Chinook RV

You really shouldn't have a single alternator charging both engine lead acid and coach lithium batteries, as they want different charging voltages. A standard alternator will have a charge profile for lead acid, of course. The options to do it properly that I've heard of are:

a) Use a Battery-to-Battery (B2B) charger like Blue suggests (I have the Sterling Power 60A B2B myself, meaning it uses a max of 60A off the alternator, which translates to maybe 50-55A to the lithium batteries because of losses due to the device doing its thing),

b) Install a second alternator in the engine compartment that is only for the coach, and has a lithium charging profile or is programmable,

c) I think I've heard of having an alternator with a separate smart charger module that is programmable, though I'm not sure if that allows for just programming the profile or if 2 different outputs can be set (one for lead acid, the other for lithium). Or maybe one alternator with two different charging modules attached to it?

The B2B (or at least any I have looked into) will also isolate house from start bank (power only flows aft). Something like a Blue Sea ACR won't work correctly anymore because it relies on the fact that lead acid batteries sink down below 12.76 volts when not charging as the signal to separate the banks while discharging. Lithium don't do that (voltage stays up). So the B2B can take over that function. Also at least the Victron will (I'm pretty sure but haven't looked at the manual in a while) also let you bypass it momentarily for self jump starting (you could also do that with an Off-1-2 switch).

If I were to install one I think I'd go with 30 amps. It sounds like 60 is fine if BobW is running it, but I'd be a little worried about the alternator. Then too though, I don't rely on the alternator for most of my charging (I have a manual switch now, and don't connect it very often).

I did look into the Sterling 30 amp at one point in time and it had a feature where you could reduce it to half (so 15 amps). Perhaps the 60-amper has that too.

Good point about the isolation. The Sterling Power B2B I have only goes from alternator to coach battery. With it installed you can not jump start the engine battery, unless you add some wiring with a switch to go around the B2B. The Sterling also has the same sort of 10 second delay on starting the engine that the isolator/separator does (no power surges on start), and also only engages as needed (when the alternator/starter battery has high enough voltage, and the coach batteries are low enough to require charging according to the programmable settings).

I was concerned about the 160A alternator as well, though it really shouldn't have had any problems with 60A for B2B and engine/cab using maybe 40-50A in general (unless you add a winch or super-sound-system or something). But since I had the original alternator from 2000 and who knows when it might break and cost a bunch in labor... I just paid for a new 225A alternator at the same time as they replaced spark plugs/coils/wires, and fan belts, because with everything already taken apart they only charged like $30 for labor. The whole thing was just good timing for me, because I had to take it in for the spark plugs due to a loss of power that traced back to one of the plugs (or coils).