Ctek D250s

Hi Phil,
Thank you for your reply. I'm using the 6B&S cable so I wont get any voltage drop. An auto reset of 50 amps will be fine then.

Cheers Sean

Sean,

Sounds good, though I'd tend to use a fuse rather than an autoreset breaker. Why? If you have a problem the last thing you need is the breaker turning back on unexpectedly! I'd suggest using a 30A fuse, which gives another advantage - you can remove the fuse to ensure that things don't turn on while you are working on the system.

Another point - "I'm using the 6B&S cable so I wont get any voltage drop" ...... not really! There is always some voltage drop, though by using heavy cable as you are, it can be reduced. I'm all in favour of dc-dc chargers and use one myself. They do have one issue though that your heavy cabling should get around. Effectively, they draw extra current to provide an increased voltage, and without heavy cabling the voltage drop must be overcome by even higher current which leads to more voltage drop, calling for higher current still, resulting in more voltage drop, higher current..... you get the picture!!

I agree with Phil that you will probably not draw more than 25A. Something worth checking - can your alternator deal with the extra 25 amps? I've had the experience of 12A for the 3way fridge, plus 40A for a 30A dc-dc charger, plus a few more amps for lights and battery charging, all from a 55A alternator - not recommended, especially when the dc-dc charger draws extra amps as the voltage from the overloaded alternator goes down!

Cheers

John

At the 4wd show today at eastern creek there were dc-dc chargers (by Motson ?) for $89

Gday John and Sean,
Nothing is perfect, so I'd also be wary of the problems with fuses. When mounted close to the battery, the fuseholders can corrode very easily and develop high resistance. So if you are to use a fuse, then mount the fuse away from the battery (like the manufacturers do) with a well insulated cable feeding it. I've seen fuseholders corrode to an unusable state within 2 years. Also if you use a fuse, then use a maxi-fuse rather than the normal blade fuse. I think 30amps might be cutting it fine, which is why I suggest 40+.

Cheers
Phil

Hi everyone,
I have decided to go with a 50amp manual reset circuit breaker. (unless someone can give me a downside?) I think this should be big enough and they are cheaper then a maxi fuse. It also means that if your out in the middle of no where and it trips it can be reset instead of buying or trying to find that spare fuse, and there is nothing worse then thinking you have fixed the short put a new fuse in and bang there goes your only spare.

Cheers Sean

Why do so many harp on with "voltage drop", there are two types of voltage drop.... acceptable and unacceptable.

Voltage drop is usually caused by three issues..... faulty or bad workmanship or people trying to save a few cents...... in most cases it is a combination of two or three out of the three.

Acceptable is up to .3 -.5 of a volt in standard automotive applications unless we are talking 5v transducer outputs.

John :- re your comments about alternators...... alternators also have a duty cycle and most standard automotive ones hate running at maximum capacity for extended periods...... hence why some are starting to go water cooled.

And Phil... you need two circuit protectors, one at the originating feed point and the other at terminating output point.

Hi Olcoolone,
I don't understand what you mean by feed point and terminating output point. Can you please explain.

Cheers Sean

Sean,what i think Olcoolone is saying (and it is aso what I do) is you need the same circuit protection at both ends - on the aux battery as well as the starting battery, because a short anywhere along your 6B&S cable can pull big currrent from either battery. As for the solar panel, it will be hooked directly into the CTek, so you don't need it fused. If your solar panel were to be directly connected to the battery, it is safest to use a fuse.

Hi Phil,
So your saying to connect like this. positive to main bat 30cm away circuit breaker, then cable to Anderson plug at back of car then Anderson on camper then instead of going straight to ctek have another circuit breaker then 30cm of cable to the ctek.
Do i have to do this for the auxiliary battery it will be 30cm away from the ctek can i put a circuit breaker in the middle?

Cheers Sean

Sean,

What Phil and Olcoolone are pointing to is the general rule that every significant power SOURCE should be fused (or circuitbreakered if that's a word!) Any connection to either the main battery or the auxilliary ('house') battery should be fused, since either can source serious current. You don't need a fuse on the input side of the ctek, (other than the one feeding it from the main battery) though there should be one close to the aux battery, which will amount to having one between the ctek output and the battery.

Cheers

John

Sean, i have a 50A auto reset CB next to the battery in the car. The Ctek has an inbuilt battery isolator, so I just ran 6 B&S all the way to the back to the anderson plug on the car. Have not had any problems with the CB.

The camper was wired with 6 B&S, and the builder terminated it with a 30A maxi-fuse. Not quite sure why it's only 30A, but I left it as-is and fed it straight to the Ctek when i installed it. I also have the Smartpass.

I didn't use a fuse between the solar and the Ctek.

The fitting instructions are a bit vague, but I just followed the pictures and the system seems to work okay.