I wouldn't call it the "lap of luxury" ... It is a very comfortable and functional system.Sweet...sounds like the lap of luxury!!Thanks for taking the time to write this up.
dj
Charging LiFePo4 Batteries With Just Solar
- Thread starter GeneraiT001
- Start date
dj
Many boats have only solar as charging, or at least for all practical purposes.
Many multihulls, including my PDQ 34 catamaran, have outboards for power. Mostly we sail, and the engine charging output is trivial. It hardly even counts in the power equation. My trimaran has no engine charging. One the other hand, mutihulls can spread a lot of solar very easily.
No charging on rainy days? True. You plan on it. Turn off the stuff you don't need. Have enough batteries. And have enough solar to recharge in a day or two. In fact, even on rainy days a large array will put out enough for the things that are vital. The rest isn't vital (not all boats even have power, certainly not back in the day).
Nigel said figure on 3 hours of charging, but the industry standard is 5 hours at full rating. 3 hours is VERY conservative in anything but high latitudes off season, which is probably what he was thinking. Yes, winter is a challenge for solar in the UK and in the winter.
Many multihulls, including my PDQ 34 catamaran, have outboards for power. Mostly we sail, and the engine charging output is trivial. It hardly even counts in the power equation. My trimaran has no engine charging. One the other hand, mutihulls can spread a lot of solar very easily.
No charging on rainy days? True. You plan on it. Turn off the stuff you don't need. Have enough batteries. And have enough solar to recharge in a day or two. In fact, even on rainy days a large array will put out enough for the things that are vital. The rest isn't vital (not all boats even have power, certainly not back in the day).
Nigel said figure on 3 hours of charging, but the industry standard is 5 hours at full rating. 3 hours is VERY conservative in anything but high latitudes off season, which is probably what he was thinking. Yes, winter is a challenge for solar in the UK and in the winter.
It is feasible, but if your LFP house bank has the ability to start the engine I would retain that option. Also if you do add an Orion XS 50A DC-DC to charge your LFP from the alternator (set to around 25A for your Hitachi) you can reuse it to charge your start AGM from the house if you upgrade to a high output alternator later. So it won’t be wasted $$. Also the Orion XS may support bidirectional charging soon… the hardware supports it, Victron is working on the firmware…In an effort to avoid all the changes/complications/expense in adding a bigger capacity alternator + external regulator + wiring is it feasible (and sane) to just totally isolate the LiFePo4 batteries from the mix and just have the LiFePo4 isolated for house duty only. This should be easy to do (I think)
Yes for cloudy days a Honda EU1000i pairs nicely with a 50—60A charger, and the Honda EU2200i would support a 100-120A charger. We use our Honda 2200 to charge via a Multiplus 3kVA (120A charger) as a backup.
A good DC-DC charger installed for this purpose should not have a negative effect on the start battery. There should be no charging of the house LFP unless the voltage at the start battery is high enough to prevent any discharge of the start battery.
This shouldn’t be considered a primary source of charging. In this scheme, solar and generator are the primary charge sources, with the alternator supplementing when the engine is running for propulsion. This way there is not appreciable increase in operating cost.
If the alternator is going to be a primary source of charging, then the upgrade to an externally regulated alternator is probably warranted, with all the associated costs.
I have (on the PDQ). Hard tops are handy this way. Lots of room for panels. LED lighting helps a lot. Also not relying on refrigeration all the time. Sometimes we turned a lot of stuff off. Compromises. Just sayin'.
If I had a diesel I would have hooked it up for charging. Obviously. But that wasn't an option. And many days we had no reason to run the engine; starting up for charging would feel wasteful to me.
I agree, your LFP should have the ability to start the engine...
As to the Orion (I'm not familiar with it) - two things:
1) I personally don't like to use new to the market devices - I prefer to use devices that has a history of working well. So for me, the "coming soon" doesn't get me interested. However, if this works well as a DC to DC charger, and fills the need now, it could be part of an upgrade in the future to switch over to use it to charge the LA from the LFP - I assume. Again, I don't know that device. If it can do that it's not a bad option. You are still however, going to eventually go to an externally regulated alternator if a high output alternator is ever on the horizon as it's only a 50 A device. (You did say this - just repeating)
2) You still have the problem of getting the LA fully charged (more later).
I think the Honda's are great! If money is really tight - picking one up may be a really good option to get going.
It's not that a DC to DC charger has a negative effect on the LA battery - its the fact it's really hard to get a LA fully charged to 100% unless you are charging it for a very long time.
I snatched this from BU-403: Charging Lead Acid
Look at the time frames - hours - in the "Topping Charge" regime - this is where you are getting that last 5% or 10% charge into the LA battery. You can't avoid this - the internal resistance of LA batteries rise to where you simply can't push enough current into the battery to achieve 100% charge. When a LA battery is not at 100% charge - it is sulfating. The deeper the discharge state, the faster the sulfation occurs, the deeper into the plates it gets deposited. Equalization will remove sulfation, but it can't remove it from deep within the plates and if you are discharging to below about 75% state of charge, you are depositing deep in the plates.
The sailing community seems to feel that getting 4, 5 or maybe even 8 years out of a LA battery to be "acceptable". However, LA batteries if correctly cared for should get more like 15 years of good service. (I can actually cite internationally accepted consensus standards for this number in addition to personal experience).
LFP battery chemistry is actually revolutionary in sailboat battery systems. Think about it. LFP does not sulfate. They are perfectly happy living their entire lives at some partial state of charge. They do not need to be fully charged - like ever. LFP batteries can absorb charge from very low state of charge to practically a 100% state of charge so any, and all, charging systems you have connected to them pretty much the entire amount of energy you can produce gets dumped into those batteries (yeah, I know, there are some losses and there is a limit to how much current they can take).
Now, take that wonderful ability to not care about being at any partial state of charge and then hook those batteries to your LA batteries via a DC to DC charge system and the LFP will charge those batteries for however long it takes to bring them back to 100% state of charge.
Coming to understand this simple fact is truly a game changer in the way we should be looking at how to run our battery systems once we incorporate LFP into the mix.
dj
The Orion XS is Victrons new(ish) DC-DC. I think its been out for 2 years or so. The bi-directional feature was mentioned last year, but it seems its low priority reading their community forum. It may even be a new hardware version, so I suppose it was a mistake to mention that as a possible feature. But it is very efficient and will network with a Victron battery monitor and/or a GX (Cerbo)
Absolutely if you are letting the start battery get discharged more than a few percent. Then you will need to fully charge it at the proper absorption voltage. But starting typically only use something like 1/10th of an Ah, so it should be fine with the voltage in the mid 13s. Really its not much different than using an ACR.
Really good info on charging lead acid
I think what was posted above is that Calder uses a rule of thumb of 3x the rated panel wattage for Wh/day - not 3hrs of solar charging per day.
That rule of thumb is in the general ballpark for all but the highest latitudes off season.
Mark
We used an EU2000i with our Multiplus and it was screaming at full load at ~90A, and would choke at 100A. Surprising that the extra 200W of the EU2200i gets you to 120A.
A few months of listening to that thing scream at full load had us selling it and installing a 275A alternator. Now we get over twice the charging capacity with 10x less noise.
Mark
Turning off the reefer and freezer during periods of cloudy days is not an option for a live aboard cruising boat. You will have spoiled food in no time.
You either rely on constant reefer/freezer, or you go without. Otherwise, you randomly toss out a lot of money if it is raining, then rebuy again when it is sunny?
Mark
Well we set the input limit to keep it around 1800W. There are other AC loads so, we dont hit 120A charging. Maybe 100-105A. Yes at rated load it is freaking LOUD. We direct the exhaust aft on the swim platform and inside it doesn’t bother us. But I don’t like running it with anyone within 500’. We definitely prefer the 48V 6kW APS for noise, but that was a bit of $$$ for the whole setup.
Sadly it's not quite that simple. There is the issue of self-discharge. A quick search shows the following:
The typical self-discharge rate for a lead-acid battery is 4-6% per month under moderate temperature conditions. This rate is significantly affected by the battery type and storage temperature, with higher temperatures leading to faster discharge.
Temperature: Temperature is the most critical factor. For every 15°F (8°C) increase in temperature, the self-discharge rate roughly doubles. For example, a flooded cell battery might lose 3% per month at 77°F, but up to 24% per month at 122°F.
So lets just say the OP hits the high seas, sails from Newfoundland to the Caribbean - beautiful trip, he makes the trip in two weeks. He's been able to sail the whole trip so he hasn't had to run his engine. Let's say it's been a lovely trip, nice temps, so when he gets to the island of his choice, his lead acid batteries are only about 2% discharged due to the lovely temperatures and trip conditions. He fires up the engine to get into port, used 1% to start, charges that back up so his batteries are sitting at only a 2% discharge state. Not bad. But then he gets invited to visit some amazing places, he locks his boat up and heads out for a week to go enjoy this lovely island. The boat is all locked up, it's the Caribbean so the temperature inside his boat while he's gone for that week runs up to that 122F. So in that week, the battery now drops another 6%, so it's now sitting at an 8% discharge. Here we now need a couple hours at least of charging to bring that battery back up to 100% full charge. This is not a fantastical scenario. Even if he isn't going anywhere, and he just anchors out for a week or longer - He has to contend with the self-discharge fact of LA batteries. I've anchored in beautiful anchorages where I haven't moved my boat for a month or more.
Think about how much discharge the LA batteries would have undergone in say 6 weeks of just hanging out and enjoying where you are...
LFP to the rescue - you have a DC to DC charger connected from the LFP batteries to the LA batteries and that problem goes away - it automatically keeps those LA batteries fully charged. This past summer I was sailing on a friends boat for 2 months. My boat was all buttoned up - I can't even imagine what my LA batteries would have looked like upon returning if they were not being constantly maintained using my LFP house bank...
It's amazing how LFP batteries can reduce or eliminate the craziness of LA batteries on a boat... It really doesn't matter how good your LA batteries are on a boat - LFP batteries are such a game changer - if you can wrap your head around how best to use them...
dj
I haven't lived on land more than a few days at a time since 1989. I think that counts as long-term cruising. On my first boat (a Westsail 32) I mostly charged my batteries off the engine's alternator. That wasn't ideal, but I made it work. I bought my current boat in 1994. I've never owned a generator and I scarcely fire up the engine. Over the years, I have added more and better solar panels. I tried wind for a spell, but it is never worth it - never.
If I'm on the hook for a few days, I'll hang more panels. When sailing, I find it easier to adjust my habits to minimize power usage than it is to try to feed a big appetite. More and more, I see cruisers adding more hardware to produce and store electricity when I think they should be figuring out ways to reduce consumption.
We can run a crew of a half-dozen with six 100-watt panels indefinitely without having to be particularly careful. We can actually get by on just two, unless conditions are poor for a sustained period, but it requires careful budgeting. I have 5 x 200 Ah 24-volt LiFePO4 batteries, so we can go days without charging efficiently before we need to start being careful.
What you are proposing is absolutely reasonable. You didn't say but it sounds like you are assuming a 12-volt system. And, you didn't say but I believe you are at a high latitude. I don't know what your goals are but you must be interested in staying off the grid indefinitely. Broadly, your numbers are reasonable if you don't run a fridge or any other power hippo.
This might help:
I plan on 250 Wh/day per 100-watt panel, on average. We tend to improve on that, averaging about 300 Wh/day across all weather conditions (at mostly lower latitudes) but I like 250 as a good round number for rough planning. It also does a fair job of compensating the for the fact only about half of panels are angled toward the sun at any given moment. It is a good planning number that won't disappoint you.
I don't know your crew size or loads, but if you only have a couple of people on board, you should be able to budget well under 150 Ah/day (assuming 12 volts) and definitely if you are running 24 volts. Those are 1800 and 3600 Wh/day respectively, which is quite generous for a cruising budget. It is definitely reasonable to assume you can cruise within that capacity.
Your 400 Watts of solar will then get you something like 1000 Wh/day on average, pretty safely. That means that your power production will be roughly half of your consumption. If you cut your usage, which is entirely feasible, you can keep your consumption budget within that production capacity.
If you have a 12v 400Ah battery, you can go about 2 days with no charging or about 4 days with normal charging.
I would focus on reducing your consumption. You could add another 200 watts of solar on a boat your size, without too much clutter, but you could also trim that off of your consumption, quite easily.
If I'm on the hook for a few days, I'll hang more panels. When sailing, I find it easier to adjust my habits to minimize power usage than it is to try to feed a big appetite. More and more, I see cruisers adding more hardware to produce and store electricity when I think they should be figuring out ways to reduce consumption.
We can run a crew of a half-dozen with six 100-watt panels indefinitely without having to be particularly careful. We can actually get by on just two, unless conditions are poor for a sustained period, but it requires careful budgeting. I have 5 x 200 Ah 24-volt LiFePO4 batteries, so we can go days without charging efficiently before we need to start being careful.
What you are proposing is absolutely reasonable. You didn't say but it sounds like you are assuming a 12-volt system. And, you didn't say but I believe you are at a high latitude. I don't know what your goals are but you must be interested in staying off the grid indefinitely. Broadly, your numbers are reasonable if you don't run a fridge or any other power hippo.
This might help:
I plan on 250 Wh/day per 100-watt panel, on average. We tend to improve on that, averaging about 300 Wh/day across all weather conditions (at mostly lower latitudes) but I like 250 as a good round number for rough planning. It also does a fair job of compensating the for the fact only about half of panels are angled toward the sun at any given moment. It is a good planning number that won't disappoint you.
I don't know your crew size or loads, but if you only have a couple of people on board, you should be able to budget well under 150 Ah/day (assuming 12 volts) and definitely if you are running 24 volts. Those are 1800 and 3600 Wh/day respectively, which is quite generous for a cruising budget. It is definitely reasonable to assume you can cruise within that capacity.
Your 400 Watts of solar will then get you something like 1000 Wh/day on average, pretty safely. That means that your power production will be roughly half of your consumption. If you cut your usage, which is entirely feasible, you can keep your consumption budget within that production capacity.
If you have a 12v 400Ah battery, you can go about 2 days with no charging or about 4 days with normal charging.
I would focus on reducing your consumption. You could add another 200 watts of solar on a boat your size, without too much clutter, but you could also trim that off of your consumption, quite easily.
The EU2200i costs $1,000. Our Zeus 275A alternator and Balmar 618 regulator also cost $1,000. Another $400 for the pulley conversion kit, and a bit for larger wires. So converting to an HO alternator isn't that much more than the EU2200i. Maybe 50% more, but they really aren't comparable in terms of charging ability, noise, and convenience.
Mark
Perhaps my wording was not as clear as it could have been, but I meant exactly what you said; X hours at 100% panel rating, no credit for other hours. Except the industry standard is 5 hours, not 3 hours. 3 hours is a good fit in the UK and in winter in snowy latitudes (assuming you clear the snow, obviously), but 5 hours works in temperate areas in the warmer seasons, including clouds and rainy days. Winter cruising, running the heat and lights half the night, and with low sun angles and short days, are tough, but how many cruise in the depths of winter? I have on my PDQ, and 3 hours is about right then.
You know, I forget I got my EU2200i on sale so it only cost me something like 1/2 that... If you have to pay full freight - I'm with you.
I do prefer the Wakespeed controller. When I looked at them compared to Balmar there was no contest - the Wakespeed was notably better. I understand there is a new Wakespeed 500 pro or something like that. But in any case, looking at what's currently available is a good idea as things change.
dj
I think most people who do this do not use their AGM start batteries to charge their house bank, they use a DC-DC charger that only charges their house bank when the engine is running and only after their start battery is recharged. Many people used to use an ACR this way when both battery banks were AGM, but LFP batteries need different charging parameters and an ACR does not accommodate the differences. DC-DC chargers are smart enough to accommodate the differences between LA and LFP batteries.
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That's not exactly correct. It will combine batteries any time the voltage is over 13.6v for 30 sec or 13.0v for 90 seconds. It doesn't matter what the source of the power is, charger, alternator, or solar. It will not open the circuit until the voltage reaches 16.0v. While LA batteries are somewhat tolerant of over voltage, LFP batteries are not. Over voltage will damage the battery and may cause the BMS to shut down.
Yes I was looking at Zeus or Wakespeed which is another $500 or so… but you’re right the cost difference isn’t huge in the grand scheme, if you are confident in doing an DIY upgrade. The Honda does have the advantage of being an additional AC power source.