When charging batteries that are nearly full, you are going to get strange readings, and the high amp charging sources are going to be kind of confused too as voltage will quickly rise and amps taper.
The steel ring terminaled pre made cables are simply horrible. I have, between my shunt and house battery, two 4awg cables in parallel, one was a steel ring terminal store bought cable and the other was one I had crimped on some nice term ring terminals myself.
When I got my clamp on meter I was taking readings in various places, verifying things, checking accuracy, playing with the new toy and when clamping the ammeter over these 2 ground cables together it was reading 4.2 amps, which aligned nicely with my IPN pro remote battery monitor. Whohoo! I then clamped it over only one of the two parallel ground cables, and it was passing 3.6 amps, and the other parallel cable was passing 0.6 amps.
When I cut off the steel ring terminals and crimped on some brass terminals, each 4awg cable then shared the load exactly. And the steel was not all crusty either, I had filed it shiny and the Shunt bolt and battery stud had compressed the ring terminal nicely, there was just excessive resistance in the terminal ends, as the autoparts 4awg cables with steel ring terminals are simply convenient junk!
Crimping quality terminals properly on thicker cables is a whole nother topic, and the quality of the ring terminals available vary from Yugo to Bugatti. Try and find some thick walled tinned copper lugs, but the proper crimping tool and the skills to use it properly are required as well. The hammer crimper, IMO, is not a good low resistance connection, merely a mechanical one prone to failure and heating.
If the terminals are heating up you should be able to feel them with your fingers easily. You can get an IR thermometer gun to check for heat as well. These become very useful for many different things, like checking various areas in the fridge. Just know the laser dot is not the exact point temperature is taken, just a general guideline. Move the gun around the expected heat source to find the hottest spot, and the closer you get it to the source, the better.
you should be taking hydrometer readings often while you figure out where these batteries are and how they respond to your charging sources. Volts and amps readings are not enough, and if there are loads on the system while charging the net current the Trimetric is counting is not going to be the same as what the charging sources are outputting.
