I run two 120 Ah secondary batteries (
https://4x4direct.co.za/deep-cycle-batt ... gKrVfD_BwE)** in my 3.0Di, the diesel Patrol has space in the engine bay for one and the other one sits quite high up in the left rear in the rack system (uses up the wasted space above the solid "pocket type" storage on the left fender side of the load bay against the window). Both batteries are AGM Hybrid GEL batteries in plastic battery boxes and I just used to run it through a NL solenoid charging system and never had issues, even two weeks in the Kgalagadi and Mebuasehube in January last year with temperatures in the 40s and not too much driving. The box in the engine bay is insulated for the heat, 5mm asbestos sheet in bottom and 13mm thick polystyrene on the engine side, of the upright sides.
Some days when we moved camp, we would do maybe 3 hours and some days an hour, some days nothing. One day near the end we did 8 hrs moving from Mebuasehube to Khutse.
I know that after fitting the Madman and finally having a way to measure the standard factory fitted alternator output voltage under load, it was sitting at 14.1v for about 5 or 10 mins and after that would settle at around 13.8 and 13.9v. I also had a 30 amp DC to DC charger lying around and reading its operating instructions, installed it after talking to Tinus about a year ago, and set up its dip switches for a GEL battery, which means its output should be at 14.7 or 14.8v (during ABSORPTION charge cycle) to effectively charge the two batteries. This is not happening. It "absorption charges" at only 14.4v and settles at 14.2v.
When I turn the car off, the battery sits at 12.6v. After running the NL 90lt overnight now while camping in the December heat, it was at 14.4 the next morning with the freezer set at -6C, at times it went as low as 12.2v, but never less. I charged it during the day with panels totalling about 180w, again only getting the batteries to 12.6v, maybe some nice sunny days to 12.8v.
I went out and bought a WRND 20a charger when I got home. I will be fitting this in place of the SDC-1130 DC to DC charger, maybe it is faulty.... (
http://www.mantech.co.za/datasheets/pro ... C-1120.pdf)
I believe the WRND's "learn" what the batteries are and can set themselves up to charge at the correct voltage. I hope so, at least!! Up until now I have been using the standard regulator that came with the solar panels, when charging the batteries with the solar panels, but I am afraid it just does not do the job on a GEL type battery.
I am most definitely not spending the money they want for the Ctech Dual, the 2505 is it? I permanently use a Ctech 5 amp charger when parked at home, also set to "GEL" and "RECON", but the max it settles on at stage 7 or 8 is 12.6v. The fridge freezer stays running in the back of the Patrol all the time. Sometimes I turn of the 220v for it to run off the charging batteries for a few days.
At what voltage is the AGM and or the GEL batteries fully charged and at what voltage should it sit 2 hours after being fully charged, with nothing connected?
PS
** Those two batteries are called 120ah batteries, but someone in the industry told me they are actually only 105ah. They are the same size as other 105ah batteries...