MPPT function in hydro mode

[caldoverde]

I've just installed the Classic 250; not for reasons of long cable runs, but because I'm using the high voltage configuration of Hugh Piggott's 1kW axial flux alternator design to generate power from a water wheel, so the charge controller needs to handle up to 250V input.

The winter rains have failed to materialise yet, so we're playing around with summer flow levels - when it was never envisaged we'd run the hydro as the solar panels are more than adequate - but weather patterns are all over the place here as much as anywhere so we're now working to maximise the hydro potential even at these low levels in case this is going to happen more often.

At the moment, the alternator is running pretty much on the edge of its cut-in speed. When we first tested it, we connected it up to the Flexmax 80 which runs the panels and, after a lot of tweaking of settings, got the MPPT function converting the input voltage to around 21W. (Yeah, I know ... we'll be re-siting the wheel to almost double the head, but that's not going to get done immediately.)

We've tried a similar amount of tweaking on the Classic 250, but the voltage input (around 140V) appears to be just shy of what's needed to kick the MPPT function into play, so the controller does nothing with the input voltage but continually sweep between the set voltage range and flip in and out of resting state. It would be kind of nice if we could get it producing, even if its only 21W. Any advice on what we could try tweaking to get it to do that? Or are the hydro algorithms such that it's likely to stay out of range?

[boB]

I would say that if you can wait just a few days, there is a new firmware release being tested that I think will help with this issue.
And, yes, it does have an "Insomnia"  selection where it can stay on at low powers and if you really need to, can lower the
wattage at which it does turn off to less than 20 watts.

Hang on if you can and maybe this will help.  Should just be maybe 3 or 4 days away.

boB

[caldoverde]

Ahhh ... so now I have to find a PC from somewhere ...?

[boB]

Ahhh ... so now I have to find a PC from somewhere ...?

Uh Oh !!

Well, maybe there's another way....

If you have any power capacity from the hydro, if you set the charger voltage for the hydro slightly higher than the solar,
the hydro should preside unless you don't have that waterwheel turning and then the solar will preside.

Have you also tried U-Set  mode ??  If you can kind of guess what the open voltage is you could set the percentage
say, just below what you would expect the MPP Voltage to be and it will come down to that voltage but I would
still set the charge voltage of that Classic slightly above the solar set point voltage on the MX/FM or whatever
charger controllers is being used for that.

boB

[caldoverde]

Yes we tried the U-set mode, but it didn't make a lot of difference.

I've managed to source a PC, so we'll keep an eye out for the firmware updates.

[caldoverde]

Any update on that firmware upgrade boB?

I don't know whether it was the constant on-off that was discombobulating the controller some, but it started intermittently braking the wheel like there was something shorting out somewhere, accompanied by a slight smell of 'warm new electronics', which hadn't been evident before, while all the while the screen said it was just resting. Then the braking became permanent, so we've turned it off and disconnected it until the firmware is ready.

[boB]

Any update on that firmware upgrade boB?

I don't know whether it was the constant on-off that was discombobulating the controller some, but it started intermittently braking the wheel like there was something shorting out somewhere, accompanied by a slight smell of 'warm new electronics', which hadn't been evident before, while all the while the screen said it was just resting. Then the braking became permanent, so we've turned it off and disconnected it until the firmware is ready.

What are you reading on the Classic for input voltage when the hydro is turned off and disconnected
from the Classic  ?

  i.e. is the Classic still operational ?   Or is the input shorted ??

boB

[caldoverde]

Sorry for the delay boB. With the hydro disconnected the controller reads 0V. It appears to be still operational.

It was reading about 28V before being disconnected, which would probably be about right for the speed it had slowed the wheel down to. We thought at first it might be a short circuit in the alternator, but apparently not. That's functioning fine and is presently hooked up to a voltmeter off the rectifiers which is registering 150V - exactly right for the rpm it's doing.

When the intermittent braking started, the input was coming right down to 7-8V, while the controller was displaying 'resting'. When the braking became constant, the voltage went up to around 28V, 'resting' still being displayed.

[boB]

With the hydro disconnected the controller reads 0V. It appears to be still operational.

Normally, with the input of the Classic disconnected from everything, the voltage at the input terminals will read somewhat more than 1/2 of the battery voltage.  So, with 24 V battery I would expect to see  something like 12 Volts or so after a minute of input being disconnected.
Now, if there is something else connected to the input when the Classic is resting, it can be 0.0 volts, but not usually if it is completely disconnected.  This is because of an internal resistor that goes across the relay contacts.  It tends to lightly charge the input capacitors from
the battery itself but will never get to battery voltage.  That's why I asked.

If for some reason that resistor wasn't there or went open, then the input would go to 0 volts, but also if the Classic blew its FETs, that cal also cause that to happen or something else loading the Resting Classic's input down can do that as well.
Thanks,
boB

[caldoverde]

Normally, with the input of the Classic disconnected from everything, the voltage at the input terminals will read somewhat more than 1/2 of the battery voltage.  So, with 24 V battery I would expect to see  something like 12 Volts or so after a minute of input being disconnected.

Would you still expect to see that after the Classic has been turned off and then turned back on again, as was the case here?

Now, if there is something else connected to the input when the Classic is resting, it can be 0.0 volts, but not usually if it is completely disconnected.  This is because of an internal resistor that goes across the relay contacts.  It tends to lightly charge the input capacitors from
the battery itself but will never get to battery voltage.  That's why I asked.

If for some reason that resistor wasn't there or went open, then the input would go to 0 volts, but also if the Classic blew its FETs, that cal also cause that to happen or something else loading the Resting Classic's input down can do that as well.

Nothing else is connected to the Classic. Powering it up, the input voltage reads 0.0V and the battery voltage correctly reads whatever it happens to be at that moment.

Basically all it's had to play with since we connected it to the hydro is between 140-160V of input. The Outback FM80 successfully converted this into a charging current for the batteries (about 27V at 0.8A to give around 21W), but as I mentioned above, we couldn't get the Classic to play ball. We would occasionally see a brief flash of between 5-7W registering, but that's all. The rest of the time it was continually flipping in and out of resting state with the voltage going up and down according to whether the alternator was being placed under load or not.

What's our next step to determining whether it's still operational or not? Would continually flipping in and out of resting state blow the FETs (whatever they are)?

[boB]

Normally, with the input of the Classic disconnected from everything, the voltage at the input terminals will read somewhat more than 1/2 of the battery voltage.  So, with 24 V battery I would expect to see  something like 12 Volts or so after a minute of input being disconnected.

Would you still expect to see that after the Classic has been turned off and then turned back on again, as was the case here?

Now, if there is something else connected to the input when the Classic is resting, it can be 0.0 volts, but not usually if it is completely disconnected.  This is because of an internal resistor that goes across the relay contacts.  It tends to lightly charge the input capacitors from
the battery itself but will never get to battery voltage.  That's why I asked.

If for some reason that resistor wasn't there or went open, then the input would go to 0 volts, but also if the Classic blew its FETs, that cal also cause that to happen or something else loading the Resting Classic's input down can do that as well.

Nothing else is connected to the Classic. Powering it up, the input voltage reads 0.0V and the battery voltage correctly reads whatever it happens to be at that moment.

Basically all it's had to play with since we connected it to the hydro is between 140-160V of input. The Outback FM80 successfully converted this into a charging current for the batteries (about 27V at 0.8A to give around 21W), but as I mentioned above, we couldn't get the Classic to play ball. We would occasionally see a brief flash of between 5-7W registering, but that's all. The rest of the time it was continually flipping in and out of resting state with the voltage going up and down according to whether the alternator was being placed under load or not.

What's our next step to determining whether it's still operational or not? Would continually flipping in and out of resting state blow the FETs (whatever they are)?

With nothing connected to the input of the Classic, I would expect the input voltage to rise (from 0.0) over the next minute
or 2 after turning it on.

i.e.  I believe your Classic has a problem.

I will now message you and CC Ryan on this so we can get you going again.

Thanks and sorry for any inconveniences.
boB

[caldoverde]

With nothing connected to the input of the Classic, I would expect the input voltage to rise (from 0.0) over the next minute
or 2 after turning it on.

i.e.  I believe your Classic has a problem.

I will now message you and CC Ryan on this so we can get you going again.

OK. Thanks. Let me check it one more time tomorrow when it's light, because when we turned it on again to check the voltage reading we didn't leave it for 1-2 minutes to see if anything changed.

Although clearly something's not right ...

[Halfcrazy]

Caldoverde
I think there is some FETs in need of replacing. If you want Email me at Ryan@midnitesolar.com and we can get the unit repaired ASAP.

Ryan