CTEK D250 SE and solar panel.

[Square Peg]

As a newbie to both campervans, and the forum, please be gentle. I've searched and read the forums for an answer, and have ended up with a fried brain, so apologies if the answers already out here.

I have the D250SE installed, and have just purchased a Dokio 100w foldable solar panel. I read a bit about COV, and took note that for the D250 SE it's 23v. The Dokio panel spec on Amazon stated the COV as 22.5v. However, the technical data sheet that came with the panel states a maximum solar voltage of <25v.

Is this something to worry about, and likely to fry the D250 SE, or will it be OK.

 

[roadtripper]

If the limit on the CTEK input is 23v then anything higher is a risk and if you damage the CTEK you loose both your solar and normal DC-DC charging.

As a first solution I'd consider returning the panel to Amazon as miss described and find a panel that is within the documented tolerance of the CTEK.

It would be safer to take a risk of you had an independent solar controller. Also that will generally have a higher tolerance, the CTEK tolerance is quite low these days.

 

[roadtripper]

If you're struggling to find a panel, and I think you might, your other option is to have an independent MPPT charger, the Victron ones are a popular choice on the forum and are not that expensive for a 10A or 15A version.

I recently got the Renogy 100w foldable and that is rated as 24.3v OCV, again too high for the CTEK.

I know others have used the Dokio panels and they are not bad, good value without being so cheap they don't last, so that might be a route for you.

 

[Square Peg]

If the limit on the CTEK input is 23v then anything higher is a risk and if you damage the CTEK you loose both your solar and normal DC-DC charging.

As a first solution I'd consider returning the panel to Amazon as miss described and find a panel that is within the documented tolerance of the CTEK.

It would be safer to take a risk of you had an independent solar controller. Also that will generally have a higher tolerance, the CTEK tolerance is quite low these days.

The panel came with a PWM controller, and seems to work OK charging the car battery, so I might stick with that till I become more knowledgeable. Many thanks for the response.

 

[roadtripper]

There's an option for you then. PWM controllers don't squeeze as much energy out of the panel as an MPPT does but if it was included it gets you going and you can find out how well a panel will work for how you use your van

You might want to consider if you can wire in a fused Anderson SB50 connection to give it a reliable connection to your leisure battery. The 12v cigar style sockets shouldn't be used over 8A continuously and your panel is close to that but properly OK for initial testing - so long as you know which socket is connected to your leisure battery.

 

[Square Peg]

If you're struggling to find a panel, and I think you might, your other option is to have an independent MPPT charger, the Victron ones are a popular choice on the forum and are not that expensive for a 10A or 15A version.

I recently got the Renogy 100w foldable and that is rated as 24.3v OCV, again too high for the CTEK.

I know others have used the Dokio panels and they are not bad, good value without being so cheap they don't last, so that might be a route for you.

The Victron is one of the solutions I've been looking at, so good to hear. I think I need to research a bit more, and maybe I'll eventually understand the subject more.

 

[roadtripper]

You have enough kit to trial things this season though by the sounds of it, so try that and see if it works for you.

You might find out you like the idea but you'd rather have a roof top panel so it charges all the time.

One of the downsides of the portable panels is they are really only suitable if you are with the van as they are a bit of theft risk and you need some way of routing the cable into the van. Also for maximum power you'll want to turn them around a bit to follow the sun.

 

[Square Peg]

We've booked a week away in Wales soon on a site with no EHU, so I should know a lot more about how this set up will work by the end of that. I guess the Dometic CRX 50 fridge will be staying switched off.

 

[TallPaul_S]

23/22.5v open circuit voltage is higher than 25v when you take into account the temperature coefficient. Basically, solar panels are more efficient when they're cold.

As @roadtripper suggests, I'd get a Victron MPPT 75/10 (£45 on Amazon) or 75/15 (£55 on Amazon) and attach this to the back of the panel, then wire in an SB50 Anderson connector to your battery and to the MPPT battery terminals.

You'll then have the option of upgrading to a 200w portable panel or 200w roof panel and use the same controller. You'll also get closer to the 100w from your portable panel rather than the 60-70w max you'll get with the PWM controller

Your CRX50 fridge will be using 1-1.5Ah per hour, and with a 100w solar being able to put in 5A, 6x hours of sun gives 30Ah, which over a 24hr period is basically what the fridge is taking out.

So with a PWM controller you might not actually be replacing what the fridge is using.

What size is your leisure battery? AGM or LiFePO4?

 

[Square Peg]

23/22.5v open circuit voltage is higher than 25v when you take into account the temperature coefficient. Basically, solar panels are more efficient when they're cold.

As @roadtripper suggests, I'd get a Victron MPPT 75/10 (£45 on Amazon) or 75/15 (£55 on Amazon) and attach this to the back of the panel, then wire in an SB50 Anderson connector to your battery and to the MPPT battery terminals.

You'll then have the option of upgrading to a 200w portable panel or 200w roof panel and use the same controller. You'll also get closer to the 100w from your portable panel rather than the 60-70w max you'll get with the PWM controller

Your CRX50 fridge will be using 1-1.5Ah per hour, and with a 100w solar being able to put in 5A, 6x hours of sun gives 30Ah, which over a 24hr period is basically what the fridge is taking out.

So with a PWM controller you might not actually be replacing what the fridge is using.

What size is your leisure battery? AGM or LiFePO4?

It's 115Ah YUASA VBX Active Leisure L35-115 that was already fitted when we bought the van 6 weeks ago.

 

[TallPaul_S]

It's 115Ah YUASA VBX Active Leisure L35-115 that was already fitted when we bought the van 6 weeks ago.

Ahh so AGM/Lead Acid. So, you'll have 57Ah maximum usable capacity out of that, which with no solar will probably last you 2 days with the fridge running.

I've currently got an OEM 75Ah battery and split charge so only 22.5Ah usable. In a 24hr period at a campsite I used 29Ah with just a CRX50 fridge, LED lights for a couple of hours, and charging my phone.

As you've got the panel with the PWM controller you may as well use it - it may replace half what the fridge is using if you get decent sun. That'll get you another day, maybe.

You do always have the option of running the engine for 30-40 minutes every couple of days, that will top the battery back up.

 

[Square Peg]

I'd be quite happy being without the fridge as I'm into backpacking and wild camping, but it was my partners dream to get the van. I dare say she'll survive if we don't use the fridge for now, as we owned a small sailing boat for 17 years with a very basic 2 battery set up that just ran a VHF, Sat Nav, and lights.

The week away will be a step on what seems to be a very large learning curve.

 

[DXX]

I'd be quite happy being without the fridge as I'm into backpacking and wild camping, but it was my partners dream to get the van. I dare say she'll survive if we don't use the fridge for now, as we owned a small sailing boat for 17 years with a very basic 2 battery set up that just ran a VHF, Sat Nav, and lights.

The week away will be a step on what seems to be a very large learning curve.

Even without power if you pack the fridge with a mixture of chilled / frozen food and resist opening the door unless you need to you’ll have fresh food for 2-3 days.
Put a thick towel in the bottom to absorb any condensation.

 

[Square Peg]

Even without power if you pack the fridge with a mixture of chilled / frozen food and resist opening the door unless you need to you’ll have fresh food for 2-3 days.
Put a thick towel in the bottom to absorb any condensation.

When we went away last weekend for two nights, we tried the fridge on tge EHU to see how quickly it chilled. My partner kept opening the door to check what lights were on when the compressor wasn't on and trying to work our why. We've since read the manual....

 

[DXX]

When we went away last weekend for two nights, we tried the fridge on tge EHU to see how quickly it chilled. My partner kept opening the door to check what lights were on when the compressor wasn't on and trying to work our why. We've since read the manual....

My previous suggestion about packing frozen food might be a waste of time then!

 

[Square Peg]

I'm not so sure. We have some of the plastic freezer packs that we can put in the fridge, and hook up at home to get it cold before heading off, so we'll take it from there.

 

[TallPaul_S]

I'm not so sure. We have some of the plastic freezer packs that we can put in the fridge, and hook up at home to get it cold before heading off, so we'll take it from there.

You may as well keep in on whilst driving to your campsite too, as the battery will be getting charged from the alternator.

 

[Square Peg]

You may as well keep in on whilst driving to your campsite too, as the battery will be getting charged from the alternator.

It's a 4 hour drive from home, so that makes sense. Might not even need the hook up at home first.

 

[DXX]

I'm not so sure. We have some of the plastic freezer packs that we can put in the fridge, and hook up at home to get it cold before heading off, so we'll take it from there.

Frozen food is better, you can eat it.

 

[russed68]

We always slap the fridge on the coldest setting possible whilst driving to site , then turn it down when parked up