Start your engine with 4 eve lifepo4 cells, lead makes no sense for this task!!

[bill good]

EVE cells being sold by vendors are really reject cells (I believe but not confirmed by me) that failed to meet specs for EV production but then re-purposed for solar etc. Therefore the specs sheet are not true. We just do not know why the rejection.However for short pulsed start so long as the terminal connection is good I see no problems. The reason the terminals are blocks is the batteries for EV application has to be laser welded i.e. no screwed terminals. The design of the BMS for high current is another point that should be looked at. Currently have EVE cells sold as 305A/H but believe 280K & even with suspected poor quality can run microwave + jug with no problems. (using Bi-Stable relay rated at 300A continual) in the BMS.
Battery & case 25Kg replaces 700A/H lead.

[CaptainRivet]

Originally Posted by Dorin

If you don't see a glaring error that could cause a fire, you are useless and hopeless. Take that to the mods.

That says all you cannot even justify yourself...

[CaptainRivet]

Originally Posted by bill good

EVE cells being sold by vendors are really reject cells (I believe but not confirmed by me) that failed to meet specs for EV production but then re-purposed for solar etc. Therefore the specs sheet are not true. We just do not know why the rejection.However for short pulsed start so long as the terminal connection is good I see no problems. The reason the terminals are blocks is the batteries for EV application has to be laser welded i.e. no screwed terminals. The design of the BMS for high current is another point that should be looked at. Currently have EVE cells sold as 305A/H but believe 280K & even with suspected poor quality can run microwave + jug with no problems. (using Bi-Stable relay rated at 300A continual) in the BMS.
Battery & case 25Kg replaces 700A/H lead.

Due to EV crises not anymore rejected cells from a lot of resellers, you can get for 90Euro real 304AH EVE grade A now from QSO, Cmon or nkon.
https://eu.nkon.nl/eve-lf304-prismat...v-a-grade.html
Even with the good new terminal that avoids you can strip the terminal.
The old Gen 1 and 2, mostly m6 or M8 terminal with thread or welded stud that can only do 1C cont and 2C peak due to spec but suffer lifespan if used above 0.5C as these are pure storage cells. The newer gen3 280AH and 304 with the double terminal are much better also as starter as they can do real 2C cont and 3C peak without suffering and lifespan reductions. Also the new gen4 306 and 316AH cells are really good all purpose with even 3C continious and 4C peak can do the 1400CCA the OP stated...gen 1 and 2 never, gen 3 with reduction in lifespan.

And yes with prices down to 60Euro for grade b or C gen 3 280AH EVE it even makes sense using a 1p4S 280AH as starter, these cells will differ in capacity and internal resistance for sure but an active balancer will cure that, for a starter totally sufficent and that they most likely have 265-270AH doean't matter when starting costs you less then 1AH.
You are absolutely right regarding BMS, especially the mosfet BMS which don't like the surges a starter creates.