I’m not 100% sure, but it seems to me that both the Multiplus and the Multiplus II are lacking good LifePO4 profiles, while the cheaper Blue Smart IP22 charges do have good (and adjustable) LifePO4 settings. Am I missing something or are the LFP profiles in the Multiplus indeed simplified? And why would that be? 3 examples.
1. You can change the absorption voltage, however, you cannot absorb adaptive and set a tail current for absorption, like in the simple Blue Smart charger. This is not the best way to charge LifePO4.
2. The Multiplus has an repeated absorption interval, which can be changed in days, but cannot be put off. Why, for gods sake? You don’t want to charge LifePO4 if not needed to 100% in a maritime setting.
3. The Multiplus seems to have no Re-bulk setting / Voltage, which triggers another Bulk load when the LifePO4 battery is below a certain treshold. The simple Blue Smart has.
So, in more ways it seems that the Multiplus inverter/charges are not a good choice in a maritime environment as both charger and inverter. While they could have been a perfect charger because of their bigger capacity to charge larger LifePO4 banks.
Am I missing something or is above indeed the case and am I stuck to the more or less cheap but brilliant Blue Smart IP22 loaders?
I’d suggest using VictronConnect’s Demo Library to load a demo product of whichever (MultiPlus-II or MultiPlus, either one) product you’re interested in so that you can see what settings are actually available, as indeed both models are highly capable of charging LFP battery banks!
Ah okay, yeah what’s in there is what’s there. It’s worth noting that you can certainly change Absorption back to adaptive if you want to; switching the “Lithium” switch on does change it to fixed, but you can still change it back, though true - adaptive in this case is based on time in Bulk, not based on tail current.
The repeated absorption is still a thing, yes, I have mine set to 45 days which I believe is the max and meh… doesn’t matter much since it kicks into it every month and a half but does very little, hangs out at 28.4 for while without pushing any appreciable current unless my battery bank was depleted at the time.
There is a Rebulk Voltage Offset in these, you just can’t adjust it independently. For Pb batteries I believe it’s 0.4v below the programmed Float voltage, and LFP 0.1v below the programmed Float voltage, but don’t quote me on that - it’s specified somewhere in the docs, I just don’t recall offhand exactly where.
At the end of the day, the MultiPlus range certainly does just fine. Ideal? Eh… suppose it depends who you ask. After 15-ish years of using LFP batteries in various service modes, personally I think a lot of people worry about it too much. I have a 12-year old Dragonfly 10012 (from before they decided to go with Battle Born as their main brand name) that I’ve beat the absolute bones out of, deliberately abusing it since it was sent to me for testing back then, overcharged it, undercharged it, drained it and let it sit, froze it, threw it, overheated it, and worse (not all at once, of course) and I literally to this day can pull 107Ah out of it at a 10-hr rate so I’m entirely convinced personally that LFP is not nearly the delicate flower of a chemistry as some would still argue.
Thx for your reply Justin. Still, I don’t get it (the Victron philosophy). I get what you are saying. And probably LFP is indeed more stronger than expected, since every cheap Chinese battery also performs and most owners are happy with them. However, since Victron has a lot of knowledge and implemented imho a really good LifePO4 profile with Expert adjustable settings, I still don’t see why they don’t implement that in the far more expensive Multiplus II. I’m aware that I don’t know everything. The more I study LifePO4, the more I see that there is a lot what I still don’t know. However, what I do know is that charging LifePO4 in the right way gives awesome results in the lifetime and health (capacity) of the cells. So a tail current is important for me, since charging with 3.45/cell with the right adaptive settings and the right tail current gives me an almost 100% SOC state of the cell (>99%). There is a lot of proof already that there is no need to go to 3.65, so, when not necessary, why stress the cells? Same for charging once in a time to full SOC by repeated absorption. The simple Blue Smart chargers don’t do this. And are made especially for (sailing) boats, more or less. Where you indeed don’t need that and don’t want that. So, what’s wrong with an expert modus or good LifePO4 profile in the Multiplus too? They already have that knowledge:-) Please use it in the Multiplus too.
Use batteries where the BMS communicates the required charge voltsge and current limits through a GX device to the Multiplus and you do not need to worry about the Multiplus charger settings as it is externally controlled by the BMS. That way, if the battery needs more time in absorption for balancing it can be achieved and if the cells are in balance absorption can be very short based just on tail current.
The lack of eg tail current may well come down to hardware capabilities in the Multiplus so without an updated model this option can not be made available.
Yeah, these are some minor ‘solutions’. However, it seems I’m probably the only one who’s not happy with the LFP profile of these chargers. Like said, the simple Blue Smart chargers seem to be perfect for LFP. With my Multiplus II I’m forced to do concessions regarding absorption time, rebulking and which bothers me most, forced repeated absorption. Like said; it works and for most people it will do. However, coming from a ‘Rolls Royce’ this is a big step back. So I’ve mixed feelings. BTW, does anyone know what tailcurrent will be used by these chargers to end absorption?