High voltage readings with solar panels

[lesrollins]

Can anyone help with this one please.

 

I have just fitted two solar panels to the boat and when the sun as been fully out I have had readings of 16.25v on the battery monitor this causes the inverter to cut out when it is reading 16.10v. If I disconnect the panels and run the engine to charge the batteries everything is fine with no high readings.

These are a list of items I have used

 

Solar panels

2 x 140w

current atpmax 7.83a

voltage at pmax 17.9a

short circuit current 8.39a

opencircuit voltage 21.4v

 

Batteries

3 x 12v LFD 180

new a month ago

 

Controller

Victron blue solar mppt 40a solar charge controller

 

Battery monitor

Victron BMV-600S battery monitor

 

Inverter

Victron phoenix multiplus compact 12/1600/70

 

The solar panels have been wired positive to positive, negative to negative then into the controller with the battery being connected to the controller first. The battery monitor was set at 200amps (factory settings) but as been reset to 540 amps for the above battery bank no other settings have been touched, the manual says it automatically picks up the data once the new amps have been put in. How do I lower the voltage input or could I have some faulty goods will it damage the batteries. Cheers

[matty40s]

 

 

Controller

Victron blue solar mppt 40a solar charge controller

 

 

I was looking at one of these at the Braunston do at the weekend and questioned the readings on the unit. The unit was showing 13.5V and only 1.2A average over about 5 minutes. It was handling a single 140W panel, the sky was hazy/overcast but you could still see the outline of the sun through the clouds.There were other devices and lighting being run from the battery.(200AH Victron)

The salesman was explaining solar to some other customers and said that you didn't get much out of the panels unless it was sunny.

I asked if the battery was at float charge, that's why the reading was low, He said no, thats all it will produce in these conditions. My Tracer will produce around 7-8A under similar conditions.

I would love to have a test drive of this Victron unit against the opposition as it does not sound as though everything is quite right.

[Grace and Favour]

Can anyone help with this one please.

 

I have just fitted two solar panels to the boat and when the sun as been fully out I have had readings of 16.25v on the battery monitor this causes the inverter to cut out when it is reading 16.10v. If I disconnect the panels and run the engine to charge the batteries everything is fine with no high readings.

These are a list of items I have used

 

Solar panels

2 x 140w

current atpmax 7.83a

voltage at pmax 17.9a

short circuit current 8.39a

opencircuit voltage 21.4v

 

Batteries

3 x 12v LFD 180

new a month ago

 

Controller

Victron blue solar mppt 40a solar charge controller

 

Battery monitor

Victron BMV-600S battery monitor

 

Inverter

Victron phoenix multiplus compact 12/1600/70

 

The solar panels have been wired positive to positive, negative to negative then into the controller with the battery being connected to the controller first. The battery monitor was set at 200amps (factory settings) but as been reset to 540 amps for the above battery bank no other settings have been touched, the manual says it automatically picks up the data once the new amps have been put in. How do I lower the voltage input or could I have some faulty goods will it damage the batteries. Cheers

 

There are many, many more experienced folks than me on the subject of electrickery . .

 

But I think that if your monitor is correct, and your controller is putting 16v> into your batteries - it will not be doing them any good whatsoever . . . . I'd disconnect the solar panels straight away until you get better qualified advice from the forum

[Arthur Brown]

It should be hard to put 16v across a 12v VRLA battery of any size (assuming this is a house battery?!?) As a lead acid rises far past 14.4v then it starts to gas and uses up water.

 

Yes in ultra bright sunlight a solar panel will produce more than rated power.

 

(They should be rated for a typical sunny day but a high brightness day beats that for light and hence electricity. The Victron book attempts to quantify power gained in brighter (than Europe) sunlight (Med and Caribbean)

[Bobbybass]

I was looking at one of these at the Braunston do at the weekend and questioned the readings on the unit. The unit was showing 13.5V and only 1.2A average over about 5 minutes. It was handling a single 140W panel, the sky was hazy/overcast but you could still see the outline of the sun through the clouds.There were other devices and lighting being run from the battery.(200AH Victron)

The salesman was explaining solar to some other customers and said that you didn't get much out of the panels unless it was sunny.

I asked if the battery was at float charge, that's why the reading was low, He said no, thats all it will produce in these conditions. My Tracer will produce around 7-8A under similar conditions.

I would love to have a test drive of this Victron unit against the opposition as it does not sound as though everything is quite right.

I would have thought that figure was about right for an overcast day...but others..may say otherwise...

[smileypete]

I have just fitted two solar panels to the boat and when the sun as been fully out I have had readings of 16.25v on the battery monitor this causes the inverter to cut out when it is reading 16.10v. If I disconnect the panels and run the engine to charge the batteries everything is fine with no high readings.

What sort of charge current at 16.25V?

 

Sounds like you have 'maintenance free' batts and the controller is leaking a small (we hope) current even when batts are 100% charged.

 

First port of call could be Victron to see what they say about it.

 

cheers, Pete.

~smpt~

[Gibbo]

You need to try to pin it down a bit better otherwise you could end up chasing herrings.

 

Get a multimeter and measure the voltage directly at the battery terminals. It could well be very different to what your battery monitor is seeing.

 

The other thing to remember is that with fully, or nearly fully, charged batteries, once the battery voltage gets above the gassing voltage, it takes almost no energy whatsoever to raise the battery voltage to quite scary levels.

[lesrollins]

I have just taken some measurements with a meter. Time 7.36pm. At the controller solar panels in 19.76 volts batteries out 13.25 volts. Monitor reading 13.22volts. All three batteries each tested 13.25 volts. I will have to see if we have some strong sun tomorrow to test for the higher readings.

[lesrollins]

If the bm and batteries are showing roughly the same reading coukd the controller be faulty and if so how can it be tested.

[lesrollins]

I took a couple of readings again from the controller at 1,15 am just before i set off to work. On the pv side it read 4.03 volts and on the battery side it read 12.76 volts the battery monitor also read 12.76 volts. Should i be getting any reading at all from the solar panels when it is pitch black outside. Still waiting for some bright sunshine to see if it still gives me high readings. I have disconnected and reconnected the negative terminals to the controller in case the controller picked up the system as a 24 volt instead of 12 volt. I was advised to do this by the dealer who sold me the controller. I have emailed victron but i am still waiting on a reply. Any thoughts on this please.

[Justme]

I too get some residual voltagr showing over night with my outback controller, its normal.

[Chris Pink]

I have just taken some measurements with a meter. Time 7.36pm. At the controller solar panels in 19.76 volts batteries out 13.25 volts. Monitor reading 13.22volts. All three batteries each tested 13.25 volts. I will have to see if we have some strong sun tomorrow to test for the higher readings.

 

This is completely normal.

 

Unlike the 16.25V.

 

So if the higher voltage happens again then confirm the BMV-600 reading by taking an independent reading (ie with a multimeter) at the battery terminals and solar controller output. Although your inverter shutting down seems to confirm this but it could be a dodgy connection between controller and batteries, depending on where in the system your inverter is wired.

[bottle]

Slightly tangential, a friend of mine actually got an output on his solar panels at night, so he told me,,,,,,,,,,,,,,,,,,,,, he was moored under a very bright security lamp.

[lesrollins]

This is completely normal.

 

Unlike the 16.25V.

 

So if the higher voltage happens again then confirm the BMV-600 reading by taking an independent reading (ie with a multimeter) at the battery terminals and solar controller output. Although your inverter shutting down seems to confirm this but it could be a dodgy connection between controller and batteries, depending on where in the system your inverter is wired.

 

 

The inverter as been on the boat since it was built 2005 and before I fitted the solar panels it as never shut down. The controller as different settings from 0 - 9 for which batteries you are using.

 

Position

0 Equalize 1 float 13.2 absorption 15

1 Equalize 2 float 13.2 absorption 15.5

2 Deep cycle lead acid 1 float 13.3 absorption 15

3 Lead calcium 1 float 13.6 absorption 14.3

4 Gell cell 1 float 13.7 absorption 14.4

5 Gell cell 2 float 13.5 absorption 14.1

6 Lead calcium 2 float 13.2 absorption 14.3

7 AGM (default setting) float 13.4 absorption 14.6

8 Nicad 1 float 14 absorption 16

9 Nicad 2 float 14.5 absorption 16

 

Equalization charging is the process of deliberately charging a battery at a high voltage for a set period of time. Equalize charging remixes the electrolyte, helps to remove sulfate buildup on the battery plates, and balances the charge of the individual cells. Equalize the batteries every month or two (depending on usage) prolongs the life of the batteries and provides better batter performance.

 

The batteries I have fitted are deep cycle sealed batteries so I use the setting 2. When I use this setting I took a reading from the controller pv reading 20.3 battery side keeps jumping up and down from 14.96 to 14.14. Wnen I use setting 2 pv reading 19.2 battery side a steady 15.21. With the engine running the phoenix multi control shows float and the battery monitor reads 15.60. With the engine stopped and the mikuni heater and fridge running the pv reading was 16.19 and the battery monitor was showing 13.02. Today at one point the pv reading was 17.1 and the battery side was showing 15.91 which I thought was high, how high should the battery figure be before it should show signs of concern. Without knackering the batteries. If someone tells me how to upload photos I could upload some photos of the batteries and how they are wired. Cheers

[lesrollins]

Should the battery monitor and solar cables be using the same positive and negative terminals on the batteries ? There is a shunt fitted for the battery monitor. What can cause a reading of 16.25 i thought the controller would of shut down befote it allowed the voltage to go that high. Would it be better to put the solar cables and the battery monitor cables on the furthest battery terminals apart.

Edited June 28, 2012 by lesrollins

[Chris Pink]

Should the battery monitor and solar cables be using the same positive and negative terminals on the batteries ? There is a shunt fitted for the battery monitor. What can cause a reading of 16.25 i thought the controller would of shut down befote it allowed the voltage to go that high. Would it be better to put the solar cables and the battery monitor cables on the furthest battery terminals apart.

 

1. Yes (the shunt is irrelevant in this discussion except that nothing except the shunt should be connected to the batteries, the solar negative should be connected to the other side of the shunt - you will have a common negative post or busbar.)

 

2. There are three possible causes for 16.25V that I can come up with at this distance. that you read it wrong/there's a fault with the monitor (unlikely given your inverter confirms your reading) that there's a cable fault between the solar controller and your batteries or thirdly that the controller has a fault

 

either fault would appear to be intermittent

 

A photo is unlikely to help, a wiring diagram would

 

3. no

 

The next thing to do is to confirm whether the 16.25V reading, if repeated, is the same at the solart controller output and the battery terminals measured with a multimeter

Edited June 28, 2012 by Chris Pink

[lesrollins]

Thanks, it sounds as if the guy who fitted it all in may have got it wrong, i know the negative from the mppt controller shares the same negative battery post as the cable to the shunt. I will let you know when i get back this afternoon. Could this of caused any damage and/or be giving false readings at the battery monitor.

[smileypete]

The inverter as been on the boat since it was built 2005 and before I fitted the solar panels it as never shut down. The controller as different settings from 0 - 9 for which batteries you are using.

 

Position

0 Equalize 1 float 13.2 absorption 15

1 Equalize 2 float 13.2 absorption 15.5

2 Deep cycle lead acid 1 float 13.3 absorption 15

3 Lead calcium 1 float 13.6 absorption 14.3

4 Gell cell 1 float 13.7 absorption 14.4

5 Gell cell 2 float 13.5 absorption 14.1

6 Lead calcium 2 float 13.2 absorption 14.3

7 AGM (default setting) float 13.4 absorption 14.6

8 Nicad 1 float 14 absorption 16

9 Nicad 2 float 14.5 absorption 16

As your batts are sealed lead calcium leisure batts, setting 3 would be more appropriate. Maybe setting 7 in winter or if the batts don't seem to fully charge.

 

Setting 2 would be intended for those 6V proper semi traction batts like Trojans etc, (even so it seems a little high for frequent charging.)

 

If the high voltage reading only occurs with engine running, it may be the engine alt causing it.

 

cheers, Pete.

~smpt~

[lesrollins]

Got home yesterday and the negative from the controller was sharing the same post as the shunt, so i moved it to the other side of the shunt also moved the battery setting to number 3. What a difference it seems to be doing everything it supposed to without any high readings. Thanks to everyone for your help. Chris if you are ever in or around gloucester let me know the drinks are on me.

What next ? changing the fire from oil to multifuel in september. Help ! 2 months to do some homework and they say boating is relaxing. 4 months into it and my nerves are shot. Where,s the chill pills lol