Li-0n, these look interesting

[rusty69]

Has anyone got a data sheet for the EVE cells used in fogstar/lifebatteries? I would be interested to see what they say abut cell compresion, and how it has been achieved (if at all).

[nicknorman]

36 minutes ago, IanD said:

Whether built-in heating is needed for boats in the UK is debatable, you can charge LFP at reduced rates (i.e. fractional-C, the ones typically used on a boat) below 0C (down to -20C for BYD IIRC) -- but many drop-in LFP suppliers just put a blanket ban on charging below 0C because it's easier, or apply heating like Fogstar.

 

Having said that, the Fogstar batteries do look well built and good value (and with support!) if they're what you're looking for... 🙂

 

Heating - true, but in my case the battery is for my caravan in the Highlands of Scotland where apparently it does sometimes get a little bit below zero! Since Mr Loddon no longer has a boat I was presuming that his application would be something similar.

19 minutes ago, rusty69 said:

Has anyone got a data sheet for the EVE cells used in fogstar/lifebatteries? I would be interested to see what they say abut cell compresion, and how it has been achieved (if at all).

You don't need to do cell compression. Well, unless you intend to seriously abuse them. All you need to do is ensure they are well supported so mechanical load doesn't go onto the terminals

[magnetman]

It is interesting to read about how the heating mats actually work. 

[rusty69]

2 minutes ago, nicknorman said:

You don't need to do cell compression. Well, unless you intend to seriously abuse them. All you need to do is ensure they are well supported so mechanical load doesn't go onto the terminals

Is that your opinion, or what EVE's data sheet advises?

[magnetman]

For EVE 280Ah cells

 

Cycle Life at 
25℃
≥3500 cycles @1C/1C
At 25±2℃，the battery under 300kgf 
fixture ： charging the cell with charge current 1.0C(A) and constant voltage 
3.65V,0.05C cut off,rest for 
30min,discharge to 2.5V cut off with the current of 1.0C(A),rest for 30min,and then  start the next cycle,end with the capacity 
decrease to 80% of the initial capacity.The  number of cycles is defined as the cycle life 
of the battery

 

 

--- 

 

 

I wonder what 'under 300kgf fixture' means. 

 

 

https://batteryfinds.com › EV...PDF
EVE Energy Co., Ltd Product Specification

[rusty69]

11 minutes ago, magnetman said:

For EVE 280Ah cells

 

Cycle Life at 
25℃
≥3500 cycles @1C/1C
At 25±2℃，the battery under 300kgf 
fixture ： charging the cell with charge current 1.0C(A) and constant voltage 
3.65V,0.05C cut off,rest for 
30min,discharge to 2.5V cut off with the current of 1.0C(A),rest for 30min,and then  start the next cycle,end with the capacity 
decrease to 80% of the initial capacity.The  number of cycles is defined as the cycle life 
of the battery

 

 

--- 

 

 

I wonder what 'under 300kgf fixture' means. 

 

 

https://batteryfinds.com › EV...PDF
EVE Energy Co., Ltd Product Specification

Quote

Under 300 kgf ± 20 kgf initial compression force, 0.5 C / 0.5 C, 2.5 V ~ 3.65 V, Capacity retention≥ 80 %. Or follow the EVE recommended cycling method

Which I suppose means that compression adds to the cell life, and is not mandatory.

[nicknorman]

25 minutes ago, rusty69 said:

Is that your opinion, or what EVE's data sheet advises?

My opinion. If you are going to exert the batteries by fully charging at 1C and fully discharging at 1C then I think compression might be advisable, but for the sort of usage that is going to happen on a boat, it's pointless. Well I certainly didn't apply an compression. I did however make sure that the batteries were well located so that they couldn't move at all, and thus keep stress on the terminals to a minimum (bent bus bars also help here of course.

[IanD]

2 minutes ago, rusty69 said:

Which I suppose means that compression adds to the cell life, and is not mandatory.

Here's the actual EVE specification:

 

https://batteryfinds.com/wp-content/uploads/2022/11/EVE-280Ah-Lithium-Iron-Phosphate-LiFePO4-LFP-Prismatic-Battery-Cells-Specification.pdf

 

The only mention of compression are in the thickness spec and the test conditions used for lifetime testing at 1C/1C charge/discharge i.e. the "1-hour" rate which is 900W/cell (3.6kW per 12.8V/280Ah battery) -- at this rate they'll be warming up due to about 20W dissipation (0.25mohm ESR). The fast charge/discharge and high power causes the cells to swell and shrink slightly between charge and discharge, compression is recommended to try and stop this and maximise lifetime.

 

Such high rates are never likely to be found on boats, something closer to 0.2C ("5-hour" rate) is much more likely, at which the power dissipation drops to about 1W. Together with the much slower reaction rates inside the cells, this makes compression much less important -- many boat installation don't use it, just make sure the batteries are snugly fitted so they can't move and put stress on the terminals/busbars.

[rusty69]

2 minutes ago, nicknorman said:

My opinion. If you are going to exert the batteries by fully charging at 1C and fully discharging at 1C then I think compression might be advisable, but for the sort of usage that is going to happen on a boat, it's pointless. Well I certainly didn't apply an compression. I did however make sure that the batteries were well located so that they couldn't move at all, and thus keep stress on the terminals to a minimum (bent bus bars also help here of course.

 

Ok, thanks. I think the OP is talking about a van, not a boat. Not that it probably makes any difference.

 

I did compress my cells FWIW. It wasn't much of an extra job, and it seemed an easy thing to do that would cause no harm. However, mine are the plastic thundersky cells, not the aluminium cased EVE thingies. I suppose in the great scheme of things, if the worse that happens is a loss off some of their extremely long claimed life, then its not going to bother too many people, just another thing not complied with by the manufacturer (depending what the EVE recommended cycling method actualy entails).

[IanD]

12 minutes ago, nicknorman said:

My opinion. If you are going to exert the batteries by fully charging at 1C and fully discharging at 1C then I think compression might be advisable, but for the sort of usage that is going to happen on a boat, it's pointless. Well I certainly didn't apply an compression. I did however make sure that the batteries were well located so that they couldn't move at all, and thus keep stress on the terminals to a minimum (bent bus bars also help here of course.

Dammit, posts that cross in the night... 😉

 

(the busbars linking cells on mine are not solid, they're made of a lot of thinner strips as well as being kinked upwards, so any battery movement causes much less stress)

 

The issue for manufacturers is that they have to make recommendations which cover all cases including high-rate charge/discharge, hence the recommendations for compression and blocking any charging below 0C. If they start officially allowing compromises for easier use cases (no compression, charging below 0C) then sure as eggs is eggs somebody will do this under stressful conditions and then make a warranty claim if the batteries fail... 😞

 

The reason some suppliers (e.g. BYD) allow things like sub-0C charging is that the batteries log data, and to meet the guarantee terms this data has to be stored and/or regularly uploaded to BYD so they can check the batteries haven't been abused -- also the inbuilt BMS deals with things like temperature-dependent charge current limiting.

Edited November 7, 2023 by IanD

[rusty69]

2 minutes ago, IanD said:

 

(the busbars linking cells on mine are not solid, they're made of a lot of thinner strips as well as being kinked upwards, so any battery movement causes much less stress)

Same here. I made hundreds of them out of copper strip. Never again.

[IanD]

6 minutes ago, rusty69 said:

Same here. I made hundreds of them out of copper strip. Never again.

Or you can buy them -- I believe these are what mine use...

 

https://shop.gwl.eu/Brands/ThunderSky-Winston/WINSTON-Terminal-Connectors-For-TSWB-LYP700AHA.html

 

"Flexible terminal connector for Winston cells LFP700AHA. Connector is composed of several thin layers, copper material. Including screws and washers.

A very important characteristic of the original connection terminal is its flexibility. Especially when used with battery cells arranged in mobile applications. A variety of material handling machines, electric vehicles. Important, if used, non-genuine Connectors, for example, from a single piece of sheet metal at case of vibration and shock risk of damage to the internal connection terminals of cell."

Edited November 7, 2023 by IanD

[rusty69]

Just now, IanD said:

Or you can buy them -- I believe these are what mine use...

 

https://shop.gwl.eu/Brands/ThunderSky-Winston/WINSTON-Terminal-Connectors-For-TSWB-LYP700AHA.html

Yeah, I know. I thought I would save a few quid and make my own. What a mistake that was.

[Alan de Enfield]

1 hour ago, rusty69 said:

Has anyone got a data sheet for the EVE cells used in fogstar/lifebatteries? I would be interested to see what they say abut cell compresion, and how it has been achieved (if at all).

 

Wasn't there a video posted a couple of days ago about Lithium Cell Compression ?

 

It looked to have quite violent results.

Edited November 7, 2023 by Alan de Enfield

[nicknorman]

An update on my 105Ah Fogstar Drift, which has been in my caravan in the Highlands for a few weeks but seen little use. It is connected via a BMV712 battery monitor. And also of course the Fogstar has its internal BMS with Bluetooth and an App that you can see the BMS’s SoC.

Today SoC from both was around 70%. My Kipor generator wouldn’t start - it had been outside overnight in -3C and I’ve had some issues with water in the fuel, so my diagnosis was ice in the carburettor! So I took it onto the van, opened the side panel and pointed a fan heater at it. Fan heater on 1kw setting was taking about 103A from the battery. Which is fairly cruel,  but near enough within the max continuous rating of 100A (and the BMS was cold soaked at around 5C).

 

The voltage dipped to about 12.8v which was not unreasonable for the high current drain. But I saw on the App that almost immediately (ie within 30 seconds), the SoC had plunged to zero, with a red battery icon. I turned the fan heater off after about a minute, and the genny subsequently started. But in the mean time, despite the voltage recovering to 13.3v or so, the battery BMS SoC remained at zero. I then plugged in the charger and the BMS SoC slowly started crawling up from zero in accordance with the current going in. It seemed as though it would continue to do that for the 25% or so that needed to be replaced into the battery, then presumably it would jump from 25% to 100% as the “fully charged” algorithm kicked in.

 

In summary, it seems to me that the BMS SoC estimation is absolute rubbish. It’s a JBD BMS which is a well know make. Maybe this is par for the course, but you would think a mainstream BMS like that would use Ah counting as a major element of SoC estimation, no just voltage. It’s not a big deal for me as I will use the BMV712, but it does seem odd.

[Tony1]

2 minutes ago, nicknorman said:

An update on my 105Ah Fogstar Drift, which has been in my caravan in the Highlands for a few weeks but seen little use. It is connected via a BMV712 battery monitor. And also of course the Fogstar has its internal BMS with Bluetooth and an App that you can see the BMS’s SoC.

Today SoC from both was around 70%. My Kipor generator wouldn’t start - it had been outside overnight in -3C and I’ve had some issues with water in the fuel, so my diagnosis was ice in the carburettor! So I took it onto the van, opened the side panel and pointed a fan heater at it. Fan heater on 1kw setting was taking about 103A from the battery. Which is fairly cruel,  but near enough within the max continuous rating of 100A (and the BMS was cold soaked at around 5C).

 

The voltage dipped to about 12.8v which was not unreasonable for the high current drain. But I saw on the App that almost immediately (ie within 30 seconds), the SoC had plunged to zero, with a red battery icon. I turned the fan heater off after about a minute, and the genny subsequently started. But in the mean time, despite the voltage recovering to 13.3v or so, the battery BMS SoC remained at zero. I then plugged in the charger and the BMS SoC slowly started crawling up from zero in accordance with the current going in. It seemed as though it would continue to do that for the 25% or so that needed to be replaced into the battery, then presumably it would jump from 25% to 100% as the “fully charged” algorithm kicked in.

 

In summary, it seems to me that the BMS SoC estimation is absolute rubbish. It’s a JBD BMS which is a well know make. Maybe this is par for the course, but you would think a mainstream BMS like that would use Ah counting as a major element of SoC estimation, no just voltage. It’s not a big deal for me as I will use the BMV712, but it does seem odd.

 

That's a bit disappointing for such a nice battery. A BMV unit might set you back another £150, but I'd get one if I had a bank of these things, so I could keep track of the SoC. The voltage curve is so flat,  it's not that much use in judging SoC. 

I have seen some cheaper current counting battery monitors for half that price, but no idea what the quality is. 

 

[MtB]

I too have the exact same Foggy batt and also little used. Partly because the BMS detects both the Foggy and my LifeBatteries similar spec drop-in. Whereas theLifeBatt BMS only detects the LifeBatt despite supposedly both batts supposedly containing the same JBD BMS.

 

What can we really expect though, choosing the cheapest drop-ins money can buy?

 

 

[MrFish]

I am pretty sure I read on the Fogstar Facebook page that the SoC takes a few cycles to start learning the true SoC. 

 

I have only just fitted my 560ah batteries so too early for me to tell with mine yet. They are connected at 4 in series plugged into a Victron multiplus II 48/8000 with Cerbo GX and 712 battery monitor

Edited November 26, 2023 by MrFish
Spelling mistake

[nicknorman]

39 minutes ago, MtB said:

I too have the exact same Foggy batt and also little used. Partly because the BMS detects both the Foggy and my LifeBatteries similar spec drop-in. Whereas theLifeBatt BMS only detects the LifeBatt despite supposedly both batts supposedly containing the same JBD BMS.

 

What can we really expect though, choosing the cheapest drop-ins money can buy?

 

 

Presumably in this post when you say “BMS” the first 2 times, you mean the App? Yes the Foggy App is a bit annoying in that it detects anything with Bluetooth, you have to pick the right one to connect to. But I could forgive that if when you have selected the correct BMS, the SoC was reasonably accurate.

 

Oh and they’re not the cheapest, but cheap ish I’ll grant you, and the BMS is a well known brand.

Edited November 26, 2023 by nicknorman

[MtB]

14 minutes ago, nicknorman said:

Presumably in this post when you say “BMS” the first 2 times, you mean the App? Yes the Foggy App is a bit annoying in that it detects anything with Bluetooth, you have to pick the right one to connect to. But I could forgive that if when you have selected the correct BMS, the SoC was reasonably accurate.

 

Oh and they’re not the cheapest, but cheap ish I’ll grant you, and the BMS is a well known brand.

 

Yes.

[GUMPY]

Mine arrives Friday, I don't intend to install it for a while as the LA battery and solar will cope with the alarm over winter and I possibly don't have enough solar  to warm up the Fogstar when it's at 0degC.

[dmr]

Roamer looked to have started out as a couple of camper van enthusiasts who started to sell batteries, but are now fairly rapidly expanding, including getting into the 48volt domestic market. They look to have some technical expertise. Has anybody had any dealings with them and their batteries?

I suspect a big issue is that most smaller companies (and maybe some big ones too) are using a chinese BMS that comes with limited documentation.

[nicknorman]

3 hours ago, MrFish said:

I am pretty sure I read on the Fogstar Facebook page that the SoC takes a few cycles to start learning the true SoC. 

 

I have only just fitted my 560ah batteries so too early for me to tell with mine yet. They are connected at 4 in series plugged into a Victron multiplus II 48/8000 with Cerbo GX and 712 battery monitor

Yes this is mentioned in the JBD BMS. However surely this is only fine tuning of the SoC calculation - in particular learning the actual capacity of the battery vs what was entered into the configuration. I can't see how my issue of SoC plummeting from 70% to zero in 30 seconds is going to be addressed by a bit of fine tuning cycling.

[n-baj]

21 hours ago, nicknorman said:

An update on my 105Ah Fogstar Drift, which has been in my caravan in the Highlands for a few weeks but seen little use. It is connected via a BMV712 battery monitor. And also of course the Fogstar has its internal BMS with Bluetooth and an App that you can see the BMS’s SoC.

Today SoC from both was around 70%. My Kipor generator wouldn’t start - it had been outside overnight in -3C and I’ve had some issues with water in the fuel, so my diagnosis was ice in the carburettor! So I took it onto the van, opened the side panel and pointed a fan heater at it. Fan heater on 1kw setting was taking about 103A from the battery. Which is fairly cruel,  but near enough within the max continuous rating of 100A (and the BMS was cold soaked at around 5C).

 

The voltage dipped to about 12.8v which was not unreasonable for the high current drain. But I saw on the App that almost immediately (ie within 30 seconds), the SoC had plunged to zero, with a red battery icon. I turned the fan heater off after about a minute, and the genny subsequently started. But in the mean time, despite the voltage recovering to 13.3v or so, the battery BMS SoC remained at zero. I then plugged in the charger and the BMS SoC slowly started crawling up from zero in accordance with the current going in. It seemed as though it would continue to do that for the 25% or so that needed to be replaced into the battery, then presumably it would jump from 25% to 100% as the “fully charged” algorithm kicked in.

 

In summary, it seems to me that the BMS SoC estimation is absolute rubbish. It’s a JBD BMS which is a well know make. Maybe this is par for the course, but you would think a mainstream BMS like that would use Ah counting as a major element of SoC estimation, no just voltage. It’s not a big deal for me as I will use the BMV712, but it does seem odd.

This is what happened to me, a month with the new 460ah battery the soc indicator was at about 40%. After using kettle and microwave for porridge (nowhere near used 180ah) it was at 0% and so I suspected it does need cycling to zero and 100% to ‘teach’ the bms.

 

I’ve only gone to fully charged (14.4v) /discharged(around 11.5v) a couple of times now and while it’s gone better it still does drift (no pun intended) and I suspect as the bms cannot detect any load/charge currents below 0.5 amps then the soc indicator does seem to over read the actual soc as low loads such as power saver mode on the inverter, internet router, even the lights on the dc distribution board isn’t detected by the bms and so doesn’t count the tiny drain on the battery, which causes the soc indicator to drift over time. The bms resets to 100% when the voltage reaches 14.2v and 0% at 11-odd volts. I see the indicator as a bit of a rough guide and tend to go off cell voltages as these are reported to 3 d.p in the app.

 
Apart from the soc indicator not being too accurate over time I’m impressed with the battery. Generator was last used 2 weeks ago (and that was only to fully charge the battery to reset the soc indicator while I was not near anybody) and probably won’t get used for the rest of the year and as the recent sunny weather has put in more in than what I’ve been taking out decided to try to run the washing machine (2kw) at 40 deg c to take some charge out as the battery has been sat at a high soc for a couple of weeks now. As I use the hot water from the calorifer for the washing machine that has saved a couple of hours engine running on moving day 😃

 

 

Edited November 27, 2023 by n-baj

[Tony1]

2 hours ago, n-baj said:

 

Generator was last used 2 weeks ago... and probably won’t get used for the rest of the year and as the recent sunny weather has put in more in than what I’ve been taking out.. 

 

 

My dear Mr Baj, have you moved that boat to the Bahamas? 

How is a normal human being able to make 460Ah of battery charge last for 2 weeks? And how is there so much solar? 

 

Having had the dubious pleasure of making your acquaintance, I know for a fact that I have twice as many solar panels as you do, and I've had to run the engine to charge on two days out of three recently. 

 

All that said, I am one of those decadent bourgeois swine who run a fridge in the winter, so perhaps its that making the difference...