LFP, LiFePo4 batteries, cells bms etc.

[Raul]

This thread hopefully will help anyone to build their own LFP, source good deals of ready built, or any free discussions to help others.
There are many offerings on the market now, with huge selections from Far East of cells, bms, and ready to use 12v blocks.

 

[Vipar]

Ain’t got a. Clue what your talking about.

Any pictures to help us numpties what’s it for? Do I need one?

 

[funflair]

My understanding is that it will be a point of discussion for anybody thinking of building or with existing experience in building their own Lithium battery rather than buying an off the shelf product, after all the off the shelf ones are just a collection of bits.

Other than that I know nothing but will watch with interest.

 

[Raul]

This includes the off the shelf category. Some suppliers quote some minimum maximum parameters. Some are optimistic, some do deliver and above the spec. For example ultramax lfp tested by myself, so far deliver what it says on the tin. Less on the charging, they will struggle to absorb much current above 0,3C rate. Discharging no problem 1C. The temperature has a big factor to. The cooler it is the slower will charge. Maybe is a protective feature built in the bms? Don’t know for sure. Once they are out of warranty period, I will open them up, as I’m dead curious what cells they use. Victron uses winston cells on their smart batteries. You can get winstons from Check Republic at reasonable price. EVpower EU is their shop.

 

[Tombola]

The temperature has a big factor to. The cooler it is the slower will charge. Maybe is a protective feature built in the bms? Don’t know for sure. Once they are out of warranty period, I will open them up,

Yes to charge when low temps, a normal current will damage the linthiums. They need a really low current to gradually bring them up

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[Raul]

I am aware of that. Same goes for deep discharge, if you take them below 3vpc volt per cell 12v block, it should be charged with no more than 0,1C , 10a for 100ah batt, until they climb above 3vpc. After that, normal charging can resume. Some expensive bms have this built in, but the budget once don’t.
I was charging 15-16 deg C, optimum is 25 deg.

 

[caddy camper]

i used this video to recently build my own lifepo4 battery it was fun and interesting to do

I would use EVE or Lishen cells if i made any more battery's as the littokala cells i used in the Video have mixed reports but they are cheap.
i only got 76ah out of a supposedly 105ah but have just been refunded £90 from AliExpress as i filed a claim so the 4 cells only cost me £48 a dally smart BMS £50 battery box £35 total £133 for 76ah with Bluetooth high and low temp disconnect ect

here's a massive 280ah Eve cells high quality 12v battery build

 

[Two on Tour]

i used this video to recently build my own lifepo4 battery it was fun and interesting to do

I would use EVE or Lishen cells if i made any more battery's as the littokala cells i used in the Video have mixed reports but they are cheap.
i only got 76ah out of a supposedly 105ah but have just been refunded £90 from AliExpress as i filed a claim so the 4 cells only cost me £48 a dally smart BMS £50 battery box £35 total £133 for 76ah with Bluetooth high and low temp disconnect ect

here's a massive 280ah Eve cells high quality 12v battery build

Here's my 280Ah battery pack that I built with CATL "A" grade cells and a 100Ah Daly Smart BMS a couple of months back.
In the black box is an active cell balancer.

 

[caddy camper]

wow thats a beast nice build did you get close to the rated capacity?

 

[Two on Tour]

wow thats a beast nice build did you get close to the rated capacity?

They are actually 271Ah cells, but the advantage of "A" grade cells is that they often have a greater capacity than stated.
The pack tested at a tad under the 280Ah

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[caddy camper]

brilliant

 

[the1andonly]

Raul Low temp charging of Lithium the ULTRAMAX in particular. Do you know if it has a BMS that prevents charging bellow 5 degree C. ITS the Bluetooth version. If not its a manual switch for the B2B which is not included in my strategy yet.
I use a BMV712 relay to control a SSR to control power in to a Votronics MPPT based on SOC. Does the victron bmv software allow an OR on the relay switching ie SOC OR Temperature (only just thought of this whilst writing)

 

[jongood]

Im not understanding why people are making such a biggie of low temp charging. Surely the battery will be inside the mh and if you were using it it would not be that cold and if you had it stood then you wouldn't be charging it because there's no need.

 

[Two on Tour]

Im not understanding why people are making such a biggie of low temp charging. Surely the battery will be inside the mh and if you were using it it would not be that cold and if you had it stood then you wouldn't be charging it because there's no need.

We are going away in our van for Christmas, and for anybody setting out in very cold weather in a van that has been standing un-heated for some time, the lithium battery will be at ambient temperature, plus the lithium battery is likely to be on the low side having had little or no solar to keep it in a high state of charge, to then wack in 30 - 60 amps from a B2B when the engine starts is not going to make for a happy battery.

High amp low temp charging of our lithium is a potential problem I would rather not have, so have in place measures to avoid the scenario.
Our battery sits on a temperature controlled heat mat, which stops the battery falling below 6c, plus the MPPT's are set to switch off at 4c as they are unlikely to produce any wattage the would trouble the battery in winter conditions. I have my 60 amp Sterling B2B set to be switched manually rather than voltage or D+ sensing so I can decide when the B2B is charging.

 

[funflair]

Im not understanding why people are making such a biggie of low temp charging. Surely the battery will be inside the mh and if you were using it it would not be that cold and if you had it stood then you wouldn't be charging it because there's no need.

I think you are right Jon other than not everyone has the batteries inside the van and nice and warm,————— and bascally what he just said above.

Except we don't have a heated mat.

EDIT I should also add that not all batteries say they don't like to be charged below 5 degC, for example SuperB Epsilon say -10 degC and our SuperB Nomia are 0 degC

EDIT EDIT Don"t know where I got -30 from (original post), I was sat on the exercise bike thinking "that can't be right?" I knew it was lower BUT so checked again and -10 degC so altered the original text

Are you confused yet? I am.

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[Raul]

Raul Low temp charging of Lithium the ULTRAMAX in particular. Do you know if it has a BMS that prevents charging bellow 5 degree C. ITS the Bluetooth version. If not its a manual switch for the B2B which is not included in my strategy yet.
I use a BMV712 relay to control a SSR to control power in to a Votronics MPPT based on SOC. Does the victron bmv software allow an OR on the relay switching ie SOC OR Temperature (only just thought of this whilst writing)

The version with Bluetooth I don’t know, I have the ones without Bluetooth. I use a victron battery sense glued on the case, networked. I have tried mine below 0, and it does charge. Maybe internal bms reads different or doesn’t have a probe. If van unattended, the only time it could charge is ehu or solar. Ehu is used via multiplus, and solar is networked with the temp sense. So I’m ok there. The last is the B2B, yes, you guest it, I have a swich on ignition feed signal. Default is of. It only goes on if: battery is discharged and needs topi g up, temp is above 5C on the temp sense. Despite the van warms up fast, in batt compartment can lag few deg. So I go by what’s there.
The Bluetooth version you will need to test if stops at 0C, otherwise a swich on signal wire to B2B will be handy. Mine is below armrest driver seat.

 

[the1andonly]

The Bluetooth version you will need to test if stops at 0C, otherwise a swich on signal wire to B2B will be handy. Mine is below armrest driver seat.

Well the temperature is right for testing (bloody cold) but i took the simple method of adding a switch in the D+ line to the B2B from the CBE300. So its in the back of van not convenient but its there and off right now.
Ive got another question but it would take the thread totaly off line. See new thread.

 

[donkey]

Here's my 280Ah battery pack that I built with CATL "A" grade cells and a 100Ah Daly Smart BMS a couple of months back.
In the black box is an active cell balancer.

View attachment 567344

Hi

Interesting project.
One question please: Why do you have a separate balancer, I thought the Daly BMS had an in-built cell balancer? I guess it is the bunch of coloured cables on the left.

Geoff

 

[Two on Tour]

Hi

Interesting project.
One question please: Why do you have a separate balancer, I thought the Daly BMS had an in-built cell balancer? I guess it is the bunch of coloured cables on the left.

Geoff

Daly quote 0.03 amp for the balance on their BMS, but it is not even that when the voltage flattens out near to a higher SOC, and on a larger capacity battery pack it's doing bugger all, plus the Daly BMS only balances one cell at a time.
The active balancer I have fitted is quoted as 5 amps (Chinese amps ) and it balances by bleeding of the higher voltage cells to the lower voltage cells, and all cells at the same time.

As you can see, the active balancer is doing a pretty decent job.

 

[donkey]

Thanks for that, I thought there must have been a good reason.
I hope this thread has legs as it would be good to gain knowledge of lithium, it looks like it will take over from the others.

Geoff

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[caddy camper]

Daly quote 0.03 amp for the balance on their BMS, but it is not even that when the voltage flattens out near to a higher SOC, and on a larger capacity battery pack it's doing bugger all, plus the Daly BMS only balances one cell at a time.
The active balancer I have fitted is quoted as 5 amps (Chinese amps ) and it balances by bleeding of the higher voltage cells to the lower voltage cells, and all cells at the same time.

As you can see, the active balancer is doing a pretty decent

Hi Two on Tour that's a great idea
Cell 4 in my pack is discharging to quickly once it hits 30% it stays in balance for 70% of the discharge then when cell 4 hits 2.5v the BMS disconnects but cell 1 2 & 3 still have over 20% charge left hence the 76ah not 105ah.
i'm thinking if i slap a balancer on i may get another 10-20ah from it
i ordered this last night it's only 1.2 amps not 5 amps like yours (just noticed that lol)

LiFePO4 1.2A LED Active Equaliser Balancer

would you have a link for the 5 amp balancer you used out of interest?
i will give this 1.2a a try first as after a little research there is people using these on 12v lifepo4 cells
Many thanks james

 

[Two on Tour]

Hi Two on Tour that's a great idea
Cell 4 in my pack is discharging to quickly once it hits 30% it stays in balance for 70% of the discharge then when cell 4 hits 2.5v the BMS disconnects but cell 1 2 & 3 still have over 20% charge left hence the 76ah not 105ah.
i'm thinking if i slap a balancer on i may get another 10-20ah from it
i ordered this last night it's only 1.2 amps not 5 amps like yours (just noticed that lol)

LiFePO4 1.2A LED Active Equaliser Balancer

would you have a link for the 5 amp balancer you used out of interest?
i will give this 1.2a a try first as after a little research there is people using these on 12v lifepo4 cells
Many thanks james

I have tried the balancer you have linked to and it was bloody useless, sorry to be the bearer of bad news.

I had a quick look, but could find no UK sellers for the one I'm using, well at a sensible price that is.

If you do want one and can not find a UK seller, then I have a couple of spares.

 

[caddy camper]

Thanks Two on Tour i couldn't find any in the UK i can get one delivered from china mid Jan so not too bad.

thanks so much for the offer id be more than happy to take you up on that if you have more than one spare id pay you a import fee on top of what you paid plus P&P of course.
like i say only if you have spare i wouldn't want you going short haha and mid jan isn't too far away
thank you very much james

 

[Dutch 68]

One for Lenny HB , 90 volts going through everything metal he touches in the MH when on EHU, from the N&B Facebook page, seems like a unpleasant experience to me

 

[Two on Tour]

Thanks Two on Tour i couldn't find any in the UK i can get one delivered from china mid Jan so not too bad.

thanks so much for the offer id be more than happy to take you up on that if you have more than one spare id pay you a import fee on top of what you paid plus P&P of course.
like i say only if you have spare i wouldn't want you going short haha and mid jan isn't too far away
thank you very much james

James caddy camper you have a PM

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[Lenny HB]

One for Lenny HB , 90 volts going through everything metal he touches in the MH when on EHU, from the N&B Facebook page, seems like a unpleasant experience to meView attachment 567789

Is he on a French site with a two phase supply?

 

[Raul]

Reverse polarity?

 

[Dutch 68]

Is he on a French site with a two phase supply.

Not sure he doesn’t say but he put this extra detail in the comments box

 

[Dutch 68]

Is he on a French site with a two phase supply?

What if he is, do you need to be aware of doing something different?

 

[Lenny HB]

Not sure he doesn’t say but he put this extra detail in the comments box View attachment 567801

With that comment more likely to be to do with
The charger inverter. Most Victron inverter have a jumper inside allowing selection of floating earth or earth bonded to neutral. Sounds like he has it floating.

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