Replacing Sargent controller with Victron

[RobbieBobby]

I have a 2014 Autotrail Navajo with the original 100W solar panel and Sargent EC500. I have bought a Victron smart solar mppt controller to improve the solar charging. My current set-up is shown in the diagramme. The current set-up has just 2 connections from the regulator, one is the solar panel, the other goes to the Sargent board marked Solar Reg. The new Victron has 3 connections, Panel, battery and load. How do I make te change to the new Victron unit? I would like to retain the "smart" charging of the original if possible.

Thanks everybody.

 

[autorouter]

Wire it exactly the same as the original controller, except you completely ignore the load terminals.

The load terminals are useful when the solar controller is used in other applications, like street lights, street signs, CCTV cameras etc. In a motorhome application the load terminals are almost always not used.

 

[Diabalo]

As above just connect like for like I have a EC500 and changed mine for a Victron MPPT, just remove the EC500 on mine the solar control was cable tied to a upright strip of alluminium remove it and replace with the new Victron MPPT, make sure you take a note/photo of the originol connections.

 

[Mike123]

Does anyone have pics of the above re “before / after installation” ?

 

[Diabalo]

Mike123 No pics but it's dead simple, Undo the 4 screws that hold the EC500 inplace and pull it out, there is enough length on the loom. Locate the old solar controller and disconnect the 4 wires, 2 solar output that goes onto the board and the 2 input wires that come from the solar panel, then connect the new Victron MPPT in the same way. It really is that simple. Maybe you should get someone to do it for you as you don't seem too comfatable about doing it yourself.
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[RobbieBobby]

Mike123 No pics but it's dead simple, Undo the 4 screws that hold the EC500 inplace and pull it out, there is enough length on the loom. Locate the old solar controller and disconnect the 4 wires, 2 solar output that goes onto the board and the 2 input wires that come from the solar panel, then connect the new Victron MPPT in the same way. It really is that simple. Maybe you should get someone to do it for you as you don't seem too comfatable about doing it yourself.
.

I'm more than comfortable doing the job. I have pulled the Sargent unit out so I could look at the existing arrangement and I was thinking exactly what you have said i.e. the Victron "battery" connections go to the EC500 board rather than to the battery terminals. It's just that the Victron manual that I downloaded from their site is more about a completely fresh installation rather than using the Sargent unit. Will the Sargent unit still give me the "smart" charging function? I'm thinking that it will as the battery connections are to the EC500 i.e. the EC500 will manage where the solar charging current is routed.

 

[Diabalo]

I'm more than comfortable doing the job. I have pulled the Sargent unit out so I could look at the existing arrangement and I was thinking exactly what you have said i.e. the Victron "battery" connections go to the EC500 board rather than to the battery terminals. It's just that the Victron manual that I downloaded from their site is more about a completely fresh installation rather than using the Sargent unit. Will the Sargent unit still give me the "smart" charging function? I'm thinking that it will as the battery connections are to the EC500 i.e. the EC500 will manage where the solar charging current is routed.

Nothing changes at all, smart charging will work just the same as it did..

 

[Diabalo]

RobbieBobby I forgot to mention, It's important to connect the battery terminal wires to the charge controller FIRST.

 

[Mike123]

Mike123 No pics but it's dead simple, Undo the 4 screws that hold the EC500 inplace and pull it out, there is enough length on the loom. Locate the old solar controller and disconnect the 4 wires, 2 solar output that goes onto the board and the 2 input wires that come from the solar panel, then connect the new Victron MPPT in the same way. It really is that simple. Maybe you should get someone to do it for you as you don't seem too comfatable about doing it yourself.
.

Thanks for that - seems straight forward (which I was hoping for).

 

[RobbieBobby]

Nothing changes at all, smart charging will work just the same as it did..

That's great. Thank you. My confusion, if you can call it that, came from having the Sargent in the mix. As an extra question, if I added more solar, say another 100W panel, I'm thinking that this shouldn't go through the Sargent (it must have a maximum current) and should be wired independent.

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[RobbieBobby]

RobbieBobby I forgot to mention, It's important to connect the battery terminal wires to the charge controller FIRST.

Thank you. I saw that in the manual that I downloaded. It's not that clear in the sheet that comes with the unit. The downloaded manual is very comprehensive but it doesn't cover the case where you keep the existing Sargent EC500 as part of the controls.

 

[Mike123]

Couple of questions, if someone can help.

100w Solar with 2 battery’s (vehicle and Leisure), Solar divided by volts (100 / 24 ) - assume 10 amp MPPT should be adequate. Any reason you would go for say 15 amp ?

When replacing the internal Sargent solar charger with the external MPPT are there any issues with location (i.e. Sargent is located at bottom of wardrobe) so MPPT would be at bottom of wardrobe re unit getting hot, etc…

Thanks

M

 

[autorouter]

100w Solar with 2 battery’s (vehicle and Leisure), Solar divided by volts (100 / 24 ) - assume 10 amp MPPT should be adequate. Any reason you would go for say 15 amp ?

I think your voltage will be 12V, not 24V. Most motorhome electrics are 12V, except for some of the bigger RVs. So the amps would be 100/12 = 8A. Or actually since the voltage is more like 14V, the amps would be more like 7A. A 10A MPPT would be fine for a 100W panel. The 10A is not a 'hard' limit - of the panel produces more than 10A the MPPT just wastes it, no damage happens. Anyway, you're lucky to get more than 80% of a panel's rated output if it's flat on the roof (not tilted) and you're anywhere north of Gibraltar.

The only reason to fit a 15A is if you might add more panels in the future. If you have no intention of doing that, stick with the 10A.

 

[Mike123]

I think your voltage will be 12V, not 24V. Most motorhome electrics are 12V, except for some of the bigger RVs. So the amps would be 100/12 = 8A. Or actually since the voltage is more like 14V, the amps would be more like 7A. A 10A MPPT would be fine for a 100W panel. The 10A is not a 'hard' limit - of the panel produces more than 10A the MPPT just wastes it, no damage happens. Anyway, you're lucky to get more than 80% of a panel's rated output if it's flat on the roof (not tilted) and you're anywhere north of Gibraltar.

The only reason to fit a 15A is if you might add more panels in the future. If you have not intention of doing that, stick with the 10A.

Was using 24v as assumption, as we have two 12 volt batteries, but in theory 12v as only charging one battery at a time?

 

[autorouter]

Was using 24v as assumption, as we have two 12 volt batteries, but in theory 12v as only charging one battery at a time?

If you had two 100Ah leisure batteries, they would normally be connected positive to positive, and negative to negative. That arrangement is called a parallel connection. The combination would act just as if it was one big 200Ah battery, with a voltage of 12V. You can connect a number of batteries in parallel, the voltage stays the same at 12V, and the capacities (Ah) add together to behave as one big 12V battery.

It's the same with the starter and leisure batteries. When the engine is running, there is an electrically operated switch that connects the starter and leisure batteries in parallel so the alternator can charge them both. When the engine stops, it disconnects them.

The other type of connection (series connection) is when there is a positive to negative link between two batteries. Then the voltage between the negative of one and the positive of the other would be 24V. That is used in large RVs and HGVs, but not in most motorhomes and cars.

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[headlight]

Couple of questions, if someone can help.

100w Solar with 2 battery’s (vehicle and Leisure), Solar divided by volts (100 / 24 ) - assume 10 amp MPPT should be adequate. Any reason you would go for say 15 amp ?

When replacing the internal Sargent solar charger with the external MPPT are there any issues with location (i.e. Sargent is located at bottom of wardrobe) so MPPT would be at bottom of wardrobe re unit getting hot, etc…

Thanks

M

MPPT is sized by the max output of the solar not the battery/batteries it is charging.
A 10 amp MPPT will handle a 100 watt panel comfortably.
For 2 x 100 watt panels you would need a 15 amp MPPT and so on.

 

[Diabalo]

That's great. Thank you. My confusion, if you can call it that, came from having the Sargent in the mix. As an extra question, if I added more solar, say another 100W panel, I'm thinking that this shouldn't go through the Sargent (it must have a maximum current) and should be wired independent.

You are correct Sargent says that only 1 panel can go through the EC500 PSU but for the last 9 years I have had 2 panels with a total output of 200W without any problems. I fitted the extra panel without knowing the restrictions of the EC500 that Sargent's quote. It's not the wiring it's the copper tracks on the main PCB so I am told. As I said I added an extra panel and not had any issues. It's your choice if you want to risk it.

 

[autorouter]

There are other ways to do this. As well as the setup that Diabalo described, you could just wire the MPPT output directly to the leisure battery, and you could then use whatever panel setup you want. Or if you want to keep the smart charging you could have one 10A MPPT through the Sargent unit with one 100W panel, and another MPPT with other panels direct to the leisure battery.

If the only reason you want to keep the smart charging is to keep the starter battery topped up as well as the leisure battery, then a good option is to wire the MPPT output direct to the leisure battery, bypassing the Sargent unit, and fit a BatteryMaster battery maintainer between the leisure battery and the starter battery. The BatteryMaster will keep the starter battery topped up by taking a bit of charge from the leisure battery. But the leisure battery is being charged by the solar, so that will work fine.