270ah DIY LiFePO4 build

[sailaboutvic]

Hi do you have a link for your supplier?

Luoyang Tianhuan Energy Technology Co., Ltd.
But I had a bit of back luck ,
I got an email this morning to say there shipping company now say they cant deliver as I am in a remote place , one would think when I given them the country post code they would had said then , not three days after the order .
Now have to wait 15 days for a refund .
So getting them from Germay now .
More expensive by a couple hundred euros but at less not far to send back if there a problem .
Plus he done me a deal for the cells , victron B2B , 123,smart and a 250/700A relay

 

[Poey50]

Luoyang Tianhuan Energy Technology Co., Ltd.
But I had a bit of back luck ,
I got an email this morning to say there shipping company now say they cant deliver as I am in a remote place , one would think when I given them the country post code they would had said then , not three days after the order .
Now have to wait 15 days for a refund .
So getting them from Germay now .
More expensive by a couple hundred euros but at less not far to send back if there a problem .
Plus he done me a deal for the cells , victron B2B , 123,smart and a 250/700A relay

That 200 euros will soon be forgotten.

 

[vas]

so, Vic, you are keeping the Trojans?

Means inverter/charger/solar/engine alternator will charge the trojans and a B2B will charge the LiFePO4?

All loads sucked from the LiFeP04?

 

[sailaboutvic]

That 200 euros will soon be forgotten.

Yes it will ,
Like most things we hum and grm about buying some thing but once we part will the money it done and dusted
I'm more pissed off that they taken the order waited three days to tell me now have to wait 15 days for a refund .
It is what it is

 

[sailaboutvic]

so, Vic, you are keeping the Trojans?

Means inverter/charger/solar/engine alternator will charge the trojans and a B2B will charge the LiFePO4?

All loads sucked from the LiFeP04?

No reordered from a guy in Germany who keeps them in stock , same cells just more money . But he been very helpful so far .
Only concern is how I going to wire the inverter for big loads when the batteries are full , like the hob , seen a big relay is the answer ,

 

[vas]

crossed lines, sorry.

Meant that anyway you are thinking of running the trojans together with the LiFeP04, or by the looks of it you plan to remove the trojans completely!
care to draft the way you plan to wire the lot?

V.

 

[sailaboutvic]

crossed lines, sorry.

Meant that anyway you are thinking of running the trojans together with the LiFeP04, or by the looks of it you plan to remove the trojans completely!
care to draft the way you plan to wire the lot?

V.

Ok with you now Trojan have lost so much capacity they not worth keeping ,
I was thinking of using two 6V in series to replace my LA starter battery , alThought that's battery is four years old I reckon it's probably got more life in it then the trojans .

Re wiring the lithium, that's still in the planning stage .

 

[sailaboutvic]

Here a question for the know how's here ,
I sure I talked about this before , I don't really want to buy a power supply not so much the cost but more that once I finished balance the cell I not got the room to keep it so it probably get bin .

So I was thinking if the cells voltage are close to each other ,
what if I just wire 4 cells in series fit the BMS and charge with my shore charger which as a Gel setting 14.5v Bulk 13.5 float then leave without any load and let them balance them self with the 123smart BMS I should be able to monitor the voltage in each cells .
Once happy all are close to the other 4 cells .
Do the same to the other 4 x200ah cells
Lastly wire both banks in parallel to end up with a 400ah 12 v bank ?
Can anyone see anything wrong with that .
Other then it may take some time doing ?

 

[Poey50]

Here a question for the know how's here ,
I sure I talked about this before , I don't really want to buy a power supply not so much the cost but more that once I finished balance the cell I not got the room to keep it so it probably get bin .

So I was thinking if the cells voltage are close to each other ,
what if I just wire 4 cells in series fit the BMS and charge with my shore charger which as a Gel setting 14.5v Bulk 13.5 float then leave without any load and let them balance them self with the 123smart BMS I should be able to monitor the voltage in each cells .
Once happy all are close to the other 4 cells .
Do the same to the other 4 x200ah cells
Lastly wire both banks in parallel to end up with a 400ah 12 v bank ?
Can anyone see anything wrong with that .
Other then it may take some time doing ?

Vic, this comes up all the time in forums. Those whose opinion I respect say "get a power supply unit and do a proper top-balance". Check out the dimensions and price of this one. It's cheap and tiny but also very good.
DC Power Supply Variable,0-30V /0-10A,（precision 00.01V，00.01A）4-Digital LED Display Adjustable Switching Regulated Power Supply Digital,with Alligator Leads UK Power Cord Used for Spectrophotometer: Amazon.co.uk: Business, Industry & Science

 

[sailaboutvic]

That may be the only way forward if the voltage is way out and offcause it Be the route I would take , but Will power do suggest that there no need to top balance if your not in a rush and a good BMS will do it for you .
Plus it's easy and cheap to buy that if your in the UK , remember I'm not . Which was the problem with the cells .
Anyway just tho I throw the question out there , thanks you your In put its always good to get input from people who done it .

 

[Poey50]

That may be the only way forward if the voltage is way out and offcause it Be the route I would take , but Will power do suggest that there no need to top balance if your not in a rush and a good BMS will do it for you .
Plus it's easy and cheap to buy that if your in the UK , remember I'm not . Which was the problem with the cells .
Anyway just tho I throw the question out there , thanks you your In put its always good to get input from people who done it .

When you first get the cells you should find then fairly closely balanced. Sometimes people then feel they don't need to do a top-balance but imbalance only shows up once the cells reach the upper knee of the charging curve. You may be fine to use the BMS if that is all you can do but, as said, most of those in the know recommend a careful initial top balance with a power supply.

 

[Poey50]

The only BMS that GWL sell is the 123SmartBMS but even they recommend a top-balance first with their LFPs. Mind you I wouldn't do it the way Michael is doing it here - that takes forever. I posted a link to better instructions further back in the thread.

 

[halcyon]

When you first get the cells you should find then fairly closely balanced. Sometimes people then feel they don't need to do a top-balance but imbalance only shows up once the cells reach the upper knee of the charging curve. You may be fine to use the BMS if that is all you can do but, as said, most of those in the know recommend a careful initial top balance with a power supply.

Have you looked into the problems with 12 volt batteries, have a customer who wants to possible convert from FLA to LiFePO4 next year. So I am having to try and produce him a new switch panel and charge system that covers both battery types, rather a long thread to search through. Started looking at your links in #1, are you monitoring each cell to spot a faulty cell ?

Brian

 

[Poey50]

Have you looked into the problems with 12 volt batteries, have a customer who wants to possible convert from FLA to LiFePO4 next year. So I am having to try and produce him a new switch panel and charge system that covers both battery types, rather a long thread to search through. Started looking at your links in #1, are you monitoring each cell to spot a faulty cell ?

Brian

That seems like quite a small question but in fact is potentially massive. Do you mean 12 volt drop-in batteries with an internal battery management system? These are the simplest approach to installing LFP on a boat but, in general, the least suitable.

 

[Poey50]

are you monitoring each cell to spot a faulty cell ?
Brian

I'll try to answer this part of the question as I think it goes to the heart of the difference between lead acid cells and LFP cells.

For all their considerable advantages LFP cells need constant supervision. Unlike lead acid an LFP cell will keep taking charge until it swells up and over time will go into thermal runaway. It's like those breeds of dogs that never know when they are full and will eat themselves sick. On discharge the cells will not slowly dim the lights but suddenly dip too low and this can permanently damage the cell causing what is sometimes called a 'time bomb' effect. At high temperature the cell capacity may be seriously damaged, the same applies if they are charged below zero degrees. The effects of all these things are either to create long term damage (loss of capacity) or can destroy a cell from the inside. So a battery management system is not looking out for a faulty cell as one might do with lead acid but is a permanent life-support for the cell - it simply cannot function without it. Some people do without a BMS by becoming their own battery manager but that takes a lot of care, understanding and not ever getting distracted when charging or discharging - something that I'm personally incapable of. All this management has to be done at cell level, not at battery pack level as cells can get out of balance. The voltage of a pack under charge may be looking OK at 14.4 volts for example but three of the four cells in series may be at a safe 3.53 volts but the fourth at a damaging 3.81 volts.

A reasonable basic BMS will therefore isolate the circuit if any cell is threatened with over-charge, over-discharge, over-temperature and under-temperature. In addition it should also have some ability to balance the unevenness between the cells (another big subject in its own right).

On a 12 volt drop-in battery all these functions are undertaken by a BMS housed inside the case. But if there is any form of disconnect then the battery is in a non-communicating state neither providing power nor accepting charge - not the kind of thing you want on a boat. If it shuts down with the alternator running then the voltage spike may take out the alternator diodes as well as expensive marine electronics. So the whole question of safe design is how this is all to be managed on a boat - it can be done but not easily or satisfactorily with drop-ins.

The Nordkyn Design articles on my post #1 go into design in depth but the single big question to ask of any LFP battery is what are the compensation methods when it closes down to protect itself. As I've said several times in various threads people properly like the idea of a battery management system but don't always realise that the BMS of a drop-in battery is only concerned with protecting the battery - it has no interest in protecting the user or her or his boat. The lights may go out, all coms lost, the alternator blown, the chart plotter destroyed, the nav lost but the drop-in will be absolutely fine!

 

[sailaboutvic]

If I may add as a novice who be researching these batteries for over six weeks day and night, yes I need to get a life,
I was going buy a couple of dropping not only you don't need to know all the stuff about building them or how they work but there can be cheaper but the more I looked into it the more I started to accept how unsuitable are they for boat using heavy loads unless you go for something like master volts or Victron and then your looking at big bucks .
Problem with dropping I found is
1 you don't know how or with what cells they made up with .
2 the BMS are inside and if for any reason that goes pop you probably not going to be able to do much with it.
3 like LA you have v+v- post and every thing goes through the BMS and if the BMS isn't rated high enough putting a ligh load for say a bow T will just cut the BMS out , now for most people with a boat just running the run of the mill stuff that's probably not going to be a problem but for tho running inverter with heavy load it's going to be .

With cells you can over ride the BMS and put in relays , leaving the BMS to look after the cells and the relay to take the big loads why the BMS keeping an eye on the cells and shutting down only when the cells get to low .
But before anyone start to take that route of building your own bank you really need to do a lot of research depend how you plain to use them .
Every day I finding some thing new , why I can't do this or that and having to change my plain .
@Poey50 correct me if I wrote something that's not quite right .
As said still a novice .

 

[sailaboutvic]

Have you looked into the problems with 12 volt batteries, have a customer who wants to possible convert from FLA to LiFePO4 next year. So I am having to try and produce him a new switch panel and charge system that covers both battery types, rather a long thread to search through. Started looking at your links in #1, are you monitoring each cell to spot a faulty cell ?

Brian

Just to try and answer your question , if you have a good BMS something like the smart or the Daly with Bluetooth you can see what each cell doing
. A lot BMS don't have this function so you don't know what's going on and if they go wrong it maybe too late by the time you realised.
I guess in time to come you be able to monitor all BMS

 

[vas]

the last four posts nicely demonstrate why IMHO hybrid systems (as in both LA and LiFePO4) are so much more user friendly and safe
pity (and correct me if I'm wrong) no BMS built for that in mind and user has to do all sorts of custom work with contactors, signalling, etc
OK, hybrid concept is drafted in a couple of docs and an experimental system is running on a boat for over a year now somewhere in Caribbean.
Again IMHO, problem is not having some solar and a decent alternator regulator running LiFePO4, but adding a 2-3KVA inverter in the mix.
Hybrid BMS is my next season's microcontroller project just hope I can get 8X200-280Ah cells for under a grand by then (in EU tax paid)

cheers

V.

 

[sailaboutvic]

Personally we all still learning some know a lot more then others but we are all still learning. A guy in this marina spend 10k having a big set up on their cat , by a very well known company dealer recommended engineer,
Blue batteries come to mind ,
If he uses his ele winch and his wife put the kettle on the same time the bms shut down .
Just goes to show the so call experts get it wrong at times .
His nice expenses blue batteries are seal so they cant be pulled apart , Anyway he wouldn't know what to do anyway
the dealer engineer 1500 miles away and he getting very little help from them .
The company answer is go to another dealer and get it sorted at he own cost .

 

[sailaboutvic]

the last four posts nicely demonstrate why IMHO hybrid systems (as in both LA and LiFePO4) are so much more user friendly and safe
pity (and correct me if I'm wrong) no BMS built for that in mind and user has to do all sorts of custom work with contactors, signalling, etc
OK, hybrid concept is drafted in a couple of docs and an experimental system is running on a boat for over a year now somewhere in Caribbean.
Again IMHO, problem is not having some solar and a decent alternator regulator running LiFePO4, but adding a 2-3KVA inverter in the mix.
Hybrid BMS is my next season's microcontroller project just hope I can get 8X200-280Ah cells for under a grand by then (in EU tax paid)

cheers

V.

Try the people I was going to use l, Luoyang Tianhuan Energy Technology Co., Ltd. They where just under a 1K poundS for 8x200ah they do bigger cells .
But do make sure they can deliver ddp to your address .
I found them very helpful even when I ask about refund she walked me through it,
shame the shipping company missed it up .