Wiring in a solar panel shortcut?

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Wiring in a solar panel shortcut?

Post by m8form8 on Thu Apr 02, 2015 3:28 pm

confused3 Not actually looked at it in detail, but notice the habitation panel is above the rear door in my Amethyst with a fuse board. Anyone know if i could sneek a solar panel via a regulator direct into this rather than to the battery itself?  confused3
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Re: Wiring in a solar panel shortcut?

Post by Paulmold on Thu Apr 02, 2015 3:59 pm

Can't comment on your panel but my solar was installed via regulator into wiring inside the wardrobe and not directly to either battery, so yes it should be feasible to wire a shortcut.

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Re: Wiring in a solar panel shortcut?

Post by Peter Brown on Thu Apr 02, 2015 5:01 pm

Be careful.  An installer did this on my friends Talisman but he connected it to the load side of the distribution system.  So when the habitation circuitry was switched off the solar panel was not connected to the battery.  Apart from the leisure battery (and engine battery via battery mate) not being topped up by the panel; assuming it was bright enough, the solar panel was operating any habitation lights that had been left switched on whilst the engine was running.

So the idea is good but make sure you find the wires that come direct  from the battery.

Peter

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Re: Wiring in a solar panel shortcut?

Post by m8form8 on Thu Apr 02, 2015 6:27 pm

Thanks for that Paul, will take on board warnings Peter, just logistics of getting wires from a panel to the front are a nightmare and we only really need it for habitation side.  up!
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Re: Wiring in a solar panel shortcut?

Post by Johno on Fri Apr 03, 2015 12:55 pm

Hi m8

I fitted a solar panel to my excelsior which apart from the seating is the same as your van, I connected the cables via a regulator mounted in the adjacent cupboard to the habitation panel which did save a lot of faffing about running cables to the leisure battery.
When you remove the habitation panel you will see two fairly thick cables red and black which run towards the front of the van and connect to the leisure battery which in the excelsior was under the bonnet, from memory I think the terminals on the habitation panel were big enough to enable the cables from the solar panel regulator to be connected alongside the existing leisure battery cables.

You can always double check that you are connecting to the correct cables by checking the voltage at the habitation panel using a multimeter or 12 volt test lamp then disconnecting the positive cable from the leisure battery which will show as a loss of voltage at the panel.  

Hope this helps, cheers John up!
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Re: Wiring in a solar panel shortcut?

Post by m8form8 on Fri Apr 03, 2015 1:13 pm

Thanks for that John, sounds very helpful information.  up! I will in time investigate further.
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Re: Wiring in a solar panel shortcut?

Post by Pug boxter on Tue Jun 27, 2017 6:53 pm

I'm doing this on my 2002 Nuevo, I'm going to add the positive feed from the solar panel controller to the positive feed from the charger that goes to the centre of the vehicle/habitation switch. So I can charge the vehicle battery in winter and if needed at any other time in addition to the leisure batteries..
Then tap into the negative feed from the charger to batteries lower down behind the fire. the negative feed at the panel only seems to be for the pump light and battery indicator.

Hopefully that will be okay? Any input greatly received.
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Re: Wiring in a solar panel shortcut?

Post by -mojo- on Tue Jun 27, 2017 7:21 pm

In my opinion it's always better - if you have the option - to take the solar panel directly to the leisure battery. That way you can use top-quality cable all the way to ensure that as much as possible of the solar panel's output gets into the battery. If you tap into existing wiring you will be adding an unknown amount of resistance into the circuit, and the resulting voltage drop may reduce the maximum charge rate that you can achieve.

You can then use either a Battery Master to ensure that the vehicle battery is topped up automatically, or replace the Split Charge relay with a bidirectional VSR, which has much the same effect. Either way, you won't have to remember to manually switch between batteries to keep both topped up - it will be done automatically for you.
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Re: Wiring in a solar panel shortcut?

Post by Pug boxter on Tue Jun 27, 2017 7:42 pm

-mojo- wrote:In my opinion it's always better - if you have the option - to take the solar panel directly to the leisure battery. That way you can use top-quality cable all the way to ensure that as much as possible of the solar panel's output gets into the battery. If you tap into existing wiring you will be adding an unknown amount of resistance into the circuit, and the resulting voltage drop may reduce the maximum charge rate that you can achieve.

You can then use either a Battery Master to ensure that the vehicle battery is topped up automatically, or replace the Split Charge relay with a bidirectional VSR, which has much the same effect. Either way, you won't have to remember to manually switch between batteries to keep both topped up - it will be done automatically for you.

Yes that sounds like the best solution. The positive feeds for the two separate batteries are pretty beefy from the switch. It's just the negative feed that isn't as thick, does that matter?
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Re: Wiring in a solar panel shortcut?

Post by meanchris on Tue Jun 27, 2017 8:12 pm

I used to pooh-pooh solar panels, until I got one with our latest van which just keeps both batteries charged without any intervention from me.

Another worry off the list. allthumbz

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Re: Wiring in a solar panel shortcut?

Post by -mojo- on Tue Jun 27, 2017 8:36 pm

Pug boxter wrote:It's just the negative feed that isn't as thick, does that matter?

Yes - if the negative goes right back to the battery rather than earthing to the chassis (which would in my experience be unusual) the negative is just as important - a light-gauge there will introduce a voltage drop in exactly the same way as on the positive.
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Re: Wiring in a solar panel shortcut?

Post by Greyhound on Wed Jun 28, 2017 9:28 am

Pug boxter wrote:I'm doing this on my 2002 Nuevo, I'm going to add the positive feed from the solar panel controller to the positive feed from the charger that goes to the centre of the vehicle/habitation switch. So I can charge the vehicle battery in winter and if needed at any other time in addition to the leisure batteries..
Then tap into the negative feed from the charger to batteries lower down behind the fire. the negative feed at the panel only seems to be for the pump light and battery indicator.

Hopefully that will be okay? Any input greatly received.

In my old Nuevo (2004) the centre switch position didn't charge either battery, was more of an off position.

I tested this with a voltmeter when on hook up and the charge only flowed to the habitation electrics with it in the hab position.  So wiring to the centre position possibly wouldn't charge either battery unless your wiring is different.
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Re: Wiring in a solar panel shortcut?

Post by Pug boxter on Wed Jun 28, 2017 10:18 am

Greyhound wrote:

In my old Nuevo (2004) the centre switch position didn't charge either battery, was more of an off position.

I tested this with a voltmeter when on hook up and the charge only flowed to the habitation electrics with it in the hab position.  So wiring to the centre position possibly wouldn't charge either battery unless your wiring is different.

Yes that's correct the centre feed is from the battery charger and as you say when the switch is in the central position no power is being fed anywhere.
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Re: Wiring in a solar panel shortcut?

Post by Greyhound on Wed Jun 28, 2017 10:23 am

Pug boxter wrote:
Greyhound wrote:

In my old Nuevo (2004) the centre switch position didn't charge either battery, was more of an off position.

I tested this with a voltmeter when on hook up and the charge only flowed to the habitation electrics with it in the hab position.  So wiring to the centre position possibly wouldn't charge either battery unless your wiring is different.

Yes that's correct the centre feed is from the battery charger and as you say when the switch is in the central position no power is being fed anywhere.

OK, maybe I've misunderstaood what you're trying to do.  I simply wired direct to the leisure battery, running the wires down and through the bench seat.

The vehicle battery lasted a couple of months without charge and would fire the van up fine so I never bothered worrying about charging that outside of plugging in EHU occasionally when stored over winter.
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Re: Wiring in a solar panel shortcut?

Post by Pug boxter on Wed Jun 28, 2017 10:32 am

Greyhound wrote:


OK, maybe I've misunderstaood what you're trying to do.  I simply wired direct to the leisure battery, running the wires down and through the bench seat.

The vehicle battery lasted a couple of months without charge and would fire the van up fine so I never bothered worrying about charging that outside of plugging in EHU occasionally when stored over winter.

Yes I just want the option of being able to charge the vehicle battery. As has been suggested you can add something that will do it automatically, but I'm happy to pop into the van and flick a switch over every now and then, or if away have some way of boosting the voltage up.

My original vehicle battery did very well lasting 11 years, however since I replaced it I'm not having the same experience with the replacements, I've already had one replaced under warranty, and the replacement one isn't much better. I did think Exide where a good brand, but my experience shows otherwise.
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Re: Wiring in a solar panel shortcut?

Post by HairyFool on Wed Jul 05, 2017 10:22 pm

The current levels available from a small solar panel are not particularly high (Divide its wattage by the lowest typical charge voltage) so the voltage drop along a reasonable gauge cable should not be significant. Add into that as the battery voltage comes up the charge current will fall so ultimately the battery will still come up to full charge. Typical 6A equipment wire has a resistance of around 20 Ohms per 1000m, the higher the cable current rating the lower the resistance.

Having said that I found my Cigarette lighter socket is live even with the ignition of so I have put a plug and socket on the Solar panel feed and a matching socket on a long lead ending in a cigarette lighter plug. Lighters are normally rated at 20A, well above the maximum output of the panel.

Being an auto it has two batteries under the bonnet as well as the leisure battery. Today in full sun after a few days on the drive off charge it peaked at 3.3A total into both batteries (90W panel). Therefore on site with hookup the charger can keep the leisure battery charged and the otherwise unused panel will look after the vehicle battery
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Re: Wiring in a solar panel shortcut?

Post by Pug boxter on Wed Jul 05, 2017 10:35 pm

I've just this evening got the new panel up and running, just need to put a few bits and bobs back in place and the job is done.
Fingers crossed I will now be able to charge my e-bike when not on an electric hook-up.
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Solar panel wiring

Post by art on Fri Jul 21, 2017 2:05 am

The charge controller should be wired as close as possible to the battery to be charged , and the cross sectional area of the cable used as large as possible.
The charge controller needs to measure the true battery voltage , so the voltage drop that can be created by using  a long and/or small diameter cable will mislead the controller , and can overcharge/fry the battery over time.
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Re: Wiring in a solar panel shortcut?

Post by Peter Brown on Fri Jul 21, 2017 9:08 am

art wrote:The charge controller should be wired as close as possible to the battery to be charged , and the cross sectional area of the cable used as large as possible.
The charge controller needs to measure the true battery voltage , so the voltage drop that can be created by using  a long and/or small diameter cable will mislead the controller , and can overcharge/fry the battery over time.

As the battery approaches full charge, the current flow will be minimal and hence the volt drop minimal so the controller can be located in any convenient position. It is always advisable to use wire of the largest csa as is practical for power transmission, in this case a min of 1 mmsq and ideally 2.5mmsq.

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Solar panel controller wiring

Post by art on Tue Jul 25, 2017 6:08 am

Peter wrote
As the battery approaches full charge, the current flow will be minimal and hence the volt drop minimal so the controller can be located in any convenient position. It is always advisable to use wire of the largest csa as is practical for power transmission, in this case a min of 1 mmsq and ideally 2.5mmsq.

As the battery approaches full charge, the current flow will only be minimal if the controller can sense the true battery voltage.
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Re: Wiring in a solar panel shortcut?

Post by HairyFool on Tue Jul 25, 2017 2:03 pm

From the typical automotive electrical cable used in these vehicles the voltage drop I would have had at 3.3 A is around 20mV. Not enough to confuse any charge controller for solar panels and would be considerably less as the current reduces.

1.5mmSq cable has a current rating of 17A and resistance of 17.3 Ohms/KM
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