I'm fairly far along in my LiFePo4 install on my liveaboard
sailboat, and yet perhaps only half way there at the same time.
My current situation is "horrible" when on multi-day trips. I drag the existing batteries down to 50% twice a day just with basic equipment
, auto pilot, night lights. They were here when I bought it and I don't think they are in great condition, so am always monitoring them and running the engine
for two hours in morning and evening to compensate.
What's done so far:
- replaced 1500W 20gal hot water heater
with isotemp 750W 11gal, and re-wired to allow both shore and inverter
powered use, also now heats via diesel
hydronic exchange (cabin heater) in addition to engine
- new Magnum Energy 2000watt inverter
, 100 amp charger, ARC50 remote
and battery monitor
- Electromaxx 160amp alternator with serpentine belts and MC-614 regulator
- 420W (3x140W) solar on top of bimini
arch, with Tristar 45amp MPPT
- Aquair 100 towed generator
with D2B regulator
(the D2B is new this year, it has dump loads and doesn't constantly connect/disconnect the generator)
- Duocharge to maintain start battery from house bank, all charge and load sources wired to house bank, starter still wired to start battery. New battery switch on/off/combine, don't need to twiddle with it 8x a day now.
- internal and external lights to LEDs (god what a savings that was for external lights)
What remains is that I haven't actually put the new batteries into this system yet, it's all still hooked up to 2 FLA 4Ds and a group 27. So far its felt like nothing has changed except my wallet ;-)
I have 5 100ah GBS 12V packs from elite power, and the accompanying balance boards and battery monitor
(this is separate from the magnum monitor).
Everyone here seems to favor CALB, and even though it's a bit late for me, I wouldn't mind any major reasons why. I would have definitely preferred the lower CALB pricing than elite power's mark up. I almost went the direct from china route
for GBS, but wasn't willing to risk it. It also wasn't significant given the total cost of this multi-month project
, the cells are a small part.
Here is my new charging settings for the above equipment, once the Li go in, and is what I'm largely writing this for... as well as any other feedback you may want to add.
- LVCO to 12.9 (to turn inverter off), for charging set to do absorption at 13.8V and hold for 30 minutes, then turn off until bank falls to 13.0V and restart. Float is set to 13.2V but never happens automatically (Silent final charge mode on the magnum).
- 14.1V bulk, 13.9V absorption, 13.2V float, belt load manager to reduce field by 15%, bulk->absorb field threshold at 90%, float<->absorb at 80%, 14.4V max voltage, 14.3V temp limit, temp compensation turned off, reduce minimum times per stage from 18 mins to 6 mins
- temp sensor
on the frame
- Maine/T1 I think have referenced lower settings on the MC-614 but the manual says 14.1 and 13.9 are the minimums for bulk/absorb. Does it actually let you go lower (I haven't tried yet)? I'm probably going to keep it here anyway, because it will better fit the AGM's profile just after starting the engine, and is still within the Li range.
- Absorption until 13.8V then hold for 45 mins, float at 13.2V, equalize at 14.16V every 5 days for 15 mins
- When at the dock most of the time, shore power/magnum charger will mostly do nothing, as solar will top it off each day and the daily loads will not draw it down to the 13.0V level for the magnum to kick off a charge cycle. The magnum is there as a safety
net against the solar not keeping up. My daily load at the dock is around 40 amp-hours (half fridge).
- The magnum and elite battery monitors need periodic topping above 14.08V to reset to 100% SOC, also the balance boards kick in at 3.55V or 14.2V, 14.16V is 3.54V so may cause a few boards to kick in if they are a little uneven (yes i know the error in the equipment makes this a bit moot)
- 13.8V max charge voltage, equalization
pulses periodically for 1 second (not configurable). equalization
mode is max current for 1 second, the towed generator
puts outs 40-60W sailing, its a 100W generator.
- This is a weird charge controller, its highly variable on voltage, on the premise that its less stressful to the battery. Given that its only used on multi-day trips and that I don't think the voltage will be able to rise much with 60W for 1 second, I'm thinking this is good, but it's probably the most questionable part of this whole setup.
- Forwards current from house to start when input voltage is 13.6V to 14.3V. My new starter battery is a mastervolt AGM
(14.2V absorb, 13.8V float)
- This range means the start battery is only linked to the house at the very peak of charging and during the absorption hold period. It will also get the ~once a week equalization charge from solar at 14.16V
- Everything has temp compensation off, except for the duo which does have a temp sensor
on the AGM
start battery. Even without it, at these settings, I figure I'm good until about 95F, which in the seattle
area is pretty rare
- The elite power bms will be connected to two EV200s one for charge and one for load sources (for high voltage and low voltage bms alarms)
- The magnum inverter-charger will be on the charge side. My thinking is that the magnum has its own low voltage cut off (LVCO) at 12.9, and the only thing I'll even be inverting at measurable load away from the dock is the water heater
which I'll be manually turning on/off anyhow. So better to have it be on the charge side, where I may not be on the boat at all and need it cut out.
- I'm not currently planning on doing long parallel strings of cells, as the balance boards won't connect to the bms easily then. So will instead have 5 parallel 12V batteries, each a series of 4 cells (which is also how they were shipped to me, so is easier). I expect a few here may advise against that, but I'm hoping at just 20 cells, keeping them in balance won't be much of an issue. Obviously if I observe that not working well then I'll revisit this and repack into 4 series of 5 paralleled cells.
- Also, I don't really know how to rewire that properly anyway, with proper fusing throughout the big cell block, so if someone wants to comment that be nice. I've seen various wiring
diagrams and its not clear to me what makes one version better/safer than the others. I've been meaning to look into the EV forums
as I'm sure they have this better documented.
- No floating at night, pure discharge
- 13.2 floating during the day from solar, with a daily charge cycle in the morning/noon at 13.8
- inverter-charger as backup charge source when on shore power
- my daily cycle at the dock (90% of the year) will be 90-100% SOC
- when away from shore, my loads will be closer to 150amp-hours/day, my goal was to be able to go several days without sun or engine runs. i can reduce consumption
if needed as well.
All this yields long life yes? Hope so.
Areas I'm concerned about
- cell arrangement (4S5P vs 5P4S)
- D2B regulator's variable voltage, and its equalization mode
- use of AGM start battery mixed with Li house
BTW, thanks for reading if you got this far.