Simple LifePo swap sense check

[Neeves]

Following a recent thread in which I ruled out switching to LifePo I have taken a good look at myself.

I can’t get my head round the technical stuff but then I don’t need a state of the art installation- I don’t need more power, but I am very attracted to the lower weight (our battery box is part of the furniture and the only way I can fit 400+AH of agm is with 2xc.65kg batteries, which are not getting any easier to manhandle) It must of course be safe. Seems to my simple mind I might get away with:

1. Replace 400ah agm service battery with 200ah Renogy drop in LifePo with built in BMS: 12V 200Ah Lithium Iron Phosphate Battery w/ Bluetooth

2. Disconnect alternator feed (via Sterling charge splitter) from service bank and install DCtoDC charger from engine start battery to service battery.

3. Retain 400 watts solar via 2xVictron mppt controllers to LifePo (continuing to use Smartsense?)

4. Adjust charge parameters of Mastervolt Mass Combi smart charger/inverter (non-lfp model) to LifePo manufacturer spec (read something somewhere about switching to one stage rather than 3 stage charging?).

5. Adjust LifePo BMS to 12 - 14.2v range?

6. Install a type t fuse (whatever that is) <7” on consumer side of battery +ve
I am sure it can’t be this easy. But could it. Any complicating factors?

You don't define, fully, what your ambitions are for the switch to LITHIUM. You mention replacing Lead but you don't define what other ambitions you might have, like extending usage of the power for your galley.

You can't really have too much battery capacity, the great thing about LiFePO4 is that it's very happy sitting around partially charged. One caveat is that you do want to get them up to nearly 100% every so often for the balancer to do its job, but that's not a big deal and you'll not really notice any imbalance if you're staying around mid charge anyway.

We started out with 270Ah and ran like that for about two years, doing almost all of our cooking electrically, as well as running the fridge and freezer. We recently increased to 550Ah which lets us get through a few days of dull weather.
We do occasionally still use gas, that's our main backup if the battery is low, rather than engine charging. There's also a couple of meals that better suit gas cooking. But cooking off solar power has slashed our gas use. We're still using the same 2.9kg bottle we bought in April, and we cook onboard every night.

Kelpie started off with 270 amps - but then extended to 550 amps - to get him through a few dull days - but still occasionally uses gas (but also underlines some meals are better cooked on gas anyway). Geem has also extended his house battery bank.

If you want to extend the power available to the galley you will need to incorporate an inverter (maybe something else to drop hints about for Xmas). I might have missed this in your posts. The specification for your inverter needs to extend to what you have and also what you want (1500 watts for hot water) and 2000 watts for an induction hob (though you might find an acceptable hob you can run at 1500 watts). But a 1500 watt inverter will only allow you to use one device at a time......

It depends on your ambitions - but I think you will find your ambitions grow and a 200amp Lithium battery will quickly appear to be too small. I don't have enough experience but I think you will also need a bigger solar array. None of this directly impacts all the foregoing - and you might not find my comments sufficiently credible to act (but I'm simply pointing out what tiers have said, and done). So... you don't need to action anything other than your initial posts - but you might want to bear in mind you might find you need another battery (which wants to be the same size and make as the one your initially buy) and the inverter. (One recommendation suggested not only the same size battery but from the same batch - which seems a difficult one)

You might have followed my thread where I have built a Lithium house bank at home with a solar array on the roof. We don't find a 200 amp battery sufficient. Our 300 watts of solar is more than enough on a sunny Sydney day but get 3 days of overcast and the solar/battery are inadequate. Knowing the weather is going to deteriorate impacts your future (in terms of days) usage - as you simply don't know what solar you you will farm. One, I can assure you - many, might say my set up is 'ideal' and unrealistic for a yacht - which simply reinforces our idea that what it offers is inadequate. We can live with a 1500 watt inverter but will invest, in the fullness of time, with something bigger - not sure how much bigger.

The battery(s) you buy, according to Morgans Cloud, needs hard wired BMS in addition to Blue Tooth and must allow owner 'intervention' - so not simply displaying but allowing manipulation (but this might be standard for any blue tooth enabled BMS - but hard wiring is not provided on all BMS).

I don't know your Victron MPPT controllers, are they compatible with Lithium.

There is some excellent advice on Lithium here on YBW - you are in good hands. Watch for any contradictions - and query them, most, all, of those who have invested in Lithium are very supportive.

Jonathan

 

[stranded]

You don't define, fully, what your ambitions are for the switch to LITHIUM. You mention replacing Lead but you don't define what other ambitions you might have, like extending usage of the power for your galley.

Kelpie started off with 270 amps - but then extended to 550 amps - to get him through a few dull days - but still occasionally uses gas (but also underlines some meals are better cooked on gas anyway). Geem has also extended his house battery bank.

If you want to extend the power available to the galley you will need to incorporate an inverter (maybe something else to drop hints about for Xmas). I might have missed this in your posts. The specification for your inverter needs to extend to what you have and also what you want (1500 watts for hot water) and 2000 watts for an induction hob (though you might find an acceptable hob you can run at 1500 watts). But a 1500 watt inverter will only allow you to use one device at a time......

It depends on your ambitions - but I think you will find your ambitions grow and a 200amp Lithium battery will quickly appear to be too small. I don't have enough experience but I think you will also need a bigger solar array. None of this directly impacts all the foregoing - and you might not find my comments sufficiently credible to act (but I'm simply pointing out what tiers have said, and done). So... you don't need to action anything other than your initial posts - but you might want to bear in mind you might find you need another battery (which wants to be the same size and make as the one your initially buy) and the inverter. (One recommendation suggested not only the same size battery but from the same batch - which seems a difficult one)

You might have followed my thread where I have built a Lithium house bank at home with a solar array on the roof. We don't find a 200 amp battery sufficient. Our 300 watts of solar is more than enough on a sunny Sydney day but get 3 days of overcast and the solar/battery are inadequate. Knowing the weather is going to deteriorate impacts your future (in terms of days) usage - as you simply don't know what solar you you will farm. One, I can assure you - many, might say my set up is 'ideal' and unrealistic for a yacht - which simply reinforces our idea that what it offers is inadequate. We can live with a 1500 watt inverter but will invest, in the fullness of time, with something bigger - not sure how much bigger.

The battery(s) you buy, according to Morgans Cloud, needs hard wired BMS in addition to Blue Tooth and must allow owner 'intervention' - so not simply displaying but allowing manipulation (but this might be standard for any blue tooth enabled BMS - but hard wiring is not provided on all BMS).

I don't know your Victron MPPT controllers, are they compatible with Lithium.

There is some excellent advice on Lithium here on YBW - you are in good hands. Watch for any contradictions - and query them, most, all, of those who have invested in Lithium are very supportive.

Jonathan

Thanks Jonathan. You’ll see from later posts that I have indeed reconsidered how much capacity I need and have plumped for a 460AH battery. That is to give me extended time off grid rather than increasing my daily usage (much!). Our 600W of solar will have to do - don’t know if the mppt controllers have a lithium setting but they are programmable so I should be able to invent one. Then within those constraints we will continue to adapt to what the sun provides - after all, if it’s not shining I don’t go swimming or get sweaty so a shower can wait, and a French press coffee instead of a double espresso is not such a hardship. I love my 4 burner GN Espace stove, so no plan to go electric. All in all our 3kw inverter is sufficient for our needs I think.

Over time I imagine we’ll refine things further, but to start I hope that even our “that’ll do” approach will yield significant improvements.

 

[GHA]

- don’t know if the mppt controllers have a lithium setting but they are programmable so I should be able to invent one.

With 12v LiFePo4 bank I have absorption set to 13.8v , no absorption time so as soon as the voltage hits 13.8v it goes straight to "float" @ 13.3v. This means to solar just averages out at powering house loads, no more charging. Charging up to 13.8v is a little way up the top voltage "knee" so not far off 100% but with the voltage not too high at 3.45v per cell. Important that you have a smartshunt or smartsense so the regulator decisions are based on battery voltage, not regulator voltage.

 

[Neeves]

Over time I imagine we’ll refine things further, but to start I hope that even our “that’ll do” approach will yield significant improvements.

We can go with that, with the caveat we have planned to be wrong.

Jonathan

 

[Pete7]

Unless you have something odd like so

The battery(s) you buy, according to Morgans Cloud, needs hard wired BMS in addition to Blue Tooth and must allow owner 'intervention' - so not simply displaying but allowing manipulation (but this might be standard for any blue tooth enabled BMS - but hard wiring is not provided on all BMS).

Jonathan

Jonathan, this comes from the American Boat and Yacht Council (ABYC) and followed by MC. Despite the formal name ABYC hold no statutory authority. Their guidance is that a BMS should give advance warning of an imminent shutdown. The ABYC guidance is behind a paywall. However, there is an option to register for two weeks for free. Since they have little bearing in the UK and are anti hybrid systems, I chose not to. Equally i didn't renew my membership of MC, preferring an environment were you can question the leader on their "my way or the highway" stance on a number of subjects, anchors in particular.

There are a some key take away's from ABYC. Firstly, they use the word "should" not "shall". Secondly, very few drop in LFP batteries currently have these features. To paraphrase Francis Urquhart, "you might think a deliberate choice of words given some of their membership have vested commercial interests in lithium, I couldn't possibly comment".

So back in the real world what can we achieve with drop in LFP batteries to remove single points of failure? Well, the use of a DC>DC charger can be used to ensure the alternator is kept within safe working limits. Alternatively an external regulator could achieve the same thing, just pricey. To reduce the problem of a BMS shutting down unexpectedly, a second LFP in parallel or a lead acid battery extension could be installed to complement the domestic battery bank ensuring the VHF, lights and chart plotter don't turn off as you enter a strange harbour at night. The Victron DC>DC charger can also be switched instantly via Bluetooth to power supply rather than charger mode, not sure about other makes.

Looks like Stranded plans a mix of gas and electric cooking, a good example of ensuring no single point of failure. He also acknowledges that things might be refined in the future. Indeed mission creep very likely as we found out. All we wanted was an electric kettle, toaster and induction hob in the event of running low on gas.

Pete

 

[Kelpie]

Mission creep is real!
I wanted lithium because I was about to move on to the boat permanently and knew that lead acid was no cost effective over long time periods.
Why replace a £700 set of deep cycle lead acids every 5yrs, when for just over £400 I could assemble a lithium battery which could last 20?

But once I'd set my sights on lithium, I quickly went down the electric galley route. Toaster and air fryer are big hits. Having a 1000w wet and dry vac is great too.

 

[geem]

@Pete7 Re T class fuses, I have noticed a gentle drop in prices post Covid stock issues. Shop around.

In the UK NH00 fuses are about £8. They have the same or higher AIC. I just fitted one instead of a class T on my second lithium battery

 

[geem]

With 12v LiFePo4 bank I have absorption set to 13.8v , no absorption time so as soon as the voltage hits 13.8v it goes straight to "float" @ 13.3v. This means to solar just averages out at powering house loads, no more charging. Charging up to 13.8v is a little way up the top voltage "knee" so not far off 100% but with the voltage not too high at 3.45v per cell. Important that you have a smartshunt or smartsense so the regulator decisions are based on battery voltage, not regulator voltage.

I do it slightly differently. We charge to 3.5v/cell (14v). We then run absorbtion for 30 mins to allow the active balancer time to do some balancing. We then drop the charge to 3.35v/cell (13.4v) float.

 

[lustyd]

Same here, the BMS doesn't kick off a balance until voltage is stable.

 

[GHA]

I do it slightly differently. We charge to 3.5v/cell (14v). We then run absorbtion for 30 mins to allow the active balancer time to do some balancing. We then drop the charge to 3.35v/cell (13.4v) float.

Don't have a bms but closely monitor them. Have a 4 channel opamp in differential being read by ads1115 voltage sensor to keep an eye on things but not fitted at the moment, might make 2 so can measure each individual cell rather than the bus bar joiners.

Just put a fluke multimeter on each cell across the base of the terminals.

Every cell reading exactly the same - 3.315v after nearly a year in full time use, istr top balancing around last xmas/new year .

These things are amazing. Jenny Wu , do love you 415UKP delivered.

https://docantech.en.alibaba.com/pr...l?spm=a2700.shop_plgr.41413.14.6fcb2cfcjfOvJ7

 

[Neeves]

I'm reading the voltage at the shunt and manually not allowing it to exceed 14v. I'm awaiting a new solar controller so am doing this manually. I'm using a 'condemned' built in BMS, no external control, no reading of individual cells, 200a battery. If I'm unable to monitor, when we are not to be at home, I simply disconnect the solars until we return. Clunky - and hopefully it works.

My interpretation is that GHA and, originally, Kelpie did something similarly - clunky. Interesting that GHA has no BMS at all.

Unless you have something odd like so

Jonathan, this comes from the American Boat and Yacht Council (ABYC) and followed by MC. Despite the formal name ABYC hold no statutory authority. Their guidance is that a BMS should give advance warning of an imminent shutdown. The ABYC guidance is behind a paywall. However, there is an option to register for two weeks for free. Since they have little bearing in the UK and are anti hybrid systems, I chose not to. Equally i didn't renew my membership of MC, preferring an environment were you can question the leader on their "my way or the highway" stance on a number of subjects, anchors in particular.

There are a some key take away's from ABYC. Firstly, they use the word "should" not "shall". Secondly, very few drop in LFP batteries currently have these features. To paraphrase Francis Urquhart, "you might think a deliberate choice of words given some of their membership have vested commercial interests in lithium, I couldn't possibly comment".

So back in the real world what can we achieve with drop in LFP batteries to remove single points of failure? Well, the use of a DC>DC charger can be used to ensure the alternator is kept within safe working limits. Alternatively an external regulator could achieve the same thing, just pricey. To reduce the problem of a BMS shutting down unexpectedly, a second LFP in parallel or a lead acid battery extension could be installed to complement the domestic battery bank ensuring the VHF, lights and chart plotter don't turn off as you enter a strange harbour at night. The Victron DC>DC charger can also be switched instantly via Bluetooth to power supply rather than charger mode, not sure about other makes.

Looks like Stranded plans a mix of gas and electric cooking, a good example of ensuring no single point of failure. He also acknowledges that things might be refined in the future. Indeed mission creep very likely as we found out. All we wanted was an electric kettle, toaster and induction hob in the event of running low on gas.

Pete

Thanks Pete.

It is not clear why MC, who seems to be repeating the ABYC, and the ABYC are demanding hard wiring of the BMS and find Blue Tooth, in isolation, unacceptable. There has never been a mention of discomfort to blue tooth here, on YBW (and we have a number of house banks being described). In looking at batteries for sale I commonly see them being promoted with Blue Tooth - but there is never mention of hard wiring (and lots of reputable batteries come from America).

I can see the merit of having advance warning - and Geem in an earlier thread mentioned how he is going to achieve same.

Part of the recommendation is identical to words of warning here - don't use a 'drop in' battery with internal BMS that does not allow owner manipulation.

I have a variety of digital meters through my system all offering volts and all reading, slightly, different. I'm relying on the voltage at the shunt as being indicative of the actual voltage at the battery, as the shunt is the only device directly connected to the battery, and the shunt is then connected to a long bus bar.

Interesting that no-one is charging to 14.2v (which I think is the voltage recommended by NASA for their Lithium Clipper shunt and monitor).

The link to Jenny Wu has been provided in the past - I think by Geem (but you would need to read through lots of threads to find it). I understand she is THE person from whom to buy your cells (for anyone considering building their own battery).

Does Jenny Wu also offer an accepted/recommended BMS? - I have seen them, Chinese sourced, on Alibaba/Aliexpress but without any commendations on YBW.


I made mention that I have read that if you want to increase the size of your battery bank, this refers to Lithium, that you should use the same sized battery (and the battery ideally should come from the same batch (which seems an impossibility). I read this as meaning if you have a 200amp house battery and have 'creep' you should extend with another 200amp battery from the same supplier and not one of 150amp or 2 x 100amp. No-one has commented. This recommendation might be to ensure the battery makers has repeat business - or because it referred to a battery with internal BMS to ensure the 2 BMS were the same. It is common, on YBW at least, to extend the size of your original ideas on a house bank - it merits factoring in when you consider where to locate your original battery, for example Stranded, (that you might then extend with another similarly sized battery).

edit

We have already decided that our 100amp Lithium battery (the hated 'drop in') is not adequate, not only because it is a 'drop in' but because it is too small. For a permanent installation we would want 200amps (and maybe if we had 200 amps - we would want more...... ....)

There is a compromise between the size of the battery bank, the size of your solar display, the amount of charge you develop from that display in your chosen geographic location and the size of your bank balance. Commonly there is a limit to your solar display, you run out of space, and the smaller the display the greater the need for the larger battery bank - all of which needs an increasingly larger bank balance.

We have 300 watts of solar which produces 20/25 amps as a max in Sydney's clear sun. The panels are on the roof of the house and get clear sun, with the panels ideally angled, but after around midday/1pm, the roof is shaded by a huge gum tree. I do not move the panels. But give us a run of inclement weather and we are harvesting 2 amps, max, and a run of inclement weather can be 4 days. Increasing the solar display in a yacht context becomes increasingly difficult - which leaves increasing the battery house bank size (hence our conclusion to increase from a 100a battery bank to 200a).

Some bright spark will suggest my terrestrial testing is totally irrelevant to a yacht application - but they will omit to mention why.

end edit

Jonathan

 

[geem]

Don't have a bms but closely monitor them. Have a 4 channel opamp in differential being read by ads1115 voltage sensor to keep an eye on things but not fitted at the moment, might make 2 so can measure each individual cell rather than the bus bar joiners.

Just put a fluke multimeter on each cell across the base of the terminals.

Every cell reading exactly the same - 3.315v after nearly a year in full time use, istr top balancing around last xmas/new year .

These things are amazing. Jenny Wu , do love you 415UKP delivered.

Jenny Wu Docan Catl 3.2v Lifepo4 310ah For Solar Energy Systems Bicycles Scooters Electric Vehicles From Jenny Wu - Buy Solar Storage Battery,Lifepo4 320ah,Lithium Rv Battery Product on Alibaba.com

At 3.315v they are likely to be the same with no or light load/charge. At close to fully charged, the cells will likely wander a little. I run fairly high loads on my batteries when cooking so the cell Delta can be fairly wide. About once a week or two I allow the cells to hit 3.5v per cell and do a balance. Normally about 10mV delta that is soon sorted out by the active balancer.

 

[stranded]

I do it slightly differently. We charge to 3.5v/cell (14v). We then run absorbtion for 30 mins to allow the active balancer time to do some balancing. We then drop the charge to 3.35v/cell (13.4v) float.

Same here, the BMS doesn't kick off a balance until voltage is stable.

Don't have a bms but closely monitor them. Have a 4 channel opamp in differential being read by ads1115 voltage sensor to keep an eye on things but not fitted at the moment, might make 2 so can measure each individual cell rather than the bus bar joiners.

Just put a fluke multimeter on each cell across the base of the terminals.

Every cell reading exactly the same - 3.315v after nearly a year in full time use, istr top balancing around last xmas/new year .

These things are amazing. Jenny Wu , do love you 415UKP delivered.

https://docantech.en.alibaba.com/pr...l?spm=a2700.shop_plgr.41413.14.6fcb2cfcjfOvJ7

At 3.315v they are likely to be the same with no or light load/charge. At close to fully charged, the cells will likely wander a little. I run fairly high loads on my batteries when cooking so the cell Delta can be fairly wide. About once a week or two I allow the cells to hit 3.5v per cell and do a balance. Normally about 10mV delta that is soon sorted out by the active balancer.

None of this seems to meet my primary condition that a switch to LFP has to be simple. Rather it suggests that I do indeed need a battery management system that I can control, not just monitor, and I don’t have the knowledge to do that. Is this because you lot are battery geeks (meant fondly!), or am I likely to blow up my boat if I don’t get it right - remember, I just want it to do roughly what LifePo4 does, safely, not design the cleverest system in the world.

 

[Kelpie]

None of this seems to meet my primary condition that a switch to LFP has to be simple. Rather it suggests that I do inif youdeed need a battery management system that I can control, not just monitor, and I don’t have the knowledge to do that. Is this because you lot are battery geeks (meant fondly!), or am I likely to blow up my boat if I don’t get it right - remember, I just want it to do roughly what LifePo4 does, safely, not design the cleverest system in the world.

If you buy a half decent drop-in battery, there will be a user configurable BMS inside it, with Bluetooth connectivity.
Ask on here and we'll suggest suitable numbers to set it to. The default settings will also work, you won't actually need to change anything unless there's a good reason.

Changing these settings is basically you choosing how much you want to mollycoddle the battery. Set everything conservatively, and your battery will probably outlive you, but you'll be more at risk of it deciding to go offline.
Set the parameters wider (the default settings are usually like this) and it will stay online as long as possible, but at the cost of battery lifespan, because it'll be spending more time at the extremes of fully charged/discharged, temperature, current flow, etc.
It'll still massively outlast any lead acid battery, even if you don't touch a thing.

 

[Neeves]

I'd go a bit further than Kelpie is suggesting.

Ask before you start.

Define what you actually want the Lithium to do for you - and this thread is part of that. This thread is maybe not giving you all the answers - so raise specific questions.

Then ask for recommendation of what, specifically, you might invest in - and those who have used the kit, the same or similar (based on previous threads) will bend over backwards to offer advice.

This should allow you to hone what you want and allow you to summarise your purchase list - prior to investing.

etc.

I have not been afraid to underline I'm a newbie - I don't mind being thought of as an idiot - but I'm learning. I'm learning from your thread, as will others. That's what PBO is for - though no-one ever predicted that Lithium would overtake anchor threads

Jonathan

 

[lustyd]

None of this seems to meet my primary condition that a switch to LFP has to be simple. Rather it suggests that I do indeed need a battery management system that I can control, not just monitor, and I don’t have the knowledge to do that. Is this because you lot are battery geeks (meant fondly!), or am I likely to blow up my boat if I don’t get it right - remember, I just want it to do roughly what LifePo4 does, safely, not design the cleverest system in the world.

No, the BMS in my Fogstar Drift battery is automatic. It will allow 14.4 volts but cuts the charging before problems occur. The charge sources are set lower to extend life of the battery since it doesn’t need to be full, mine gets to about 98%.
No complexity after the initial setup at all, and we can help with that, just don’t let any charger start without checking its settings.
Even if I’d done nothing it would have been safe, it just might have lasted a few less cycles over the years.

 

[stranded]

OK great - given that for the benefits the actual batteries now look decidedly cheap (don’t often get to say that in a sailing forum) I’m not going to stress about squeezing the last bit of life from it. So the Fogstar Drift 460 left to do its own thing it shall be. I will though definitely be taking you up on the kind offers to help with checking my charging settings before the grand switch on!

 

[lustyd]

So the Fogstar Drift 460 left to do its own thing it shall be.

I suspect the other makes mentioned have a similar BMS. I just keep mentioning them because they are British and they have given excellent support and service. Oh, and they're pretty cheap

 

[stranded]

I suspect the other makes mentioned have a similar BMS. I just keep mentioning them because they are British and they have given excellent support and service. Oh, and they're pretty cheap

Oh, are they cheap - I hadn’t noticed!

See they’ve got a pretty conservative continuous discharge rate - still more than enough for me - presumably that is their choice, to prioritise longevity over absolute performance. But I guess I still need to size cable and fuse for the max 400A rate?

 

[lustyd]

Cheap is all relative, try pricing up Victron to demonstrate to yourself what a bargain they are

That discharge is specced to the BMS. Yes, Class T fuse and cable for something bigger is what I did.

TBS DCM Class-T Fuse Holder M10 (225-400A)

On mine I then connected the Class T fuse holder to one of these for distribution, with the mega fuse leading to main battery switch. The midis are used for MPPT and Eberspacher which are direct connected, and I put two spare midi fuses in there so I can find them easily

Mega-Midi Fuse Box