Expert advice sought!

[KMarkN]

My solar controller seems to have both battery outputs connected, but I think that they are both connected to the leisure battery. This is because the dealer says they only connect van battery if requested, and it costs extra, plus the wiring seems to only go to leisure battery. Also, both LEDs showed 'fully charged' even when the van battery was down to 12.2v. Finally, and this is my question, the measured voltage across both of the output terminals was identical (13.7v) at same time as leisure battery voltage was also 13.7 (and van 12.2) - does the output terminal voltage represent the output of the solar panel, or will it equate with the battery that is connected to it? What am I measuring exactly? Many thanks!

 

[funflair]

If your battery connected to the solar regulator is full as the light says then you are measuring the battery voltage while the regulator is in float mode solar voltage would be higher, why both battery outputs would be connected to the one battery is lost on me unless somebody thought the regulator is set up to waste that power if not used (don't think so), best plan might be to find a start battery connection and wire it yourself.

 

[autorouter]

why both battery outputs would be connected to the one battery is lost on me unless somebody thought the regulator is set up to waste that power if not used (don't think so),

Agreed, the description says if only one battery is connected it will charge until full. If 2 batteries are connected, it will charge the first until 70%, then charge both until full.

 

[Stealaway]

How big is the solar panel? Are those cables big enough?
You do need to run some cables to the van battery - not always easy.

 

[KMarkN]

Yes I can't see why there is any advantage to connecting the second output to the same battery as the first.

I've just been out in dark to measure when solar panel not working. Van is on EHU so mains charging the leisure battery. Across terminals showed 13.7v, and solar controller outputs were both 13.7v also. Then I disconnected the EHU, and turned on inside lights. Leisure batt was now 12.7v across terminals, and both solar controller outputs showed 12.66. Throughout all this the van battery, which is on a mains trickle charger, was showing 13.2v. So it does seem as if the solar controller has both outputs connected to leisure battery?

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[KMarkN]

How big is the solar panel? Are those cables big enough?
You do need to run some cables to the van battery - not always easy.

It's 100W. I have wired up a Victron charger to the van battery, with a plug under the passenger seat, so I can keep it charged when it's on drive at home. Thats fine. But yes a wire from solar would be useful. Routing is problematic in our pvc. I guess I could have a detachable wire that I could plug in when needed, so i don't have to work out how to route it behind panelling in bathroom etc?

 

[DBK]

Finally, and this is my question, the measured voltage across both of the output terminals was identical (13.7v) at same time as leisure battery voltage was also 13.7 (and van 12.2)...

The voltages across both terminals will be the same as from the description they are connected to the same battery - the leisure battery.

... does the output terminal voltage represent the output of the solar panel, or will it equate with the battery that is connected to it? What am I measuring exactly? Many thanks!

From what I can determine though the same company make MPPT controllers yours is a PWM which means the panels will be at the same voltage as the batteries. This is not very efficient but is cheaper, £40 versus about twice or a bit more for an MPPT controller. It will work but you could get a significant improvement in charging current with a better controller.

 

[KMarkN]

The voltages across both terminals will be the same as from the description they are connected to the same battery - the leisure battery.

That’s the logic I’m using to infer that both controller outputs have been wired to the same (leisure) battery. But not sure why the fitter would do this as there isn’t an advantage as far as I can see. Why not just use output 1 and leave output 2 free?

 

[DBK]

It's 100W. I have wired up a Victron charger to the van battery, with a plug under the passenger seat, so I can keep it charged when it's on drive at home. Thats fine. But yes a wire from solar would be useful. Routing is problematic in our pvc. I guess I could have a detachable wire that I could plug in when needed, so i don't have to work out how to route it behind panelling in bathroom etc?

You need to have a rummage around with a multimeter where the van electrics are. I suspect you may find a wire which is permanently connected to the 12v vehicle battery which could be used to charge the vehicle battery. You shouldn't have to run a wire to the battery itself.

 

[DBK]

That’s the logic I’m using to infer that both controller outputs have been wired to the same (leisure) battery. But not sure why the fitter would do this as there isn’t an advantage as far as I can see. Why not just use output 1 and leave output 2 free?

Leaving output 2 free would be the normal way. You could ask the dealer and at the same ask them why they didn't fit an MPPT controller which in the right circumstances can put in around 50% more energy.

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[KMarkN]

You need to have a rummage around with a multimeter where the van electrics are. I suspect you may find a wire which is permanently connected to the 12v vehicle battery which could be used to charge the vehicle battery. You shouldn't have to run a wire to the battery itself.

That would be an elegant solution. I’d be worried about putting current through the wrong circuit though!

 

[autorouter]

You need to have a rummage around with a multimeter where the van electrics are. I suspect you may find a wire which is permanently connected to the 12v vehicle battery which could be used to charge the vehicle battery. You shouldn't have to run a wire to the battery itself.

Terminal 7 (the top left one of the three rows below the fuses) is the fridge 12V power wire, coming from the starter battery. This wire powers the fridge while the engine is running. When the engine is stopped, the EHU charger uses this wire to charge the starter battery.

To connect a new wire, make a short wire with a male/female connector at each end, and crimp an extra wire into one of the connectors. Then pull out the wire from terminal 7, connect the short wire to it, then plug the short wire into terminal 7. That way you could if necessary put it all back exactly as it was.

 

[KMarkN]

Terminal 7 (the top left one of the three rows below the fuses) is the fridge 12V power wire, coming from the starter battery. This wire powers the fridge while the engine is running. When the engine is stopped, the EHU charger uses this wire to charge the starter battery.

To connect a new wire, make a short wire with a male/female connector at each end, and crimp an extra wire into one of the connectors. Then pull out the wire from terminal 7, connect the short wire to it, then plug the short wire into terminal 7. That way you could if necessary put it all back exactly as it was.

Thanks for this. We must have a wire supplying the fridge, as you say, but the EHU on our van only charges the leisure battery and not the van one. Can this wire be used anyway? And, probably a question that betrays my lack of knowledge, but where should the neg wire go to? Thanks again

 

[autorouter]

Any old negative will do, they are all connected together anyway. But the specific wire that's the negative for the fridge is terminal 15 (middle row, third from left). You could use the same method with the short wire to break into it.

Best to double-check these wires with a multimeter. Should read the same voltage as the starter battery.