Flat lithium battery.

[ChrisL]

Yes, low temperature cut off charging.

It's a Fogstar Drift I think, so should be heated when charging at low temperatures?

 

[Raul]

It's a Fogstar Drift I think, so should be heated when charging at low temperatures?

If its heated and the charging amps are too low, not enough for the heat pad, then it will NOT charge.

 

[Tio64]

Hi all,

Apologies for not getting back, with the help of my electrician we found out the source of my problems.

In my van, the Nordelettronica NE350 charger module is mounted in such a way that while the fuses and most connections are easily accessible at top, the connections underneath/at other end are not. This is where the mains feed plugs in.

On removing the Nordelettronica we found that the mains cable was not fully home into its connection. This is either our fault from when we fitted the battery, or when refitting the base that the battery sits on we impinged on the cable and possibly pulled it down. It does seem the mains doesn't click home like the other connections do. We'd had to access the other end of the unit to access the dipswitches. It has to be said that the wiring under the battery base is a mess, on our 3 yr old Adria, with none of the cabling clipped in, fixed or routed as might be expected.



My electrician then continued to check on voltages, including to and from the B2B module. Not happy with what he was finding he went to disconnect the module, on removing a small cover we discovered a blown 30A fuse, which my electrician wasn't aware of the existence of. With this replaced the voltages then made sense.

With everything back in place it all seems to be working, though my van was inside his large workshop, (we carried out this work Friday pm), I'm still yet to remove the vehicle from his workshop to confirm the solar is working. I'll do that tomorrow (Monday) morning.

When we fitted the battery we had confirmed all was working, I can only think that the drive to the campsite had allowed the cable to move just enough to lose the connection.

Hey ho, for what it's worth, I'm a lot wiser now.

I'm still puzzled at how completely my 105ah lithium battery depleted overnight on site, such that I was convinced the app was misreading completely, this is something I'll learn more about through experience.

Thanks for all your help, guys.

 

[AdrianChen]

Glad you're sorted.

 

[McLouis]

Glad you're sorted.

Crikey am I glad I built my own LFP I measured the capacity of each cell, top balanced the cells in parallel with the same discharge/charger that the manufacturers use. I also used J-K bms that it is possible to set virtually every parameter know to mankind. I have always used a shunt to determine a SoC, but I tried a number of different shunts, including Votronic, Victron and a couple of cheap Chinese shunts and after a few cycles there was next to no difference between any of them. However, the Victron has the highest max current.

Now operational I have the balance turned off and after 3 months of use the cell voltage delta is never greater than 3-5 mV. I would echo that in a real environment the bms shunt is not as accurate as an external Coulomb counter and use the Votronic shunt for SoC. However, on the J-K bms it is possible to calibrate both V and current draw.

I do believe that suppliers such as Fogstar should top balance the cells, determine the battery capacity and provide clarification of this and then discharge to their shipment level. Folks can at least know what they have. All top quality new generation cells will deliver.

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[ChrisL]

I do believe that suppliers such as Fogstar should top balance the cells, determine the battery capacity and provide clarification of this and then discharge to their shipment level

Doing that would add to the cost for the consumer, how hard is it for a customer to charge a new battery to 100% at install? Re capacity, my battery was sold to me as rated at 230ah, as long as it meets that claim i'm happy, the fact that it appears to hold 243ah is a bonus.

 

[Raul]

Crikey am I glad I built my own LFP I measured the capacity of each cell, top balanced the cells in parallel with the same discharge/charger that the manufacturers use. I also used J-K bms that it is possible to set virtually every parameter know to mankind. I have always used a shunt to determine a SoC, but I tried a number of different shunts, including Votronic, Victron and a couple of cheap Chinese shunts and after a few cycles there was next to no difference between any of them. However, the Victron has the highest max current.

Now operational I have the balance turned off and after 3 months of use the cell voltage delta is never greater than 3-5 mV. I would echo that in a real environment the bms shunt is not as accurate as an external Coulomb counter and use the Votronic shunt for SoC. However, on the J-K bms it is possible to calibrate both V and current draw.

I do believe that suppliers such as Fogstar should top balance the cells, determine the battery capacity and provide clarification of this and then discharge to their shipment level. Folks can at least know what they have. All top quality new generation cells will deliver.

Few things to take on board if you like.
I also build batteries with cells and bms from JK and seplos so far. The balance should NOT be turned off never, UNLESS the active balancer is a secondary to a integrated resistor balancer like JBD. What you do, after you happy with the balance, after few cycles, you increase the delta trigger and voltage per cell trigger. The balance should be allowed on charging and discharging. If an event of a cell or more goes south, there is no balancer to correct the imbalance, and it will end up with a large delta before you figure it out, capacity drop, cel UV-OV disconnection triggers.

Voltage calibration, is at a pack value, then the rest are calculated based on that, by the bms. You can calibrate voltage AT REST ONLY, and confirmed with a known good voltage meter, preferably a meter with a calibration cert in date.

Current calibration, is more tricky, calibrate at low current, and will be out at high currents, and vice versa. The reason? Bms shunt does not have enough resolution. A tipical 200A bms will be calibrated at 100A. I also calibrate at midd range amps known to be used: if my max draw is 100A, I calibrate at 50A, that way the discrepancies will be even at low and at high charge -discharge.

If you run the latest firmware supported by the your hardware JK, you will be able to set a voltage per cell to trigger the 100% SOC ( first cell that reaches that value). This setting it is not supported by older hardware versions.
I hope this helps anyone interested.