3rd battery with a ctek dc-dc

[lg 91]

Hay guys iam after a 3rd battery for my truck to run my fridge for a few days.

I've allready got a 95 amp hour calcium battery under the bonnet parrallel to the main with a 150amp projecta unit. that works fine but iam in need for a bit more.
So my plan is to fit a 135amp hour Agm or bigger in the rear of the truck wired through a ctek dc-dc charger and with the option of a solar panel.

So my question is do I run the ctek of my main or second battery and what size cable would be suitable taking in mind it's gotta run to the rear of the truck and if I decide to run a solar panel do I need a solar regulator as well or will it just Connect straight to the ctek.

Cheers

[rainsey]

Oky Dokey,

If and only if the Ctek you are talking about is D250

1: no need for a regulator for solar as the Ctek has a MPPT controller built in. Just remember you are limited to 20 amps max input.

2: I would connect it to you main battery. This way the Ctek can also charge your main battery from the solar should your rear battery be fully charged.

3: Very thick 4 guage wire. Any thing over about 3 meters in length from the main battery needs to be very thick to reduce loss.

4: put an inline fuse, say a 50 amp, in the beginning of the line from your starting battery.

Am using this set up and it works a treat.


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[lg 91]

Oky Dokey,

If and only if the Ctek you are talking about is D250

1: no need for a regulator for solar as the Ctek has a MPPT controller built in. Just remember you are limited to 20 amps max input.

2: I would connect it to you main battery. This way the Ctek can also charge your main battery from the solar should your rear battery be fully charged.

3: Very thick 4 guage wire. Any thing over about 3 meters in length from the main battery needs to be very thick to reduce loss.

4: put an inline fuse, say a 50 amp, in the beginning of the line from your starting battery.

Am using this set up and it works a treat.


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Thanks mate yeah the d250 so ur saying if I run it off the main the solar will charge the agm then run back to the main. Also will it isolate it from the main if the agm drops past a certain voltage

[rainsey]

Thanks mate yeah the d250 so ur saying if I run it off the main the solar will charge the agm then run back to the main. Also will it isolate it from the main if the agm drops past a certain voltage

According to the Ctek documentation, and you can download it off their web site, the Ctek will act as a battery isolator.

Upon charging up the auxiliary battery it will then divert output to the main battery.

Oh ... Also I think the unit will also use both the solar and the alternator where as the Redarc will only use one or the other.

I have a Redarc unit servicing dual 100 amp hour AGM's in the back of my ute and I have a Ctex D250 in my camper. I had to go with the Redarc on the truck as I have more than 20 amps of solar input on my truck.

Download the manual and sus it out. It is a bloody great unit.


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[lg 91]

Yeah cool that's what I was hoping that way I can leave my original set up under the bonnet. When you say more then 20amp how big of a solar panel could I run

[megatexture]

They can take up to 250 watts of solar

[rainsey]

Power = Volts x current.

Therefore 12 volts x 20 amps gives u 240 watts.




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[rainsey]

Having said that based on the bad efficiency of a solar panel and the actual output, you can no doubt go higher than 240w and be safe that you will not exceed the 20amp input limitations.

I did not go the Ctek on my truck as I have 2 x 200watt panels on the roof and am going to place another on the roof racks.

With the 2 200watt panels I have not actually measured more than 20 amps in but the. Again I do not sit there all day with my ammeter measuring output at peak periods.

On my camper I have a roof mounted 40w unit and a fold out 160w panel. This is what I use the Ctek with.

Kindest regards
Rainsey


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[megatexture]

They take up to 250 watts of solar and they don't charge off both alternator and solar at the same time it will switch between the optimum source of input, though it may look like its using both the lights are just indicators to say you have a connection for trouble shooting should you have any issues

[rainsey]

They take up to 250 watts of solar and they don't charge off both alternator and solar at the same time it will switch between the optimum source of input, though it may look like its using both the lights are just indicators to say you have a connection for trouble shooting should you have any issues

Fair enough. I have probably mis interpreted the user manual.

Easy way to check and that is to measure the current from both the Solar array and the alternator at the same time. If the alternator takes precedence during the charge cycle, the current draw from the solar will drop to zero and the voltage at the output will rise to around 20 volts.

If the solar takes precedence, my in dash ammeter connected to the Ctek from the alternator supply should effectively be zero.

Will check next time I have the camper hooked up for my own piece of mind.

Cheers
Rainsey

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[rainsey]

Sorry, re the 250 watts ... Power is a subjective figure based on 2 variables, the volts and the current supplied.

Ctek state that the maximum charging current is 20 amps. Based on a 12 volt supply the maximum power input is effectively 240w.

If one uses the stated charging voltage of 14.4 volts with the max input current of 20amps you are looking at a power input of 288 watts.

The use of power as the input rating of any device needs to be used carefully. The reason is that you can easily in a vehicle system have two variables, I
I.e. Your voltage input can fluctuate from probably 11 to 14.5 volts. Of you have a fixed known input of the device such as a DC to DC charger that states it can only support a certain current input, then the effective power specification is then the second variable.

Cheers
Rainsey




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[megatexture]

Charging current they are referring to is output to the house battery (20amp) not input to the ctek unit