DIY 304Ah EVE cells with Daly 250A BMS

[gray webber]

18650 had a store on Aliexpress, it was a scam. You are correct that 18650 was a supplier.

Docan may not be the cheapest but if you are looking for cheap, I would suggest you change your search parameters to reliable. Docan will be right up there on that list.

Sounds good. Yes, not cheap but most often you gat what your willing to pay for. I’m discovering lots! Trying to steer away form crap.
Thanks.

 

[gray webber]

Sounds good. Yes, not cheap but most often you gat what your willing to pay for. I’m discovering lots! Trying to steer away form crap.
Thanks.

I have just finished my battery build plan. It will be built into an insulated box. It will have a snap action stat controlling 2-12watt heat pads. The EVE 280ah cells will be under compression using poly banding. I’ll use a JK -BMS 200a. I’ll take pics when I build it and post them. It will have two low temp charge cut off safeties , one is in the BMS and the other is in the EPEver temp sensor shut down. The heater can be shut off for warm season.
Starting to feel confident about this build thanks to a great deal of sharing on this forum.

 

[jwwh]

you shouldn't set the balancing voltage at 3v, it will destroy the battery balancing. It is good to set the bulk charging voltage to 3.45v or 3.5v, then balancing starting voltage at around 3.41v. If your charge your pack at 3.4v the absorption time will be super long.

 

[gray webber]

you shouldn't set the balancing voltage at 3v, it will destroy the battery balancing. It is good to set the bulk charging voltage to 3.45v or 3.5v, then balancing starting voltage at around 3.41v. If your charge your pack at 3.4v the absorption time will be super long.

My current plan is charge voltage 28.4. Absorb time of 15 min.
Float of 27.6. Low voltage cut off of 24.8.
I hope to operate between 15-95% for 80% of charge cycles????? Where is my error?
I will set my JK BMS at 3.55 max and active balancing. Hope this will work?

 

[Eorury]

Hi all,

as a long time reader and now, first time poster, I have just built my first LiFePo4 battery with 304Ah Eve cells. Find below some pics and specs. Happy for any constructive feedback or if anyone spots a mistake. The battery is intended for our offroad vehicle

1. EVE 304AH cells with rubber foam in between cells as spacer
2. Daly 250A BMS & active balancer (can optionally be plugged in if I notice too much cell drift)
3. Double bus bars, taped & with plastic cover on the screws (positive terminal also has one but wasn't on the photo)
4. Custom fabricated metal housing
5. Pack tied with filament tape and hollow-chamber plastic board (no idea what this is called in english) as insulator against the housing (visible in the lid)

Generally, I tried to insulate and separate everything as much as possible to avoid any damage caused by vibration and subsequent shortening.

(Very conservative) BMS Settings:

• High-voltage: 3,4V (Total: 13,6V)
• Low-voltage: 2,85V (Total: 11,4V)
• Diff voltage: 0,26V
• Balance open start voltage: 3.0V
• Balance open diff voltage: 0.05V
• Chg high temp protect: 42°C
• Chg low temp protect 3°C
• disChg high temp protect: 55°C
• disChg low temp protect: -15°C

I do have some questions though:

1. The laser welded studs seem to have a very small surface contact area. What is the maximum amperage they can handle?
2. The Daly 250BMS only has a 2AWG wire which seems a bit low for currents up to 250A. Do you see any issues on running a continuous 2-2.3kW (150-170A) load?
3. There is a very minor voltage between the main positive terminal and the case but no voltage between each of the cells and the case. So my suspicion is, that this is from the BMS being screwed onto the case. Do you think this is an issue?

Hey
Andy from the Off Grid Garage tested the change with the new post design today. Its a nice watch.

 

[Just John]

• Balance open start voltage: 3.0V

Cells do not diverge until above 3.4v. Setting this lower is counterproductive and will unbalance your pack.
Daly is not a good choice, I know, I own 3 of them. If it works well for you, then don't worry.

 

[Just John]

Interesting. Those numbers were roughly based on the SOC charts I found here in the forum. My plan is to keep the battery between 10-90% SOC for longevity. Guess I will have to play around a bit and cycle test it a few times with slightly adapted settings until I hit the sweetspot.

It listed 3.32V as 90% SOC so I figured 3.4V would be plenty.

Found the charts in this thread.

Using voltage as a state of charge indicator in LFP is an exercise in futility unless you wait a substantial amount of time between charge or discharge and taking the reading. Try it yourself and see.