Upgraded Solar Control System with Victron MPPT Controllers

[2SGBRB]

Baileys Adamo

I had a Truma Dual Solar control fitted and one 100watt Solar panel . See photo

I have removed the dual controller and added two Victron MPPT control and another 120 solar panel .

One feeding Leisure Battery

One feeding Starter Battery

The truma has four wires . Two each + - feeding to both batteries.

There is a relay that four wires go into

The + red cable goes into pin 30
The - blue goes into pin 87a

My question is as I have wired the other cables into a separate MMPT do I need to check anything else ….

Go easy lol

 

[autorouter]

Do you know what the relay does? I guess the blue wire is from the solar controller output, and the red wire is from the leisure battery. The Blue/yellow wire switches it on and off. Where does the blue/yellow wire come from?

Be careful of the order that you connect to the Victron MPPTs. Before you connect the solar panels, connect the battery. The MPPT senses the battery voltage type (12V or 24V), and remembers it. If you don't, there's a chance the solar panel voltage will send the battery output voltage high, to maybe 19V or so, and the MPPT registers the battery as 24V. It may send out excessive voltage to a 12V battery. It can be corrected in the App, but it's easier to get it right to start with. Battery first, then panels.

I'm not sure one panel for each battery is the best way to do this. The starter battery needs hardly any charge to keep it topped up. Usually you arrive on site or back at home with the starter battery fully charged from a drive. It just needs a trickle-charge to stop it going flat over a couple of weeks. If you dedicate one panel to that, a lot of the power will be wasted.

You could fit a relay, just like the one in your picture, to switch the second panel between the starter and leisure batteries. Then you could switch it to the starter battery for one day every week or so.

The connections would be solar controller positive to 30, starter battery to 87, leisure battery to 87A. Then to switch it, connect the negative to 85, and the switched positive to 86.

 

[Lenny HB]

You would be better connecting the outputs of both Victron units to the Leisure battery and then fitting a battery maintainer like the Ablemail or Batterymaster to keep the starter battery topped up.

 

[2SGBRB]

You would be better connecting the outputs of both Victron units to the Leisure battery and then fitting a battery maintainer like the Ablemail or Batterymaster to keep the starter battery topped up.

Thanks Lenny really appreciate taken the time to reply…. are you saying just put the two PV cables from both solar panel into one MPPT … the one that feeds the leisure battery

 

[2SGBRB]

Do you know what the relay does? I guess the blue wire is from the solar controller output, and the red wire is from the leisure battery. The Blue/yellow wire switches it on and off. Where does the blue/yellow wire come from?

Be careful of the order that you connect to the Victron MPPTs. Before you connect the solar panels, connect the battery. The MPPT senses the battery voltage type (12V or 24V), and remembers it. If you don't, there's a chance the solar panel voltage will send the battery output voltage high, to maybe 19V or so, and the MPPT registers the battery as 24V. It may send out excessive voltage to a 12V battery. It can be corrected in the App, but it's easier to get it right to start with. Battery first, then panels.

I'm not sure one panel for each battery is the best way to do this. The starter battery needs hardly any charge to keep it topped up. Usually you arrive on site or back at home with the starter battery fully charged from a drive. It just needs a trickle-charge to stop it going flat over a couple of weeks. If you dedicate one panel to that, a lot of the power will be wasted.

You could fit a relay, just like the one in your picture, to switch the second panel between the starter and leisure batteries. Then you could switch it to the starter battery for one day every week or so.

The connections would be solar controller positive to 30, starter battery to 87, leisure battery to 87A. Then to switch it, connect the negative to 85, and the switched positive to 86.

Thanks autorouter for taken the time to reply.. I have taken your advice regarding the MPPT. I am not sure what the relay switch does. I like your thought process however not sure how I would manage to wire the relay … I confident as most wiring however relays are a new beast to me …. Would I take a feed from the current relay and loop the wires I require to the new relay

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[DBK]

Thanks Lenny really appreciate taken the time to reply…. are you saying just put the two PV cables from both solar panel into one MPPT … the one that feeds the leisure battery

No, connect each panel to one MPPT controller then connect the outputs to the batteries. This method is used, although not widely, but it has the benefit of minimising the effect of one panel being shaded because the unshaded panel will still work at full efficency.

 

[peterc10]

I agree with Lenny HB . The engine battery does not need much charging to keep it in good condition, so most of the time there will be no charge going to it. That means you are wasting most of the potential power output of its 100W panel.

 

[Lenny HB]

No, connect each panel to one MPPT controller then connect the outputs to the batteries. This method is used, although not widely, but it has the benefit of minimising the effect of one panel being shaded because the unshaded panel will still work at full efficency.

Also doing that way if the panel voltages are slightly different you won't get any loses.
If the panels are different voltages the output will be dragged down to the lowest one when in parallel, not a lot of difference but it all helps.

 

[autorouter]

If you're not sure about relays, the best solution is what Lenny HB says, fit a battery maintainer. It will trickle charge the starter battery from the leisure battery automatically. Also it works whatever is charging the leisure battery, so it works on mains hookup too, not just solar. The VanBitz BatteryMaster is a good option, a favourite on here, and is available from the Motorhome Fun Shop. Totally automatic, fit and forget, it just works.
[Broken Link Removed]

It needs three connections, starter battery positive, leisure battery positive and a common negative. Because the amps is very low, it doesn't much matter where you connect it. The instructions mention connecting to the split charge relay, but that's only because all three connections are conveniently available there. It looks like those connections are available near the solar controllers too, so that is also a good place to connect the BatteryMaster.

The existing wire to the starter battery can be connected straight to the BatteryMaster, no need to connect anywhere else. The leisure battery and common negative can be connected to the solar controller leisure battery connections. It doesn't matter which solar controller, if they are both connected to the leisure battery.

 

[2SGBRB]

I haven’t changed anything yet all the settings are fine and all are set at 12v however it’ sunny day here in south wales and the solar charger that is linked to the cab battery is over charging. It only shows over charging on the DcDc charger not the MPPT settings .. checked with meter again the reading is correct 16.5 ..,,,

If I plug the ECU in voltage drops back to normal .

If I turn off and back on the DCDC it drops back down..

The DCDC unit comes on even when the engine is not starting … I know this is due to voltage increase

Can I install something to stop the surge in voltage to the cab battery

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[2SGBRB]

This is the settings when plugged into ECU everything goes back to normal as the dual charger takes over