Solar charge controller - load terminals - what practical use in a MH ?

[Deleted member 62288]

Hello Team,

I'm aware that there are countless threads that mention solar panels and charge controllers here and elsewhere, but my question is specifically aimed at the terminals on my MPPT Solar charge controller (or any other PV controller) that provides a pair of LOAD terminals.

I am currently half way through removing the PV-Elecktroblock charge controller (LR1218) along with a Victron battery monitor (BMV-700).
Replacing these with a Victron MPPT Blue Solar charge controller and a NASA BM1 battery monitor.

Reasons in a nutshell, the victron battery monitor is too complex & too small - I need the reading specs on and the handbook handy to get any info from it. The LR1218 is an 18A device, the replacement Victron unit can manage 40A, If you have sufficient panels to feed it this much. The NASA BM1 battery monitor is old scrote friendly with big numbers that I can read without specs.

My overall objective is to get my battery bank up to around 400 Ah to lengthen the periods that I spend off-grid.
The mppt and monitor are contributes to this.

After being previously educated by members here on this topic, today I am part-way through this upgrade and I am pondering what use can I find for the load terminals and wondering, how they could provide me with a useful function, over what I already have.

Secondly, are the load terminals "dead" at night, when the panels are inactive (dark) or does the pv controller "back-feed" to the load terminals from the leisure battery at all times, providing the battery has capacity ?

My 3 way fridge is already catered for, so are all of my existing needs, lights, 12v appliances etc..

The only practical use I can think of is to use them to feed into a 12v to 12v charger and hook them into my engine battery so that the sunshine tops up the starter battery.

How can these be used in the motorhome ?

What do you use them for ? - Any novel ideas ?

Thanks for reading and more so with constructive feedback.

james

 

[wildebus]

What Victron Charge Controller are you looking at?
You mentioned it is one that can handle upto 40A, but it is only the very smallest Victron Controllers have a "Load" Output.
Just thought worth clarifying as it might make the general question a bit redundant? (unless it is an older unit before they dropped that feature?)

Generally speaking, they tend to be active only when there is power to the panels and a popular use (on the few occasions they get used) is to drive auxilary cooling fans for a fridge for example (as they will go off at night automatically when it would get cooler anyway)

 

[Deleted member 62288]

What Victron Charge Controller are you looking at?
You mentioned it is one that can handle upto 40A, but it is only the very smallest Victron Controllers have a "Load" Output.
Just thought worth clarifying as it might make the general question a bit redundant? (unless it is an older unit before they dropped that feature?)

Generally speaking, they tend to be active only when there is power to the panels and a popular use (on the few occasions they get used) is to drive auxilary cooling fans for a fridge for example (as they will go off at night automatically when it would get cooler anyway)

The victron unit and the BM1 are pictured below, this is progress-to-date, the hardware is in place and it is part wired, should be completed tomorrow.
The unit doesn't have a model number that I can see.

If the victron unit fails to meet expectations, I've lost nothing if I need to buy a current model.

james

The mppt controller is new-old stock, it's been in a locker for a few years.

 

[wildebus]

I am sure it will still do the biz no point in changing it for the newer model if it works :dance:

Still don't think the "Load" output is a great deal of use

 

[Deleted member 62288]

I am sure it will still do the biz no point in changing it for the newer model if it works :dance:

Still don't think the "Load" output is a great deal of use

Neither do I, hence the questions posed.

I'm tending towards trickle charging the starter battery via a 12v to 12v charger as I suspect that, by removing the LR1218 Elektroblock unit, I also removed the solar charging of said engine battery.

The next stage is to decide on battery upgrades - which is discussed in an earlier thread of mine on here.

Thanks for the input.

james

 

[Nabsim]

If your LR1218 was connected to an EBL then it was already charging your starter battery, or at least it does on some but I dont know about all. You can get a lead for the Victron units to connect to an EBL, the advantage being the EBL is already handling charging leisure and starter batteries. Downside it I dont think older EBL's will handle 40Amps.

 

[Deleted member 62288]

If your LR1218 was connected to an EBL then it was already charging your starter battery, or at least it does on some but I dont know about all. You can get a lead for the Victron units to connect to an EBL, the advantage being the EBL is already handling charging leisure and starter batteries. Downside it I dont think older EBL's will handle 40Amps.

Thanks Neil, the ebl.as you say is limited to 20a, I am upgrading to a 40a mppt controller to overcome this limitation.
Elecktroblock charge controller (LR1218) that I have just removed has the cable assembly with it, so I have removed the solar-starter battery charging.

looks like I now know what to do with the load terminals.



james

 

[Nabsim]

Better than mine, I think its a 15 amp fuse for the solar connection on my EBL. Can't decide if I should do similar to you or not when I get round to having solar but I have time yet

What are you going to do with the load terminals then, trickle charge starter battery or fridge fan?

 

[molly 2]

I had a stecca controller the load output could be turned on and off ,and programmed to switch on and off at night .

 

[QFour]

I have one in the shed in the garden with a solar panel connected. Charges the 12v car battery up during the day and then at 5pm it switches the output on which is fed to a motion detector. If you walk towards the shed after 5pm and before 8am then the shed lights come on. These controllers are programmable and are basically all the same. You can have any 12v item connected. You can also program them to come on only when the solar panel is producing power.

 

[QFour]

Better than mine, I think its a 15 amp fuse for the solar connection on my EBL. Can't decide if I should do similar to you or not when I get round to having solar but I have time yet

What are you going to do with the load terminals then, trickle charge starter battery or fridge fan?

That does not work as the load terminal can provide 10A which is hardly a trickle charge. What you need is the TWIN output version that connects to both batteries. Programable so that the main leisure battery gets most of charge and if anything left over it goes to the starter battery.

 

[Deleted member 62288]

That does not work as the load terminal can provide 10A which is hardly a trickle charge. What you need is the TWIN output version that connects to both batteries. Programable so that the main leisure battery gets most of charge and if anything left over it goes to the starter battery.

CAN provide up to 10A - that is enough to warrant adding a trickle charger to the engine battery.

The engine battery will only pull what it needs, given that it should be fully charged from driving, once I get parked up and off-grid the solar will make sure it stays full.
There are some functions that operate off the engine battery, such as the alarm, radio, drivers cab lights etc, so it sees a small drain when stationary.

james

 

[Deleted member 62288]

Better than mine, I think its a 15 amp fuse for the solar connection on my EBL. Can't decide if I should do similar to you or not when I get round to having solar but I have time yet

What are you going to do with the load terminals then, trickle charge starter battery or fridge fan?

I think I'll use the load function to feed a battery charger to keep the engine battery full.

james

 

[Nabsim]

I used to have a small solar panel that I left on my bike for a while to just keep a small charge going in the battery (was a BMW K1100lts with electric clock) Bike stood outside so could get very cold in winter and prolonged downtime but panel was enough to keep battery up. Worked until a particularly windy night when it got blown away

Bike battery was a lot smaller but a fair AH for a bike and panel was only 1.5amp I think so I would be happy that 10amp would keep it topped up. Does depend what you have drawing down from it when off though I know

 

[Deleted member 62288]

Question: MPPT Load terminals & EBL 100B socket 7

Does anyone have experience with using the EBL 100 (Elektroblock) Block 7 input terminals ?

Looking at the circuit diagram, there is currently vacant Block 7 input port that is designated as an Zusatzladegerat with a 20A fuse socket. As I understand it, this is a provision for adding an addition charger into the system.

So unless I am missing something from my calculus, I can simply route a pair of cables from the MPPT load terminals and connect these to the EBL block 7 inputs and et voila, I have the solar excess power available for the EBL and hence the facility to charge the engine battery via the EBL.

This negates my provisional plan to install a battery to battery charger, while simplifying the installation and saving the (high) cost of a B2B charger.

Any views on this ?

Ta, james

 

[wildebus]

Does anyone have experience with using the EBL 100 (Elektroblock) Block 7 input terminals ?

Looking at the circuit diagram, there is currently vacant Block 7 input port that is designated as an Zusatzladegerat with a 20A fuse socket. As I understand it, this is a provision for adding an addition charger into the system.

So unless I am missing something from my calculus, I can simply route a pair of cables from the MPPT load terminals and connect these to the EBL block 7 inputs and et voila, I have the solar excess power available for the EBL and hence the facility to charge the engine battery via the EBL.

This negates my provisional plan to install a battery to battery charger, while simplifying the installation and saving the (high) cost of a B2B charger.

Any views on this ?

Ta, james

I don't know much about the EBL but my view on your plan is that it makes good sense in principle

As a temporary measure, I have actually been charging my starter battery via a Mains Charger connected to an Inverter that is powered by the leisure battery!
The inverter could be a really low power one (most mains chargers use very little wattage) and potentially powered off the Load output - this would give you a managed charge profile as well for the starter.

 

[Deleted member 62288]

I don't know much about the EBL but my view on your plan is that it makes good sense in principle

As a temporary measure, I have actually been charging my starter battery via a Mains Charger connected to an Inverter that is powered by the leisure battery!

That'll work but is inefficient, with power being wasted in the inverter. But, as you allude, it's a temporary measure.

james

 

[Nabsim]

On my EBL100-2 block 7 is the input connector for adding an additional battery charger (I added a second Schaudt unit to this as battery bank was way bigger than charger could cope with)

 

[wildebus]

That'll work but is inefficient, with power being wasted in the inverter. But, as you allude, it's a temporary measure.

james

People have this idea of Inverters being very wasteful. I don't sign up to that (and my opinion is based on monitoring the power and not just the hype)

My victron inverter off-load uses about 2W. My inverter is on 24/7 anyway feeding the 230V fridge and Network router and Booster which means very very little additional wasted power when driving the mains charger

(I was back to 100% SOC by 9:30 this morning (my low overnight is typically 95% with a constant 40W draw from the various devices, jumping to 75W 2 or 3 times an hour as the fridge clicks on) and both my inverters were on overnight - the Victron on feeding the always -on stuff, ands the 2500W one feeding nothing right now (forget to turn it off yesterday after it was driving the Alexa Echo))

 

[Deleted member 12539]

I have recently upgraded my regulator to a 20A MPPT item and included a standalone monitor, with a view to add a solar panel to my current 100A panel.
There is a programmable Load ouput on the MPPT, which I do not use, but as I understand, this can be used when the panel is not "active" as the Load supply comes from the battery(s).
I am yet to test this theory though.