15 year old lithium battery
- Thread starter geem
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GHA
Well-known member
Mine are 13.8v absorption with no duration so goes straight to float which is 13.35v. The mppt voltage bluetoothed to the shunt actually lags the smartshunt voltage a little so will "catch up" when the fridge runs.
vas
Well-known member
hm,
I also go up to 27,7V when charging (13,85V for 4cell banks) there it tapers off, stays on 27V (13,5V ) float for 30mins and then BMS wont let anything in the cells. No current whatsoever.
I also go up to 27,7V when charging (13,85V for 4cell banks) there it tapers off, stays on 27V (13,5V ) float for 30mins and then BMS wont let anything in the cells. No current whatsoever.
GHA
Well-known member
At 13.35v I will have usually round about 250mA going into the LiFePo4, then when the fridge cycles on there will be a draw and the smartsolar MPPT ramps up the current output from the panels to cover that, when the fridge turns off again there is a lag as the smartsolar ramps the current down again over a few minutes.
vas
Well-known member
OK, I get that, so you're happy to have the mppt pumping something to make up for the loss of the fridge cycling and keep them effectively at 98 or so SoC for say an afternoon?
[I'm assuming you reach full charge on a day at midday, not running anything heavy and till the solar goes to sleep, so you have 5-7h fully charged]
thought it was bad practice so unless I do something that triggers a charging cycle, I'll keep them from midday till next morning without any input.
GHA
Well-known member
The voltage is relatively low per cell compared to 3.65v & all the papers & research I've come across seem to be OK with that, as soon as the voltage hits 13.8v it goes down. All "float" does is just mostly keeps up with the house loads apart from a tiny bit out/in as the mppt react slow. Too small to show up on the 0.1% resolution of SOC from the smartshunt. Almost identical setting to Rod Collins 15 year olds & he said just had them 2 years straight on float at 13.5v so seems OK. It's quite tricky as there basically is no data whatsoever, apart from this video now, about running LiFePo4 long term on a boat, not enough time gone by yet.
Update - found this on marineHowTo>
Drop-In LiFePo4- Be an Educated Consumer
Though disagree with the higher charging voltage of 14.2v, 13.8v is into the start of the top knee & very close to full anyway. Nothing much to be gained going higher in the real world with no balancing happening.
Just changed "float" to 13.25v / 3.3125v pc to see what happens.
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Neeves
Well-known member
If you recall I was heavily criticised for running a terrestrial Lithium power station
- Rod is doing the same thing. I'm a pariah - he is to be copied. I'm in no way comparing - just sayingA lot of the data and practices are single data points - because all the experiences are newish and all the installations are different. We are all at different points of the learning curve. Its not ideal - but its what we have.
Rod seems to have something right - its not to say that it can be copied by everyone
Just one example
Are the batteries that he has been using for 15 years exactly the same as batteries now - have there been no developments.....in those ostensibly similar cells. Are the electronics he used 15 years ago, say 20 year old technology, the same as he is using now - has nothing changed?
Jonathan
Sea Change
Well-known member
That's not how I see it. There's absolutely nothing wrong with running a solar/lithium system on land. But I seem to remember that you were weighing in on discussions without being open about that fact, and there are some fundamental differences between a marine system and a terrestrial one.If you recall I was heavily criticised for running a terrestrial Lithium power station
Several posters on here seem to have a bit of a bee in their collective bonnet about lithium, and will peddle easily disproved myths as a way of reassuring themselves that it's not worth the hassle to switch. Such myths include:
- lithium batteries are more expensive
- you'll have to rebuild your entire electrical system from scratch
- your boat will catch fire
- you can only use the 20-80% SOC range so there's barely any advantage over AGM
- you must install a huge inverter and electric galley
- you must install an arch and 1000s of watts of solar
As always happens on these threats, I will now be accused of being a zealot and claiming that lithium is the One True Way and anybody who chooses lead acid is a heathen. Which is nonsense, I still have four large lead acid batteries on my own boat, for engine start, windlass, and a handful of low power domestic circuits. If I wasn't bluewater cruising I might not have bothered to install lithium at all.
GHA
Well-known member
100%!!
But for long term never plugged in cruising it really is impossible to overstate what a complete gamechanger LiFePo4 batteries are compared to lead acid. Life changing.
We got batteries that work, weather forecasts that are available & mostly pretty good, SasPlanet for sat images & charts, dyneema which doesn't break & makes great shackles, anchors which work, even starlink for watching silly cat videos in every anchorage if you want
It's all sooo much easier now
Sea Change
Well-known member
It's worth remembering these things when people mutter about how it was all so much better in the old days!100%!!
But for long term never plugged in cruising it really is impossible to overstate what a complete gamechanger LiFePo4 batteries are compared to lead acid. Life changing.
We got batteries that work, weather forecasts that are available & mostly pretty good, SasPlanet for sat images & charts, dyneema which doesn't break & makes great shackles, anchors which work, even starlink for watching silly cat videos in every anchorage if you want
It's all sooo much easier now
Neeves
Well-known member
And:
They are.....?
I'm testing what is needed for a Lithium house bank to be used on a yacht, I happen to be building it on land as we don't have a yacht, currently - but have the time to try things.
One thing that developed was Sydney's weather over the last fortnight, 13 days of which it rained ever day, we had twice the average rainfall for the period and half the sunlight, average of 2.5 hours vs 5 hrs. It has nothing to do with a terrestrial or marine house bank - but it certainly is not something you can ignore. Noelex who is an expert on these things mentioned he had never known Sydney weather to be as I describe, it last happened in 2022 when the big wet lasted 16 days. My idea of an all electric galley takes a bit of a hit.
I could have waited till we had a new yacht - but then the errors I'm making now might be more critical (if we had relied on an all electric galley).
So tell me - what are the differences with building a Lithium house bank on land and building the same arrangement on a yacht. What have I missed?
What are these fundamental differences.
Jonathan
GHA
Well-known member
Why not go and do your own research, then post it on here with links to the sources.
Neeves
Well-known member
If I knew the answers I would not have posed the questions. But I'm here to learn - from people like.... you.
Jonathan
Sea Change
Well-known member
Fundamentally, it's about the level of redundancy and safety.
If you power your whole boat from lithium, including nav lights, autopilot, AIS, you need to be prepared for what you will do if the system shuts off. Not really a problem in a house, where you are unlikely to hit a reef or be run down by a tanker.
There may be more subtle differences in approach too, e.g. on land you have almost unlimited space for solar, whereas on a boat you are constrained. This will affect the choice of panels and possibly how you arrange them (series vs parallel).
In a house you could sit the whole thing in a shed some distance away, which may lead you to make different choices about safety margins for things like cables and fuses. On a boat it's sensible to take these things extremely seriously.
rogerthebodger
Well-known member
I am also here to learn but its becoming so confusing to me anyway that its all putting me off.
I would love a simple path forward with recommended sources of supply, but it may be too early in the process of development as definable setup
I would love a simple path forward with recommended sources of supply, but it may be too early in the process of development as definable setup
vas
Well-known member
not sure what SC had in mind, but since I'm currently designing a system for my home (in a city, with all services working, so no off-grid) I can list a few:
less limiting setup regarding orientation size and NUMBER of solar panels
mixing/matching production with grid, sending/receiving according to local legislation
EDIT: SC beat me to it
Neeves
Well-known member
If you hit a reef or are run down by a tanker you will have problems within which Lithium will be a minor issue. I think I'm old enough to know of the constraints of space on a yacht. I have noted Geems consistent comment on fuses. I think on a yacht a skipper needs to take everything in terms of safety - very seriously.
As they say here "You are the skipper, your are responsible" - you don't treat anything lightly.
I'm trying to find why building a Lithium house bank on land designed to be used on a yacht has fundamental differences to what I am doing.....so far you 'seem to think' I treat it lightly - and that's the sum total of difference.
My bus bar terminals are all individually covered and each complete bus bar has another cover on top - are yours so well isolated. I have one lead, to the bus bar, from each battery terminal - I take note of Mr Rainbow's comments.
Basically, or (If you like) fundamentally, there is no difference between what I have built so far and a small marine installation and there are no differences (plural). Not entirely true - we have a power lead from the Lithium bank to the kitchen and use the bank to power, as much as we can - the kitchen (or galley in yacht speak).
You surely can do better than that and come up with some real 'differences'
What is interesting is that Rod has been working on his terrestrial system for 15 years and has come to some conclusions, which are widely accepted here (I have no argument with his conclusions, I have no basis to argue). The worry is what else that we think we know - is actually not best practice, Rod has found some areas that contradict what I thought was fundamental, he has found some real differences (on a terrestrial system).
It seems there is still more to learn.
Jonathan
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Sea Change
I misunderstood one of the differences - relying on Lithium to power the yacht systems. We don't have AIS - the dangers on the Australian coast are not large ships but small commercial fishing boats and run-about that don't have AIS - we need to keep an active watch and not rely on electronics. We have always kept a running log and always know where we are, should the GPS fail (one of which is operated on penlight batteries). We carry all the relevant Australian charts and the Admiralty Pilot Books. We have battery operated SW radio from which we can access all the marine weather forecasts. The biggest inconvenience is the loss of autopilot - which would only be relevant in Mid Pacific - but we don't have ambitions in that direction. We are required to carry an EPIRB if offshore. We have battery operated navlights.
I think I know how to deploy an anchor without the windlass (and I have never intended, though that might change) to run the windlass off Lithium
You rightly think we all use yachts like you use yours, you cross the Atlantic - we don't need to lose sight of land, except crossing Bass Strait. - Australia is huge - you could sail round Australia for years and never been in the same anchorage twice. You can sail from the snow covered hills in Tasmania to the tropics in winter - and not need a passport. Different ways to use a yacht, needing different requirements.
Jonathan
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Sea Change
Well-known member
That's a shame. I'll try to boil it down.
LiFePO4 batteries charge faster and last far longer than any type of lead acid. And at today's prices are cheaper than anything other than bargain basement car batteries.
But they have slightly different characteristics. You need to charge them slightly differently (lower voltage, no float period). So you need your charge sources (MPPT, shore power, alternator) to have the right settings for lithium.
They can discharge at high rates, so it's usually necessary to upgrade your master fuse, and possibly some cables, isolator, etc.
They can charge at high rates, which is only a problem for your alternator, which could burn out. Several ways of tackling that, from my approach (just don't connect the alternator to the lithium, and rely on solar only), to the money-no-object option of replacing your alternator entirely.
The other consideration is that because any LiFePO4 battery worth fitting to a yacht should have a BMS (any off the shelf battery will have this inside it) you face the possibility that it could go offline when certain parameters are exceeded. You don't get this with lead acid, your lights just go a bit dimmer and things gradually shut down. Lithium doesn't give you that warning.
If you're using the lithium to power vital circuits like your autopilot, you should think about what happens in the unlikely event that the battery shuts off. If you only use it to power your fridge etc, it's not such a big concern.
As to suppliers... best prices are obtained direct from sellers on Alibaba, which can be a bit intimidating. I looked up reviews on YouTube (Will Prowse) and the DIY Solar forum to find a good supplier. Nobody wants to be the first to buy from somewhere. There are also very active Facebook groups where you will get feedback on this stuff.
It can't be that hard... I managed to build a whole system from scratch with no previous experience...
Sea Change
Well-known member
I'm not sure if you're being deliberately obtuse here. Maybe I wasn't clear enough? If your lithium system goes down on your yacht and you lose your lights, plotter, autopilot, etc, then things could quickly become more serious. You could, worst case, find yourself unlit and with no idea if where you or anybody else are. Which is where the reef, tanker, etc comes in. I was suggesting that these events would be an outcome of battery failure rather than a cause. I hope that is clear enough for you?
If your system fails on land, it's unlikely to lead to further problems, and you can just fix it without worrying about drifting around in an unlit vessel.
It's similar to my attitude to petrol... I'll happily use last year's fuel in my lawnmower but I'd prefer not to use it on my outboard.
A system designed for a yacht will work perfectly well on land, assuming you don't want grid connectivity. But a system optimised for land use may have different choices which don't transfer to use at sea. These have already been spelled out a couple of posts above, by myself and others, but just in case, it would primarily come down to choice/size/layout of the solar panels, because you don't have the same space constraints. A second point would be you safety margins. Absolutely nothing wrong with building to ABYC standards on land, but you could probably save some money if you chose to.