Smartgauge v MPPT regulator

[Trev]

Hi, Brain picking time please....... I have some solar panels regulated by an MPPT controller. I have a separate display module which indicates what the panels are producing etc. I also have Smartgauge/Smartbank fitted. The issue i have is that the MPPT regulator indicates that the batteries are fully charged when according to Smartgauge they are only at 75% or 80% state of charge. I am concerned that the regulator will be reducing the output from the panels as it thinks the batteries are fully charged. The regulator has a 'LOAD' connection which I have not used but could a direct connection from this to the battery bank overcome the 'fully charged' issue? Has anyone had a similar issue? Thanks

 

Trev.

[Justme]

I would bet that the MPPT control is non adjustable so they have erred on the side of caution with the V settings so that it can be used with all battery types.

 

If you can charge the V settings do so, if not trust the SG but you are loosing out on charge from the controller if its dropping to float at to low a V.

 

Which controller is it & is it adjustable?

[Trev]

Hi thanks for that.

Its an IVT MPPT Solar Panel Charge Controller Regulator 30 A MPPT. Bought from ebay.

They ship from germany.They are still selling them. Dont know if its adjustable or not I have emailed the company and am awaiting a reply.

Trev

[WotEver]

Hi thanks for that.

Its an IVT MPPT Solar Panel Charge Controller Regulator 30 A MPPT. Bought from ebay.

They ship from germany.They are still selling them. Dont know if its adjustable or not I have emailed the company and am awaiting a reply.

Trev

What voltage is it dropping down to when it goes into float? If it's around 13.3V then it'll still get your batteries up to full eventually; it'll just take an awful long time.

 

Tony

[Trev]

Hi Tony, I am not sure on that one I will check and see what it does.

Thanks

Trev

[Trev]

Looking at the spec of the unit the fully charged led comes on from 13.5 volts.

[Justme]

Looking at the spec of the unit the fully charged led comes on from 13.5 volts.

 

Thats the problem.

 

Ok a grid mains powered charger will eventually fully charge a battery thats not in use but a solar controller wont fully charge a battery that gets used every day, ever at that voltage.

[Trev]

So if the regulator I have cannot be adjusted it's another regulator thats reqd? What about using the 'LOAD' outlet to charge the batteries?

[blodger]

So if the regulator I have cannot be adjusted it's another regulator thats reqd? What about using the 'LOAD' outlet to charge the batteries?

 

When you are on the boat you could just short out the controller by a switch between the solar negative input to the controller and the controller negative output to the battery

 

The load connection is the batteries connected but it is switched off by the controller at low voltage to protect the batts; it's not at the solar voltage

Edited August 15, 2011 by blodger

[Trev]

Hi, thanks for that. I have two outputs from the controller to the batt. Excuse my ignorance but would it be to the pos or neg?

[blodger]

Hi, thanks for that. I have two outputs from the controller to the batt. Excuse my ignorance but would it be to the pos or neg?

 

Solar controllers for some reason Gibbo knows seem to have their positives commoned and do their work through the negatives. That's why I say to improve charging when on the boat to switch out the controller. A simple switch inserted across the negative of the solar input and the negative output to the battery achieves this on my two controllers. When the switch is off controller on, switch on means the controller is bypassed.

[mickspangle]

I'd be very interested to know what IVT say as I've got exactly the same controller and a smart gauge and am seeing the same thing. Switching the controller out isn't really an option though as the panels are unisolar 24v and the battery system is 12v.

Edited August 15, 2011 by mickspangle

[ditchcrawler]

I'd be very interested to know what IVT say as I've got exactly the same controller and a smart gauge and am seeing the same thing. Switching the controller out isn't really an option though as the panels are unisolar 24v and the battery system is 12v.

Interesting that, and as I don't know much about solar panels I am interested to read what replies you get.

I think most 12 volt panels have a much higher open circuit voltage than 12 volts, probably 20 or so. Do you mean yours are designed to charge a 24 volt battery bank so could well have an O/C of 35-40 volts.

[jelunga]

This is an interesting problem. My Heart inverter/charger does the same going to float even when Smartgauge says only 85% +\- solare panel controller, non mppt does the same. The only time I get a 100% charge reading from smartgauge is when Adverc regulated engine alternators are charging. I have though about a switch to disconnect solar panel for when charging from the mains since I am unsure what effect the solar panel output will have on the so called smart charger in the Heart.

Would love to get a solution to this. Is the Smartgauge tellibg tge trutv? I believe it is since when being charged by the engine it does get to 100%.

[blodger]

Most solar controllers just shut off and stop charging once they reach the magic number preset 13.5/13.7, holding that and, assuming the batts are now full. However the SOC is probably somewhere between 85/9X% charged. It will take a long time for the batts to be really full being charged at 13.6ish volts. When engine charging the alt does not shut down the charging volts at 13.6 but 14.2/14.7ish so is more effective at the last bit of charging albeit at low amps, as I see it. Simply, the LEDs on the solar controller are misleading but there are some that hold at 14.4vfo up to 55 mins and will even equalise at a slightly higher voltage for a similar period; so they are getting better

[mickspangle]

Interesting that, and as I don't know much about solar panels I am interested to read what replies you get.

I think most 12 volt panels have a much higher open circuit voltage than 12 volts, probably 20 or so. Do you mean yours are designed to charge a 24 volt battery bank so could well have an O/C of 35-40 volts.

 

Yes. I normally get 28-32v out of them.

[Trev]

I have just had an email reply from the manufacturers of my IVT MPPT 30 amp solar regulator and basically rock and a hard place spring to mind! They have confirmed that the regulator goes into float mode around 13.7 volts which on occasion could mean a Smartgauge reading as low as 78% charged!! They add that the controller will at this point keep 'pulsing' a charge into the batteries believing them to be fully charged. Not a lot of use and i dont believe my solar panels will ever get the batteries to 100% before the sun goes down!! ( I wasnt expecting the panels to do this anyway but I was hoping for around 90%)

 

One thing the panels are good for is on a reasonably sunny day we can run all our electrical bits, tv laptops etc and the panels will compensate by upping the charge going into the batteries so the bank does not discharge it would remain at the same SOC. But as for actually charging the batteries it is not a good plan!

 

 

I cant by-pass the controler as mentioned in an earlier post as the panels are 24v and I run on 12 volts. There does not appear to be a way to adjust the float charge limit on the controller so my experience of using solar power has left me somewhat wanting. Does anyone know of an MPPT controller that has a higher float charge rate or at least one that can be adjusted?

[WotEver]

Does anyone know of an MPPT controller that has a higher float charge rate or at least one that can be adjusted?

Blue Sky: http://www.shop.solar-wind.co.uk/acatalog/blue_sky_mppt_solar_charge_controllers.html

 

25A though, not 30A (dunno if that matters to you).

 

Tony

 

13–16VDC (14.0VDC initial factory setting)

 

Just noticed they do a 40A one too, but you're getting pricey now.

[blodger]

I have just had an email reply from the manufacturers of my IVT MPPT 30 amp solar regulator and basically rock and a hard place spring to mind! They have confirmed that the regulator goes into float mode around 13.7 volts which on occasion could mean a Smartgauge reading as low as 78% charged!! They add that the controller will at this point keep 'pulsing' a charge into the batteries believing them to be fully charged. Not a lot of use and i dont believe my solar panels will ever get the batteries to 100% before the sun goes down!! ( I wasnt expecting the panels to do this anyway but I was hoping for around 90%)

 

One thing the panels are good for is on a reasonably sunny day we can run all our electrical bits, tv laptops etc and the panels will compensate by upping the charge going into the batteries so the bank does not discharge it would remain at the same SOC. But as for actually charging the batteries it is not a good plan!

 

 

I cant by-pass the controler as mentioned in an earlier post as the panels are 24v and I run on 12 volts. There does not appear to be a way to adjust the float charge limit on the controller so my experience of using solar power has left me somewhat wanting. Does anyone know of an MPPT controller that has a higher float charge rate or at least one that can be adjusted?

Perhaps you could bypass if you did so through a 24 to 12v converter depending on the amps to be handled. Lorry types go quite cheap from time to time on Ebay. Just a thought

[Justme]

There are lots available but they are not cheap.

[blodger]

There are lots available but they are not cheap.

 

24V to 12V DC to DC Car Power Supply Converter 30A

 

On Ebay now at 5.99 + 3.99P&P

[Justme]

24V to 12V DC to DC Car Power Supply Converter 30A

 

On Ebay now at 5.99 + 3.99P&P

 

 

You miss understood. I dint quote you nor was I replying to you.

 

I was talking about the quality MPPT controllers that can be adjusted, not dc dc converters.

[blodger]

You miss understood. I dint quote you nor was I replying to you.

 

I was talking about the quality MPPT controllers that can be adjusted, not dc dc converters.

 

I was not sure; agree regarding adjustable controllers

[Trev]

Hi, thanks for the info and sorry for the late reply but just moored up! I will have a look at the 24v to 12v converter and see if that would work for me. It is certainly the cheapest option. I have also had a look at the link re another MPPT controler with a higher float. Getting expensive but I could always offset the cost by selling my existing MPPT kit on fleabay.

Thanks again.

 

Trev.

[blodger]

Hi, thanks for the info and sorry for the late reply but just moored up! I will have a look at the 24v to 12v converter and see if that would work for me. It is certainly the cheapest option. I have also had a look at the link re another MPPT controler with a higher float. Getting expensive but I could always offset the cost by selling my existing MPPT kit on fleabay.

Thanks again.

 

Trev.

Not applicable to you but related. I am awaiting a 17/30v to give 13.6v amps converter second hand from Ebay (about a tenner all in) to see how that fairs on a single 30/40 watt 12v nominal panel instead of a controller. I am not impressed with the efficacy of solar controllers