Running a Ctek MSX25 along side the Setec ST20

[graphic1972]

Hi all,

It didn't take me long to realise that the built in charging system in expandas are pretty poor (Setec ST20).
Although I have been happy with everything else the Setec does in 12v power distribution.
I wanted to install something more efficient and powerful for faster charging of the internal battery when on a powered site but I didn't want it to effect or conflict with the installed Setec.

I had already installed a Ctek Dual 250 and was impressed by what it had to offer in size and functionality on the DC to DC side of things, So I decided to install a Ctek MSX25.

After trawling through pages and pages on forums and the interweb
I couldn't find any information on how to stop the Setec from charging the van battery without effecting the 12v distribution.
So I thought I would share with the community my DIY solution which seems to work.
Now bare in mind i'm no electronics expert and please correct me if you are an expert and think this is a bad idea.

I turned off the Setek and unpluged, I also disconnected the battery.
I located the positive wire coming from the Setek to the Battery and cut it. ( white in my case)
I used one side of a 35amp bridge rectifier (Diode) to act as a one way valve. ($4.50 from Jaycar)
I then used thermal paste and bolted it to a heat sink also from Jaycar.
The rectifier was then placed in-between the cut wires with soldered spade connectors making sure it was around the right way allowing 12v from the battery to the Setek but not from the Setek to the battery.
I didn't really know if it was going to get hot or not which is why i opted for a 35amp rectifier and heat sink.
I reconnected everything and power up........All good.
Battery no longer being charged but all of the lights 12v sockets and TV works great.
I then connected the new Ctek MSX25 to the mains and battery and hey presto it charges like a dream and the rectifier stays stone cold.

This solution has worked for me so far and it was pretty simple to install
I hope this helps somebody out who maybe wanting to do the same thing.

Kind regards

Let me know if you want images.

Please seek professional advice if you are unsure.

 

[straydingo]

I'm not a electrical professional or nuthin, so just curious - Why a bridge rectifier instead of just a 'standard' automotive rectifier?
Does a bridge allow a second battery to be installed later in the same manner straight onto the other side of the bridge ?

However, the ST20 provides a 20A charge rate for the battery, whereas the MSX25 is 25A. Is that enough of a charging difference to bother?

 

[graphic1972]

Hi straydingo,
I'm sure an automotive rectifier would do the same job, I liked the one I got from Jaycar as it has a hole in the middle allowing it to be bolted to a heat sink. I'm not sure on reading whether an automotive one would dissipate heat as well. (if any)

The ST20 is a 20A unit but only allows 10A for charging so I actually get a 15A gain.
I also was thinking about the possible addition of the smart pass in the future bringing the total unto 100A i think.

Regards

 

[bigcol]

interesting

 

[straydingo]

The ST20 is a 20A unit but only allows 10A for charging so I actually get a 15A gain.

thanks @graphic1972 , just went trough the manual again - says 20A for "powering the load and charging of batteries" (which was what I had read and remembered) but follows up later with "charging...limit to 10A". Didn't read far enough....

Thinking about the question of dual battery. I think it could work if my diagram is correct. thoughts?

But if running solar also, then a second rectifier would need to be on the RHS with solar on one point and ctek on another to avoid blowing the whole system out?
Edit: or use a Ctek D250s instead of the MSX25. What benefit does the smartpass also have over the D250S alone?

 

[graphic1972]

Hiya,
On reading further the Setek is even lower ...more like 5A in reality :-(
In my situation with only one battery i feel i have found a solid solution.

Setek ST20 deals with the distribution and fuse board for the 12v side.

Ctek D250 looks after the DC to DC side of things (charging the battery in the van from the tow vehicle (at 25A) as well as a solar regulated input for free camping.

Ctek MSX25 for general conditioning and charging of both the van battery and the batteries in the tow vehicle if needed as it has a 6m reach when at a powered site.

But in your case when running 2 or more batteries you would at least need a 40A charger (Redark) its also better to not mix age and type of batteries.

If i were to upgrade to a 2 battery system I would link my batteries in parallel join my D250 to a smart pass and bainbridge fuse box giving 100A and pull out or just disconnect the Setek all together.
A much more powerful, inteligent and efficient system in my humble opinion.

Regards

 

[graphic1972]

Check this out, pretty much sums up the smartpass system.