Flat lithium battery.

[ChrisL]

I think that it is necessary that if you fit a new fogstar drift you should charge it as soon as possible to 100% and then for the next 6 or 7 cycles to recharge it to 100%, this allows the BMS to calibrate itself, i've also found that after say 3 weeks off grid and sometimes not getting to 100% from solar that the BMS will go out of sync a bit with the shunt however recharging to 100% will put them back into sync. This is just my experience from having a 230ah Fogstar Drift fitted in June this year.

 

[AdrianChen]

Decent is not a word I would use for Renogy, but it's very cheap but you do get failures.
I wouldn't expect the BMS to be that far out unless you have charged it quite a few times and not reached 100%.
More lightly to be a charger problem.

Don't know how the Renogy AC-DC chargers work - If the cells are 3.92 now, is it possible the charger hit it's "battery charged" setting before the bms reset, a while back before the screenshots, and has dropped to float or stopped, so no charge going in until the battery drops down a bit more?

On the Victron our re-bulk is set to 0.2v, so the charger will go back to bulk when the battery hits float less 0.2v, from memory....
Not sure what is needed to get the Renogy to do that, other than switch it off for a while.

Only info I found suggests it outputs 14.5/6 until charging is complete - Is there a green light on?

It maybe the battery BMS is being a bit misleading, but should reset to 100% if the charger does get it there over a few cycles.

 

[headlight]

I think that it is necessary that if you fit a new fogstar drift you should charge it as soon as possible to 100% and then for the next 6 or 7 cycles to recharge it to 100%, this allows the BMS to calibrate itself, i've also found that after say 3 weeks off grid and sometimes not getting to 100% from solar that the BMS will go out of sync a bit with the shunt however recharging to 100% will put them back into sync. This is just my experience from having a 230ah Fogstar Drift fitted in June this year.

I've been running a Fogstar 230AH for 11 months now.
Irrespective of how many cycles you put on the battery the BMS simply cannot detect low draws.
Fogstar themselves posted on their owners Facebook forum about a week ago that the BMS on the 105AH cannot detect draws under 1AH, the 230AH and 280AH cannot detect anything under 1.5AH and the 300AH and above nothing under 2AH.
I have a constant 0.1AH parasitic drain so that is 2.4 amps/day or 16.8 amps a week that my BMS can't detect.
I also have a Battery Master that draws 1AH when it is working which again is lower than the BMS can detect.
The SOC on the app can be quite far out but my Victron shunt is far more accurate and it is the shunt that I use to determine SOC.

 

[ChrisL]

Irrespective of how many cycles you put on the battery the BMS simply cannot detect low draws.

I did say that over a period where the battery is not getting charged to 100% the BMS will go out of sync with the shunt, which is effectively saying the same thing you are. From personal experience I can say that initially the BMS displayed a total capacity of 230ah but was charging to 243ah, now the BMS after 11 cycles reports the capacity as being 243.4ah, so it has calibrated itself, and the SOC displayed is likely to be more accurate then it was initially, but ofcourse a correctly setup shunt will be more accurate still, especially if the battery is not reaching 100% every day.

 

[headlight]

My Fogstar 230AH BMS has only ever shown a max capacity of 230AH and that is after 14 cycles.
I do belive though that Fogstar changed the cells after I bought my battery and the newer batteries do have more than 230AH capacity.
Lenny HB has 2 x 230AH's and I think both of his show a capacity of about 244AH?

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[ChrisL]

My Fogstar 230AH BMS has only ever shown a max capacity of 230AH and that is after 14 cycles.
I do belive though that Fogstar changed the cells after I bought my battery and the newer batteries do have more than 230AH capacity.
Lenny HB has 2 x 230AH's and I think both of his show a capacity of about 244AH?

I had to wait for a few weeks until Offgrid got some new stock in when I bought mine, and I believe the new stock had an upgraded BMS fitted if i've remembered correctly.

 

[Blofeld]

Irrespective of the number of cycles the BMS cannot and will never detect any draw under 1.5AH on the 300AH Fogstar.
So the SOC shown on the app can be quite a bit out.
A shunt detects all amps in and out of 0.1AH so is far more accurate.
I don't use the app to monitor the SOC on my Fogstar, I use a Victron Shunt.

Doesn’t that depend on the round trip efficiency of the battery?

 

[Guigsy]

I've been running a Fogstar 230AH for 11 months now.
Irrespective of how many cycles you put on the battery the BMS simply cannot detect low draws.
Fogstar themselves posted on their owners Facebook forum about a week ago that the BMS on the 105AH cannot detect draws under 1AH, the 230AH and 280AH cannot detect anything under 1.5AH and the 300AH and above nothing under 2AH.
I have a constant 0.1AH parasitic drain so that is 2.4 amps/day or 16.8 amps a week that my BMS can't detect.
I also have a Battery Master that draws 1AH when it is working which again is lower than the BMS can detect.
The SOC on the app can be quite far out but my Victron shunt is far more accurate and it is the shunt that I use to determine SOC.

Apologies... I'm an anal engineer.

Current drawn is measured in amps. So you're saying the Fogstar can't measure less than 1A. I think it's a bit more sensitive than that, but it certainly ignores 0.5A.

Energy stored in hab batteries measured in amp hours. So if you have a parasitic draw of 1 amp, it'll add up to a total energy use of 24 Ah per day.

Pedantry ends...

 

[headlight]

Doesn’t that depend on the round trip efficiency of the battery?

The JBD BMS used cannot detect low draws.

 

[headlight]

Apologies... I'm an anal engineer.

Current drawn is measured in amps. So you're saying the Fogstar can't measure less than 1A. I think it's a bit more sensitive than that, but it certainly ignores 0.5A.

Energy stored in hab batteries measured in amp hours. So if you have a parasitic draw of 1 amp, it'll add up to a total energy use of 24 Ah per day.

Pedantry ends...

I stated that the parasitic draw was 0.1 amps not 1 amp.
I can draw up to 1.5 amps, as shown by my smart shunt, and the Fogstar detects nothing.
Increase the draw to 1.6 amps and the Fogstar app shows a draw of 1.6 amps exactly the same as my shunt.
This is exactly in line with Fogstars own BMS figures for their 230AH battery.

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[WESTY66]

Apologies... I'm an anal engineer.

 

[jp11]

Had a bloke fit it for us but decent Renogy equipment for b2b, onboard and solar charger and 2000w inverter.

If your Renogy B2B/MPPT is the DCC40S or DCC50S then to maximise your alternator charging, make sure to switch off the solar charging if your able to, and get the full 40A or 50A when driving (when solar is active you only get half of the nominal charge from the engine).

 

[Guigsy]

I stated that the parasitic draw was 0.1 amps not 1 amp.
I can draw up to 1.5 amps, as shown by my smart shunt, and the Fogstar detects nothing.
Increase the draw to 1.6 amps and the Fogstar app shows a draw of 1.6 amps exactly the same as my shunt.
This is exactly in line with Fogstars own BMS figures for their 230AH battery.

You mixed your units. I was just being a pedant. But I do see a lot of others get very confused because their units are mixed.

 

[headlight]

You mixed your units. I was just being a pedant. But I do see a lot of others get very confused because their units are mixed.

Sorry, you are right I did mix my units as I just re-read what I'd posted

 

[MichaelT]

You mixed your units. I was just being a pedant. But I do see a lot of others get very confused because their units are mixed.

My doctor says I should stick to 14 units but I'm not sure if that's per hour, day or week, but whatever I'm sure I'm over

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[Lenny HB]

Lenny HB has 2 x 230AH's and I think both of his show a capacity of about 244AH?

One comes up at 241ah the other at 245ah.

As for the BMS accuracy on low currents mine have been charging the starter battery via my Multiplus and they are at 45% but the BMS's report 67% & 70%.

 

[suavecarve]

Yes get it to 100% over a few days then fit a shunt.

But if you do this, then where will he get his battery anxiety from ?

Let it all settle down and keep my money is my cunning tight fisted plan

 

[Tio64]

Morning all, having a frustrating time. I've had a 105ah Fogstar Drift with a Victron controller fitted and am now on site using them for the first time, at Broadway campsite.
Battery was at 100% capacity on arrival. I chose not to hook up so that I can see the battery in use and check on it's recharging afterwards.

According to the control panel in the van, the battery depleted to 29% overnight. That has come as a surprise.

Next very frustrating thing: I can get no sense from the Fogstar app, it is showing my capacity as 0.0, voltage at 11.5v, 0 current, 17 degs temp. Obviously the capacity of 0.0 is incorrect, things still work, our electric bed still rose up this morning, heating still on, etc etc.
Anyway I've now plugged in to the ehu, but the van control panel is not registering that we're plugged in and the battery is not charging from the mains. However the Truma shows we're plugged in, as does the fridge, plus our mains electric heater works.

Another question about the app- in History, what on earth do the figures on the base line represent?

Whilst I'm sitting here feeling immensely frustrated, can I just say that while this thread has come at a useful time for me, I do find the terminology used without explanations to be of little help, such that I have no idea what either a BMS or a shunt is. I have dipped into these threads on occasion but have found them of very little use, such is the desire to speak a foreign language.

I'll message Fogstar with screenshots of my useless app but I understand it can take days to get an answer, but has anyone here had any experiences like this, or does anyone have any advice that I might understand?
Cheers folks.

 

[Tio64]

Apologies, should I have posted those pics as thumbnails?

 

[Lenny HB]

Firstly ignore the control panel because Lithium run at almost constant voltage until nearly flat control panel reading is meaningless.

The Fogstar BMS needs to get in sync with the battery and the cells need to be balanced.
You need to charge the battery to 100% then discharge it to a low level then repeat this a few times before installing.
This should sort it out.

When in use be aware BMS can't read small currents below 1 amp and SOC reading will drift out telling you the battery is in higher state of charge than it actually is. This common to all lithium batteries.

The best way of measuring SOC is to fit a Shunt like the Victron Smart Shunt.

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[Pausim]

Whilst I'm sitting here feeling immensely frustrated, can I just say that while this thread has come at a useful time for me, I do find the terminology used without explanations to be of little help, such that I have no idea what either a BMS or a shunt is. I have dipped into these threads on occasion but have found them of very little use, such is the desire to speak a foreign language.

BMS = Battery Management System, all LiFePO4 batteries need this system to look after the battery and protect the cells within it. You have one inside your Fogstar.
Shunt = A device that measures the current (Amps) going into and out of the battery and is used to keep track of the state of charge.

 

[Lenny HB]

Apologies, should I have posted those pics as thumbnails?

Please don't do that far easier to look at full size pics, thumbnails often get ignored as you have to open each one.

 

[autorouter]

Fogstar themselves posted on their owners Facebook forum about a week ago that the BMS on the 105AH cannot detect draws under 1AH, the 230AH and 280AH cannot detect anything under 1.5AH and the 300AH and above nothing under 2AH.

The amps measuring device they are using measures digitally, and has a fixed number of steps that is a power of 2. The cheaper '7 bit analog to digital converter' (A-to-D) chips use 128 steps (2 to the power of 7, positive and negative). So if the max measurement is 100A, the smallest step it can measure is 100 / 128 = 0.8A. Anything less than 0.8A simply doesn't register at all.

I don't know what Victron shunts use, but I imagine it will be a '15 bit A-to-D' chip, which will be able to measure a current of 10mA with a max current of 500A, so it uses 32768 steps, ie 2 to the power of 15.

 

[ChrisL]

Morning all, having a frustrating time. I've had a 105ah Fogstar Drift with a Victron controller fitted and am now on site using them for the first time, at Broadway campsite.
Battery was at 100% capacity on arrival. I chose not to hook up so that I can see the battery in use and check on it's recharging afterwards.

According to the control panel in the van, the battery depleted to 29% overnight. That has come as a surprise.

Next very frustrating thing: I can get no sense from the Fogstar app, it is showing my capacity as 0.0, voltage at 11.5v, 0 current, 17 degs temp. Obviously the capacity of 0.0 is incorrect, things still work, our electric bed still rose up this morning, heating still on, etc etc.
Anyway I've now plugged in to the ehu, but the van control panel is not registering that we're plugged in and the battery is not charging from the mains. However the Truma shows we're plugged in, as does the fridge, plus our mains electric heater works.

Another question about the app- in History, what on earth do the figures on the base line represent?

Whilst I'm sitting here feeling immensely frustrated, can I just say that while this thread has come at a useful time for me, I do find the terminology used without explanations to be of little help, such that I have no idea what either a BMS or a shunt is. I have dipped into these threads on occasion but have found them of very little use, such is the desire to speak a foreign language.

I'll message Fogstar with screenshots of my useless app but I understand it can take days to get an answer, but has anyone here had any experiences like this, or does anyone have any advice that I might understand?
Cheers folks.

View attachment 983007View attachment 983009View attachment 983010View attachment 983011

With regard to history, the figures at the very bottom are the day and time, the blue bars represent the voltage at that time and the orange line the current charge or discharge, in your case I think the BMS may have cut off discharge because of low voltage, in my opinion when you first install a lithium battery it should be charged on hookup or with a dedicated lithium battery charger irrespective of what the app says as it takes a few cycles for the BMS to calibrate itself. Below is a screenshot of my history page so you have an idea of what to expect it to look like.

Edit: the other thing that people may not realise is that when the Fogstar batteries are delivered they are at around 30% SOC, irrespective of what the app says, they are not delivered fully charged.

 

[AdrianChen]

Morning all, having a frustrating time. I've had a 105ah Fogstar Drift with a Victron controller fitted and am now on site using them for the first time, at Broadway campsite.
Battery was at 100% capacity on arrival. I chose not to hook up so that I can see the battery in use and check on it's recharging afterwards.

According to the control panel in the van, the battery depleted to 29% overnight. That has come as a surprise.

Next very frustrating thing: I can get no sense from the Fogstar app, it is showing my capacity as 0.0, voltage at 11.5v, 0 current, 17 degs temp. Obviously the capacity of 0.0 is incorrect, things still work, our electric bed still rose up this morning, heating still on, etc etc.
Anyway I've now plugged in to the ehu, but the van control panel is not registering that we're plugged in and the battery is not charging from the mains. However the Truma shows we're plugged in, as does the fridge, plus our mains electric heater works.

Another question about the app- in History, what on earth do the figures on the base line represent?

Whilst I'm sitting here feeling immensely frustrated, can I just say that while this thread has come at a useful time for me, I do find the terminology used without explanations to be of little help, such that I have no idea what either a BMS or a shunt is. I have dipped into these threads on occasion but have found them of very little use, such is the desire to speak a foreign language.

I'll message Fogstar with screenshots of my useless app but I understand it can take days to get an answer, but has anyone here had any experiences like this, or does anyone have any advice that I might understand?
Cheers folks.

Hi, which Victron controller do you have?

The vans control panel probably uses voltage to estimate the state of charge, and this type of gauge is configured for Lead Acid (Normal) batteries, not Lithium. A lead acid at 30% State of Charge is around 11.8v. A lithium would be almost flat, and the Battery Management System in the battery would be very close to stopping any further discharge. Voltage based estimates work OK on LA batteries but are no good for Lithium, because lithium stays at a high voltage, near 13v so showing full on your vans panel, until its down to 20% left, then the voltage falls off a cliff down to 12v, when the bms will turn it off, all this time your vans panel will be reporting everything is OK!

Not charging up, the app shows the battery BMS is set to allow charging, so is the battery charger definitely turned on?

The History graph axis are voltage on the side, and date and time on the bottom I think

I think the advice above, to fully charge the battery, and then fully discharge it a few times is good, and will correct the inaccurate reporting from the battery's BMS. But as said above they are always prone to drift off, because they don't catch the very small, or very large current flows, so rely on frequent charging to 100% (which is perhaps the only time they are bang on).

So I don't think there is a fundemantal problem, just the batteries BMS needs to "learn" about the battery which takes a few cycles - shame they are not delivered new with that done, but I guess it would add to the cost somewhat.

The advice that a shunt is best to measure the State of Charge of the battery makes sense because a decent shunt like the Victron unit can measure currents down to 0.1amp vs 1amp for a typical BMS. Shunts can also measure higher amps Our Victron type is 0.1amp to 500a which is typical for a van (They go up to 6000amp).

But if you normally plug in everyday, and get your BMS through a few cycles, you may choose to rely on that, rather then learn the ins and outs of configuring the shunt!

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[autorouter]

I would have zero confidence in that app, if the app designer doesn't know the difference between amps and amp-hours, and states that current is measured in amp-hours, not amps. It's like what the statement "I've sailed 100 knots since starting this morning" says about a person's nautical knowledge.

 

[headlight]

Tio64 you are on 1 cycle.
As others have said the BMS takes a number of cycles to settle down before the app readings become reasonably accurate.
My Fogstar 230AH took 5 or 6 cycles before the app was reasonably accurate.
Get some cycles on the battery, ignore your control panel as it will be set to read lead acid battery voltage not Lifepo4.
Lastly consider a shunt, it has already been described what it does, as it is far more accurate than the app.
The BMS on the Fogstar 105AH can't detect anything under 1 amp but a shunt detects down to 0.1 amp.
Reasonable shunts can be bought for under £60.

 

[Raul]

Doesn’t that depend on the round trip efficiency of the battery?

It does, because the detection resolution is valid for draw and charge, both ways. So if the draw/charge is bellow the shunt resolution capability, it will go undetected for the charge as well as discharge.

 

[Raul]

I would have zero confidence in that app, if the app designer doesn't know the difference between amps and amp-hours, and states that current is measured in amp-hours, not amps. It's like what the statement "I've sailed 100 knots since starting this morning" says about a person's nautical knowledge.

Chinglish confusion on translation. The units are valid just need the right interpretation.

 

[autorouter]

Chinglish confusion on translation. The units are valid just need the right interpretation.

Maybe, maybe not. If that can get through their quality control and software testing processes, what else can? The difference between A and AH is fundamental to the monitoring and operation of the battery. It's as bad as confusing V and A, and shows a fundamental flaw in their quality control at the very least. Excusable in the sales flyers maybe, but not, surely, in the information display screens of the dedicated app.

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