Charging lithium battery

[vas]

Poey & others,
interesting discussion, however noone seems to be aware that lifepo4 (or anyother battery tech for that mater) doesn't work in a vaccum!
I mean, whilst the sun is out and your panels through your MPPT(s) charge your bank, you also unfortunately have LOADS working on them batteries. a fridge? lights/plotter/a/p? freshwater pump, a second fridge?

How does that affect charging voltage?
How/who takes care for compensating for that?

I mean the 13.whatever Sterling believes is safe, may actually be if you have 4A constant draw at the same time. Will be off the wall if not (at a guess)
So issue much more complex than that, imho - ready to be corrected as always!

V.

 

[Poey50]

Poey & others,
interesting discussion, however noone seems to be aware that lifepo4 (or anyother battery tech for that mater) doesn't work in a vaccum!
I mean, whilst the sun is out and your panels through your MPPT(s) charge your bank, you also unfortunately have LOADS working on them batteries. a fridge? lights/plotter/a/p? freshwater pump, a second fridge?

How does that affect charging voltage?
How/who takes care for compensating for that?

I mean the 13.whatever Sterling believes is safe, may actually be if you have 4A constant draw at the same time. Will be off the wall if not (at a guess)
So issue much more complex than that, imho - ready to be corrected as always!

V.

Yes, of course. You need to make allowance for loads - indeed you can add loads as another lever to reduce power if spending a day trying to get back to balance. And I suspect that Sterling gets away with the ludicrous 13.8 volt 'float' setting since the loads will reduce the voltage down from that insane level.

 

[vas]

Yes, of course. You need to make allowance for loads - indeed you can add loads as another lever to reduce power if spending a day trying to get back to balance. And I suspect that Sterling gets away with the ludicrous 13.8 volt 'float' setting since the loads will reduce the voltage down from that insane level.

which means that having a fridge on or something would be beneficial in silly charging voltages pity sun doesn't always play ball and even down here you have to turn off fridge for a few weeks with p!ss poor weather and half dead FLA batteries...

 

[Travelling Westerly]

Yes, of course. You need to make allowance for loads - indeed you can add loads as another lever to reduce power if spending a day trying to get back to balance. And I suspect that Sterling gets away with the ludicrous 13.8 volt 'float' setting since the loads will reduce the voltage down from that insane level.

Agreed, I've already been doing that whilst mains charging. I turned the current down from 50ah to 25ah and found putting all the lights, fridges and radios etc helped reduce the actual current in as well. Boat looks like Blackpool illuminations when I do this lol.

The solar input is kind of negligible at the moment versus my daily draw, its when I turn on the phoenix mains charger is when I'm seeing the runner/balance issue. I'm going to check out the garage videos you said about when he tested the BMS. The only thing I noticed about him was he rubbished Daly in one video but then talked them back up when somebody pointed out his testing or operation was flawed. After that I lost a bit of confidence in him. May be give him another go if you think he knows what he's talking about.

Thanks for elaborating on the balancing bit. I'm going to change the balance set points as Pete suggested

 

[Travelling Westerly]

This was particularly brought home to me by an Off-Grid Garage video when Andy tried out one of the new Heltec active balancers. This balances continuously and he was thrilled to find all his cells closely in balance. However once he charged to full everything was out of sorts - balanced cells at partial charge does not equal top balancing.

This makes a lot of sense to me as I've spent hours watching the BMS and Victron screens during charging.
With the balancing set up to work at the start of charging, the cells are very balanced - circa 0.001v between them. This rapidly changes when the SOC gets around 98%, that's when the cell DV takes off. Interestingly it's not the same cell each time?

 

[Pete7]

Pete, Poey

Thanks for the responses.

I think you have nailed it on the head re the 3 issues and I was thinking around those lines too, 30ma balance, bulk voltage too high and 2nd battery has only had 2 cycles so far.

I think I'm going to lower the all of my Victron chargers to bulk 13.8v and floats to 13.5v, as you both suggest. I assume these set points should be used on all 3 chargers, do you agree? I can't see any reason why not but worth getting some other thoughts. The 3 chargers are all fully customised, Victron units, Phoenix smart 50A 3 way, 100/20 MPPT & 30A B2B. The BMV 712 smart is networking to them providing a voltage reading from the lifepo4 terminals which takes into account any voltage drops in the wiring from the charge sources.
Looking at some voltage V SOC charts from Will Prouse, 13.8v is around 99.5%, 3.45v per cell (for a 12v set up).
I'm using a 6% tail current set point, do you agree with that for 240Ah pack? That was not a finger in the air, it was suggested on the DIY solar forum. Seems a common question asked on there too.

Interesting subject these Lifepo4 batteries, it's changed my liveaboard experience for the better. I'm using an induction hob for cooking etc (another 120ah pack to be ordered as I feel 240a is to small)

The Victron chargers have a "save" setting top right on the screen which you then name it and can "copy and paste" across different chargers. Haven't actually used it yet, but saw Andy on Off Grid Garage do it and thought that's useful. I have the Victron B2B charger set higher to thumb the watts in and then when it approaches full turn it off and let the solar take over again. We have tested it a couple of times but only needed to use it for real twice during the summer in the rain whilst motor sailing.

Can't remember what I did about the tail current, thought it was a measurement of Amps rather than a percentage.

Please stop buying all the Sterling 120 LFPs, I would like another too

The 30ma thing I picked up from Andy's Garage in one of his tests on the Daly BMS. This is for BMS's up to 150A but the larger 200A plus have a higher balance setting.

 

[Travelling Westerly]

I better get that last 120 in quick then

 

[Pete7]

This makes a lot of sense to me as I've spent hours watching the BMS and Victron screens during charging.
With the balancing set up to work at the start of charging, the cells are very balanced - circa 0.001v between them. This rapidly changes when the SOC gets around 98%, that's when the cell DV takes off. Interestingly it's not the same cell each time?

Mine is the same, since I don't really want to go to 100% each time preferring longer battery life over achieving the maximum charge I am not too worried about achieving the last bit each time.

 

[mattonthesea]

I think it is partly that LFP is not yet ready for the average sailor and partly that that the average sailor is not yet ready for LFP. There is a lot to unlearn about lead acid to return oneself to a state of ignorance to then have a blank sheet for learning about the needs of this new and alien chemistry.

Totally agree. I have been looking at lifepo for a while, getting ready for when my LAs die. I do not trust my skills to build from scratch, nor ability to check quality of cell build, so I would want to buy a battery ready made. However, the texts have scared me when reading that authors have come across BMS with limited cut out facilities. If I could buy a set of cells in a box and fit that to a sensible designed system including BMS and diodes etc. But at the moment, everyone seems to be saying about everyone else: you don't want to be doing it like that!

We all start as cowboys, and then we develop professionalism. Are we half way down this path? How can I unlearn LA? Answers on a postcard

 

[Richard10002]

However, the texts have scared me when reading that authors have come across BMS with limited cut out facilities. If I could buy a set of cells in a box and fit that to a sensible designed system including BMS and diodes etc. But at the moment, everyone seems to be saying about everyone else: you don't want to be doing it like that!

If you watch Will Prowse tear down videos, you will see that the drop in, ready made 12v Li batteries are usually actually, a set of cells in a box, with a bms and some wires.

The fact is that you don't know what kind of cells and electronics are in the box you buy, so you might get some good stuff, (I think Victron use Winston cells), or some crap stuff.

I'm sure you can buy individual cells with the bars to join them in 4's, to make a 12v unit, then add a BMS, and Bob's your Uncle - easy for me to say
I was going to buy from a company in Prague before I discovered the second hand Valences that I have.

 

[steveallan]

Question for those with Sterling LFPs. Is it possible to access the battery internals without damaging the case?

 

[Poey50]

Totally agree. I have been looking at lifepo for a while, getting ready for when my LAs die. I do not trust my skills to build from scratch, nor ability to check quality of cell build, so I would want to buy a battery ready made. However, the texts have scared me when reading that authors have come across BMS with limited cut out facilities. If I could buy a set of cells in a box and fit that to a sensible designed system including BMS and diodes etc. But at the moment, everyone seems to be saying about everyone else: you don't want to be doing it like that!
We all start as cowboys, and then we develop professionalism. Are we half way down this path? How can I unlearn LA? Answers on a postcard

I try not to encourage anyone to swap to LFP and, if reliable information discourages anyone, that too is a good result. Lead acid - because of its ability to take some neglect and abuse - is still an excellent option for many boaters. OK, they may need to change their batteries more frequently than those who know how to take the best care of them but they are not likely to ruin a thousand pounds worth or more of investment or leave themselves stranded in a shipping lane at night with no power and a battery that won't talk to them.

But for those who can make good use of LFP the notion that the problems of constructing a safe system are partially solved by buying something off-the-shelf - a 'drop-in battery' - is wrong. What you are paying for is a plastic case and a few connections that are impossible to inspect, cabling size on trust, and often a cheap BMS that all the current runs through. Constructing an LFP pack from raw cells is not difficult - see the whole series of Will Prowse videos on this - what is tricky is devising a safe system of which the pack itself is just one part. Even buying the pre-packaged case, you still have to devise the remainder of the system so why not do it all?. And when it comes to design, the drop-in limits the range of safe possibilities for marine use - separating loads and charging circuits for example. And you have to take a lot on trust. Not every seller of LFP drop-ins know what they are talking about - they import from China get a label slapped on with dubious advice and reap the profit. In another thread I posted some dialogue I had with SVB who couldn't answer my question and had to ask their importer who was just as clueless. And some companies closer to home seem also to be nearer the clueless end of the spectrum.

Alongside the considerable cost savings and the ability to build a safer system a good argument for DIY systems is that, along the way, you acquire knowledge of LFP and, in particular, how it is different to lead acid. Drop-ins offer an implicit promise that you don't need to bother with all that tricky stuff too much - the battery will take care of it. This is false thinking, I believe. On another forum it became apparent that among those who had bought expensive drop-ins were people who had no idea that higher temperature shortens life or that holding an LFP pack at full charge was a bad thing.

For anyone interested in taking things further then the opening page of the long DIY thread is linked in my signature and this contains essential reading from Nordkyn Design and Marine How To. Read all those multiple times, watch the Will Prowse videos, obsessively follow the DIY Solar Forum and the Lithium Batteries on a Boat Facebook Group until you really get a sense of what a conversion involves.

Happy Christmas by the way!

 

[mattonthesea]

I try not to encourage anyone to swap to LFP and, if reliable information discourages anyone, that too is a good result. Lead acid - because of its ability to take some neglect and abuse - is still an excellent option for many boaters. OK, they may need to change their batteries more frequently than those who know how to take the best care of them but they are not likely to ruin a thousand pounds worth or more of investment or leave themselves stranded in a shipping lane at night with no power and a battery that won't talk to them.

But for those who can make good use of LFP the notion that the problems of constructing a safe system are partially solved by buying something off-the-shelf - a 'drop-in battery' - is wrong. What you are paying for is a plastic case and a few connections that are impossible to inspect, cabling size on trust, and often a cheap BMS that all the current runs through. Constructing an LFP pack from raw cells is not difficult - see the whole series of Will Prowse videos on this - what is tricky is devising a safe system of which the pack itself is just one part. Even buying the pre-packaged case, you still have to devise the remainder of the system so why not do it all?. And when it comes to design, the drop-in limits the range of safe possibilities for marine use - separating loads and charging circuits for example. And you have to take a lot on trust. Not every seller of LFP drop-ins know what they are talking about - they import from China get a label slapped on with dubious advice and reap the profit. In another thread I posted some dialogue I had with SVB who couldn't answer my question and had to ask their importer who was just as clueless. And some companies closer to home seem also to be nearer the clueless end of the spectrum.

I think the main argument for DIY systems is that, along the way, you acquire knowledge of LFP and, in particular, how it is different to lead acid. Drop-ins offer an implicit promise that you don't need to bother with all that tricky stuff too much - the battery will take care of it. This is the bigger problem, I believe. On another forum it became apparent that among those who had bought expensive drop-ins were people who had no idea that higher temperature shortens life or that holding an LFP pack at full charge was a bad thing.

For anyone interested in taking things further then the opening page of the long DIY thread is linked in my signature and this contains essential reading from Nordkyn Design and Marine How To. Read all those multiple times, watch the Will Prowse videos, obsessively follow the DIY Solar Forum and the Lithium Batteries on a Boat Facebook Group until you really get a sense of what a conversion involves.

Happy Christmas by the way!

Thanks Poey
That pretty much sums up my progress/thoughts, especially dodgy wiring. I'll follow up your links -I think I've read Nordkyn - for interest as much as anything. Since I first looked at lifepo my plans have changed and I only live onboard for three months at a time so needs have changed.

Happy Bah Humbug ?

 

[Travelling Westerly]

Question for those with Sterling LFPs. Is it possible to access the battery internals without damaging the case?

Nope, well I haven't had a go because it works and comes with a 5 year warranty which I want to keep intact.

 

[Travelling Westerly]

I try not to encourage anyone to swap to LFP and, if reliable information discourages anyone, that too is a good result. Lead acid - because of its ability to take some neglect and abuse - is still an excellent option for many boaters. OK, they may need to change their batteries more frequently than those who know how to take the best care of them but they are not likely to ruin a thousand pounds worth or more of investment or leave themselves stranded in a shipping lane at night with no power and a battery that won't talk to them.

But for those who can make good use of LFP the notion that the problems of constructing a safe system are partially solved by buying something off-the-shelf - a 'drop-in battery' - is wrong. What you are paying for is a plastic case and a few connections that are impossible to inspect, cabling size on trust, and often a cheap BMS that all the current runs through. Constructing an LFP pack from raw cells is not difficult - see the whole series of Will Prowse videos on this - what is tricky is devising a safe system of which the pack itself is just one part. Even buying the pre-packaged case, you still have to devise the remainder of the system so why not do it all?. And when it comes to design, the drop-in limits the range of safe possibilities for marine use - separating loads and charging circuits for example. And you have to take a lot on trust. Not every seller of LFP drop-ins know what they are talking about - they import from China get a label slapped on with dubious advice and reap the profit. In another thread I posted some dialogue I had with SVB who couldn't answer my question and had to ask their importer who was just as clueless. And some companies closer to home seem also to be nearer the clueless end of the spectrum.

Alongside the considerable cost savings and the ability to build a safer system a good argument for DIY systems is that, along the way, you acquire knowledge of LFP and, in particular, how it is different to lead acid. Drop-ins offer an implicit promise that you don't need to bother with all that tricky stuff too much - the battery will take care of it. This is false thinking, I believe. On another forum it became apparent that among those who had bought expensive drop-ins were people who had no idea that higher temperature shortens life or that holding an LFP pack at full charge was a bad thing.

For anyone interested in taking things further then the opening page of the long DIY thread is linked in my signature and this contains essential reading from Nordkyn Design and Marine How To. Read all those multiple times, watch the Will Prowse videos, obsessively follow the DIY Solar Forum and the Lithium Batteries on a Boat Facebook Group until you really get a sense of what a conversion involves.

Happy Christmas by the way!

I agree with all of this except 1 big factor that may be an issue and that's insurance. Sure its not rocket science building your own Lifepo4 and totally agree you will learn a lot during the build but, my Lifepo4 units come CE marked and should there ever be an issue with them resulting in an insurance claim, I hopefully won't find myself explaining my technical qualifications etc that allowed me to make and install a home brew battery.
You will save money making your own but that, for me, doesn't matter. I prefer a professional made commercial unit. Sure there will be a load of follow up comments about what is a professional made commercial unit and for me that's a CE marked Sterling stamped LFP.
That's my personal view, as I say there will probably be some posts going the other way but that's their view, horses for courses

 

[Poey50]

I agree with all of this except 1 big factor that may be an issue and that's insurance. Sure its not rocket science building your own Lifepo4 and totally agree you will learn a lot during the build but, my Lifepo4 units come CE marked and should there ever be an issue with them resulting in an insurance claim, I hopefully won't find myself explaining my technical qualifications etc that allowed me to make and install a home brew battery.
You will save money making your own but that, for me, doesn't matter. I prefer a professional made commercial unit. Sure there will be a load of follow up comments about what is a professional made commercial unit and for me that's a CE marked Sterling stamped LFP.
That's my personal view, as I say there will probably be some posts going the other way but that's their view, horses for courses

It's not my intention to criticise those who have gone the drop-in route and will, along with others certainly try to add to the pool of information to help those who have, but I'm aware that these threads have many readers some of whom may be on the brink of deciding which way to go with an LFP installation so I think it important to provide fair information for an informed choice.

Insurance is an important issue. I am aware of one UK insurance company - Topsail - immediately terminating insurance on the basis of being informed of a change to LFP. They weren't interested in any details. Other companies, including mine, seem not to have developed a position on LFP as it is still quite new in the UK.

As far as I understand it, stand-alone lithium batteries or cells may not require CE marking. However, products that contain lithium batteries might be covered by one or more CE directives such as the EMC Directive, RoHS Directive, Radio Equipment Directive or others. Winston Thundersky cells as imported by GWL have CE certificates. Mine imported direct from RJ Lithium have various international certificates of compliance including a CE mark although, regrettably, CE on Chinese goods often only means Chinese Export and the letters are made similar to the European mark as an attempt to con - Chinese trading ethics sometimes veering toward the dubious. My BMS and bistable relays purchased in Europe are all CE marked.

Purchasers do need to be aware of emerging installation standards since these are likely to form a benchmark for surveyors and therefore insurers. The US is ahead of things here by way of the ABYC which has recently issued technical guidance TE13, which is very likely to form the eventual standard there and may prove influential here since authorities often copy each other. Two issues are particularly relevant - the proposed requirement for Class T main fuses (to manage the enormous power that LFP can pour into a dead short) and the proposed requirement for a system to provide audible and visual warnings prior to a BMS disconnect*. My DIY system has both of these features - or will do if Cactus ever are able to get hold of Class T fuses - whereas only one drop-in battery is, as far as I know, able to meet the warning standard and that is Lithionics, only available in the US. Not even the premium product Battleborn offers this.

As I say, nothing is clear but when considering a long-term investment a CE marked drop-in LFP battery is not a sure-thing insurance-wise.

* For those considering the DIY route there are on or two new players who are designing systems for the small marine market. X2 BMS is offering a range of systems all of which are complaint with the emerging requirement for advanced warning of disconnect. Combing this with GWL-purchased Winston cells will give a complete suite of CE marked equipment and meet the eventual ABYC directive or equivalent.

X2 BMS 12/24 – batterybalance

 

[Pete7]

You will save money making your own but that, for me, doesn't matter. I prefer a professional made commercial unit. Sure there will be a load of follow up comments about what is a professional made commercial unit and for me that's a CE marked Sterling stamped LFP.
That's my personal view, as I say there will probably be some posts going the other way but that's their view, horses for courses

Matches my reasoning to buy from Sterling rather than take the risk of of importing from China. Sure lots of people manage to receive good quality batteries, but note the warning that the likes of Rod Collins reports of seconds being sold out of the back factory gate to get rid of them. Or some of the disasters publicised on Wills DIY Solar Forum of batteries poor grade cells arriving damaged or worse. Anyone wanting to see the cheap end of the market should search Facebook for Lithium to see cells with missing QR codes, warped cell cases or used cells that have been badly re-wrapped as new.

Sterling offer a 5 year warranty that I am willing to pay for to avoid these sorts of problems. Victron would be nice but quite a lot more expensive. Tried Valance but the UK dealer wouldn't talk to me. Sterling supplied in 48 hours, not 3 months from China. If I was to buy loose cells then the Winston's from GWL would be the current choice. Pricey but high quality. It's a choice we all have to make based on price and risk acceptance.

Pete

 

[Poey50]

Matches my reasoning to buy from Sterling rather than take the risk of of importing from China. Sure lots of people manage to receive good quality batteries, but note the warning that the likes of Rod Collins reports of seconds being sold out of the back factory gate to get rid of them. Or some of the disasters publicised on Wills DIY Solar Forum of batteries poor grade cells arriving damaged or worse. Anyone wanting to see the cheap end of the market should search Facebook for Lithium to see cells with missing QR codes, warped cell cases or used cells that have been badly re-wrapped as new.

Sterling offer a 5 year warranty that I am willing to pay for to avoid these sorts of problems. Victron would be nice but quite a lot more expensive. Tried Valance but the UK dealer wouldn't talk to me. Sterling supplied in 48 hours, not 3 months from China. If I was to buy loose cells then the Winston's from GWL would be the current choice. Pricey but high quality. It's a choice we all have to make based on price and risk acceptance.

Pete

Yes, direct imports from China are certainly the Wild West and this is not for everyone but there are ways of avoiding getting burnt. Here are some ...

1. Read all the threads on current trends on purchasing on the DIY Solar Forum. You will find that three or four companies are favoured at any one time, not just on price, but on reliability, willingness to honour warranty and customer service. When I bought my cells RJ Lithium were one of the three and I had seen several reports of them honouring warranties by exchanging cells when - rarely - there was a problem and, in one case where the problem was obviously caused by poor installation.
2. When getting a quote and purchasing, mention that you are member of various LFP forums. Sellers won't con you if they know that one post from you to thousands of forum subscribers can kill their reputation in seconds.
3. Never buy from a company that has not established a reputation despite the wonderful looking bargains.
4. Get a quote "to your door' - including all taxes, duties and transport costs. Otherwise transport costs can be added on later and can inflate the price.
5. Pay either by PayPal or a credit card even though this will be 2-3% more expensive. This gives a safety net in case of problems.
6. When it comes to the aluminium blue cased cells, don't trust that these are brand new cells, however it is a reasonable expectation that the capacity of the cells will be as advertised. Winston from Sky Power - see below - are however new and Grade A
7. Buy a capacity tester for around £30 and check that you got what you paid for. Very rarely is this not the case but it gives peace of mind. These days you can also buy relatively inexpensive resistance testers to check how well the cells are matched on resistance.
8. If importing top quality Winstons then there is a single outstanding figure - Julia Yu of Sky Power sales@skypowerintl.com Many on Lithium Batteries on a Boat Facebook Group have imported through her. This is typical of the experience ... "I just wanted to say that I could not be more impressed by the level of service provided do far by Julia Yu of Sky Power. I recently ordered 4 x 400ah Winston cells. Dealing with an overseas company can make one nervous, but Julia provided frequent updates, including photos of my batteries and compression plates in their shipping crate!" (I have no personal connection to her or the company. I wish!)

But as ever .. buyer beware. If you are sensible then you can save a considerable amount of money and, in my view, make a better system than with 'drop-ins'.