MPPT connection (again I know!)

[hector]

Hi everyone,

 

I know this gets asked a lot, but the answer always seems to involve a certain amount of "every boat is a one-off" so I am asking again...

 

Our narrowboat currently has no solar panels and I want to install a basic 1 or 2 panel kit, which will come with an MPPT, to keep the leisure batteries up. The starter battery has it's own alternator so I'm not planning on trying to have the solar charge it.

 

My question is simply whether I can just connect the MPPT directly to the + and - of the first battery, with an appropriate fuse in line with the + (they are 12v batteries connected in parallel), or whether I have to worry about some more complicated integration with the shoreline charging controller (not an invertor combi) or charging from the alternator.

 

So, I will have the alt, the charger, the MPPT and the batteries all wired in parallel, and in this case am I right in thinking they will all just 'see' the highest individual voltage and behave accordingly... so to speak.

I have attached (I hope) to this post, a rough block diagram of the domestic power set-up as is.

 

Many thanks,

 

Hector.

[Tracy D'arth]

Use a fuse or switch to isolate the panels from the mppt controller as if you disconnect the controller from the battery the controller will blow.

Fit a fuse and an isolator switch near the battery to connect the mppt positive.

 

Yes, all connected, highest output charges battery best.

[Tony Brooks]

37 minutes ago, hector said:

My question is simply whether I can just connect the MPPT directly to the + and - of the first battery, with an appropriate fuse in line with the + (they are 12v batteries connected in parallel), or whether I have to worry about some more complicated integration

 

No, nothing more complicated and I am sure it will work as intended from the solar because it will provide a comparatively low current in most cases. However, theory tells us the Pos and Neg from the MPPT should go to opposite ends of the bank. Theory says that the current going into any battery should ass through an identical number of battery interlinks, but with the BSS demanding 25 sq mm CCSA battery cables it is unlikely to make a practicaal difference.

[jpcdriver]

59 minutes ago, Tracy D'arth said:

Use a fuse or switch to isolate the panels from the mppt controller as if you disconnect the controller from the battery the controller will blow.

This is always mentioned when solar panels and controllers are discussed but I'm not sure why it should be, particularly with the more sophisticated MPPTs. Surely when the controller is disconnected from the battery the control circuitry goes dead and the panels are into a dead or open circuit. Would seem very bad design for it to be otherwise.

[Jen-in-Wellies]

10 minutes ago, jpcdriver said:

This is always mentioned when solar panels and controllers are discussed but I'm not sure why it should be, particularly with the more sophisticated MPPTs. Surely when the controller is disconnected from the battery the control circuitry goes dead and the panels are into a dead or open circuit. Would seem very bad design for it to be otherwise.

I believe some designs could do this. I've accidentally done it to several solar controllers, without wrecking them, but it is still good practice, just in case.

[Tony Brooks]

20 minutes ago, jpcdriver said:

This is always mentioned when solar panels and controllers are discussed but I'm not sure why it should be, particularly with the more sophisticated MPPTs. Surely when the controller is disconnected from the battery the control circuitry goes dead and the panels are into a dead or open circuit. Would seem very bad design for it to be otherwise.

 

Because most MPPTs are dual voltage, 12/24. If you disconnect the battery but leave the panels connected the voltage will rise to the panel's open circuit voltage and in some cases that causes them to set to 24 volts. If you have panels in series the high open circuit voltage might damage the electronics. We have had at least two instances here of a controller setting itself to 24V with a 12V battery bank. It does the batteries no good at all.

[Alan de Enfield]

1 minute ago, Tony Brooks said:

We have had at least two instances here of a controller setting itself to 24V with a 12V battery bank. It does the batteries no good at all.

 

Me Sir, Me Sir - I am one !

[jpcdriver]

6 minutes ago, Tony Brooks said:

We have had at least two instances here of a controller setting itself to 24V with a 12V battery bank. It does the batteries no good at all.

That is bad design on a particular controllers. Looking at my Victron MPPT it only auto detects battery voltage on very first connection or after factory reset. I can see it is not good for the batteries (at all) but does it also fry the controller if it could be normally cope with a 24v battery bank?

Edited August 25, 2022 by jpcdriver
added 'very'

[Tony Brooks]

Just now, jpcdriver said:

That is bad design on a particular controllers. Looking at my Victron MPPT it only auto detects battery voltage on first connection or after factory reset. I can see it is not good for the batteries (at all) but does it also fry the controller if it could be normally cope with a 24v battery bank?

 

I have not heard of an example that has but who knows. Better safe than sorry so connect the batteries first. Not everyone has a Victron MPPT and in my view the lack of any decent info from a display or the need for a computer would put me off them.

[Murflynn]

17 minutes ago, Tony Brooks said:

 

Because most MPPTs are dual voltage, 12/24. If you disconnect the battery but leave the panels connected the voltage will rise to the panel's open circuit voltage and in some cases that causes them to set to 24 volts.

 

as I found out to my cost when I had to buy an expensive Victron dongle in order to re-set my MPPT controller.

[Tony Brooks]

2 minutes ago, Murflynn said:

 

as I found out to my cost when I had to buy an expensive Victron dongle in order to re-set my MPPT controller.

 

Whereas those with lesser and supposedly badly designed controllers seem, in many cases, to just disconnect panels and battery, leave for a while, and then connect the batteries before the panels.

[Alan de Enfield]

37 minutes ago, Tony Brooks said:

 

Whereas those with lesser and supposedly badly designed controllers seem, in many cases, to just disconnect panels and battery, leave for a while, and then connect the batteries before the panels.

 

When I inadvertently disconnected the batteries from the MPPT (whilst leaving the panels connected to the MPPT) the MPPT had a 'wobbler' and refused to play the game.

 

Spoke to Bimble (the MPPT supplier) who said it has defaulted to 24v, now the MPPT is trying to put out 24v and the batteries are looking for 12v so the MPPT is having a sulk.

It is possible for the sulk to turn into a full blown tantrum with 110v going into the MPPT and the only thing coming out of the MPPT is smoke.

 

1) Disconnect the panels from the MPPT

2) Wait 30 seconds +

3) Disconnect the batteries from the MPPT

4) Wait 30 seconds +

5) Reconnect batteries to the MPPT

6) Reconnect the Panels to the MPPT

 

"Smiley face"

Voltage from panel to MPPT = 110v

Voltage from MPPT to battery 14.2v

 

Panels charging my 12v battery bank at full tilt,

Edited August 25, 2022 by Alan de Enfield

[jpcdriver]

2 hours ago, Murflynn said:

Because most MPPTs are dual voltage, 12/24. If you disconnect the battery but leave the panels connected the voltage will rise to the panel's open circuit voltage and in some cases that causes them to set to 24 volts.

This makes no sense to me. All these controllers are run by a microprocessor which should be powered off the battery side, so it shouldn't turn on until the battery is connected. The input (panel) side should not be connected through to the battey until the controller knowns what voltage it is connected to. Hence why I say they are poorly designed controllers or there is something wrong if they cannot cope with the battery being disconnected and reconnected whilst the panels are still hooked up. Why should the user have to make sure the panels get disconnected.

 

Also, I'm not saying the Victron is necessarily a better product, I think some people have pointed out some deficiencies, I was just trying to use my experience from that particular manufacturer to show my point of view. I don't have any personal experience of any other controllers.

[ditchcrawler]

2 hours ago, Alan de Enfield said:

 

Me Sir, Me Sir - I am one !

I understand Victron like doing that

[jonathanA]

2 hours ago, Tony Brooks said:

 

I have not heard of an example that has but who knows. Better safe than sorry so connect the batteries first. Not everyone has a Victron MPPT and in my view the lack of any decent info from a display or the need for a computer would put me off them.

To be fair the newer blue tooth victron solar controllers need neither computer or display just a smartphone with the victron app. 

I particularly like the fact you can set them to 'OFF' so you can safely connect / disconnect the panels and or batteries without risking any drama.

The app is very good IMHO.

[Tony Brooks]

10 hours ago, jonathanA said:

To be fair the newer blue tooth victron solar controllers need neither computer or display just a smartphone with the victron app. 

I particularly like the fact you can set them to 'OFF' so you can safely connect / disconnect the panels and or batteries without risking any drama.

The app is very good IMHO.

 

That is exactly what I have against much of what Victron are up to. Fit a decent switch between panel and controller and you do not even have to to find your phone. The modern assumption that everyone has, wants, or can use a smart phone seems deigned to deny certain sectors of society the use of products or services. My non-smart mobile does not have Bluetooth and is cost so little it is no great drama if dropped in the cut or damaged.  It may surprise many people but not everyone can use smartphones unless they are happy for everything they and other say in the vicinity of the phone to be transmitted to Apple/Google for analysis and profit. It Victron wanted to that feature could be provided by a simple push button.

 

It is just another example of toys for boys and minimizing the cost of manufacture.

 

<<Rant off>>

[Higgs]

If I have to open an account to run a device, apart from the phone, that device is likely to stay in the shop. 

 

 

[Jen-in-Wellies]

I am currently helping install a big Victron set up on some ones boat. Everything is set up differently. On the solar controller, you set the battery type with a trim pot tool in a rotary switch. On the mains battery charger, you set the battery type with a push button to cycle through different types. On the battery to battery charger, you can only set it via the Victron app.

To be fair to the Victron app (Android), I've found it simple to use on what is now an old and very out of date smart 'phone and needing only minimal permissions, excepting that location needs to be turned on, which is usually something I keep off. No account needs to be set up to use it. It certainly communicates with Victron as it is used to download firmware updates. Who knows what information is flowing back to them? I accept @Tony Brooks point that not every one has a smart phone and is happy using mobile apps. However they are a lot easier to use than Victron's older methods of complex configuration changes, using a laptop and some expensive USB dongle to interface with the Victron wired network connection. The simplest configuration changes were/are with the internal dip switches, but these can only provide a relatively limited number of options. The recent Victron stuff can be configured for a huge variety of different use cases and that wouldn't be easy with physical switches, or trim pots.

Jen

[jonathanA]

Whilst I understand and respect @Tony Brooks position. I think its verging on the paranoid to assume Google apple microsoft and more likely Amazon and listening to everything we are saying. I've no doubt they a have very clever AI trying to work out how to send us adverts etc that might appeal to us based on browsing history, cookie info and indeed anything we say to alexa, siri etc.  All fairly easy to  manage or avoid  but probably not quite so easy to completely switch off. 

It's  not hard to setup a junk email account for those devices that require you provide an email address to setup an account. Anything requiring any form of payment info (e.g for age verification) I regard as a scam and would avoid. 

 

I'm sorry to say that it won't be long before people without even simple smartphones are going to be second class citizens.....  I'm not saying that's right. 

[Higgs]

3 minutes ago, jonathanA said:

Whilst I understand and respect @Tony Brooks position. I think its verging on the paranoid to assume Google apple microsoft and more likely Amazon and listening to everything we are saying. I've no doubt they a have very clever AI trying to work out how to send us adverts etc that might appeal to us based on browsing history, cookie info and indeed anything we say to alexa, siri etc.  All fairly easy to  manage or avoid  but probably not quite so easy to completely switch off. 

It's  not hard to setup a junk email account for those devices that require you provide an email address to setup an account. Anything requiring any form of payment info (e.g for age verification) I regard as a scam and would avoid. 

 

I'm sorry to say that it won't be long before people without even simple smartphones are going to be second class citizens.....  I'm not saying that's right. 

 

It actually does get ridiculous, when you can't have a new battery in a car, without having to use the dealers to set the controller, etc. My view is; I buy something, the job of the manufacturer is to honour any guarantees and not make something that keeps me hooked into their controlling it. 

 

 

[ditchcrawler]

13 minutes ago, jonathanA said:

Whilst I understand and respect @Tony Brooks position. I think its verging on the paranoid to assume Google apple microsoft and more likely Amazon and listening to everything we are saying. I've no doubt they a have very clever AI trying to work out how to send us adverts etc that might appeal to us based on browsing history, cookie info and indeed anything we say to alexa, siri etc.   

I am moored in Chester for two nights, last night I received information about Chester Co op Funeral Care

[Tracy D'arth]

12 hours ago, jpcdriver said:

This makes no sense to me. All these controllers are run by a microprocessor which should be powered off the battery side, so it shouldn't turn on until the battery is connected. The input (panel) side should not be connected through to the battey until the controller knowns what voltage it is connected to. Hence why I say they are poorly designed controllers or there is something wrong if they cannot cope with the battery being disconnected and reconnected whilst the panels are still hooked up. Why should the user have to make sure the panels get disconnected.

 

Also, I'm not saying the Victron is necessarily a better product, I think some people have pointed out some deficiencies, I was just trying to use my experience from that particular manufacturer to show my point of view. I don't have any personal experience of any other controllers.

I don't know why I bother trying to be helpful to folk on here when I seem to be so much at odds with some members.

I give the best advice simply and then get shot down in flames by someone who I don't know just because I don't want to have to program daft modern controllers with my phone.

So sort it for yourselves, melt your mppt controllers at will, I could not care less.

[jpcdriver]

1 minute ago, Tracy D&#x27;arth said:

I don't know why I bother trying to be helpful to folk on here when I seem to be so much at odds with some members.

I give the best advice simply and then get shot down in flames by someone who I don't know just because I don't want to have to program daft modern controllers with my phone.

So sort it for yourselves, melt your mppt controllers at will, I could not care less.

Whoa whoa whoa. No one has said your advice was rubbish. No one (and certainly not me) has said you must use a daft modern controller. I'm sorry I even mentioned the make of my controller now because I certainly didn't want to divert the discussion down that avenue.

 

I asked a question because I didn't understand this talk of frying controllers if the panels are not disconnected when the batteries are. From the knowledge I have it does not make sense and to me suggests a faulty or very poorly designed controller. 

 

There is lots of experience on this forum so shouldn't we be pulling together our knowledge to help others. If there are particular controllers that cause problems can we name them so we can advise people to avoid them. However, it is still vallid to tell people it is best practice to install an easy way to disconnect the panels from the controller.

[hector]

Hi everyone, well thanks for all this - the basic Q answered, but plenty more to think about

I've had my eye on an all-in 200W kit from Renogy which afaik is 12v only, and I'll consult with them about if/where/when I need to be able to break the circuit. I agree that where that problem exists it seems like wilfully bad design, but I've bought plenty wilfully badly designed technology in the past.

 

But the fact I can add panels onto the system without completely reconfiguring it is good news, I can proceed with caution. Cheers!

 

H.

 

 

 

[Tony Brooks]

44 minutes ago, jonathanA said:

I think its verging on the paranoid to assume Google apple microsoft and more likely Amazon and listening to everything we are saying.

 

So please explain how Alexa/Siri etc. work. If you are in some way disabled so you can't reliably touch tiny buttons then if you want to use a smartphone you are reliant on voice commands. How do you think your voice commands are parsed and processed? I simply do not believe your average mobile phone has the processing power or storage to do that all on its own. I am fairly sure that your voice command gets sent back to the operating system company's servers to do all the hard processing. That allows them to grab more data to build your profile, that they hold for marketing purposes. The phones and some TVs etc. are equipped with microphones so can you tell me how you can be sure they are not passing everything said within earshot back to their servers?