CTEK D250S DC Charger

Is anyone using the CTEK D250S DC battery charger? I've been researching it and seems like a good solution for running the fridge on DC while traveling and still charge the battery. I'm particularly interested in how you have it wired (location, wire size, etc).

[Bill]

These DC-to-DC chargers are fascinating. We've had some really good discussion on this board, and at least one of our members laid out the cash (they are not cheap) to get one. I'll see if I can find the discussion - or surely somone else will post shortly.

[Aha! It was Dave / Shrimp Burrito. I should have known! http://www.trailmanorowners.com/foru...ad.php?t=10587 ]

In the case of the CTEK, I'm not entirely sure what this particular device is supposed to do. I think the idea is that it would take power coming from the tow vehicle into the TM, and use it to charge the TM battery and run the TM refrig. Since the voltage arriving at the TM is low, due to voltage drop in the long connecting wires, the device must boost the voltage back up to the normal range. If the device is expected to do that, then the first question you would ask is "How low can the incoming voltage go, while still allowing the boost device to work?" Can it work when the incoming voltage drops to 11 volts? 10 volts? 9 volts?

For the CTEK device, this spec is nowhere to be found, either on the web site or in the PDF owner's manuals. So maybe I misunderstand what this device is, and it is not a booster. Can anyone help me out here?

Bill

Bill,
Thanks for the reply. I've read both threads regarding towing with the fridge on.

•Input voltage range: 10V DC - 22V DC
•Output ratings:◦Maximum voltage: 14.4V DC, temperature compensated
◦Maximum amperage: 20A http://www.etrailer.com/p-CTEKD250S.html

After reading and researching this DC/DC charger, I think the way to go is to run a wire from the alternator independent of the bargman. For a 10 meter run (30 ft) they recommend 10mm2 (not sure what AWG that is). http://www.caranda.ro/Manual%20D250S_DUAL.pdf

The other nice thing about it, is that it has 2 DC inputs (TV alternator or battery and solar panel). I'm not suggesting to use it as a solar controller, but if you go this way it will work. So I could hook the solar to it in the campground.

I'm really hoping others that may own one chime in.

[ShrimpBurrito]

Looks interesting. It appears that 10mm2 is about an 8 AWG wire. Not real big, but probably better than what you have now. You can also use the new wire and the Bargman wire in parallel. If you're going to run a new wire, you're probably also going to want to run another ground lead.

If you want to have a more predictable result in determining what size wire you should install, you need to decide how much current you want to have at the battery (and thus drawn by the charger) and try to predict what the resistance will be. If you don't have enough current, you obviously need a bigger wire.

I like my charger, but ever since upgrading to interior LED lights, I monitor our power consumption way less than I used too -- it's really only an issue in the winter when the furnace is running.

Dave

[clan_salmons]

I've been pondering a DC to DC charger for quite a while and haven't had the guts to try it. My alternator is water cooled and virtually inaccessible. My battery is under my drivers seat and almost as inaccessible as the alternator. Either way the wiring would be a pain. But so is arriving at a campground with a dent in my charge.

Regardless, the Ctek model looks interesting. I like the built in MPPT controller. I have had my eye on Sterling Power ProCharge DC to DC charger. Its marine grade IP68 so you could mount it just about anywhere. It has separate charge settings for different types of batteries. Up to 14.8v for wet batteries, but requires 13.3v to kick in.
http://www.sterling-power-usa.com/Pr...lt-12volt.aspx

The Ctek looks like it may provide charge at a lower voltage. I wish they would provide more details on what they can get out of them at various inputs.

Keep us posted on what you decide to do. I may make this my next project after I get my rear view camera installed. Come on spring!

[scrubjaysnest]

Originally Posted by cbossc

Bill,
snip......................................
•Input voltage range: 10V DC - 22V DC
•Output ratings:◦Maximum voltage: 14.4V DC, temperature compensated
◦Maximum amperage: 20A http://www.etrailer.com/p-CTEKD250S.html

A couple of concerns here, 14.4 Vdc will only get the TM batteries to about 80% soc. Second, 20 A - 14.4 A = 5.6 A to charge the battery(s) and also may not be enough. At 14.4Vdc the Norcold draws 14.4 amps.

After reading and researching this DC/DC charger, I think the way to go is to run a wire from the alternator independent of the bargman. For a 10 meter run (30 ft) they recommend 10mm2 (not sure what AWG that is). http://www.caranda.ro/Manual%20D250S_DUAL.pdf

Since we had a 40 ft run from isolator to TM batteries this is what we did with 8 awg wire.

The other nice thing about it, is that it has 2 DC inputs (TV alternator or battery and solar panel). I'm not suggesting to use it as a solar controller, but if you go this way it will work. So I could hook the solar to it in the campground.

I'm really hoping others that may own one chime in.

Again with output limited to 14.4 Vdc you won't reach 100% soc with solar and wet lead acid battery(s). It will be ok with AGM or Gels.

Note: 5 step charging is AD hype there is no such thing, mppt is DC to DC conversion for solar applications so for this device it may be more AD hype.
This maybe the greatest thing since sliced bread but I am always wary of does everything claims.

[clan_salmons]

Originally Posted by scrubjaysnest

A couple of concerns here, 14.4 Vdc will only get the TM batteries to about 80% soc.

Good point. That's one reason I focused on the Sterling. 14.8v is the recommended absorption charge for my Trojans.

Second, 20 A - 14.4 A = 5.6 A to charge the battery(s) and also may not be enough. At 14.4Vdc the Norcold draws 14.4 amps.

I guess it depends on what we are trying to accomplish. I was looking to avoid draining my charged batteries while driving with the frig on. Adding charge wasn't my primary objective, but its a nice option to have in my pocket in case I get stuck in clouds for a week in cold weather.

You know better than I on this one. You are the true road warrior. I'm happy that we got 30 nights in our TM last year.

Note: 5 step charging is AD hype there is no such thing, mppt is DC to DC conversion for solar applications so for this device it may be more AD hype.
This maybe the greatest thing since sliced bread but I am always wary of does everything claims.

Can't argue here. I guess that's why I tend to look at marine sites for ideas. When your rear end depends on your equipment, it needs to be good.

I don't want to hijack this thread about the Ctek equipment, but the DC to DC charging is very interesting.

[Bill]

OK, I'm naturally suspicious of miracle cures, so I went right to the factory and bluntly asked the question.

My question to the factory:

Subject: CTEK D250S. I want to be sure I understand. Can this unit actually boost a low input voltage if needed? For example, if I connect it to a power source that supplies 11 VDC, will the unit boost that voltage into the 14+ VDC range, in order to charge my battery?

And the factory response:

D250S DUAL starts charging the target battery when the supply voltage exceeds 13.1 V for 5 sec (engine on). The charger stops charging the target battery when the supply voltage drops below 12.8 V for 10 sec (engine off). Best regards

In other words, no, it does not boost. It simply waits until the supply voltage (solar or alternator) gets high enough that the supply could begin to push some current into the battery on its own, and then it takes control of the process.

Since it does not boost a low supply voltage, it is not the solution to the problem of low voltage due to voltage drop in the wiring. As Dave / Shrimp Burrito discovered, true DC-to-DC boost chargers are very rare, and this isn't one of them.

Bill

Bill, Thanks much for contacting the factory and getting the "skinny".

I still have a question: If I run, say 6 AWG (or whatever it takes), independent of the bargman, and get a good voltage to this charger (which is installed near the battery), from my alternator, I would think it could charge the TM battery and run the fridge at the same time. The TM battery would actually be running the fridge. On the e-trailer website they have some wiring diagrams that show this. They even have some FAQs that address this.

I'm just trying to figure out the best solution for this "problem". Cath and I are planning to be on the road for about 5-6 months out of the year. We don't want to have to use hook-ups all the time, plan to have 2 Honda EU2000is with us, but want to be able to run the fridge when towing without killing the batteries.

And a note to all: The information I've gleaned from this forum is invaluable. During the past year I've read almost every thread. Thanks to everyone!

[ShrimpBurrito]

I'm sure Bill will respond, but IMHO:

• if your only objective is to run the fridge without draining the battery, you may be able to accomplish that with the stock wiring on your truck, particularly since it has the tow package.
• given your 5-6 month outing, I would personally rather buy a nice battery and solar array setup instead of spending the money I did on the DC/DC charger. That way, you are likely to make the drain on your battery irrelevant, since a good-sized solar array will make up for it. And not only that, you may find that they sufficiently charge your batteries so that you rarely have to use your generators, which would be a huge plus.

That being said, you can definitely add new wire to your truck and TM to provide a healthy charge to the TM batteries while the fridge is running. Someone on this forum ran some heavy welding cable and was getting a very healthy charge to his (4?) batteries on the TM while running the fridge. And he accomplished that only by adding wire, e.g. no DC/DC charger.

Dave