MPPT setup

[blackrose]

I finally got my new solar system up and running a few days ago. Very pleased with the results so far, however I do have a couple of questions:

 

I set the controller up for flooded batteries and changed the capacity to 450Ah for my battery bank but that's all I've changed.

 

It seems to sit at 14.9v for a long time and the default settings for "boost charge" (absorption) is 120 mins. My separate battery monitor is reading 14.8v so I'm not overly concerned about the voltage just the length of time it stays there as it seems longer than my battery charger would normally stay on 14.8v. Will 2 hours at 14.8v do any damage to the batteries? I'm still fitting my new PSW inverter so I'm not using a lot of the power that the panels are generating at the moment as I'm still on mains in the evenings.

 

The other thing I don't understand is why no load figures are displayed when I switch something on. To be honest I don't really understand how it could display load without it's own shunt, or is the idea that you buy a separate shunt for the controller? I don't really need this feature by the way as I have amps in/out on my battery monitor. I'm getting about 0.6A less on my battery monitor than the figure shown on the MPPT display.

 

It's an Epever Tracer 6415AN MPPT with a MT50 remote display and the user manuals aren't very user-friendly which is why I'm asking these questions.

 

Edited November 9, 2022 by blackrose

[David Mack]

The Load readings refers to the output of the Load terminal on the MPPT. You probably haven't got anything connected to this, hence the zero output reading. It's nothing to do with the load drawn from your batteries, which the MPPT knows nothing about.

Edited November 9, 2022 by David Mack

[Alan de Enfield]

It will only show the load if you have something connected to the MPPT 'load' output termials (the two are the far right of the unit)

[blackrose]

1 minute ago, David Mack said:

The Load readings refers to the output of the Load terminal on the MPPT. You probably haven't got anything connected to this, hence the zero output reading.

 

Ah, ok, I can see the load interface in the manual. So what would you normally connect to this?

[Alan de Enfield]

1 minute ago, blackrose said:

 

Ah, ok, I can see the load interface in the manual. So what would you normally connect to this?

 

I have had a VHF radio connected to this, but normally "nothing"

[David Mack]

Not sure you would connect anything to the Load terminal on a boat, but in some applications it can be used to run something else directly from solar power (when there is enough sun) without drawing from the battery.

[blackrose]

Ok thanks, so it's direct load from the MPPT. Could that be used for a 12v immersion heater for example without drawing from the batteries?

Edited November 9, 2022 by blackrose

[Tony Brooks]

1 minute ago, David Mack said:

Not sure you would connect anything to the Load terminal on a boat, but in some applications it can be used to run something else directly from solar power (when there is enough sun) without drawing from the battery.

 

Maybe a 12V immersion heater once the batteries are charged. I have also seen the suggestion that it can be used to charge the engine battery, but I am not sure about that re any regulation etc.

[Jen-in-Wellies]

38 minutes ago, blackrose said:

finally got my new solar system up and running a few days ago. Very pleased with the results so far, however I do have a couple of questions:

• There seem to be a lot of comets left over beyond the outer planets. Should I clean these up, or will they be fine there, despite being a bit untidy?
• The third planet out is now covered in a horrible green rash on the land surfaces and the atmosphere is full of Oxygen, which I never intended. Is this normal? Should I whack a big asteroid in to it and start again?

Sorry, couldn't resist! 😀

[rusty69]

2 hours will be fine at 14.8V if you have Trojan batteries of the t105 variety, and you could even increase it to 3hrs. It may be a bit high if you haven't though if you charge them on a regular basis. The duration is fully configurable under the custom/user settings menu though.

Edited November 9, 2022 by rusty69

[Alan de Enfield]

42 minutes ago, blackrose said:

Ok thanks, so it's direct load from the MPPT. Could that be used for a 12v immersion heater for example without drawing from the batteries?

 

I do not know if it is load-limited. 

A 1Kw immersion element will be taking about 90 amps - does your solar supply that ?

 

My manual is on the boat so cannot check - have a look at your manual

[Higgs]

 

I have one of these hooked up to the load output side of my main solar charge controller. It's really a buck boost converter. It's set up to charge the electric bike 36v battery, which charges at 42v. 2A.

 

 

 

MPPT Solar Charge Controller MPT-7210A LCD Display 24V 36V 48V 60V 72V 10A Adjustable for Lithium Battery,Power Supply : Amazon.co.uk: Business, Industry & Science

 

 

 

 

Edited November 9, 2022 by Higgs

[blackrose]

2 hours ago, rusty69 said:

2 hours will be fine at 14.8V if you have Trojan batteries of the t105 variety, and you could even increase it to 3hrs. It may be a bit high if you haven't though if you charge them on a regular basis. The duration is fully configurable under the custom/user settings menu though.

 

Thanks, I have Trojan T1275 x3. I'll leave it as it is for the time being. I'm not charging at all now other than from the panels.

 

2 hours ago, Alan de Enfield said:

 

I do not know if it is load-limited. 

A 1Kw immersion element will be taking about 90 amps - does your solar supply that ?

 

My manual is on the boat so cannot check - have a look at your manual

 

No, I only have a 60 amp MPPT and work 910w of panels I never expect to get that much out of it. I doubt I'll fit a 12v immersion it was just a thought.

 

Float charge on the Epever is set to 13.8v. seems a tad high to me. Would 13.6v be more appropriate?

 

I'm actually struggling to change any settings. I managed to change the battery type and capacity screens, but once you scroll down it doesn't seem to want to change any of the subsequent screens. 

Edited November 9, 2022 by blackrose

[rusty69]

4 minutes ago, blackrose said:

Thanks, I have Trojan T1275 x3

Then, according to the data sheet, and assuming they are not the AGM flavour, they require a bulk voltage of 14.8V (@25 degrees C), so should be fine for two hours, probably longer.

[blackrose]

Thanks Rusty. What does it say about the float voltage?

[rusty69]

1 minute ago, blackrose said:

Thanks Rusty. What does it say about the float voltage?

13.5V. Equalisation 16.2

T1275_Trojan_Data_Sheets (1).pdf

[blackrose]

Ok thanks, I'm going have to adjust the float voltage down a bit.

[rusty69]

33 minutes ago, blackrose said:

 

I'm actually struggling to change any settings. I managed to change the battery type and capacity screens, but once you scroll down it doesn't seem to want to change any of the subsequent screens. 

On mine(not epever), but has an mt 50, you go to 'control parameters' and set the battery type to 'User', you can then change various settings.

 

ETA You do this through the MT50 interface, not the MPPT.

Edited November 9, 2022 by rusty69

[GUMPY]

28 minutes ago, blackrose said:

I'm actually struggling to change any settings. I managed to change the battery type and capacity screens, but once you scroll down it doesn't seem to want to change any of the subsequent screens. 

I can pop over at the weekend sometime to run through it with you if you want.

[PeterF]

As far as I recall from my Epever controller on my last boat, the load terminals on the MPPT were connected to the battery outlet terminals when the load output was turned on, so if the load was higher than the MPPT was generating the load would pull power from the battery. These are often used for things like outdoor lights which you can program to come on at night. I have also heard of people having their 12V fridge connected to the load terminals and the load only being activated during the day. I would be cautious of having any load on the load terminals that was of a higher rating than the MPPT to make sure the internals of the MPPT could not be overloaded. Anything on the load terminals should ideally be fused to prevent pulling too much power though the MPPT in case of a short.

[Chewbacka]

Agree above &

These controllers are ‘designed’ for things like street lights, so can be programmed to turn on the load for a pre programmed time when it gets dark (ie no solar output) so taking power from batteries.  The time ‘on’ can be adjusted so power out over a few days is less than power in etc.  As far as I can remember there is no provision to only output unwanted solar power.  Also as it is intended for ‘street lighting’ the relay is not very big, so only suitable for low current devices.  
In conclusion, for a boat I doubt you want to use the load terminals, unless you fancy some pretty fairy lights after dusk for an hour or two!!!

[blackrose]

4 hours ago, rusty69 said:

On mine(not epever), but has an mt 50, you go to 'control parameters' and set the battery type to 'User', you can then change various settings.

 

ETA You do this through the MT50 interface, not the MPPT.

 

Ok thanks, I've done it now. I still had the battery type set to flooded and didn't realise you had to change it to user.

4 hours ago, Loddon said:

I can pop over at the weekend sometime to run through it with you if you want.

 

I've got it now, thanks Julian.

[Psychalist]

1 hour ago, Chewbacka said:

Agree above &

These controllers are ‘designed’ for things like street lights, so can be programmed to turn on the load for a pre programmed time when it gets dark (ie no solar output) so taking power from batteries.  The time ‘on’ can be adjusted so power out over a few days is less than power in etc.  As far as I can remember there is no provision to only output unwanted solar power.  Also as it is intended for ‘street lighting’ the relay is not very big, so only suitable for low current devices.  
In conclusion, for a boat I doubt you want to use the load terminals, unless you fancy some pretty fairy lights after dusk for an hour or two!!!

This seems to be the way of it, though manual control is possible on some models - just switch the load on and off as required (configurable and default mode). The only way to prevent loading batteries is to add intelligence utilising the MODBUS interface - a project I haven't got to yet on mine. There are a number of implementations available using small controllers and single board computers like Raspberry Pi to produce graphs and statistics of solar generation. These could be adapted to calculate the difference between load current and battery current to control a load using an appropriate dimmer/controller.

[GUMPY]

33 minutes ago, blackrose said:

 

Ok thanks, I've done it now. I still had the battery type set to flooded and didn't realise you had to change it to user.

 

I've got it now, thanks Julian.

OK.

 

[blackrose]

This is how I've got it set up:

 

 

Boost is absorption. If there's anything I've got wrong please llet me know.

Edited November 9, 2022 by blackrose