I have been rethinking the dual battery strategy, there are two options: the direct connect isolator which I have installed or the dc to dc charger ranging from R3000 to R6000 and more for the c-tek one. In the December issue of Drive Out they tested the two systems equally and determined that the dc to dc charger exceeds only after 6 hours of constant driving. It makes sense since the dc to dc are not rated above 30A where a solenoid connect directly and can handle as much as the alternator can output.
Contrary to the December issue of SA4x4 on the trip of the Pajero's and Conquerors the stated that the Pajero has a "smart alternator" and keeps their batteries well charged, while complaining in the same breath that their batteries did not charge well because they were driving slow and rock crawling most of the day. In the tips section the said it is well worth investing in a dc to dc charger because it charges quicker than a direct connection. But their batteries did not charge properly.
So clearly the "smart alternator" and the dc to dc does not work wel together. a dc to dc can charge a more fully than a alternator can since it can bulk charge and float charge, equally I am sure the "smart alternator" can charge the batteries just as well but I believe they were working against each-other.
I believe the best combination would be to install a solenoid with the timing function such as National Luna for about R1000 for the solinoid and then invest in a good 220v charger for when you are at home or camping at a location with 220v. With a combination of possibly solar. My opinion is just after analyzing the results of Drive Out (attached picture), is 10Ah worth an extra R2000?
I have also been thinking that I am sure if i tinkered with a solar controller I would be able to use it for a dc to dc charger since they are much cheaper and both of them do similar jobs of adjusting input wattage to the correct voltage an amperage to charge the battery more efficiently. If one is determined to use a dc to dc.
Please note this in my opinion.
I would love to hear what your opinion is and what setup you installed.