Victron BlueSolar MPPT controller problem.

[crispyone]

I have 2 identical and entirely separate systems, each has 2 x 100W solar panels and a Victron 75/15 MPPT charge controller, connected to 2 x 110AH 12v leisure batteries. I have a voltmeter/ammeter monitoring the cables to the battery, with a shunt in-line in the +ve cable.

Initially everything worked fine - batteries charged to a float voltage of about 14.6V which is what I would expect. However occasionally one or both the systems starts showing a rising voltage, up to about 16.5V, measured at the controller battery connections and also (via a separate voltmeter) at the batteries, but with very low or zero charging current. Once this happens the voltage remains at that high level even in low light.

The Victron agent suggested disconnecting the controller, then reconnecting (battery first, then solar panels). This should reset the controller to charge 12v batteries (not 24V which is an option).

Have done this several times, to no avail.

I have an isolation switch to disconnect the panels from the charger, which I use when there is no solar panel input (dark or covered up). The battery voltage then drops slowly to about 12.6V.

The actual voltages may be inaccurate but the readings are repeatable and consistent - cheapo Chinese digital meters.

The batteries do not appear to be suffering.

Any idea what is going on? Is this a problem?

 

[RichardS]

I wonder if the problem is being caused by disconnecting the panels from the charger every night? I'm not sure why you would want to do this and, although it shouldn't be resetting the Victron to 24V, it might be confusing it in some way.

Richard

 

[PaulRainbow]

Been here, got the tee shirt.

Firstly, don't switch the panels off.

Secondly, configure the controller to not autosense the battery voltage. Manually set it to 12v.

Lastly, check the charging profile (or your terminology). 14.6 is not float voltage, unless you mean the voltage at which they go into float, which is also incorrect as the algorithm is more complex than just reaching a set voltage. 14.6 is the absorption voltage for open cell lead acid batteries, float voltage is around 13.4/13.6.

I would suggest you get either the bluetooth dongle or the ve direct to USB cable so you can better control/configure/monitor the controller. The dongle works with Android and the cable works with Windows.

 

[lw395]

I....
Initially everything worked fine - batteries charged to a float voltage of about 14.6V which is what I would expect. However occasionally one or both the systems starts showing a rising voltage, up to about 16.5V, measured at the controller battery connections and also (via a separate voltmeter) at the batteries, but with very low or zero charging current. Once this happens the voltage remains at that high level even in low light.
..

This could be leakage current, some DC-DC converters do not regulate properly at zero load. So the battery floats up to a high voltage with a very small current?
You could try drawing a small current, maybe an amp or even a fraction of an amp, and see if the voltage regulates at something sensible?
Some converters need a minimum load, or have a zener in the output to clamp the load.

Or possibly, the battery has got warm,due to being charged, and as it cools some secondary chemical effect produces excess charge, which manifests as an excess voltage? I have heard of something similar but TBH it's beyond what I properly understand. I vaguely remember something like this from telecomms equipment with big back-up banks.
Again a small load would dissipate the charge.

If the current is really small, the effect will be harmless. What is your idea of 'small' in this context? Most batteries seem to accept a float charge of more than 10mA without the volts rising? (or maybe I only have tired old batteries?)

Are these shiny new batteries? maybe their self discharge current is unusually low?

The other possibility is there is noise or ripple on the system causing your cheap meters to misread.
I would measure the 'AC' superimposed on the battery volts with a good mulitmeter or even a scope.

 

[crispyone]

I wonder if the problem is being caused by disconnecting the panels from the charger every night? I'm not sure why you would want to do this and, although it shouldn't be resetting the Victron to 24V, it might be confusing it in some way.

Richard

no, I don't disconnect them every night. I can disconnect them, which I always do when there is no output, if I want the controller to re-set.

 

[crispyone]

This could be leakage current, some DC-DC converters do not regulate properly at zero load. So the battery floats up to a high voltage with a very small current?
You could try drawing a small current, maybe an amp or even a fraction of an amp, and see if the voltage regulates at something sensible?
Some converters need a minimum load, or have a zener in the output to clamp the load.

that may be worth trying. I have nothing connected to the LOAD terminals. I must look into it.

 

[crispyone]

Been here, got the tee shirt.

Firstly, don't switch the panels off.

Secondly, configure the controller to not autosense the battery voltage. Manually set it to 12v.

Lastly, check the charging profile (or your terminology). 14.6 is not float voltage, unless you mean the voltage at which they go into float, which is also incorrect as the algorithm is more complex than just reaching a set voltage. 14.6 is the absorption voltage for open cell lead acid batteries, float voltage is around 13.4/13.6.

I would suggest you get either the bluetooth dongle or the ve direct to USB cable so you can better control/configure/monitor the controller. The dongle works with Android and the cable works with Windows.

interesting. I bought these as 'plug and play' and didn't consider the need to communicate with them. I'm not really into that kind of stuff (old luddite). I will look into it. Thanks for your advice. I'll let you know how I get on.

hey, guys, I never expected such a quick and plentiful response. Other forums I use produced no response at all. many thanks to all.

 

[RichardS]

no, I don't disconnect them every night. I can disconnect them, which I always do when there is no output, if I want the controller to re-set.

I thought you meant "no output" from the panels which would mean disconnecting every night. However, that's a detail .... don't disconnect them at all as you don't want the controller to reset.

Richard

 

[crispyone]

I only disconnect the panels, leaving the batteries connected, in an attempt to force a re-set of the output for 12v. batteries

 

[crispyone]

Been here, got the tee shirt.


I would suggest you get either the bluetooth dongle or the ve direct to USB cable so you can better control/configure/monitor the controller. The dongle works with Android and the cable works with Windows.

Paul, the only cable matching the Victron specification that I can find is about £30. Is it a special cable or just a re-branding of a standard cable (eg mini-USB to USB) ?

 

[RichardS]

I only disconnect the panels, leaving the batteries connected, in an attempt to force a re-set of the output for 12v. batteries

Ah, I see. You only disconnect the panels from the controller to reset it to 12V as suggested by the Victron engineer and you only do that at night. That's fine. Sorry about the misunderstanding.

Richard

 

[PaulRainbow]

Paul, the only cable matching the Victron specification that I can find is about £30. Is it a special cable or just a re-branding of a standard cable (eg mini-USB to USB) ?

It seems to be a special cable, cheapest one i found was here : https://www.onboardenergydirect.co.uk/shop/VE.Direct-to-USB-interface.html

Well worth having though as you can see exactly what the controller is doing, what it's set to and get a 30 day log. You can check that it hasn't set top 24v, which mine did, and set it to manually stay at 12v, amongst other things.

 

[jakeroyd]

It seems to be a special cable, cheapest one i found was here : https://www.onboardenergydirect.co.uk/shop/VE.Direct-to-USB-interface.html

Well worth having though as you can see exactly what the controller is doing, what it's set to and get a 30 day log. You can check that it hasn't set top 24v, which mine did, and set it to manually stay at 12v, amongst other things.

You could also buy their Bluetooth dongle.
Needs either an iPhone or Andriod phone with Bluetooth to display the data via a Victron app

http://www.ebay.co.uk/p/victron-ve-...oller-or-bmv/631079750?_trksid=p2047675.l2644

Available from lots of places.

i guess it would also send data to a Bluetooth equipped laptop but I'm unsure is there is a windows app from Vivtron for this.

 

[Ric]

It seems to be a special cable, cheapest one i found was here : https://www.onboardenergydirect.co.uk/shop/VE.Direct-to-USB-interface.html

Well worth having though as you can see exactly what the controller is doing, what it's set to and get a 30 day log. You can check that it hasn't set top 24v, which mine did, and set it to manually stay at 12v, amongst other things.

Even better is the bluetooth dongle, then you can manage the controller from tablet or phone.

 

[PaulRainbow]

Even better is the bluetooth dongle, then you can manage the controller from tablet or phone.

You could also buy their Bluetooth dongle.
Needs either an iPhone or Andriod phone with Bluetooth to display the data via a Victron app

http://www.ebay.co.uk/p/victron-ve-...oller-or-bmv/631079750?_trksid=p2047675.l2644

Available from lots of places.

i guess it would also send data to a Bluetooth equipped laptop but I'm unsure is there is a windows app from Vivtron for this.

From post #3

I would suggest you get either the bluetooth dongle or the ve direct to USB cable so you can better control/configure/monitor the controller. The dongle works with Android and the cable works with Windows.

I have the bluetooth dongle with my solar controller but a cable with the Victron battery monitor. Both work fine, it's just a shame there is no Windows support for the dongle.

 

[RichardS]

Has anyone mentioned the Victron bluetooth dongle?

Richard

 

[crispyone]

thaks, but ............... enough already!!!
I'll try the cable connection. As I said, I'm a luddite and don't do dongles, smartphones and tablets. It's an age thing - well that's my excuse for stepping off the accelerating treadmill of hi-tech progress. ;-)

 

[Ric]

Is there a bluetooth dongle by chance? That would be cool.

 

[crispyone]

Paul,
I bought the VE.Direct to USB cable and connected. You were right, the mppt controller had set itself for 24V, now corrected.
For the life of me I cannot see how Victron can justify selling an item for about £80 without providing the means of communication (which cost me an extra £26) to reset the incorrect (default???) settings. I'll have to watch the other controller to see if it also needs resetting.
Thanks for your advice.

 

[RichardS]

Paul,
I bought the VE.Direct to USB cable and connected. You were right, the mppt controller had set itself for 24V, now corrected.
For the life of me I cannot see how Victron can justify selling an item for about £80 without providing the means of communication (which cost me an extra £26) to reset the incorrect (default???) settings. I'll have to watch the other controller to see if it also needs resetting.
Thanks for your advice.

Interesting. It sounds like it wasn't resetting to 12V when you did the "connect battery first" procedure.

Can you set the default to 12V with the dongle Paul, or is it only the cable which does that?

Richard