Solar controller to aux batt connection.

[Konradical]

Hey guys,

Was hoping to get some advice on how to hook up a solar panel to the aux battery in our D4 for an upcoming Canning trip.

The car is equipped with a Traxide DBS, but after talking with the fellow travellers, it seems as though the actual driving time over the course of a day might not be enough time to recharge the batteries from the previous nights usage.

I already planned on taking a portable solar panel and connecting it to the rear Anderson plug, but I am currently toying with the idea of fixing one to the roof so we don't have to mess around unloading/loading panels when we stop.

So the question is; can I connect a solar panel through either a PWM or MPPT controller to the aux battery without it being effected by the normal charging routine.

Thanks in advance for your help.

[weeds]

I reckon your Disco will have enough time to top the batteries up......

I’m assuming you will be driving a good portion of the day each day....if you pull up early or depart late on the odd day just leave your portable set connect and let it be the last thing you deal with.

[chrisbbarnes]

check out this pic but read the info from this web site on dual battery install. i found it very very useful.

Dual Battery Systems | Alternator charging, how it
should be done (http://www.fridge-and-solar.net/dual_bat.htm)

139747

[DiscoMick]

You certainly can leave it connected and it shouldn't cause any problems going through a PWM or other regulator. Mine doesn't. When driving the battery will draw from whatever is the strongest source.

Whether you actually need it depends what you draw down from the battery and how long you drive.

[weeds]

Oh and leave you roof rack space for important stuff like fire wood.

[Homestar]

To answer your question - yes, fine to connect the panel straight to the aux battery.

As noted, you'll probably be fine with driving anyway - waht are you actually running? Just a fridge and a few LED lights/charging the phones, etc? You'll probably not pull more than 10 to 15 amp hours out of the battery overnight just doing that, so would only take a couple of hours to charge it again the next time you're driving.

If you're moving every day I wouldn't see too much of an issue but if parked up for more than a couple of days you'd want to start looking at something else.

[weeds]

If you're moving every day I wouldn't see too much of an issue but if parked up for more than a couple of days you'd want to start looking at something else.

He has portable for multiple days....given its big enough to put more in than what’s being used

[chrisbbarnes]

139754

[DiscoMick]

It doesn't have to be that complicated, really. Solar is just another power source.
This is now mature technology. Just connect a solar panel with PWM regulator to either battery and you are done. The dual battery controller will do the rest.

[Homestar]

139754

Yep, that works well - it's how I have my van set up.

[drivesafe]

Hi Konradical, and first off, you are unlikely to ever drive long enough to replace used battery capacity after some heavy use while camping before the drive.

So that info is basically correct, but it is not imparitive to fully charge the batteries after each use, but you do need to be able to replace the amount of battery capacity you did use.

That may sound like double Dutch but it is quite straightforward.

To give you a rough idea of what happens, you start you holiday with three 100Ah fully charged house batteries.

At your first free camping stop, you use say 150Ah of house battery capacity, discharging the batteries down to 50% SoC and then you hit the road.

Let’s say you drive for 4 hours. In that 4 hours you might replace 120Ah of used battery capacity, then you stope for your next camp. This leaves your batteries at 90% charged state.

Again you use 150Ah of house battery capacity, but as the batteries were at 90% SoC to start with, this discharges your batteries down to 40% SoC, and you drive for the same 4 hours, only this time you will replace the 150Ah used, getting them back to the 90% SoC, and you can do this as many times as you like.

This type of trip use is quite common, and it’s not until you get to a powered site that you will be able to fully charge state again.

The reason for being able to replace more capacity in lower discharged batteries, it that the last 10 to 20% of the charge cycle required to fully charge batteries, takes much longer to achieve so literally just ignore the top 10 to 20% of your batteries capacity, while you’re on the road, free camping.

[Konradical]

Thanks guys, this information was exactly what I needed. I was hoping I wouldn't need to have to have a secondary system in place to prevent alternator charge from destroying the solar controller or have to mess around connecting things when stopped.

So far for the trip we will basically have a Engel 40L with "two zone" extender and run it on setting 4 or freeze and some LED lights for night time. For most of the trip there won't be phone reception (yay) so no need to charge phones, but may have sat phone on charge in case. This is our normal camp set up and so far we haven't used the solar panels for a top up. But saying that, we have usually done about 6-8hrs of driving between camps.

BUT, I am considering a second 40L Engel and an inverter for the things that need it (not sure as what yet, but the minister will surely have a need). This and the fact we will probably have a broken drive of no more than 5-6 hrs a day once we hit the route.

Also if I mount the panel to the roof I can turn it into a wind deflector for the roof rack.

Thanks heaps again.

[weeds]

Thanks guys, this information was exactly what I needed. I was hoping I wouldn't need to have to have a secondary system in place to prevent alternator charge from destroying the solar controller or have to mess around connecting things when stopped.

So far for the trip we will basically have a Engel 40L with "two zone" extender and run it on setting 4 or freeze and some LED lights for night time. For most of the trip there won't be phone reception (yay) so no need to charge phones, but may have sat phone on charge in case. This is our normal camp set up and so far we haven't used the solar panels for a top up. But saying that, we have usually done about 6-8hrs of driving between camps.

BUT, I am considering a second 40L Engel and an inverter for the things that need it (not sure as what yet, but the minister will surely have a need). This and the fact we will probably have a broken drive of no more than 5-6 hrs a day once we hit the route.

Also if I mount the panel to the roof I can turn it into a wind deflector for the roof rack.

Thanks heaps again.

For my Simpson trip 10 years ago.....way back when solar panel were just getting popular I mounted a solar panel on the roof rack and it served as a wind deflector..

I also ran two Engels, one as a freezer and one as a fridge.....I’ve never run on as a freezer since, we cryovac now which works better for us.

[DiscoMick]

Thanks guys, this information was exactly what I needed. I was hoping I wouldn't need to have to have a secondary system in place to prevent alternator charge from destroying the solar controller or have to mess around connecting things when stopped.

So far for the trip we will basically have a Engel 40L with "two zone" extender and run it on setting 4 or freeze and some LED lights for night time. For most of the trip there won't be phone reception (yay) so no need to charge phones, but may have sat phone on charge in case. This is our normal camp set up and so far we haven't used the solar panels for a top up. But saying that, we have usually done about 6-8hrs of driving between camps.

BUT, I am considering a second 40L Engel and an inverter for the things that need it (not sure as what yet, but the minister will surely have a need). This and the fact we will probably have a broken drive of no more than 5-6 hrs a day once we hit the route.

Also if I mount the panel to the roof I can turn it into a wind deflector for the roof rack.

Thanks heaps again.
Your alternator won't do anything to 'destroy' your solar. The batteries will simply absorb the charge from both as required. While driving your alternator will be more powerful so it will control the state of the batteries. When stopped, the engine isn't running so the power will come from the solar. They should both work fine. Neither will affect the other.
I have an 80 watt solar panel on the roof of my Defender connected to the PWM regulator and starting battery, because you always want to be able to start the vehicle. Everything works just fine. No problems at all.
Also, I recommend against using the solar panel as a wind break, as it will increase your fuel consumption unnecessarily. Just mount the panel flat, so it is getting sunlight all day. If it's on an angle it will only charge when facing the sun, but for three-quarters of the time your panel is likely to be facing away from the sun, so it won't work well. Just mount it flat, like they do on caravans, to get some sun all day.
My experience is a permanently mounted flat panel is a set and forget solution. Hope that helps.

[Konradical]

Your alternator won't do anything to 'destroy' your solar. The batteries will simply absorb the charge from both as required. While driving your alternator will be more powerful so it will control the state of the batteries. When stopped, the engine isn't running so the power will come from the solar. They should both work fine. Neither will affect the other.
I have an 80 watt solar panel on the roof of my Defender connected to the PWM regulator and starting battery, because you always want to be able to start the vehicle. Everything works just fine. No problems at all.
Also, I recommend against using the solar panel as a wind break, as it will increase your fuel consumption unnecessarily. Just mount the panel flat, so it is getting sunlight all day. If it's on an angle it will only charge when facing the sun, but for three-quarters of the time your panel is likely to be facing away from the sun, so it won't work well. Just mount it flat, like they do on caravans, to get some sun all day.
My experience is a permanently mounted flat panel is a set and forget solution. Hope that helps.I should add that this solar set up won't be a perminant fixture. It will primarily live on my RRC. But I will if required move it across for a trip where I feel as though I need the extra electron security.

I'm curious though as why it wouldn't help deflect some of the air over my roof rack, saving a fraction of fuel? For some reason I only chose to get a 3/4 frontrunner roof rack and when I have stuff on it, it becomes a vertical wall pretty much at the stepped up section of roof. Cos we have the extended roof rails I can mount a panel at about 30 degrees or so and it wouldn't be too much of a different angle to the windscreen slope.

In regards to getting the best sun, I can easily point the car to a north direction and get enough when not needing it.

But there may be an option to mount the panel flat in the same spot, might mean I get a smaller panel than I had originally planned.

[DiscoMick]

It's a bit like people who drive around with a rooftop tent, increasing their fuel consumption.
A flat panel on an angle is like a wall, but having several objects of different sizes and shapes lets the air flow around them.
Anyway, whatever works best for you is fine.

[p38arover]

I already planned on taking a portable solar panel and connecting it to the rear Anderson plug, but I am currently toying with the idea of fixing one to the roof so we don't have to mess around unloading/loading panels when we stop.

I saw a cunning idea in a recent 4WD Action mag where the vehicle owner fitted the panels under the roof rack and attached to drawer slides. When he stops, he slides the solar panels out. It leaves the roof rack free.

I am now wondering if I can do the same thing to my Rhino Racks Pioneer Platform. The only downside I can see is that it could limit running straps over and under the rack when loading the rack.

[Konradical]

I saw a cunning idea in a recent 4WD Action mag where the vehicle owner fitted the panels under the roof rack and attached to drawer slides. When he stops, he slides the solar panels out. It leaves the roof rack free.

I am now wondering if I can do the same thing to my Rhino Racks Pioneer Platform. The only downside I can see is that it could limit running straps over and under the rack when loading the rack.I have also seen this idea.

Unfortunately for my set up I have the frontrunner table under my roof rack, BUT, it gives me the idea to use two smaller panels to lay flat in front of the roof rack by having one on top of the other and the top one slides away to expose the second when stopped. Hmm.. I like this idea. Just need to figure out weights and mounting.

[DiscoMick]

I have also seen this idea.

Unfortunately for my set up I have the frontrunner table under my roof rack, BUT, it gives me the idea to use two smaller panels to lay flat in front of the roof rack by having one on top of the other and the top one slides away to expose the second when stopped. Hmm.. I like this idea. Just need to figure out weights and mounting.
I have also seen this done. I believe one problem with sliding mounts on roof racks is stopping them from rattling, particularly on corrugations. They have to be well-clamped.

[Konradical]

I have also seen this done. I believe one problem with sliding mounts on roof racks is stopping them from rattling, particularly on corrugations. They have to be well-clamped.Nothing a good Tex screw can't fix![emoji6]

[DiscoMick]

True, but how to stop the slides from rattling?

[weeds]

It's a bit like people who drive around with a rooftop tent, increasing their fuel consumption.
A flat panel on an angle is like a wall, but having several objects of different sizes and shapes lets the air flow around them.
Anyway, whatever works best for you is fine.

Might need to get myth-busters onto it......

I didn’t see any real difference in fuel economy between before fitting solar, during (many touring trips) and than removal of the solar panel.

https://www.aulro.com/afvb/images/imported/2018/05/2.jpg