp breaker ahead of the MPPT then don't need to worry about the panels generating more than that? Or does the MPPT have that breaker already?

That's not how it works. The 15A is the rated CHARGE current, i.e. the output current. Since this unit performs DC to DC conversion of power, the output current can be higher than the input current and typically will be...

The mppt75/15 should limit output current (charge current) to a nominal 15A maximum regardless of whether the solar panel is rated at 200W or 300W or 400W...

cheers,
george.

 

[Rob Faucett]

Thanks George!! - So I can't "blow it up" by sending to much power from the panels into the MPPT?

 

[george_tlc]

You can't 'send in too much power' since it will only draw as much power until it is outputting a nominal 15A charge current...

A solar panel doesn't output any power if the load doesn't draw any power

cheers,
george.

 

[Rob Faucett]

Eye opener! Thanks.