MPPT Charge controller

[Fluenta]

Thanks for the quick reply guys. Always a good reminder to check the basics ! I have done that - and I cheated by having an electrician do the install as we are short on time to move south - and all seems good. Pretty simple from a wiring perspective and if we got it wrong it should not work at all.

As far as 24V, there is no setting on the Blue Sky for that as it senses if the V is above or below 16V and sets the nominal V as 12V or 24V from there.

I will reset the fuse and see what it does today.

[noelex 77]

Some of the charge controlers will do an automatic equalization cycle every 30 days or so. It may have just been in this cycle.
It's not also clear how you were reading the battery voltages. Some instruments, particularly multimeters with flat internal batteries can give very wrong readings.

[Fluenta]

Thanks - The DIP switch setting for equalisation is off.

V readings: from the remote for the Blue Sky itself and from the voltmeter on the circuit panel. I will take a reading direct from the batteries today too.

[noelex 77]

It's hard to imagine how the cc would display, and therefore knowingly allow, 15v output on a 12v system not in equalization.
You have covered all the options I can see. It looks like the cc is defective.

[Fluenta]

Checked the batteries directly at two different points and their voltage is what is reflected on the boat's voltmeter. Also checked the output of the charge controller slightly downstream at the fuse and it reflects what the blue sky remote indicates. They are presently 1.5V apart (15.7 at the cc and 14.22 at the batteries).

I will see if the cc goes into acceptance mode once the battery reaches 14.4v

[Jon Hacking]

Originally Posted by Fluenta

... They are presently 1.5V apart (15.7 at the cc and 14.22 at the batteries)...

Are you saying that there's 1.5v between the INPUT to the CC (the panel voltage) & the battery? 15.7 is a bit low for a panel unless it's pretty hot. 1.5v between the output of the CC & the battery indicates a HUGE wiring loss - it should be no more than 0.1v & usually much less.

[Fluenta]

Nope. Didn't go into acceptance mode (battery V was over 14.4V and the cc was showing 16+) unless I reset the fuse and then with the batteries already topped off the cc went into acceptance mode.

[Fluenta]

Originally Posted by Jon Hacking

Are you saying that there's 1.5v between the INPUT to the CC (the panel voltage) & the battery? 15.7 is a bit low for a panel unless it's pretty hot. 1.5v between the output of the CC & the battery indicates a HUGE wiring loss - it should be no more than 0.1v & usually much less.

There is a 15.5V difference between the output of the charge controller (measured just downstream of the cc at the fuse) and what I measure at the batteries. The output of the charge controller goes to the battery switch terminal vice the batteries. Could that be the source of the problems ?

[cwyckham]

Originally Posted by Fluenta

Nope. Didn't go into acceptance mode (battery V was over 14.4V and the cc was showing 16+) unless I reset the fuse and then with the batteries already topped off the cc went into acceptance mode.

Can you please give us a very precise description of where these voltages are being measured?

The panel input voltage, the cc output voltage, and the battery voltage are all of interest. The last two should be almost identical.

Does the cc have a remote voltage sensor on the batteries or is it reading the voltage directly at charge controller? Is the charge going to the battery directly, or is there charge combiner or diode of some sort in the system?

Don't assume an electrician did things right!

[cwyckham]

Originally Posted by Fluenta

There is a 15.5V difference between the output of the charge controller (measured just downstream of the cc at the fuse) and what I measure at the batteries. The output of the charge controller goes to the battery switch terminal vice the batteries. Could that be the source of the problems ?

I assume you mean the voltage downstream of the cc is 15.4 and the battery is 14 something?

Is out just a basic switch or is there a 0.7V drop from a diode? Measure voltage update and downstream of the fuse and of the switch.

Unless it's a long, tiny wire and a huge current, drop is likely to be a bad connection. Check to make sure write is sufficient, though

[Fluenta]

I just checked again at the cc terminals.

PV V: 35V
CC Output: 14.4V
Battery voltage 13.2V

Once I reset the fuse the cc went into acceptance mode. Otherwise it was staying in bulk and continuing to increase its V. At 16+V at the cc and 14.5V at the battery I shut the system down to prevent damage.

The cc does not have a remote V sensor rather uses the V from the supply to the batteries.

The positive output goes to the battery switch terminal. The negative goes to the terminal bus in the circuit panel. Should they go direct to the battery terminals ? I asked the electrician about that and he said it was okay.

Really appreciate all the support. Kinda stressed situation as lots to do before we take the boat south in two weeks.

[noelex 77]

Originally Posted by cwyckham

Don't assume an electrician did things right!

It's sad but +1

[cwyckham]

Really weird. If there's no remote sense, then it sounds like you have two separate problems.

One, defective cc as it shouldn't be putting out that much voltage.

Two huge voltage drop either due to bad connections or undersized wire

[noelex 77]

Originally Posted by Fluenta

CC Output: 14.4V
Battery voltage 13.2V

I agree with what Cwyckham and Jon are saying the CC output voltage and battery voltage should be close ( within 0.5v). This fault does not fit in with your problems, but new defective equipment is rare, and there is a problem here.

What gauge wire has been used? What is the distance of the run?

[Fluenta]

from the CC to the switch/terminal is 6 gauge. Run is about four feet. There must be a connection problem downstream from the cc. Should the cc output go direct to the battery terminals vice the battery switch and the common negative bus in the circuit panel.

Definitely too much of a drop but not sure why the cc is not stopping 14.4V. I will talk to blue sky on Monday.