Jump to content

Uses for Solar controller LOAD terminal output


reg

Featured Posts

In a couple of current threads the subject of solar controller load terminal usage has come up, whilst initially it seemed they were of little use on a narrowboat it transpires that they may be of use, interested in if and how others may use the load terminals. 

I currently, for historical reasons, have 3 Tracer BN series controllers and use the load terminal on 2 of them as follows

1.single led light used to light up the dark area where the controllers are. I use the manual red button to switch this on and off and have set the controller parameters to manual. 

2. 12v USB socket used for small charging jobs, again controlled manually. 

The item that really piqued my interest though  was this one from Bimble 

http://www.bimblesolar.com/extras/dumpload/12v-200a-relay

"Dump Load - Make use of your excess power

You can also use this relay to work as a dump load, you can set the load terminals on one of our charge controllers to come on at 14V and off at 13.6V and then wire the load terminals to the spade terminals on the relay.  Then connect your high load (upto 200A) to the large terminals and the charge controller will then turn the dump load on when the batteries are full so you can put the excess power into say a water heater or something useful.  This could be a water heater, or you could divert the charge controller power to a back up battery bank. "

Note: The pros and cons of water heating this way are being discussed elsewhere 

In essence I'm primarily interested in if and how the the load terminals are being used. 

Link to comment
Share on other sites

Heating water is the obvious.

Here some other ideas off top of ma head.

Cooling fans for the boat.

Cooling a cooling plate for food.

Charging additional items like iPads, laptop's etc.

Turning on a drinking water fountain for your pet poodle.

Edited by Robbo
Link to comment
Share on other sites

1 hour ago, Robbo said:

Turning on a drinking water fountain for your pet poodle

Danger of drowning said pet poodle on a very sunny day though:)

I've had a thought about using the relay though

Currently I have a spare reserve battery (left over from a battery swap out) in a Numax box. At the moment I charge it, when I remember, through a 240v charger via an inverter all pretty inefficient and often forget (can't be bothered? ) to do it. The dump relay may prove useful in that I can, according to the Bimble blurb, utilise spare solar capacity to charge this battery whenever spare solar capacity is available. Certainly looks like something I might look at doing in the future. 

 

Edited by reg
Link to comment
Share on other sites

7 minutes ago, reg said:

Currently I have a spare reserve battery (left over from a battery swap out) in a Numax box. At the moment I charge it, when I remember, through a 240v charger via an inverter all pretty inefficient and often forget (can't be bothered? ) to do it. The dump relay may prove useful in that I can, according to the Bimble blurb, utilise spare solar capacity to charge this battery whenever spare solar capacity is available. Certainly looks like something I might look at doing in the future. 

Just thought I could do something similar.   I have a second boat (more of a day boat) which has a small 240v battery charger as well.  Could run a "shore" line to it from my main boat to charge the batteries on it.

Link to comment
Share on other sites

1 hour ago, Robbo said:

Cooling fans for the boat

Possibly use to

run a bilge fan occasionally 

Or

Run a battery compartment fan, on the grounds that if the batteries have been recently charged then might be worth running a cooling/extractor fan over them

Link to comment
Share on other sites

Presumably this hypothetical load only works when the sun is shining and the controller is set to divert excess power to the load terminals.

In which case it doesn't work at night, nor in winter, (mostly).

Not a criticism, merely an observation :)

Link to comment
Share on other sites

2 hours ago, reg said:

In a couple of current threads the subject of solar controller load terminal usage has come up, whilst initially it seemed they were of little use on a narrowboat it transpires that they may be of use, interested in if and how others may use the load terminals. 

I currently, for historical reasons, have 3 Tracer BN series controllers and use the load terminal on 2 of them as follows

1.single led light used to light up the dark area where the controllers are. I use the manual red button to switch this on and off and have set the controller parameters to manual. 

2. 12v USB socket used for small charging jobs, again controlled manually. 

The item that really piqued my interest though  was this one from Bimble 

http://www.bimblesolar.com/extras/dumpload/12v-200a-relay

"Dump Load - Make use of your excess power

You can also use this relay to work as a dump load, you can set the load terminals on one of our charge controllers to come on at 14V and off at 13.6V and then wire the load terminals to the spade terminals on the relay.  Then connect your high load (upto 200A) to the large terminals and the charge controller will then turn the dump load on when the batteries are full so you can put the excess power into say a water heater or something useful.  This could be a water heater, or you could divert the charge controller power to a back up battery bank. "

Note: The pros and cons of water heating this way are being discussed elsewhere 

In essence I'm primarily interested in if and how the the load terminals are being used. 

I can't get this to work with the Tracer controller.

The options on the load controller are Manual, Timed or PV voltage - not battery voltage.

As it is an MPPT controller the panel voltage goes all over the place to produce maximum power for the conditions.  There does not seem to be any way to make the controller use a dump load when the batteries are in float charging mode.

I spent a while trying to make this work, but neither I nor Bimble could figure out how to do it with the Tracer series.  If the newest 3rd generation Tracers have a different setting you might be able to do it.

I was trying to use the free sunshine to heat water exactly as you are planning.  I agree with others that it is not very efficient, but every degree you could heat the water is one less you need to burn diesel or gas doing the same job.

  • Greenie 1
Link to comment
Share on other sites

1 minute ago, Richard10002 said:

Presumably this hypothetical load only works when the sun is shining and the controller is set to divert excess power to the load terminals.

In which case it doesn't work at night, nor in winter, (mostly).

Not a criticism, merely an observation :)

On better controllers, they have a programmable relay that can be set do other stuff other than come on when in float. 

Link to comment
Share on other sites

40 minutes ago, Richard10002 said:

Presumably this hypothetical load only works when the sun is shining and the controller is set to divert excess power to the load terminals.

In which case it doesn't work at night, nor in winter, (mostly).

Not a criticism, merely an observation :)

Depends how you set it up by default it is on all of the time so can be used as per any other battery connection.

Changing the controllers  parameters allows you to change this default behaviour. A typical use is to set the parameters to control light switching e.g activate load terminals at night and deactivate during the day, often used to control street lighting.

The use of the Bimble dump relay together with some controller pàrameter changes allows further modification of the default  behaviour, as I understand it then you can set the parameters to be both time and voltage sensitive. Haven't tried this but it does look promising although I'm not sure how much control I would have using my Tracer BN controllers I know I can set times but am not sure at the moment how to set voltage levels for the load terminals (will look into that on a rainy day)

ETA

Was typing at the same time as TheBiscuits so looks like third scenario above is not achievable on with the Tracer BN controllers, dont know for sure but it might be achievable with some  more expensive controllers though. Anyway greenie given for saving me some research.

Further ETA 

Looks like the third scenario may be achievable with the OUTBACK MX60 controller using the Diversion Mode 

pdf here

http://www.umiat.com/network/umiatbase/manuals/mx60_man_v3.pdf

 

Edited by reg
Link to comment
Share on other sites

26 minutes ago, reg said:

Was typing at the same time as TheBiscuits so looks like third scenario above is not achievable on with the Tracer BN controllers, dont know for sure but it might be achievable with some  more expensive controllers though. Anyway greenie given for saving me some research.

 

Actually, most of the cheaper ones do it too!  Many PWM controllers can carry a dump load, but are not as good at charging batteries as a decent MPPT controller.

I was quite miffed that the Tracer could not do this as supplied because it seems like a good idea if you don't have roof room for solar water heating.  If you really want to do this enough, you could probably cobble a separate circuit to do it, but be careful that you don't switch on the immersion heater when the charger is in absorption mode.

I still can't find a use for the PV voltage load switch other than to tell when it is daylight - and I have seen it switch when moored under a bright streetlamp!

Edited by TheBiscuits
Link to comment
Share on other sites

2 minutes ago, TheBiscuits said:

I was quite miffed that the Tracer could not do this as supplied

But then again I think the Tracer BN series of controllers are excellent at their price point so can't really complain if odd feature missing.

Link to comment
Share on other sites

32 minutes ago, reg said:

Depends how you set it up by default it is on all of the time so can be used as per any other battery connection.

Changing the controllers  parameters allows you to change this default behaviour. A typical use is to set the parameters to control light switching e.g activate load terminals at night and deactivate during the day, often used to control street lighting.

 

I appreciate that it can be set to "On" 24/7, but surely it can only be powered when the panels are generating power, thus not at night or in winter, (mostly).

I thought street lights and similar had a battery which is charged during the day, and discharges at night, perhaps with a simple dusk/dawn switch.

4 minutes ago, reg said:

But then again I think the Tracer BN series of controllers are excellent at their price point so can't really complain if odd feature missing.

I have a 40A Tracer BN, and have noticed some discussion elsewhere that suggests the Tracers dont track quickly enough. e.g. if a cloud goes by, so the power goes off, it takes some time after the cloud has gone for the MPPT tracking to resume. I dont really understand it when explained this way.

I understood that, below about 15W or so, it reverted to a PWM type of tracking, and it needed to be above 15W or so, to resume MPPT... which doesnt seem to be a big deal in the scheme of things.

Link to comment
Share on other sites

17 minutes ago, Richard10002 said:

I appreciate that it can be set to "On" 24/7, but surely it can only be powered when the panels are generating power, thus not at night or in winter, (mostly).

I thought street lights and similar had a battery which is charged during the day, and discharges at night, perhaps with a simple dusk/dawn switch.

Following applies to Tracer BN controllers

First point when no solar power available then load is taken from the batteries

Second point effectively that is what it can be a simple dusk to dawn switch with automatic battery connection. If you accept the first point above then this becomes clear the lights are powered from the stored solar power i.e the battery and so can work as long as the battery has power.

Eta

Had to do some checking on this first 

In normal operation any loads directly connected to the controller are served first any excess power is then given over to battery charging.

When no solar power is available then loads are served from the battery

 

Edited by reg
Link to comment
Share on other sites

16 minutes ago, reg said:

But then again I think the Tracer BN series of controllers are excellent at their price point so can't really complain if odd feature missing.

I agree - that's why I kept the Tracer and gave up on the dump load for water heating :D

It would have been a nice feature to have though.

Link to comment
Share on other sites

12 minutes ago, reg said:

Following applies to Tracer BN controllers

First point when no solar power available then load is taken from the batteries

Second point effectively that is what it can be a simple dusk to dawn switch with automatic battery connection. If you accept the first point above then this becomes clear the lights are powered from the stored solar power i.e the battery and so can work as long as the battery has power.

OK! So if I connect something to the load connector on the Tracer BN, it effectively uses power from the batteries, but can be timed/controlled via the PC programme, or the Display gizmo.

Link to comment
Share on other sites

1 minute ago, Richard10002 said:

OK! So if I connect something to the load connector on the Tracer BN, it effectively uses power from the batteries, but can be timed/controlled via the PC programme, or the Display gizmo.

I think that's Known as a light bulb moment which seems very apt in this case.:D

  • Haha 1
Link to comment
Share on other sites

I can see a potential problem if using this to turn an inverter onto heat the water. The significant load of the inverter (70 amps or more) will almost certainly drop the battery voltage down enough to cause the device to turn off the load, the volts rapidly rise, load switched on, volts drop and so the cycle will carry on. 

Link to comment
Share on other sites

2 minutes ago, Detling said:

I can see a potential problem if using this to turn an inverter onto heat the water. The significant load of the inverter (70 amps or more) will almost certainly drop the battery voltage down enough to cause the device to turn off the load, the volts rapidly rise, load switched on, volts drop and so the cycle will carry on. 

You can get 12V 250W immersion heaters which would be ideal for a dump load.  They would take all day to heat the water, but silently and hopefully without drawing from the batteries.  

It is indeed the cycling that made me give up the idea of doing this, and why I would have liked a setting on the controller to divert "spare" power to the load terminals only when the batteries are in float.

I'm too much of a cheapskate to buy the Outback controllers that can do this, and didn't want a PWM controller that could also have managed it - I want as much sunshine in my batteries as I can possibly get!

 

Link to comment
Share on other sites

1 hour ago, Detling said:

I can see a potential problem if using this to turn an inverter onto heat the water. The significant load of the inverter (70 amps or more) will almost certainly drop the battery voltage down enough to cause the device to turn off the load, the volts rapidly rise, load switched on, volts drop and so the cycle will carry on. 

In below linked thread, which formed part of the genesis of this thread, the use of the inverter to power the Immersion heater has pretty much been discounted. But certainly worth reiterating it here as you have done.

 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.