280ah Lifepo4 Leisure Battery - Build Thread

[Mrdanielmh]

 

[Mrdanielmh]

Battery has just reached 3.4v

 

[Mrdanielmh]

Battery has reached 3.5v

 

[Mrdanielmh]

Very quickly approaching 3.6v

 

[Mrdanielmh]

Done!

 

[Mrdanielmh]

Initial charge and top balance was successful (I think!). I used the power supply set the 3.614v and eventually the pack at the battery go to exactly 3.600. I measured across the cells and they were also all showing 3.600.

I have now configured the battery into series configuration. I have noticed that the cells have started to drain which is normally, but they are no longer in sync. I think this is normal and most likely isn't a problem. But if anyone has any feedback I'd love to hear it!

Currently the battery in series is showing as: 13.93v and the cells are as follows;

A: 3.485
B: 3.484
C: 3.479
D: 3.482

Thanks!

 

[tim0shel]

Thanks for all of your feedback add questions as this is helpful for others like myself. I have had my batteries forever and still not done this and should. Had been more focused on the build and getting the batteries in the case. Yet before all that is done I need to top balance them. I was holding off waiting for charger. What are you using to charge yours?

 

[Mrdanielmh]

Hey @tim0shel - No problem, i'm very new to this and still learning! The thing that is hardest is knowing what is normal. For example my cells are naturally dropping (which is normal) but I'm not sure if they should still be in sync, as they have started to drift!

I used a 30v/10a adjustable power supply to charge mine for the top balance.

 

[tim0shel]

Hey @tim0shel - No problem, i'm very new to this and still learning! The thing that is hardest is knowing what is normal. For example my cells are naturally dropping (which is normal) but I'm not sure if they should still be in sync, as they have started to drift!

I used a 30v/10a adjustable power supply to charge mine for the top balance.

Yes I know what you mean I also had to learn to not overthink it and just go with it lol. Hopefully here soon I'll have my battery tray finished and get these things installed in the case.

 

[Mrdanielmh]

That is very true! If something feels right, it normal is! Brilliant stuff, keep me updated with how you get on!

 

[Haugen]

I'm no LiFePo4 expert, but I don't think a few millivolts difference is going to matter.
If you were having drops of a tenth of a volt, I would start to worry.

 

[dashdrum]

I'm no LiFePo4 expert, but I don't think a few millivolts difference is going to matter.
If you were having drops of a tenth of a volt, I would start to worry.

I agree. Those look balanced enough for me

 

[Mrdanielmh]

Thank you @Haugen and @dashdrum - giving me a bit of confidence! I've order a battery box now, so I'm going to get it all built up! I will try to attach the BMS tomorrow and make sure that is all working

 

[Haugen]

My camper has a dedicated battery compartment, so I intend to construct my own restraints to hold the batteries secure.
Once I remove the battery box required by the FLA, there should be enough room to house 8 cells.

 

[Thermodynamical]

This is very interesting. Thank you for documenting this Mrdanielmh.

 

[Mrdanielmh]

Thanks @Thermodynamical -im glad its useful.

Update

Cells have been reconfigured into 4s giving a 12v 280ah battery. I have also connected up the BMS and everything looks good!



Next job is to get this packaged into some kind of box amd finish the wiring to make it a bit more useful!

 

[Mrdanielmh]

All tidied up and placed into a box. Just waiting for some cables so i can rum battery Terminal to box terminals!

 

[Airtime]

Initial charge and top balance was successful (I think!). I used the power supply set the 3.614v and eventually the pack at the battery go to exactly 3.600. I measured across the cells and they were also all showing 3.600.

I have now configured the battery into series configuration. I have noticed that the cells have started to drain which is normally, but they are no longer in sync. I think this is normal and most likely isn't a problem. But if anyone has any feedback I'd love to hear it!

Currently the battery in series is showing as: 13.93v and the cells are as follows;

A: 3.485
B: 3.484
C: 3.479
D: 3.482

Thanks!

Those look pretty close given you are still up the knee a bit at full charge. The cells are not draining, the voltage just settles a bit when charge is removed. You are still at 100.0% charge. I'll bet if you discharge 1% of your capacity, just a couple Ah, they will tighten up and be within 1-2 mV. At least that was my experience with my 280Ah cells. In fact I would discharge a bit anyway rather than leave them at 100.0% charge.

 

[Tball]

All tidied up and placed into a box. Just waiting for some cables so i can rum battery Terminal to box terminals!

View attachment 15374

Looking really good, anxious to get my 8 cells, top balance and build a box as well!

 

[Mrdanielmh]

Those look pretty close given you are still up the knee a bit at full charge. The cells are not draining, the voltage just settles a bit when charge is removed. You are still at 100.0% charge. I'll bet if you discharge 1% of your capacity, just a couple Ah, they will tighten up and be within 1-2 mV. At least that was my experience with my 280Ah cells. In fact I would discharge a bit anyway rather than leave them at 100.0% charge.

You are absolutely spot on! Ive drained a little bit out with some 12v usb chargers and they are come a bit closer together! My BMS isnt showing the correct percentage or AH so im going to try a full discharge and recharge once some stuff turns up!