Idiot's guide to a self build battery

[Joeboy]

Happy New Year Colin, stay Safe. All the best to your family from us guys.

[Colin Deng]

Happy New Year Colin, stay Safe. All the best to your family from us guys.

Thank you Joe ,Happy new year to you and your family , also everyone in this group
Actually having the CNY holiday now, just get back home today with family

[MrPablo]

Kenny, is there any data with your cells that indicate expected cycle life? I see quite a variation when it comes to the EVE 304 cells that I think you have.

[Kenny000666]

Kenny, is there any data with your cells that indicate expected cycle life? I see quite a variation when it comes to the EVE 304 cells that I think you have.

When I did my research I was looking for 6000+ cycle cells. I believe these EVEs can do this. But I think Colin would have a better idea on the data for these cells.

Here’s the spec sheet Deriy gave me -

[Kenny000666]

Ok just to note for day 3.
Batteries are all connected up everything all fine and dandy. No sparks, zaps, burns. The one time I didn’t have my gloves on, I did get pierced by small stranded wire from the battery cables.

I discharged the pylons to around the same voltage as the Batteries (approx 49.8v) and disconnected the fuse and turned off the pylons. Connected the diy pack and Pylons in parallel. Reconnected the fuse and allowed power.

I did make a boo boo here. I thought the BMS didn’t have any capability to turn on or off supply, so thought it was working. Measured current, very small current going through the DIY stack during charge (3amps) when it should be at least 1/2 of the inverter supply. I also noticed my SOC on the pylon was dropping as it did before connecting the battery.

So I realised that I didn’t turn on the Charge and Discharge function of the BMS and so it wasn’t doing anything.

After turning it on im seeing a discharge current, and a charge current when charging.



Seems you actually need to install and use the App to use the BMS. If I ever need to disconnect it, looks like I can just switch the BMS Charge/Discharge to Off and that kills the current.

So I’m done, will be keeping an eye out over the next few days and report any unusual activity.

All in all, no disasters, my house is not burned down (yet) I’m technically still 1 week early on my set up. (FYI it took 6 months to receive my pylontech)

[Kenny000666]

Checked the voltages on DIY stack and Pylons, they are now the same as reported from HA (pylontech) and the jk BMS (diy). Did not take very long for them to equalise at all.

Unfortunately, I can’t check that often as the Bluetooth on the BMS has literally <5 meter range. (Until I get it hooked into HA)

[MrPablo]

Thanks for datasheet Kenny, I'm trying to weigh up EVE 280K with high cycle life, Vs 304 with less cycles but more capacity.
All made more tricky to decide by the fact the cells will never be charged or discharged at 1C, nor see crazy high temps.

[nowty]

Thanks for datasheet Kenny, I'm trying to weigh up EVE 280K with high cycle life, Vs 304 with less cycles but more capacity.
All made more tricky to decide by the fact the cells will never be charged or discharged at 1C, nor see crazy high temps.

Don't overthink it, whichever ones you buy, your batteries will die of old age (calendar life) long before they die of exceeded cycle life. If I go off cycle life my pack should last me about a century.

[MrPablo]

Thanks for datasheet Kenny, I'm trying to weigh up EVE 280K with high cycle life, Vs 304 with less cycles but more capacity.
All made more tricky to decide by the fact the cells will never be charged or discharged at 1C, nor see crazy high temps.

Don't overthink it, whichever ones you buy, your batteries will die of old age (calendar life) long before they die of exceeded cycle life. If I go off cycle life my pack should last me about a century.

You're quite right, thinking about it logically I'm really not going to see any real issues for a very, very long time.
It's a holdover from my time playing with li-ion packs, but lfp is a very different kettle of fish.

[Colin Deng]

Thanks for datasheet Kenny, I'm trying to weigh up EVE 280K with high cycle life, Vs 304 with less cycles but more capacity.
All made more tricky to decide by the fact the cells will never be charged or discharged at 1C, nor see crazy high temps.

Hi
The EVE 280K battery
Some batteries tested capacity is more than 280ah
It can be 285ah more to 289ah
Hope this info can help