Overvoltage warning on solar charger

[Hickers]

A mystery I am hoping the forum can help solve.
The Victron Connect mppt 100/50 solar controller on board Bluechip keeps cutting the charge back to 0 amps during peak output times, after dropping to 0 then the amp rate raises again until battery voltage reaches just over 14 volts then the cycle starts again. Amp output when this happens is over 40 amps. It can cycle like this multiple times in a minute. On occasions the monitor shows a high voltage warning. The cycling significantly reduces the charging at peak sun time.

I have 2 x 345 watt sunpower panels feeding the controller which is hooked up to the house bank of 3 x 10 month old Ritar 260 amp agm batteries. The solar system was installed by a marine electrician in March this year.

The cycling occurs in both bulk and absorb stages and the only way I can prevent it happening is to limit the controller output to under 35 amps.

The normal load on the house bank is between 15/25 amps per hour on average running a freezer and 3 fridges plus water pumps/chargers etc.

I have had the controller replaced under warranty however the new one is doing exactly the same.

Any suggestions for me to investigate?


Settings

Just before it shuts down

After shutdown

 

[Peter B]

I claim no expertise here, as my solar set-up is much simpler and less powerful, with simple PWM type controllers, but is it possible that the batts are essentially still nearly fully charged because your system is so efficient, (maybe also generator running has helped reduce the discharge), so your MPPT controller is just doing what it's meant to do, & prevent overcharging..? This stop/start thing happens to my Airbreeze wind genny when the sun is out, and it senses the batt voltage is near optimal from my panels, for the same reason.

 

[DavidM]

Can you increase the absorption setting to 14.8? It looks like when it gets to the current setting of 14.4 that is when it starts cycling.


David

 

[Hickers]

David, yes I can do that however the cycling happens during the bulk charge phase as well and that I can't adjust.

Peter, yes I have wondered if that is the case and the batteries are "full" but then why wouldn't the charger be in float mode?

 

[Insequent]

Hickers
As you know I have 6 of the same panels. I started a thread on their performance, and noted that the panels gave surprisingly good results. I suspect that the 345 W rating is quite conservative. For comparison, my maximum of 2300 W from 6 panels recently and not far from where you are would mean 766 W from 2 panels, a lot higher than their rated capacity.

Looking at the spec for your controller I see it is rated for 700 W max, and with 2 x 345 W panels you are very close to the limit. Now Victron is pretty good gear and can usually tolerate operating at above rated capacity for a short period. But is it possible that your panels are throwing out more than 700 W for longer than the Victron controller can tolerate?

 

[Hickers]

Right now I have the max output reduced to 34 amps which limits the panels to around 500 watts combined and I am still seeing constant cycling so I don't believe the watts are the issue.

It's hard to catch the output at max and the minimum but these two photos are close (with output limited to 34 amps)

 

[Insequent]

But aren't you just reducing output from the controller? My thought is that the problem is upstream - its the panels output that is too high for that model controller. Perhaps try some shading of the panels to test if that's the case. If you still get controller cycling with shaded panels then I'm at a loss as to what it is. Can your controller record what the maximum input it is getting from the panels?

 

[BruceK]

Some random thoughts.You`d be dead unlucky to get 2 defective Victron controllers. The rarely if ever seen theoretical max panel output exceeds the 50A max charge shown on the shot posted. Could that wonderful Qld sun output be too much for the Victron to handle, victim of a very successful panel array? Is there a larger capacity Victron to try? Was the first Victron found faulty on return?

 

[Sfudd]

Hi Folks
I recently fitted a Victron 75/15 controller with 2 x 215w Hyundai panels. I had a problem with the controller (my fault setting it up) but the retailer gave me the phone number of the Victron Australia wholesaler. They have a tech guru there by the name of Clay who should be able to sort this out for you. Unfortunately I did not keep either number as the issue was solved but I can get them for you if needed.

 

[Hickers]

That would be helpful, it would be appreciated if you could pass the number or business name on. Thanks

 

[Hickers]

Bruce, yes two with the same problem is unlikely, perhaps the panel output it too high for the controller however their manual claims higher capacity panels are not an issue for the controller. I think it is more related to the state of charge of the battery bank so I might try running the bank down tomorrow. Even if that's the case you would think it would switch to float if the bank was fully charged !

 

[Peter B]

Bruce, yes two with the same problem is unlikely, perhaps the panel output it too high for the controller however their manual claims higher capacity panels are not an issue for the controller. I think it is more related to the state of charge of the battery bank so I might try running the bank down tomorrow. Even if that's the case you would think it would switch to float if the bank was fully charged !

See Brian's post #7. Could it be the upstream voltage or current that is overwhelming the controller, in spite of what their manual claims, rather than what is happening downstream like SoC of the batts..? But try shading the panels and running the bank down a bit, one thing after the other though, so it's clear which did what.

 

[Hickers]

Breakfast on the inverter tomorrow, that will bring them down enough I think! Then I will try covering a panel though the problem only shows up in the peak sun times

 

[Jetstream]

the problem only shows up in the peak sun times

That would seem to support the suggestion that the panels output is more than the controller can handle when they are at maximum output,

Brett

 

[Hickers]

Hi, first up thanks all for the help/contributions, it is appreciated.

The attached report shows the peak watts by the two sunpower panels are well below the rated 700 nominal capacity so this casts some doubt on the controller being unable to manage the current supplied.

Pity I am 600 nm away from the electrician who installed the system!

Let's see what tomorrow's experiment delivers though we need to move so that may add to many amps back!!

 

[twistedtree]

What's the max input voltage allowed at the controller? When it trips I see its up around 66-67V. It that more than the controller can handle?

 

[DavidM]

David, yes I can do that however the cycling happens during the bulk charge phase as well and that I can't adjust.

No three stage charger should start limiting (cycling, pulsing or whatever) current during the bulk phase. During that phase the controller should allow the voltage to rise to some set point and then it switches to absorption where the voltage is maintained at some fixed (settable in your case) voltage.

That tells me that you are exceeding the design parameters or the design parameters in the specs are wrong or that the design is fundamentally bad.

This wouldn't be the first time a sophisticated piece of electronics didn't perform as specified.

Have you tried resetting the absorption voltage up to about 14.8 as I suggested?

David

 

[Hickers]

The specs on the controller allow for up to 100 volts panel input and 50 amp output so my two panels are well within the specified limits.

I will try today to see if the problem goes away when the battery bank is at a lower state of charge. I have set the absorption rate to 14.8 but not yet been able to see any result as the charger spends most time in bulk mode.

 

[kev_rm]

No three stage charger should start limiting (cycling, pulsing or whatever) current during the bulk phase. ..
That tells me that you are exceeding the design parameters or the design parameters in the specs are wrong or that the design is fundamentally bad.


David

This is the best answer IMHO. (Another) Bad controller, bad design, or outside of spec.

 

[Hickers]

So, no genset run this morning which means the batteries are down 150/200 amps. Controller still still cycling, turn on the kettle which sucks 100+ amps out and still it's cycling. I think either the stated specifications are exaggerated and I need a larger controller or I have another faulty unit??? Is there any other possibility I have overlooked?

 

[Insequent]

Hi, first up thanks all for the help/contributions, it is appreciated.

The attached report shows the peak watts by the two sunpower panels are well below the rated 700 nominal capacity so this casts some doubt on the controller being unable to manage the current supplied.

Pity I am 600 nm away from the electrician who installed the system!

Let's see what tomorrow's experiment delivers though we need to move so that may add to many amps back!!

View attachment 58030

Peak W are well within spec as you say. On average my identical panels perform similarly - peak W per panel averaged 246 W over a 94 day period, but I do get 50% above that average from time to time. And your voltage looks very similar to mine as well.

Maybe a silly question, but have you gone over the wires from the panels to the controller? Wiggled them etc to make sure no loose connections or even dry joints?

Despite the installed panels being 690 W, and controller spec being 700 W (or 720W on a different spec sheet) it is possible that you need a larger controller.

Outback say that it is good practice to have panel capacity at only 85% of rated FlexMax controller capacity. Presumably this is to allow for transient spikes that may not show up in the max power reading which is likely averaged over a short period.

I only discovered this 85% figure recently. I might yet get into trouble during summer as I have 103.5% panel W installed. I did that on the basis of 'panels that are lying flat won't get near the spec'. But as noted earlier I have achieved up to 115% of their rated capacity. But 'trouble' should only mean a trip or two, and I can deliberately apply some shade to manage if necessary.

You have an 'interesting' problem - hope someone can help you get it sorted soon!

Maybe you could take the fuse out of one of the panels, so the controller just gets input from one panel. The input power will be much lower but voltage should stay the same so that might help further eliminate potential causes. Testing both panels connected to a larger controller would be nice to do - does Jim need a holiday at Airlie?

 

[Sfudd]

Hickers, I will get the details to you tomorrow.
The only load I have on my house system at the moment is a loaded Waeco 80l fridge/freezer set at -15C for testing. Voltage drops to approx 12.8v overnight, and is then recharged at approx 2hr30 bulk, 1hr 15 absorb and is on float for the rest of the day. Charging commences just after 5am Qld time. The boat setup consists of: Port engine with two start batteries which also power the thruster & anchor winch, Stbd engine with one start battery, and the two 120a/h AGM house batteries. The PO set up the charging of all batteries by alternator through a VSR setup for port, stbd and house, with an emergency parallel.
I have since added a dedicated 20w solar panel & regulator for each starting bank and two 215w solar panels connected in parallel for the house batteries. There has not been any problem with this setup even with hours of motoring on a sunny days.
I see that you have turned off autodetect battery voltage. I was advised to do this also.
I use Default settings and Temperature compensation is also switched off, with nothing connected to the load terminal on the controller. Are your solar panels in Parallel?

 

[Hickers]

Boom, sitting here avidly watching the power outputs and saw it hit 712 watts, beginning to think the controller might not have enough capacity for the panels, it's not shown up often because in the normal se winds here I get shading from the satdome and radar. We have ne winds at the moment so full sun!
There is a few clouds around today and when the watts fall below 500 my problem goes away!

 

[BruceK]

Looks like you are making progress Hickers.
Silly tangential question but, full sun, panels happy as, batts full, charge suspended, what happens to the excess amps?

 

[Hickers]

The controller reduces the panel watts and I presume it becomes heat??

 

[Insequent]

Wondering about that myself. I'm at the dock on shore power so panels aren't producing much at all. Do they age prematurely by being in a situation that they cannot run to their capacity?

 

[BruceK]

When I work on connections, I cover the panels. Abundant precaution. I was told once they are in sun, they are putting out amps.
One of our resident electrics gurus will see this and help out. I bet it`s something simple.

 

[Hickers]

Yes seen the sparks fly when resetting the controller!! Plus a nasty shock when my ear shorted out the output, true story!!

 

[twistedtree]

Could you remove one panel from the circuit and see if the problem goes away? That might help confirm that it's an overloading issue.

 

[Sfudd]

Such patience. Hope you had a cool one open to help pass the time.
Victron Qld number is 07 3285 8456.