DC-DC Charger installation

[Unkredible]

OK, its a very long subject and there is lots of info on other forums. I am not an electical engineer, but I have read and discussed the issue with one.
In summary, Deep cycle batteries require higher voltage to charge than most alternators supply. Patrol alternator charges at 13.8v which is not enough to properly charge a deep cycle properly. DC-DC systems perform like a C-Tek chargers ensuring that the correct charge cycle is applied.
The charger I am installing charges at 14.2v and 12-13A, and runs a 4 stage 3 level adaptive charge cycle. Aslo switches the fridge to run off the main battery whilst the car is running to ensure that the deep cycle charges optimally (quickly).
I have had too many deep cycles dying after a year because of incorrect charging. Time to upgrade my system.
Not sure if forum rules allow me to put links to other forums, but there is a lot of info out there...

[Grootseun]

Unkredible is youre only getting 13.8v charge on your patrol ill go see my Auto Electrician - you need to see between 13.8 and up to 14.5 some alternators even 14.8
My zd30 runs at 14.4 at idle

[Peter Connan]

Bruce, I am still punting the PBE system.

Yes, I know it is not a step-up system, but it also doesn't lose voltage like the solenoid-based systems. I agree with Driko that your alternator should be producing a little bit more power.

Mine produces around 14.2 Volts, and my PBE system wil easily put 25Amps into the battery in the morning. As I am sure you know, the amperage that actually flows to the second battery is a function of the input voltage and the voltage of the battery, with some effect of the cable resistances. Therefore the charging rate will automatically taper off as the second battery builds charge.

My dad's solenoid-based system struggles to transfer more than 10A even when the second battery is very flat.

Now when you are driving, the fridge is normally running, and thus consuming probably around 5A When running or a longer-term average of 2-4A (depending on how hot it is, fridge set temperature, how often you open it etc.
Which means that with your proposed charger, you are only adding about 10A to the battery. This will mean that, assuming your charger can maintain maximum current irrespective of battery charge level, you will still need around 10 hours to fully charge your battery, which in my opinion is too long.

The PBE system with a starting amperage of 20-25A will get the job done much faster. It also has more protection built-in than most other systems, and it is cheaper, smaller and easier to install. Furthermore, it is very well sealed and thus can be installed in the engine bay.

If however you do decide to stay with a dc-dc solution, choose a bigger charger capable of outputting at least 20A?

[Grant]

Gents,

Still running my 98 model National Luna system and never had a problem. We fitted it was the only available option. Never failed. dc/dc is the future and when my system fails, it will be fitted to my Troll. Currently I can manage the power drawn from by second battery as I have a digital regulator fitted (for solar charging) and all consumption is run through this system. Max draw from my 32lt has never exceeded 3 amp.

This system offer you the visibility of seeing what you are getting and then you can manage what you are using.

http://www.rectifier.co.za/Solar/Steca/Steca%20PR.html






http://www.ctek.nu/int/en/chargers/D250S%20DUAL

[ricster]

Hmmm.... I wanna know more about this..... Grant that day you organised for the trailers and battery systems.... will this type of stuff be discussed??

[tour de frans]

Hello, I am running a Dc to Dc charger. Never looked back so far.
Mine are fitted in the back of the car behind a box that make up part of a drawer system. Cant post pics.
My carravan has a duel battery system. So on tow the dc to dc not only charge the Patrol's 2nd battery, but both the batteries in the carravan to.
I am very pleased with mine.
Rdgs
Frans.

[Unkredible]

Installed my system on the weekend. Managed to fit it under the centre console. Only snag is that my ashtray no longer opens correctly - forgot to check this when I installed, but I may be able to move the unit back by 1 cm to fix the problem. Used 16MM and 6mm wire throughout. Charge voltages much better! and so far, the beer is still cold...
Will post pics once I have permanently wired the battery charge meters...

[AdrianPowrie]

Sounds good Bruce,

Wher did you buy the system and what did it cost if you dont mind me asking?

I need to get something sorted for the beer down to Kosi...

[ricster]

Yeah.... I looked at the c-tec's at the Kumho day on Saturday...... hmmmm not cheap these thingy's.... But I got to do something soon. I'm watching intently for the pics and possibly a step by step for "doffies" like me

[Grant]

Hi Cedric,


Yes they will be their.

Hmmm.... I wanna know more about this..... Grant that day you organised for the trailers and battery systems.... will this type of stuff be discussed??