Reassurance please

[Mike Ferguson]

I’m seeking some reassurance please.
I have 2×120ah AGM Batteries.
I have the Elektrobloc EBL208S installed in my 2019 Adria Twin.
It has a designated solar charge regulator connection.
My plan is to install 2 x Renogy 100w compact panels (21.6volts, 5.72amps) and a Schaudt LRM1218 regulator.
Am I correct in thinking that this particular Elektrobloc will only charge the Leisure batteries if I connect the regulator through the designated socket and not the starter battery?
Am I correct in thinking the two panels are best connected in parallel rather than in series?
In parallel input would be roughly 10volts and 12amps?
In series it would be 42volts and 3 amps?
Is Sikaflex 252 the best solution to stick the plastic panel mounts to the top of my Ducato panel van?
Many thanks,
Mike

 

[pappajohn]

In parallel input would be roughly 10volts and 12amps?
In series it would be 42volts and 3 amps

In parallel it would be 21.6v and 11.44amps.
In Parallel the voltage remains unchanged and the amperage doubles

 

[autorouter]

Am I correct in thinking that this particular Elektrobloc will only charge the Leisure batteries if I connect the regulator through the designated socket and not the starter battery?

Yes, correct. The centre pin (Pin 2) of the 3-way connector is not connected to anything internally in the EBL208S. Other EBLs have pin2 connected to the starter battery, or use it as the solar panel input to the controller.

If you want the starter battery to be trickle-charged by the solar, maybe fit a BatteryMaster.

The EBL mains charger charges the starter battery, but it goes through a relay that is only switched on by the mains charger output. When the mains is off, it's isolated.

In series it would be 42volts and 3 amps?

In series, add the voltages, take the lesser of the two currents (OK, in this case they are both the same). So, 43.2V, 5.72A.

 

[Mike Ferguson]

So, If the LRM1218 regulator is suitable for open circuit voltage of 20-32v I would need to connect the 2 panels in parallel as the 43.2v in series would be too much for the LRM1218 to handle? Is that right?

 

[autorouter]

So, If the LRM1218 regulator is suitable for open circuit voltage of 20-32v I would need to connect the 2 panels in parallel as the 43.2v in series would be too much for the LRM1218 to handle? Is that right?

Yes, usually the voltage limit is a hard limit, not to be exceeded. The amps spec is not so rigorous, the controller will automatically limit its output to the max value if the input power is a bit too high.

The 21.6V value is at 25deg C. The voltage rises as the temperature falls, but it will stay well below the 32V limit even on a cold bright day.

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[Mike Ferguson]

Thank you autorouter. I now know that my proposed set up will, as I expected, charge only my leisure batteries (I'm happy with that) and that I will need to connect the two panels in parallel. Thanks for your help. I have spent hours researching this project - its far more complex than I originally thought. All to power a fridge!

 

[berni109]

Pick up the vehicle battery charging output wire on the ebl and splice the veh batt output from the solar controller into that via a fuse.
It's what I did but obviously at your own risk

 

[Emmit]

No one has mentioned the fitting of the panels.

Sikaflex 252 is more than suitable for affixing the plastic??? fittings to the roof. Puraflex 400 is a suitable (and cheaper) alternative.

Anecdotal evidence would suggest that the plastic fittings are the Achilles heel to the proposal.

 

[Mike Ferguson]

Hi Emmit - would you suggest aluminium brackets instead? Is it still ok to use adhesive rather than drilling holes in the roof? It is a metal roof on a panel van conversion.

 

[berni109]

Just bare in mind that you are actually bonding to the paintwork not the metal body. A solvent cleaner of some type to make sure the paintwork is really clean and all traces of wax removed.
It's why I went for semi flexible panels directly to the roof - much bigger bonding area. But there must be ten of thousands of rigid panels out there that dont fly off and they are only glued on.

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[Emmit]

Mike Ferguson

Sorry for the delay in responding.
I fitted two extra solar panels on the roof of our van Hobby 650 which has a curved roof (so not as easy as most) last March/April.
First I made the 'feet' for the panels and fitted them to the panels themselves.
Without attaching the cables, I placed the panels on the CLEAN!!! roof and drew around the feet with a pencil. After removing the panels, I roughed up the surface where the feet were due to be placed to give a key and cleaned up the area with thinners and then masked up each placement. The thinners removed the pencil but I remarked them immediately. Following that, I applied the Puraflex to a depth of 3-4mm. Using 2mm tile spacers on each side of each foot placement meant that I could lower each solar panel WITH CABLE ATTACHED!!! direct onto its respective place.
A gentle squeezing down to the tile spacers ensured a even coating between the feet and the roof. Because I had masked up around each foot's place, any squeezed out Puraflex could be scraped away without gunging (technical term) up the roof. My hands weren't as lucky.
The panels are still stuck to the roof like the proverbial to a blanket.
I hope the above is of use.

 

[Mike Ferguson]

Thanks Emmit. I've finished the job now. Used 8 x Aluminium brackets for each panel. Fixed the brackets to the panels using stainless bolts. I marked the bracket positions on the roof and cleaned thoroughly. Lightly sanded the roof (obviously not enough to go through the paint) to provide a key, then stuck them down with sikaflex 252. I did this a couple of weeks ago when the temperature was above 15 degrees. Covered them with a tarpaulin for a few days to let the adhesive cure. They appear to be stuck down very well, I've tried to pull them off and cant. Drove about 20 miles down the motorway yesterday at around 70mph and nothing flew off. Fingers crossed. I'm a non-emmit by the way, born and bred in St Austell!