AC Power for DC to DC charger

Hi Mel,

This is a great suggestion, but be aware that if you want the full output current from your dc-dc charger, your supply has to able to at least match but preferably exceed the dc-dc charger's max output.

eg, if your dc-dc charger has 20 amp capacity, if you do it Bill's way you'd need a Ctek xs25000 (25 amp). The smaller supply will still work, butwill give you limited output.

Alternatively, you could use a simple 12V power supply (eg from Jaycar) with enough output amps to equal or exceed your dc-dc charger. That would be cheaper, but it is not as flexible a solution. If you are going to do it this way, and if you can afford it, I'd go for a larger battery charger that has a supply mode. That way you have a back-up.

Thanks Bill but as I dont need another charger I will go down the power supply route
Mel

Not quite correct.

Yes, the "normal way" would be to have a 240v "smart" charger connected directly to the auxiliary battery, however, there is no reason whatsoever why you cannot provide a 12vdc supply to the alternator connection on the D250S dual dc-dc charger via a source other than the alternator.
A 12vdc power source with a lower current rating will still efficiently charge the battery bank via the D250S dual. It will just take longer.

The reason why I wanted to pursue this course was two fold.
Firstly, I am unsure how "smart" the built-in charger is in my camper trailer. I have yet to test it's operation to confirm that it will deliver a "float charge".
Secondly, I wished to apply a "maintenance charge" to the battery bank from time to time, to maintain the batteries at full charge while the camper was sitting in the shed.
The XS 7000 would not work in 'normal mode' (too smart methinks) but in supply mode where the charger does not attempt an interrogation of that which is connected to it's output, it supplies a constant voltage of 13.2v at a maximum of 7 amps which the D250S charger receives, then manages the full charging routine of multi-step charging (bulk and absorption at 7 amp maximum) then pulse maintenance charging for as long as desired, without damage to the connected battery(s).

The solution I came up with and confirmed by CTEK technical support in Sweden, was that this combination would work and work well.
The 7 amp XS 7000 charger is suitable for a battery bank from 14-225Ah so I do not need a higher capacity charger. The time to reach a full charge is not important in my case. The bulk of the charging routine would be handled by the alternator while travelling, at a higher current ( up to a maximum of 20 amps for the D250S). While camping, the D250S receives input from the solar panel array connected to it and managed by it's built-in MPPT controller.
The 240vac/12vdc charger is purely employed as a "maintenance routine" from time to time, easily efficiently and effectively.

Bill my comments were correct.... you can not have a direct 240v input in to a Ctek 250.

The question was asked is there an adapter available to make the Ctek 250 run of 240v and my answer was no.

If you call a power supply an a adapter then I suppose you can do it.

We see so many vehicle come through our workshop where DIYers have tried to cut corners and improvise; it beyond a joke..... if it works for you that's fine but there is nothing like doing it properly and using the KISS method.

By making something more complicated you are increasing the risk of faults developing.

Bill you have a good quality Ctek XS7000 charger that by it's self is and you have added another component that does exactly the same thing as the XS7000..... in other words you have converted something then converted it back and then converted it again back to what the original was doing...... Bill in my books that's over complicating things and using one to many things.

Bit like putting a suspension lift kit in a 4x4 and then fitting low profile tyres to lower it down again!... no real benefit.

If it works for you Bill keep using it but it's not the way I would do it.

olcoolone,

There is only one conversion in the process, that being from 240vac to 12vdc using the xs 7000 purely as a 12v power supply.
Then the D250S receives the 12vdc exactly the same as it would have via an alternator, boosts the voltage if necessary, then outputs a multi-mode 12vdc charging routine to the batteries.
Nothing complex at all.

The XS 7000 is operating in supply mode so no charging process occurs at this point.

Your analogy re the suspension mod therefore doesn't compare at all.

I only require this process from time to time, basically to apply a maintenance charge to the camper. It is not practical to connect the XS 7000 direct to the batteries as they are enclosed behind a panel.
The connection of the XS 7000 in supply mode is simple, does not impact on the operation of the D250S dc-dc charger and is a sound, practical solution to suit my requirements.

cheers.

Bill if it works for you and you think it is the right way of doing it that's OK.

No need to justify why you have done something the way you have, if your happy with it that's all that matters.

It's fuuny when you try to tell the right way of doing something there always seem to be someone who responds who want's to argue the point...... got to love forums.

In my book there is only 2 ways of doing something.... the right way and the wrong way..... and if you think you way is the right way then it's the right way making my way wrong!

Thanks arjay
Exactly the info I was after. Did a google and found a heap more MW units.
Will order one tonight. Thanks for the detail. Its nice to have first hand experience facts.
Regards Mel