Nice, but lifpo4 will as you pull most of the times 1C charging (or more) if not regulated. Which will fry most people alternators, so I would not recommend giving this advice to anybody that has not matched their alternator output to their battery absorption profile. Even so, using elastic 4 stage charging is generally recommended for lithium batteries, and also GEL batteries if you follow the datasheet above it explains why...
Best case scenario you are damaging your cells.
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I've seen the video about Lithium destroying alternators and all I can say that testing on my real truck with my 90A, 120A or 250A alternator that has not been the case at all. There were a few fundamental flaws in the way they did it, and i repeated their tests on my own system on an actual truck without coming close to burning out any of the alternators.
There is a bit of science in my system. The recommended charge current is 20-50A, with a maximum of 100A for my batteries. I have four batteries in parallel, so I am easily within the charging limits. If I had one small battery, then the 200A would exceed the recommend maximum charge current, but the BMS would trip out to proect that, but that may possibly damage the battery long term and worse it would not charge the battery. I've not seen many people who would only fit one battery into a truck, a caravan or camper trailer maybe, and also not many would match that to a 200+A alternator either, very few cars have 200A spare capacity in their alternator. I only fitted the 250A alternator as when driving at night with all the spotlights on, I can draw over 100A and wanted to make sure I was still able to charge the batteries. If you are designing a system, you just need to make sure you don't exceed the battery manufacturers limits.
I also spoke the manufacturers of the batteries, and they said they were designed as plug in replacements, with a proper BMS to manager overcharge/ discharge etc. I'm not sure about other brands but all Lithium systems need a proper BMS to protect them. I've never seen an input into the batteries of more than about 200A, and 200A was only when all the batteries were down to 20%. Normally it starts around 150A, with the current then steadily reducing down to 0A over a few hours of driving. The charge current for mine follows that graph, with the output of the alternator steadily dropping with time. System voltage starts around 13.2V and steadily builds to around 14.1V with 0 current - it is not flat like the graph, but then neither is the Victron Lithium battery charger, the voltage curve is not flat either, the actual voltage steadily rises whist current drops off.
I know that in the old days, the DC-DC chargera were touted as a means of getting maximum charge into a battery quicker, which did make a bit of sense if you were only driving for an hour or two, and had large battery banks but most people didn't use them. These daysa I would use one if I had a small lithium battery bank and a big alternator, but most people on camper trucks have a big battery bank and a small alternator. DC to DC chargers seem to be pretty unreliable bit of kit, so you would need some redundant ones as well. This is understandable as on a big battery bank they would be working to the maximum of their capacity all the time. Very few bits of consumer priced kit are rated for 100% capacity all the time.
I would also hate to limit my charging capacity to 30A or so, that would take forever to charge up 400Ah of batteries, I would need one for each battery.