Solar Connection and SOC question

[Saffa]

I have recently installed 300w of solar. This is connected via a MPPT controller to my battery bank. The positive is via a fuse directly to the positive terminal on my battery bank and the negative is connected to the bus bar so it goes via the VIC 602 battery monitor Shunt. Is this correct?

 

Next question provided the above is correct, Before the solar I used the VIC 602 to monitor my batteries and would charge them when the voltage got down to 12,2-12,3 volts. I would monitor the charge current when running the engine and this would start at 70-80A and I would let it run down to below 5A ( 460AH battery bank) for 15 mins. The maximum charge voltage during this time would be 14.10v This would also reset my VIC SOC & AH used as the charge current went below 4% for the set time (default values I have not changed these). Now with the solar my VIC SOC and AH used reset every morning when the solar starts working so how do I know what the state of my batteries is? This evening half hour after the solar stopped charging my voltage was 12.91v. I take this as fully charged as it was a sunny day.

 

Is there a way to stop the auto reset of the SOC and AH Used on the VIC. Is that the best way forward?

 

Bottom line I do not know the state of Charge of my batteries now the solar has been installed.

 

Hope this all made sense . Thank you

[nicknorman]

Sounds like you have connected it correctly. The monitor sets itself to 100% SoC when there is a combination of voltage above a preset value, charge current below a preset value, and those two conditions are held for longer than a preset time. What is probably happening is that the preset voltage is set too low so that as the solar starts working the voltage rises a bit and exceeds the preset value before there is enough voltage to give a decent charge current. Whereas when you were charging via the engine, the voltage went straight up such that there was lots of charge current immediately.

 

Can you report the preset values that you have set in the monitor - I think Victron refers to them as Vc for the voltage, It for the current and Tcd for the time. We can then suggest better values.

 

Edited to say that I think the default value for Vc is 13.2v which seems very low. I would suggest setting it to 13.9 or 14v if your normal charge voltage is 14.1v (which is also a bit on the low side, but let's worry about 1 thing at a time!)

Edited June 8, 2015 by nicknorman

[Phil Ambrose]

Right or wrong I'm not sure but my solar charges to 14.4v at which point it cuts of and only cuts in again when voltage drops below that value. I have a Merlin power gauge which I can monitor volts, amps in and out, amp /hrs used and % remaining. The voltage output from my solar controller can be altered.

Phil

[Saffa]

Sounds like you have connected it correctly. The monitor sets itself to 100% SoC when there is a combination of voltage above a preset value, charge current below a preset value, and those two conditions are held for longer than a preset time. What is probably happening is that the preset voltage is set too low so that as the solar starts working the voltage rises a bit and exceeds the preset value before there is enough voltage to give a decent charge current. Whereas when you were charging via the engine, the voltage went straight up such that there was lots of charge current immediately.

 

Can you report the preset values that you have set in the monitor - I think Victron refers to them as Vc for the voltage, It for the current and Tcd for the time. We can then suggest better values.

 

Edited to say that I think the default value for Vc is 13.2v which seems very low. I would suggest setting it to 13.9 or 14v if your normal charge voltage is 14.1v (which is also a bit on the low side, but let's worry about 1 thing at a time!)

 

Vc is set to 13,2v

It is set to 4%

Tcd is set to 3mins

 

My understanding of that is when it gets to 13,2v below 4% charge current for 3 mins the SOC will reset.

 

My MPPt Controller (EPSOLAR Tracer-BN Series) is set to sealed batteries as I have no level inspection caps to check water levels. Its parameters are as follows

 

Equalize charge voltage - 14.6v

Boost Charge Voltage - 14,4v

Float charge voltage - 13,8v

 

The 14.10 v from my alternator, is this adjustable?

[nicknorman]

Vc is set to 13,2v

It is set to 4%

Tcd is set to 3mins

 

My understanding of that is when it gets to 13,2v below 4% charge current for 3 mins the SOC will reset.

 

My MPPt Controller (EPSOLAR Tracer-BN Series) is set to sealed batteries as I have no level inspection caps to check water levels. Its parameters are as follows

 

Equalize charge voltage - 14.6v

Boost Charge Voltage - 14,4v

Float charge voltage - 13,8v

 

The 14.10 v from my alternator, is this adjustable?

Ok so would definitely increase the Vc to say 13.9v. There is no "right answer" for It but personally I think 4% is too high (= around 16A in your case) and thus the monitor will go to 100% prematurely even when on engine charging, therefore I would set it to say 2%, or maybe even less (I use 1.5%).

 

The solar setting seem reasonable. Normally it is not possible to modify the alternator voltage but it would be worth checking for any high resistance connections, and verifying the voltage with a voltmeter. Measure the voltage at the back of the alternator whilst charging, as well as at the batteries. Depending on the model / age of alternator the 14.1 may be normal, or possibly indicative of some internal fault but either way I think it's unlikely you will be able to fix it without replacing the alternator or at least the regulator inside it.

[Saffa]

Ok so would definitely increase the Vc to say 13.9v. There is no "right answer" for It but personally I think 4% is too high (= around 16A in your case) and thus the monitor will go to 100% prematurely even when on engine charging, therefore I would set it to say 2%, or maybe even less (I use 1.5%).

 

The solar setting seem reasonable. Normally it is not possible to modify the alternator voltage but it would be worth checking for any high resistance connections, and verifying the voltage with a voltmeter. Measure the voltage at the back of the alternator whilst charging, as well as at the batteries. Depending on the model / age of alternator the 14.1 may be normal, or possibly indicative of some internal fault but either way I think it's unlikely you will be able to fix it without replacing the alternator or at least the regulator inside it.

 

Thank you very much for the assistance. I will get those settings into the VIC.

 

With regards to the alternator. I will check the voltage on the back of the unit with my tester and check the connections. I have looked for a make and model but the info is not there, it seems to have rubbed off the sticker. All I know is its a Leece Neville and size wise it as a very large unit.

 

is this something I should be concerned about and look at as a priority or will it be ok? Can this cause damage to the battery bank.

 

Out of interest, what size alternator would be appropriate for this size bank and would having a 2.5Kw inverter affect the size choice.

[nicknorman]

With regards to the alternator. I will check the voltage on the back of the unit with my tester and check the connections. I have looked for a make and model but the info is not there, it seems to have rubbed off the sticker. All I know is its a Leece Neville and size wise it as a very large unit.

 

is this something I should be concerned about and look at as a priority or will it be ok? Can this cause damage to the battery bank.

 

Out of interest, what size alternator would be appropriate for this size bank and would having a 2.5Kw inverter affect the size choice.

As usual with these things "it depends ..."! If you only ever charged to 14.1v then I think battery sulphation would be likely to set in. However you have solar as well so in summer, provided your usage is not too heavy and the solar is able to fully charge the batteries it will probably be OK. But perhaps not so in winter.

 

Leece Neville make fairly robust alternators but on the other hand, perhaps slightly old fashioned. I think it might be best in the medium term (and presuming that you find the voltage on the back of the alternator never goes above 14.1v even when the batteries are approaching fully charged) to take it to an alternator specialist to be checked and possibly have a new 14.4v regulator fitted.

 

As to alternator size I would say around 90-100A is best for a 460AH bank but once you get to 90A or so a single wedge shaped belt is starting to struggle with transferring that power, although it depends on pulley sizes and how much belt wrap you get.

 

As far as the inverter is concerned it depends more on how much power you want to take out of it, rather than how much power it is capable of producing. If you just want it for the odd charger, TV etc then an alternator as above is fine. If you want to run it at 2kw or so for prolonged periods (eg washing machine / tumble drier) then ideally you want an alternator that can cope with the 180A or more that it will require and run the engine whilst your doing it, rather than flattening the batteries.

 

We have a 2.5kw inverter and a 175A alternator but the latter has to be run via a poly-vee belt which of course requires the appropriate engine pulley.

 

Finally with alternators there is no point in having an optimal one if it is not spun fast enough to produce full power, so the pulley ratios are another factor.

[Saffa]

As usual with these things "it depends ..."! If you only ever charged to 14.1v then I think battery sulphation would be likely to set in. However you have solar as well so in summer, provided your usage is not too heavy and the solar is able to fully charge the batteries it will probably be OK. But perhaps not so in winter.

 

Leece Neville make fairly robust alternators but on the other hand, perhaps slightly old fashioned. I think it might be best in the medium term (and presuming that you find the voltage on the back of the alternator never goes above 14.1v even when the batteries are approaching fully charged) to take it to an alternator specialist to be checked and possibly have a new 14.4v regulator fitted.

 

As to alternator size I would say around 90-100A is best for a 460AH bank but once you get to 90A or so a single wedge shaped belt is starting to struggle with transferring that power, although it depends on pulley sizes and how much belt wrap you get.

 

As far as the inverter is concerned it depends more on how much power you want to take out of it, rather than how much power it is capable of producing. If you just want it for the odd charger, TV etc then an alternator as above is fine. If you want to run it at 2kw or so for prolonged periods (eg washing machine / tumble drier) then ideally you want an alternator that can cope with the 180A or more that it will require and run the engine whilst your doing it, rather than flattening the batteries.

 

We have a 2.5kw inverter and a 175A alternator but the latter has to be run via a poly-vee belt which of course requires the appropriate engine pulley.

 

Finally with alternators there is no point in having an optimal one if it is not spun fast enough to produce full power, so the pulley ratios are another factor.

 

I have recently installed a new battery bank (3 Weeks )as we have just purchased the boat and we were not sure on the history. We were having to charge the batteries daily as every morning we would wake up with the voltage down at 10-11v. This was probably cause by the low charge rate of the alternator.

 

Our power need are low at the moment, Fridge, Pumps Lights and the occasional charge of the laptop so the solar should keep the batteries topped up. We are planning to get a washing machine so something to keep in mind.

 

The alternator does have a wide belt on, about 3/4" so I'm guessing it is a larger type. We are having some work done on the boat in a marina in the next couple of months so i will look at getting the alternator off and serviced during this time. They will then hopefully be able to size this for me and I can decide new or Refurbish.

 

Thank you for your input.

 

One last thing. Is it advisable to increase the Vc in the VIC to say 16v. This will then never reset the state of charge. I will do this manually as we do move at least once a week and will get the charge current right down to about 2-3A using the engine. This way I can be sure of the current state.

[nicknorman]

I have recently installed a new battery bank (3 Weeks )as we have just purchased the boat and we were not sure on the history. We were having to charge the batteries daily as every morning we would wake up with the voltage down at 10-11v. This was probably cause by the low charge rate of the alternator.

 

Our power need are low at the moment, Fridge, Pumps Lights and the occasional charge of the laptop so the solar should keep the batteries topped up. We are planning to get a washing machine so something to keep in mind.

 

The alternator does have a wide belt on, about 3/4" so I'm guessing it is a larger type. We are having some work done on the boat in a marina in the next couple of months so i will look at getting the alternator off and serviced during this time. They will then hopefully be able to size this for me and I can decide new or Refurbish.

 

Thank you for your input.

 

One last thing. Is it advisable to increase the Vc in the VIC to say 16v. This will then never reset the state of charge. I will do this manually as we do move at least once a week and will get the charge current right down to about 2-3A using the engine. This way I can be sure of the current state.

Re: the alternator I would still check the charging voltage at the batteries vs at the alternator itself. It is possible that there are split charge diodes or the like, in between that are dropping voltage. In which case that would need to be addressed. It's an easy check.

 

Re the monitor, yes you could do that if you wish but it is reminiscent of having a dog and barking yourself! The settings are easy to change so you can experiment but if you only want it to reset when the batteries are really fully charged, why not just decrease the It to 1% or less, rather than creating a false setting that can never be reached such as Vc at 16v?

[Detling]

Your solar will wake up early at this time of year (dawn) and could easily reach 13.6 volts at 2-3 amps by 6am whilst you sleep, this will reset your monitor, the low current is due to sun being low in the sky, not the batteries limiting the current of an alternator/charger.

 

"Our power need are low at the moment, Fridge, Pumps Lights and the occasional charge of the laptop so the solar should keep the batteries topped up"

 

You will be lucky to get over 15 amps in the midday period from the solar. and I think you will struggle with only 300 watts of solar even in June, without some engine running most days. I have 300 watts of solar a fridge all LED lights and 2 hours of TV a day so use about 120-140 amp hours in a day, and only on rare completely sunny days do I get all this back from the solar usually on a dull day we are nearly 100 amp hours down, on a good day only 20 amp hours down, at this time of year. In winter of course I don't even get 20 amp hours from the solar. As I need hot water anyway 30-60 minutes of engine meets that as well as charging, best done early in the day so the sun can just top up the batteries.

[jenevers]

This is all very interesting. I too have a 300w 12v solar setup with a 30 amp MPPT. I have a automotive "blade" type fuse on the positive feed into the 720 Ah batteries but the fuse holder is a pretty cheap thing which is prone to melt when the fuse gets hot on a sunny day. Does anyone know where I can get a more robust holder? Is there a more suitable type of fuse?

Edited June 15, 2015 by jenevers

[Scooby]

You need a midi fuse holder. Go on ebay and search it.

[jenevers]

You need a midi fuse holder. Go on ebay and search it.

Yes. That looks a much more robust setup. Thanks

[Tom and Bex]

 

You will be lucky to get over 15 amps in the midday period from the solar. and I think you will struggle with only 300 watts of solar even in June, without some engine running most days. I have 300 watts of solar a fridge all LED lights and 2 hours of TV a day so use about 120-140 amp hours in a day, and only on rare completely sunny days do I get all this back from the solar usually on a dull day we are nearly 100 amp hours down, on a good day only 20 amp hours down, at this time of year. In winter of course I don't even get 20 amp hours from the solar. As I need hot water anyway 30-60 minutes of engine meets that as well as charging, best done early in the day so the sun can just top up the batteries.

That doesn't seem much solar input for 300w, what controller do you have?

 

We have 500w of solar with an mppt controller and the panels flat on the roof. With this setup we have often seen nearly 35A going into the batteries and today which has been fairly cloudy have managed to do 4 loads of washing and batteries had fully recharged from 64% to 100% by early afternoon. Not needed to run generator or engine since early March now (in fact the alternator is not working anyway at the moment!)

 

Tom

 

PS forgot to add we have fairly standard usage of LED lights, fridge, tv, pumps, laptop, etc in addition to washing machine

Edited June 15, 2015 by Tom and Bex

[Saffa]

That doesn't seem much solar input for 300w, what controller do you have?

 

We have 500w of solar with an mppt controller and the panels flat on the roof. With this setup we have often seen nearly 35A going into the batteries and today which has been fairly cloudy have managed to do 4 loads of washing and batteries had fully recharged from 64% to 100% by early afternoon. Not needed to run generator or engine since early March now (in fact the alternator is not working anyway at the moment!)

 

Tom

 

PS forgot to add we have fairly standard usage of LED lights, fridge, tv, pumps, laptop, etc in addition to washing machine

 

 

I get about 15 - 18 A with full sunshine.. I use the Tracer2215BN MPPT controller.

 

Out of interest what washing machine do you have?

[Tom and Bex]

 

 

I get about 15 - 18 A with full sunshine.. I use the Tracer2215BN MPPT controller.

 

Out of interest what washing machine do you have?

With low batteries I'd expect a bit more than that in full sun but it depends on the state of charge of the batteries. We have the 30A Tracer 3215BN controller and use the smart gauge for measuring soc of batteries.

 

We have an old Candy DQW150 washing machine that we run on our MSW inverter set to a cold wash and just add hot water via the soap drawer at the start of the cycle. Works fine if we have a 100w light bulb on at the same time!

 

Tom

[jenevers]

That doesn't seem much solar input for 300w, what controller do you have?

We have 500w of solar with an mppt controller and the panels flat on the roof. With this setup we have often seen nearly 35A going into the batteries and today which has been fairly cloudy have managed to do 4 loads of washing and batteries had fully recharged from 64% to 100% by early afternoon.

I assume you are on a 24 volt system as the 30A Tracer max for 12 volt is 390 w.

Sounds great that you can get so much washing done and still be up to 100% later on.

[jenevers]

Leece Neville make fairly robust alternators but on the other hand, perhaps slightly old fashioned.

Old fashioned in what way?

Edited July 3, 2015 by jenevers

[Tom and Bex]

I assume you are on a 24 volt system as the 30A Tracer max for 12 volt is 390 w.

Sounds great that you can get so much washing done and still be up to 100% later on.

We've got the 40A Tracer with 500w of solar on a 12V system.

 

I think the trick with the washing is to run the machine on a cold wash and just put a couple of kettles of hot water in at the start. Don't know what we'll do when this machine breaks down though - I've heard the newer machines are unlikely to run on our MSW inverter!

 

Tom

[jenevers]

With low batteries I'd expect a bit more than that in full sun but it depends on the state of charge of the batteries. We have the 30A Tracer 3215BN controller

Tom

Ah I was going off what you said here.

Edited July 3, 2015 by jenevers

[Tom and Bex]

Sorry that's what happens when you reply without thinking! Should have realised you can't get 35A from a 30A controller!

 

Tom

[jenevers]

Sorry that's what happens when you reply without thinking! Should have realised you can't get 35A from a 30A controller!

Tom

Well maybe you could..........but not for long!⚡️⚡️

Didn't want you to wreck it if it was a 30A.

[by'eck]

Sounds like you have connected it correctly. The monitor sets itself to 100% SoC when there is a combination of voltage above a preset value, charge current below a preset value, and those two conditions are held for longer than a preset time. What is probably happening is that the preset voltage is set too low so that as the solar starts working the voltage rises a bit and exceeds the preset value before there is enough voltage to give a decent charge current. Whereas when you were charging via the engine, the voltage went straight up such that there was lots of charge current immediately.

 

Can you report the preset values that you have set in the monitor - I think Victron refers to them as Vc for the voltage, It for the current and Tcd for the time. We can then suggest better values.

 

Edited to say that I think the default value for Vc is 13.2v which seems very low. I would suggest setting it to 13.9 or 14v if your normal charge voltage is 14.1v (which is also a bit on the low side, but let's worry about 1 thing at a time!)

 

Problem with setting VC on a BMV too high is that 100% SOC may take forever to reach. This since a multi-stage charge source be it from mains charger, external regulated alternator or mppt controller, will probably have dropped to much lower float voltage before 100% SOC is indicated. Its therefore never going to see the higher voltage and low current required to flip it to 100%.

 

For this reason Victron point out in manual that VC must be a value less than normal float voltage. Adjust the trigger current (It) from default 4% yes (mine set to 2%), trigger voltage (VC) no, unless you have unusually high float voltage.

[nicknorman]

Problem with setting VC on a BMV too high is that 100% SOC may take forever to reach. This since a multi-stage charge source be it from mains charger, external regulated alternator or mppt controller, will probably have dropped to much lower float voltage before 100% SOC is indicated. Its therefore never going to see the higher voltage and low current required to flip it to 100%.

 

For this reason Victron point out in manual that VC must be a value less than normal float voltage. Adjust the trigger current (It) from default 4% yes (mine set to 2%), trigger voltage (VC) no, unless you have unusually high float voltage.

This is true but if you read the OP you will see that the problem is ridiculously early resetting to 100% caused by weak solar, thus making the BMV totally useless. If the VC is raised, this will cure this problem. You are right though, that it might delay or prevent reaching 100%. However I maintain that it is better to have an SoC reading of 99% when the actual SoC should be 100%, rather than having a SoC reading reset to 100% when in fact it is only 60% or whatever. Of course it will also depend on the primary means used to charge, if from the engine (without a fancy alternator controller) this problem won't arise, if primarily from a mains charger then your principle is correct, but if from solar then I think my idea is the best compromise.

 

Or of course, get a smartgauge which doesn't suffer from this type of problem!