Fogstar Drift Problems. (1 Viewer)

[RogerIvy]

Hi Roger, thanks for the reply. I set the XS to 14.2 as discussed with you and it seemed to cut off ok at 100%. The Shunt is a BMV702 which I set to the values you recommend in your video. The 702 is a pain as it has to be disconnected from the Cerbo to connect the Bluetooth dongle to see the settings which is not easy when installed in a panel and I am concerned about too much stress on the tiny wires. I am surprised it can’t be viewed and modified with the CerboGX on the Pi. I have just checked the software version on the XS and it is Firmware v1.03 so I will have to download v1.04 as suggested by AdrianChen.
I have checked the whole installation with my Infra Red camera and there are no “HotSpots” on the batteries or any of the terminals or cables. One of my bus-bars is slightly warm at 40C so I will have to check that when I get home.
I will be able to plug-in for about a day tomorrow so will do that but I am very surprised how far everything has drifted out. How can the BMS’s be so far different to the Shunt and show a difference in the cycles when firmly in parallel. It is hardly worth having the app if the BMS can show charge values of 52% & 67% when the shunt shows 20% that is a hell of a difference and which do I believe.
It is rather defeating the perceived benefits of Lithium if it is a requirement to go onto hook-up regularly.

Unfortunately you will get drift through time, both the BMS and the shunt. By tweaking and experimenting with the shunt settings you may eventually stumble across your particular (and exact) peukert and charge efficiency.
The easier way is to charge fully to 100% so “everyone forgets their differences” (ie all your SOC indicators agree with each other) coz they’re all 100%

I mentioned the 14.3 because it removes a little margin for error, basically forces the BMS to definitely reach high cell volt disconnect.

 

[OldAgeTravellers]

Found a Motorhome dealer with a small Aire with EHU last night and connected up. Our Schaudt EBL only charges at 16A so it will take a while. The battery BMS’s reached 100% after 16 hours but not at 13.2 volt. The shunt reached 100% after 22hrs at 13volt then reached 13.2 volts an hour an a half later and cut off charging.
We have about 15 days of not too much activity let’s hope they hold up for that time.
Still confusing that the BMS’s have done different amounts of cycles when connected in parallel. If we only had the app could easily have run the batteries to zero.

 

[ChrisL]

Found a Motorhome dealer with a small Aire with EHU last night and connected up. Our Schaudt EBL only charges at 16A so it will take a while. The battery BMS’s reached 100% after 16 hours but not at 13.2 volt. The shunt reached 100% after 22hrs at 13volt then reached 13.2 volts an hour an a half later and cut off charging.
We have about 15 days of not too much activity let’s hope they hold up for that time.
Still confusing that the BMS’s have done different amounts of cycles when connected in parallel. If we only had the app could easily have run the batteries to zero.

Maybe Raul can correct me if i'm wrong but I don’t think 13.2v is fully charged for a fogstar drift, mine is set to 14.25 absorption and 13.61 float, once the voltage gets to 14.25 and the amps drop to 4.6 then it goes to absorption for a few minutes then drops to the float voltage.

 

[Lenny HB]

What source of power was that ?


I was looking at going for the ?/50 victron for 400 watts of solar but getting 180 ah in a couple of hours

I fitted a Multiplus 3000, 3000va inverter with a 120amp mains charger. I've limited the charger to 90 amps so as not to overload a 5 amp EHU.

 

[MichaelT]

I fitted a Multiplus 3000, 3000va inverter with a 120amp mains charger. I've limited the charger to 90 amps so as not to overload a 5 amp EHU.

But you never go on sites or use hook up

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[Lenny HB]

But you never go on sites or use hook up

Cost was so little extra worth having as if battery are low I can go on an Aire and fully charge for a few Euro.

 

[OldAgeTravellers]

I fitted a Multiplus 3000, 3000va inverter with a 120amp mains charger. I've limited the charger to 90 amps so as not to overload a 5 amp EHU.

I didn’t have space for a Multiplus Lenny, without running massive cables right back to the garage probably 4 or 5 metres. And now I see how quickly I can run 600ah of battery down just by boiling the kettle for tea occasionally I am glad I didn’t. Having a lazy time just doing a few miles really whacks the batteries. We are using negligible gas though which is good as it is fairly scarce in Denmark.
It’s all a learning curve. Getting the balance right. Not getting much solar either, in Spain it would be different.
The first two months when we were moving every day we had no problem as the batteries would be recharged by lunch time.

 

[TCG]

Maybe Raul can correct me if i'm wrong but I don’t think 13.2v is fully charged for a fogstar drift, mine is set to 14.25 absorption and 13.61 float, once the voltage gets to 14.25 and the amps drop to 4.6 then it goes to absorption for a few minutes then drops to the float voltage.

yes my absorption set to 14.20 --- float 13.60 - fogstar drift

 

[suavecarve]

I fitted a Multiplus 3000, 3000va inverter with a 120amp mains charger. I've limited the charger to 90 amps so as not to overload a 5 amp EHU.

Finished our 280ah lithium yesterday and fully charged it overnight to 304 ah

Wont get chance to put solar on before we go away (or a very slim chance) but I was getting 25ah of input off an idling alternator through a gel setting (no lithium) and 18ah off the 240 volts. We went with 3000 inverter as well.

400 watts of solar is where I m thinking of going and we think we will probably be ok for a month without solar by popping to the occasional aire with electric and a little bit of driving and abstracting electricity from the free ladestations and free Bosch stations for the e bikes

We are time limited for upgrades as the van came with next to nothing of interest to us. Alarm and tracker going in next week !

 

[Raul]

Found a Motorhome dealer with a small Aire with EHU last night and connected up. Our Schaudt EBL only charges at 16A so it will take a while. The battery BMS’s reached 100% after 16 hours but not at 13.2 volt. The shunt reached 100% after 22hrs at 13volt then reached 13.2 volts an hour an a half later and cut off charging.
We have about 15 days of not too much activity let’s hope they hold up for that time.
Still confusing that the BMS’s have done different amounts of cycles when connected in parallel. If we only had the app could easily have run the batteries to zero.

That’s not right, it should not stop charging at 13.2v. At that voltage with such low rate I would be surprised if the battery sees more than 70-80% SOC. What settings are on the EBL?
For fully charged you should see 13.35v rested. On the charging curve the voltage in absorb is minimum 14v for 100% charge, a 14.2v is a bit faster and more balanced cells. Then drop in float to 13.5v if you can set it, but no higher than 13.6v float.

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[RogerIvy]

yes my absorption set to 14.20 --- float 13.60 - fogstar drift

We used to use the default Victron settings for LiFePO4 and TBH didn’t experience any issues. Not that we know of anyway … would most people actually notice that their BMS never reached “high volt disconnect”?

FogStar recommend a slightly higher absorption voltage (I guess 14.25 or 14.3) to mitigate slight calibration issues in either the chargers or the BMS. It does make sense.

So …. These days we set chargers to 14.3v

 

[OldAgeTravellers]

That’s not right, it should not stop charging at 13.2v. At that voltage with such low rate I would be surprised if the battery sees more than 70-80% SOC. What settings are on the EBL?
For fully charged you should see 13.35v rested. On the charging curve the voltage in absorb is minimum 14v for 100% charge, a 14.2v is a bit faster and more balanced cells. Then drop in float to 13.5v if you can set it, but no higher than 13.6v float.

Sorry that was a typo it should have read 14.2v not 13.2v. There was a noticeable cut off of charge as it hit 14.2v. The EBL is set to GEL.

 

[Carpmart]

Why is it a problem if the voltages on the batteries (and cells) are similar?

Mine drift out reasonably quickly and over a few months continuous ‘off grid’ use (solar and DCC only charging) can get quite out of kilta in terms of their Bluetooth derived SOC. the voltages are always similar across all cells on the three battery power bank, so it doesn’t matter. Or I don’t see why it matters?

 

[OldAgeTravellers]

Why is it a problem if the voltages on the batteries (and cells) are similar?

Mine drift out reasonably quickly and over a few months continuous ‘off grid’ use (solar and DCC only charging) can get quite out of kilta in terms of their Bluetooth derived SOC. the voltages are always similar across all cells on the three battery power bank, so it doesn’t matter. Or I don’t see why it matters?

It probably doesn’t matter. I just find it strange that the BMS’s are of so little use other than perhaps to protect the battery from wildly under or over charge or discharge. Mine are correctly connected in parallel using identical length cables but were showing such different values even different numbers of cycles when they both started at zero.
Assuming that my Victron shunt is accurate. The BMS displays were so far out that the batteries would have been at zero while the BMS’s were still showing about 30%. If they are actually counting amps in and out.
It may explain why their new budget ones out in October you can’t even view the BMS. To protect themselves they have also reduced the warranty to 6 years. Probably assuming as a fit and forget they will get quite a bit of abuse thereby shortening their lives. I suspect that they are identical batteries but without a heater or user accessible BMS’s.

 

[MichaelT]

It probably doesn’t matter. I just find it strange that the BMS’s are of so little use other than perhaps to protect the battery from wildly under or over charge or discharge. Mine are correctly connected in parallel using identical length cables but were showing such different values even different numbers of cycles when they both started at zero.
Assuming that my Victron shunt is accurate. The BMS displays were so far out that the batteries would have been at zero while the BMS’s were still showing about 30%. If they are actually counting amps in and out.
It may explain why their new budget ones out in October you can’t even view the BMS. To protect themselves they have also reduced the warranty to 6 years. Probably assuming as a fit and forget they will get quite a bit of abuse thereby shortening their lives. I suspect that they are identical batteries but without a heater or user accessible BMS’s.

Are you connected direct or to bus bars?

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[Carpmart]

It probably doesn’t matter. I just find it strange that the BMS’s are of so little use other than perhaps to protect the battery from wildly under or over charge or discharge. Mine are correctly connected in parallel using identical length cables but were showing such different values even different numbers of cycles when they both started at zero.
Assuming that my Victron shunt is accurate. The BMS displays were so far out that the batteries would have been at zero while the BMS’s were still showing about 30%. If they are actually counting amps in and out.
It may explain why their new budget ones out in October you can’t even view the BMS. To protect themselves they have also reduced the warranty to 6 years. Probably assuming as a fit and forget they will get quite a bit of abuse thereby shortening their lives. I suspect that they are identical batteries but without a heater or user accessible BMS’s.

To put your mind at rest, I’ve had my original pair (now got three batteries) in use for over three years and they have quite different cycle counts and never show the same SOC precisely, yet the individual cell voltages, within each battery are pretty much identical!

So 3.8x on one cell in one pack is the same 3.8x in another cell in the other pack and indeed now on a cell in the third battery pack.

HTH’s you to be less concerned?

 

[Pausim]

I just find it strange that the BMS’s are of so little use other than perhaps to protect the battery from wildly under or over charge or discharge.

That is precisely what a BMS is there to do, protect the battery. The bluetooth, Amp counting and sophisticated cell reporting are fancy add ons and not part of the essential BMS operation. I am happy that my new Roamer battery has this information but the basic operation and protection of the battery are the important bits. My Relion battery has been running reliably for 6 years without any of this information. I have also never found the need for a battery heater.

 

[OldAgeTravellers]

I have also never found the need for a battery heater.

I have an external battery locker so thought it could be an issue in winter depending on where we travel. The majority of people with internal batteries especially under seat ones are unlikely to have problems. So I thought it important to have heaters otherwise my batteries may never get to charging temperature on a journey.

 

[Lenny HB]

I didn’t have space for a Multiplus Lenny, without running massive cables right back to the garage probably 4 or 5 metres.

That's what I did.

 

[Lenny HB]

OK I've now joined the out of Balance BMS club.
My Fogstars were behaving perfectly we have been away for 5 nights, yesterday I notice there was a 3% difference one at 68% and the other at 71% not enough to worry about.

This morning used a bit of power before we set off batteries were down to 60% on my shunt but I didn't check the Fogstar app.

Drove 2½ hours home with B2B charging them. checked the batteries one at 71% the other at 91%, now that's weird.
Shunt was at 81% so within 1% of the average of the two.

Hooked up to the mains to give them a charge, charging at 87 amps one battery at 43 amps the other at 44 amps BMS's agreed with my clamp meter.

After ¾ hour one battery at 100% charging at 5 amps the other battery at 94% charging at 68 amps.

About an hour later both batteries at 100%, 14.2v, charge current at zero.

Any comments RogerIvy

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[Carpmart]

OK I've now joined the out of Balance BMS club.
My Fogstars were behaving perfectly we have been away for 5 nights, yesterday I notice there was a 3% difference one at 68% and the other at 71% not enough to worry about.

This morning used a bit of power before we set off batteries were down to 60% on my shunt but I didn't check the Fogstar app.

Drove 2½ hours home with B2B charging them. checked the batteries one at 71% the other at 91%, now that's weird.
Shunt was at 81% so within 1% of the average of the two.

Hooked up to the mains to give them a charge, charging at 87 amps one battery at 43 amps the other at 44 amps BMS's agreed with my clamp meter.

After ¾ hour one battery at 100% charging at 5 amps the other battery at 94% charging at 68 amps.

About an hour later both batteries at 100%, 14.2v, charge current at zero.

Any comments RogerIvy

Could it be that one battery has cells with higher IR than the other battery. My guess would be one is disproportionate contributing to the power supply?

 

[Bessy765]

We have 700 watts of solar 2 x 100 amp Transporter Lithium and a Victron 12/2000/80 inverter charger, re a previous comment about limiting charge to protect the low amp hook up supply, on our Victron we can adjust the charging rate easily to whatever the site supplies, and of at a rally where we need to run our little Honda EU10i we can scale it down to 2 amps so the genny is not roaring its head off put will put 20 amps in.
Cables etc are oversized to get the maximum current flow each battery is under. A front seat wrapped in a Kevlar shroud. No B2B fitted when driving can get 80/90 amps charge. All cables connect to bus bars.

 

[Lenny HB]

Could it be that one battery has cells with higher IR than the other battery. My guess would be one is disproportionate contributing to the power supply?

Both battery cell balanced within 0.004v and have been performing identical up until today.

 

[RogerIvy]

Any comments RogerIvy

I find it quite common that with two “identical” batteries one will work a bit harder than the other.
The problem with guys like us is it drives us crazy. Maybe we should take a leaf out of Pausim ’s book

Seriously though batteries can do puzzling things.

Did it really take a full hour for the 2nd battery to catch up to the first? That would imply a significant imbalance in real Soc.

How much do you trust the two BMS’s? Have you watched as they approach 100% and see if they do actually hit OVP as they click over from 99 to 100?
(Same with the shunt)
It’s a bit tedious but handy to know how well calibrated the various shunts are.

 

[Lenny HB]

I find it quite common that with two “identical” batteries one will work a bit harder than the other.
The problem with guys like us is it drives us crazy. Maybe we should take a leaf out of Pausim ’s book

Seriously though batteries can do puzzling things.

Did it really take a full hour for the 2nd battery to catch up to the first? That would imply a significant imbalance in real Soc.

How much do you trust the two BMS’s? Have you watched as they approach 100% and see if they do actually hit OVP as they click over from 99 to 100?
(Same with the shunt)
It’s a bit tedious but handy to know how well calibrated the various shunts are.

Probably wasn't an hour I was busy doing other things.
The shunt has been spot on with the BMS's, I think I did check before driving off and they were within 3 %.
The 20% difference appears to be after charging with the B2B.

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[Carpmart]

Both battery cell balanced within 0.004v and have been performing identical up until today.

Yep they will always get to balance eventually. I see everyday the difference in IR with paired 18650 cells in my vapes. One will often work harder (and charge slower) as the higher IR one is less performant. No different with EVE based cells in the Fogstar batteries.

TBH, it would be helpful if batteries were sold, if planned to be used in parallel, with similar IR to minimise some of these issues.

 

[AdrianChen]

Probably wasn't an hour I was busy doing other things.
The shunt has been spot on with the BMS's, I think I did check before driving off and they were within 3 %.
The 20% difference appears to be after charging with the B2B.

Should have been back to 100% within 15mins I'd have thought (mine only really stop accepting when they are virtually at 100% - not Fogstars though) Any chance one battery might be getting hotter or something silly like that?

 

[suavecarve]

Yep they will always get to balance eventually. I see everyday the difference in IR with paired 18650 cells in my vapes. One will often work harder (and charge slower) as the higher IR one is less performant. No different with EVE based cells in the Fogstar batteries.

TBH, it would be helpful if batteries were sold, if planned to be used in parallel, with similar IR to minimise some of these issues.

Please tell me you have 2 vapes and you have connected them with a busbar and a BMS and you monitor the loss of power on each puff

 

[Lenny HB]

Should have been back to 100% within 15mins I'd have thought (mine only really stop accepting when they are virtually at 100% - not Fogstars though) Any chance one battery might be getting hotter or something silly like that?

It would need to be at least an hour charging at 87 amps.

 

[Carpmart]

Please tell me you have 2 vapes and you have connected them with a busbar and a BMS and you monitor the loss of power on each puff

Two 18650 cells in the same vape!

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