Choices choices, what to do

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Googlebot

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Okay, first post so be gentle. Had a previous setup on a caravan so not a complete beginner.

I already have a 90 watt panel on my 2013 Hymer Exsis, it’s connected by a morningstar (I think) PWM controller to two 105AH batteries.

I need more as we off grid a lot, so....

I have a 275 watt panel, do I do the following choices.

1, Join them together giving me 365watts then put them through a Victron MPPT to the leisure batteries with a VSR relay to the chassis battery. This means more expense as I will need the VSR relay and a more powerful Victron controller.

2, Use the 90watt panel for the chassis battery, then use a smaller MPPT off the 275watt panel just for the leisure batteries?

Pros and cons of both and any advice is very welcome.
 
Out of interest, what are the dimensions of the 275 watt panel?
 
Thanks, not sure what a vsr relay is but a battery master costing around £15 will do the same job, ie top up the starter battery when the leisure batteries are charged.
On another note I thought that hymers had an electrobloc system that allowed up to a particular wattage solar setup and starter charging built in?
 
Jimbohorlicks said:
Thanks, not sure what a vsr relay is but a battery master costing around £15 will do the same job, ie top up the starter battery when the leisure batteries are charged.
On another note I thought that hymers had an electrobloc system that allowed up to a particular wattage solar setup and starter charging built in?
Click to expand...

Voltage sensitive relay, opens up to charge the chassis battery when a certain voltage is reached.

No idea ref the electroblock, caravans weren’t so complicated. ?

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Voltage sensitive 'intelligent' relay about £15 from ebay. Your vehicle battery shouldn't need charging from solar unless you are in one spot for a very long time. All your hab electrics will be from your hab batteries.
 
All good suggestions so far, like the idea of the Votronic controller. The chassis battery will be feeding the alarm and radio amongst other parasitic loads, my thoughts are I may as well use the excess when it is there to help keep it topped up.

Let’s face it, for 9 months of the year, I probably have too much solar.
 
How are you connecting the two solar panels? If in parallel, they should be the same nominal voltage. Usually about 21V or 36V. If in series, they need to be the same current capacity. I'd guess that neither of those is true.

You may be better with two separate controllers, both going to the leisure battery. Maybe get a dual output controller for the large panel, to feed a trickle charge to the starter battery.

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Good point!

I have no idea of the specs of the 90 watt panel as it is glued on the roof and riveted to the angle, I suppose I can try and have a look underneath with a mirror or phone camera.

I am leaning toward option 1, at least then I have two independent systems I can alter to suit.
 
Jimbohorlicks said:
On another note I thought that hymers had an electrobloc system that allowed up to a particular wattage solar setup and starter charging built in?
Click to expand...
Just an easy way of connecting the solar does not control any charging.
 
I would go with both panels in parallel. If you use a Votronic control it has a separate output to charge the starter battery although only 1 amp also an AES output to control the fridge.

If you go the VSR route make it is one designed for the job either a Battery master about £60 or a CBE Solar split charge relay about £25.

I have 300 watts of panels a Votronic 350 MMP regulator. I still use a CBE Relay as I had one around and can give up to 4 amps into the starter battery. I also have the fridge wired to the AES output so when the batteries are fully charged and there is enough solar the fridge switches to 12v.
Because of the dumb firmware in the Dometic fridge I added a mains powered relay in line with the AES output otherwise stupid fridge switches to 12v when on mains if the batteries are charged.
 
If you look at your electroblock you should be able to read the model number and can then let us know so we can check the features it has. If it's like the one in our Globecar you'll need to fit a lead from the Votronic controller direct to the cab battery positive terminal (put a 5 amp max fuse in-line) as the electroblock doesn't feed the solar input to the cab battery to trickle charge it even though it looks like it does, see my website below for photos etc of my Globecar set-up.

 
If you can't read the panel specification, another option is to put a multimeter on the terminals where the panel is wired to the controller. Also measure (or read) the voltage of the large panel. If they are much the same, you can wire them in parallel. I'd guess that the small one is about 24v and the large one is about 36V, so it's not possible, but maybe I'm wrong.
 
So, alas it is only 21volts on the existing 90 watt so the panels are incompatible. Therefore I believe I am stuck with the option of moving the existing setup to the chassis battery and using the new regulator and 275watt panel for the habitation batteries.
Don’t think I will be going through the electroblock as the direct connection will be easier.
Only snag I can think of is that the fridge will think the engine is on, unless it has a separate ignition fed relay rather than a voltage sensitive one which I am sure is the case.
 
Or as Autorouter suggests, leave the current setup but use a Votronic controller to feed the cab battery as well.
Actually, that may be the best route. A 90 watt panel to top up a cab battery seems a lot.
 
I would suggest the fridge 12v feed from the starter battery is via an alternator activated relay, not voltage sensitive, so don't worry about that.

If you don't go through the electrobloc, any amp usage monitor won't give you the correct reading.

Deffo find the model of electrobloc. More modern ones will charge the starter battery as well, and you can get a cable for the Votronic MPPT solar controllers to do just that and no need for a direct battery feed, though you may need to uprate the fuse. Amp usage reading will be accurate.

Not sure about the 90w panel. Of course, if you don't care about the ammeter, suggest two solar controllers directly connected to the batteries; a decent MPPT for the 275w and charge both hab and cab batteries, and the 90w just for the hab.
 
I don’t believe the electroblock model I have is equipped with an ammeter. It is the one with the rotating dial and lights for the gauge levels. When on hookup though it does trickle charge the chassis battery.

I think it’s an EBL 21, or might be 29. I can check when I get home.

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Shame. Our 1995 Hymer has an analogue ammeter. Nicely old school. ?

I mounted three 80w panels in parallel, through a Votronic MPPT controller, then via the special cable into the electrobloc. The 'bloc is too old to charge the cab battery from the cable, so the special output from the controller goes straight to the cab battery. The ammeter still correctly reports [dis]charge.
 
It’s an EBL 29 so no ammeter.
Not bothered really as long as it’s charged.
Going to go for a Votronic 350 with direct connections to batteries, fused of course.
Thanks for the help everyone.
 
Googlebot said:
I don’t believe the electroblock model I have is equipped with an ammeter. It is the one with the rotating dial and lights for the gauge levels. When on hookup though it does trickle charge the chassis battery.

I think it’s an EBL 21, or might be 29. I can check when I get home.
Click to expand...
That is correct it will be a EBL29.
 

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