Just a warning that this isn't about separators clicking. OTOH, it's a kind of natural thread morph...
Hi Bob (and all others too of course),
I helped a friend put in a lithium system over the winter and even though he bought a premium brand (Victron), I was a bit frustrated about the charging guidance (I'm spoiled by the Lifeline Battery Manual which tells you everything, in great detail, complete with graphs and charts - that way if you want to treat your batteries well, all you have to do is follow the guidelines). Oh they had guidance...... but it was different in every place you found it!
I imagine what is "known" is changing, and that must be part of it, but it was still annoying. OTOH as usual their kit is spiffy and nice to work with.
Anyway, my understanding, like yours, is that they don't necessarily "want" to get up to 100% all the time like lead acid batteries prefer. And also, like you say, that the charging is basically bulk right up until it's done (no more sitting in absorb for hours!). My buddy still has a bit of "lead-acid brain," so he bought a larger bank than he probably needed. Thus, he's getting up to 100% fairly often and not discharging very deeply.
Another thing I seemed to notice in my reading is that charging recommendations for this type of lithium bank keep going down (lower bulk ending point, less absorption time, lower voltage float). Also, it has become known that they are rather sensitive to heat (that's older news though).
Between consulting with Victron, and reading what I could find elsewhere, we came up with the plan that he would set his absorb point (i.e. bulk stopping point) to (IIRC), 14.1 or 14.2, and the absorb time for one minute. (i.e. it basically gets to that point and stops). Then, once a month or so, he would let them absorb for a longer time (one or two hours, IIRC). That apparently makes sure all the cells have time to balance (again, lots of IIRC here). Obviously this means that easily adjustable chargers are key. Luckily lots of them are nowadays. He just put a reminder on his calendar.
One thing we found is that a number of chargers (especially shore chargers) don't let you lower the absorb time to basically nothing, even in custom settings. And some "lithium" settings either aren't, or seem to reflect older thinking. It was a bit easier with solar controllers to find ones that would work well. One of the issues for him is that although he had a big Magnum charger/inverter in his last setup (he changed RV's), he found that he's using much less in the way of inverter or big Peukert loads, so didn't really have a need for one. (They may tend to have more adjustability?). So he just wanted a straight shore charger (plus a modified sine wave 1500 watt stand-alone inverter for occasional use). So far there hasn't been a "right sized bear" shore charger in terms of charge settings, so he just bought a Victron portable 15 amp smart charger (he doesn't need a shore charger much) for now, figuring newer chargers would come out in time.
In a way, he doesn't really use the full advantages of lithium, since he basically runs no heavy Peukert loads (even got rid of the microwave on his new rig), and has no plans to run an AC from batteries, or etc. BUT, he has limited real estate for solar panels on the roof, and wanted to get out from under the long absorb time, plus the need to get up to 100% less often is handy. He also of course had to put in a new system on the new RV anyway (it came with two Group 24 flooded batteries, oh boy).
I would have fun setting up a lithium system in my Chinook. But at this point --- somewhat to my annoyance --- I completely don't need it. Reasons:
1) I have 375 amp hours of Lifeline AGM's. I load tested them this May and they are still over 90% health. Guess I should have been rougher on them
2) Although weight reduction is always nice, I really don't need to do that. Mine sit fairly forward, right on the frame rail, and my Concourse is not overweight. I also don't need to remove them on a regular basis (so no need to carry them around).
3) I don't tend to run a lot of heavy/Peukert type loads (no microwave, A/C, etc.). The ones I do run are infrequent and short (heat gun, vacuum, other corded tool), so I just combine and run the engine and/or do it when the batteries are full and the sun is out. No muss.
4) I'm able to get back to 100% most days via solar at this point in time.
I don't set out the list above because I'm refuting your getting them. Not at all! I just noticed some other folks thinking about it and so I thought I'd spell out why I'm not moving to them in my Chinook right now. OTOH, if my AGM's had tested unhealthy? Hmm, well then I'd have a choice on my hands. Still no NEED for ltihium, but I'd be more tempted if I were buying batteries anyway. I have also made sure than any chargers or etc. I buy are suited (not all that say they are, are, I have found -- due to charge setting limitations...)
OTOH, I still get to have fun on another vehicle I have which needs new house type batteries, on which light weight is important, and plus I remove the batteries for storage (oh my aching back). Sorry budget, you're not going to win on that one
BG
PS: Hmm, yeah, interesting thought about whether to connect house and start banks, and how, with lithium house bank. I have been thinking about that for my other (non-Chinook) project. On that one I definitely need to use the alternator (which I most often don't on my Chinook). I think I will probably be going with a Victron Buck Boost. Reason being that not only do I want to "groom" the charging profile (like with other B2B chargers), but I want to be able to limit the amount of current the lithium bank can take. The Buck Boost allows that in a setting (so for example I could only "let it" have 20 amps of charging current, or whatever). This vehicle has a small alternator, and I don't want to worry about a thirsty lithium bank putting too much strain on it. Probably not as much of an issue with a big alternator like we have on the Chinooks (depending on house bank size?). Unfortunately it's expensive due to having other features that I won't need (things like vibrate start for Sprinters vans and stuff). Before I buy I'll see if anything else suits.
I guess my impulse would always be to not connect the stock Chinook/Ford charging system to the house bank unless absolutely necessary. For me that's a few times a year, and I basically use it as "cheap bulk" charging, never expecting it to finish off the charging properly.
With a B2B it's different of course. I haven't really thought about how I would do it then (the friend I helped with the lithium system does not really have vehicle charging because it is a trailer type RV).
