CTek D250S with 30 VDC solar

[BillyGoatCountry]

I purchased a CTek D250S dual battery / solar charge controller

The makers blurb claim these will take solar panel input but i now find it can only take solar input up to 22 Volts , my 200W panel puts out 30 volts so i cant use this product.

Unless there is an easy way to reduce the voltage without losing too much power ?
Whats the easiest , reliable safe method ?

Will a solar charge controller work without interfering in the D250S charge management ?

Or a DC-DC converter ?
https://au.rs-online.com/web/p/isolated ... s/1325404/

The converters above are $ 160 and too small at 200 watts so maybe i am better to flog this on ebay and buy a Redarc or EPower unit.
Redarc BCDC units take up to 32 volts and EPower DC2DC will take up to 43 volts solar.

[HK1837]

My thoughts.
I wouldn't use that Ctek unit as a standalone anyway as it does not separate the aux battery from the load. If you have say a fridge hanging off the aux battery the Ctek unit will end up overcharging the battery as it gets confused as to what voltage the battery requires - a battery needs different voltages at different stages of charge and a quality charger reacts accordingly. If a fridge is cutting in and out the charger has no idea what is going on and will sulfate the battery.
Depending upon what type of battery you have, with a solar input you will normally be better of with a solar regulator, something like a Victron 75/15 or even 100/30 if the 200W panel outputs more than 15A max. The solar regulator hangs the load off it and separates the aux battery from the load, so whilst the sun is shining the panel supplies the load and charges the battery separately, only giving the battery the charge profile it needs. You can program them for different voltage profiles too if you are using an AGM or other non standard type of battery.
Then you just use a simple dual battery setup between the main battery and the aux battery, if you are using a deep cycle lead acid aux battery then something very simple like a Projecta or Redarc dual battery setup is fine, it will get the same sort of charge from the alternator as the starting battery does. If the aux is something that needs a different charge voltage and/or profile then you'll have to look for something more complicated involving a dc-dc converter, but make sure if it has a solar input and the aux battery load is separated from the battery as mentioned above. Looking at the Redarc BCDC they seem to have a separate solar input and MPPT but they do not separate the load from the battery.

[BillyGoatCountry]

thankyou.

that makes sense as my batteries are getting killed off faster than they should be.

The battery is an Optima D27F yellow case.

The load is a discrete 4 channel CCTV system that pulls 52 watts , ~ 4 amps

With only 30 minutes drive to and from work the battery is not getting charged enough to maintain the load and the battery will pull down to 10 volts overnight , hence i want to add the solar panel so it gets a full day of charge.

I dont have a 240 V outlet near where i park it so i cant use a mains charger to boost it.

What you are saying is clear enough , i need to separate the load from the battery and run load from the Victron 75/15 .

The Solar panel puts out 8 - 10 amps so that unit should handle it.

If i do the above , will the CTEK still not be suitable ?

The CCTV still pulls its load when driving in day or night conditions , when driving at night the Victron will not be getting solar input so charge voltage will revert to the CTEK and alternator.

Whats your thoughts ?

[HK1837]

Is that Optima a hybrid sort of battery? It has both CCA and Ah ratings, and it isn't a very high Ah rating.

I'd suggest that one of the reasons you are killing batteries is they are being discharged and charged too often and too deep. I have an N70 Century deep cycle that is 105Ah, and with about 3-3.5A of Engel 38L fridge running off it I do not get enough charge from 30min drive twice a day to keep the battery charged, and a fridge only runs maybe 10-20% of the time. If you have 4Amps continuous then you need 96Ah for a 24 hour period.

I added 110W of solar panel, not because I particularly desired 110W but it fitted perfectly between the racks on the Hilux's canopy roof racks. It is only a cheap one but has worked flawlessly so far:
https://www.4wdsupacentre.com.au/advent ... gL4CPD_BwE. By the Victron unit (via the Bluetooth connection where I can look at solar delivery and load consumption) it delivers more than enough to both keep the aux battery in float and run the fridge. So 220W should do the job for you. Although I still reckon the Ah rating on your battery might be a bit on the small side, when it dies next I'd try to go to something around 105Ah or whatever you can fit close to that. I find I have to add maybe 40-50cc of demin water to the Century battery every 2-3months as the continuous charge of the battery from solar does evaporate it a bit more than normal, but it is like $3 for 4 litres at Woolies or Coles.

The Ctek may well do what you want if you use it as a simple dual battery setup, I only had a quick look at it. You may have to try it and see how it behaves with a separate solar regulator. What I have found with the Project unit is it monitors the voltage on the starting battery, so when I'm driving it parallels the batteries. When I turn the car off the solar regulator is putting charge voltage and decent charge current into both batteries, so the voltage appearing at the starting battery keeps the two batteries paralleled. Thus both batteries are charged and then kept at float by the solar regulator. If the sun goes away and the fridge running pulls the batteries below 12.5V then the Projecta unit separates them. It isn't meant to work that way but it does, and I get the benefit that the starting battery gets a full charge whilst the solar is active too. If I don't want them paralleled then I have a switch that turns the Projecta off and it stays off then until the car is started again.

[HK1837]

Have a bit of a read here. Lots to take in but worth the time to read it.

https://outbackjoe.com/macho-divertisse ... inverters/

[BillyGoatCountry]

Thanks for the contributions above .

My panel is a flexible one measuring about the same as your 110 watt so again it fits perfectly between my canopy roof racks.

I checked out the projecta unit but it’s maximum solar voltage is too low.

I am waiting for confirmation from redarc that their system won’t have the same overcharging issues that the CTEK does when it has a constant load confusing the charge algorithm.

Using the solar charge regulator on the service battery still sounds like a better option , with the load connected to the regulator instead of direct to battery . The only uncertainty now being if I should put a 2 pole relay on the regulator to switch off the solar and switch in the CTEK when the engine is running.

I will start reading your link now.

Thankyou.

[chevaps]

With all due respect to the contributors above, but saying that a load connected to a battery will confuse the charger and cause overcharging is incorrect.

The CTEK D250S is rated to 14.4V output at 25 degrees C, give or take a few fractions of a volt depending on temperature. Make sure the temperature probe is on the battery to ensure you afford your battery protection against overcharging. Any voltages much higher than this points to a faulty CTEK unit. Also, from my understanding, the new Hilux requires the D250SA (i am yet to verify this on my own car, but still bought the SA version for myself anyway), so what you may find is the voltage of the alternator may not be triggering the unit to charge your aux batteries.

Just as an FYI, using the DC-DC converter as per your link can result in an unstable input voltage into the D250 due to how the MPPT works (this is way beyond the scope of this forum). Also, consider the case when a panel is not in direct sun, if the solar panel's output voltage drops below 18V, then your DC-DC converter may not function correctly.

In my opinion you have 3 options to address your solar panel issue:
1) have 2 independent charging supplies to your batteries (D250S and solar) wired through a changeover switch depending on the ignition status (i.e. use D250S when car is running, use solar when car is not running). NOTE: this is assuming the solar panel already has an MPPT attached.
2) buy new solar panels with an open circuit voltage not exceeding 23V.
3) sell the D250S and buy another charger that can accept the max open circuit voltage of your solar panel.

Regarding your concern that the batteries are being killed off faster than expected, just be aware that just because a battery may be rated at 66Ah (at a specified discharge rate), discharging a battery more than 50% of it's rating will send it to an early grave, deep cycle or not! It may seem deceptive from a marketing perspective, but while the battery is capable of delivering it's full rated capacity when required, don't expect to be capable of doing it more than a few times. I suspect your issue with batteries failing prematurely is because you have incorrectly selected the total battery capacity required. As an example, for a 4A load to be supplied by batteries only for 12 hours, i would suggest 96Ah as a minimum, but would highly recommend 160Ah based on a 30% depth of discharge. If your driving habits don't allow for sufficient charging, then you should also consider a 240V trickle charger for use when the car is parked at home.

Just for your reference, I have 2x 105Ah batteries in the tray of my Hilux with a D250SA to supply an ARB fridge for more than 24 hours continuously.

Cheers.

[HK1837]

I disagree. It is a known issue with any profiled/optimised battery charger that if you cycle battery loads on and off particularly loads that look like the battery wants more charge, the charger assumes that battery no longer wants a float voltage but wants for example a bulk charge voltage and ups the output voltage, forcing the battery to take charge when it doesn't need or want it.

The Ctek 250S battery temperature probe is as far as I am aware is primarily there for changes in ambient temperature so the charge voltage is adjusted for temperature which is a good thing, but I doubt it will protect against overcharging for the periods where aux battery loads are cycling. Maybe it will, however I doubt it.

Totally agree with the rest of the post though, I do like the standard dual battery isolator and a solar panel to charge the lead acid aux battery with the load off the solar regulator - I don't think there is a better setup unless you are running a battery requiring a very different charge profile to the starting battery, then the dc-dc to charge when the engine is running is probably a must, with the solar regulator taking over once parked. Just how you do it would be the challenge although if it is a situation where the solar panels are only used once parked then its easy. My solar panel is on the roof and working whist ever the car is in the sun, driving or parked. In this case the solar regulator just dumps whatever energy is available (over and above the fridge load) into the combination of the starting and running batteries plus the vehicle loads whilst ever the batteries are paralleled by the dual battery controller.

To overcome the overcharging issue when loads are cycling I have actually seen someone fit a plain old 12-24V dc-dc converter and feed the 24V into a solar regulator that then looked after the aux battery and cycling loads on separate outputs. Pretty neat setup even with the additional losses in the 12-24Vdc conversion, could be better again if you had a solar regulator with dual solar inputs, stick the panel into one and the 12-24 dc-dc into the other (if such a thing exists?).

[BillyGoatCountry]

I have gone with a Victron 75 / 15 solar regulator and the 4 amp load off that.

A 60 Amp relay isolates the solar panel once the engine is running , for most of a working week the engine run time is typically 8 % of a 12 hour day or 1 hour per day.

This setup gives me 10 amps by day from solar which is around 6.5 hours in summer and 4 hours winter while the vehicle is not running , when i am driving the CTEK will give 20 amps.

I do get away for longer drives on weekends but i still have to factor in that most of the week is short driving distances.

I have fitted an inline 20A fuse at the solar panel positive terminal and a 10 amp fuse at the output from the Victron even though it has built in short circuit protection.

I spent a few hours looking for cheaper solar regulators but the Victron is way ahead.

Most of the regulators you see on ebay for example dont even state an output capacity for the load side or if they do its extremely low such as 0.5 - 2.5 amps.

Here is the joke for anyone looking at solar regulators and intend hanging a load off it.

Many of the chinese factories that manufacture these have maybe copied off real ones where the output is indicated with a "light bulb symbol" , and the chinese assume that the light bulb symbol actually means people use it to run a light.

People among us who are not deadshitz would understand that these things are used to run fridges , radios , CCTV , GPS trackers and the load capacity should be as high as possible.