robbob2112
Doing more research, mosty harmless
I have been bitten by the bug and the only cure is to build a couple.
I have a wattcycle 300ah battery that turns out to be a 280ah battery. And from Will's review it doesn't have any over-current protection until you get well up around 800amps. So I am replacing that BMS with a JBD BMS SP04S060 - the 300amp variety with all the ports on it. I don't need heat, but doesn't mean I can't use the port for something else.
jiabaida-bms.com
Of course since I got bitten by that bug I ordered 8 of the 314ah MB31 EVE cells from 18650battery.com . They are currently backordered, but come with bus bars. ETA is Feb 21st so it will be a month wait.
So I ordered 2 more of the BMS.... so I will have 2 of them from Aliexpress and one from their official store... so I can compare all three and see if the aliexpress version is inferior in some way and get a refund if it is. If it fell off a truck or was a QA reject that might not show until hooked up.
Funny thing on the MB31 EVE cell data sheets - some say the continuous discharge rate is 1C and some say it is 0.5C ... so I am not sure what is right - will see what the paperwork that comes with them says.
I will be looking to see if they are factory EVE cells with the terminals laser welded on or not - what I can find says the factory cells with terminals have countersunk dots on the lower part with a red and blue dot of paint in them and that the weld depth is 2mm. The other option would be for 18650 to have contracted with someone that buys the raw cells and adds the terminal after the fact - not sure which it will be. So long as the QR codes are untampered with and check out I think it will be fine. I do have a bench PSU and a load tester so I can check that they have the correct capacity when I get them.
Does anybody know what the ardiuno board with voltage measurements is? I saw it used in the MRBF explosive testing, but was thinking it might be a good way to watch/record/verify the capacity test independant of the meter I have which is the purple board with 4 resistors and is capable of 11 amps.
Beyond that I have some 3mm poron on order to put between the cells as insulators and am still deciding on either aluminum or steel or wood end plates. Presumably if I go to the local metal fab place with a drawing they can just use a laser and cut out the plates for me from either cold rolled steel or 5052 or 6061 - depending on what they stock. I only need 4 of the endcaps. I have 10ft of 1/2in threaded rod already and would just need to put springs over it to compress the cells.
I have a wattcycle 300ah battery that turns out to be a 280ah battery. And from Will's review it doesn't have any over-current protection until you get well up around 800amps. So I am replacing that BMS with a JBD BMS SP04S060 - the 300amp variety with all the ports on it. I don't need heat, but doesn't mean I can't use the port for something else.

JBD Smart BMS 4~22S 8S 17S 20S 21S 100A Li-ion Lithium Battery PCB for Freeshipping - Jiabaida BMS
Jiabaida BMS JBD Smart BMS 4~22S 8S 17S 20S 21S 100A Li-ion Lithium Battery PCB With Uart Rs485. High quality better service and favorable price with free shipping. Battery Management System for NMC/Li-ion Lifepo4 battery

Of course since I got bitten by that bug I ordered 8 of the 314ah MB31 EVE cells from 18650battery.com . They are currently backordered, but come with bus bars. ETA is Feb 21st so it will be a month wait.
So I ordered 2 more of the BMS.... so I will have 2 of them from Aliexpress and one from their official store... so I can compare all three and see if the aliexpress version is inferior in some way and get a refund if it is. If it fell off a truck or was a QA reject that might not show until hooked up.
Funny thing on the MB31 EVE cell data sheets - some say the continuous discharge rate is 1C and some say it is 0.5C ... so I am not sure what is right - will see what the paperwork that comes with them says.
I will be looking to see if they are factory EVE cells with the terminals laser welded on or not - what I can find says the factory cells with terminals have countersunk dots on the lower part with a red and blue dot of paint in them and that the weld depth is 2mm. The other option would be for 18650 to have contracted with someone that buys the raw cells and adds the terminal after the fact - not sure which it will be. So long as the QR codes are untampered with and check out I think it will be fine. I do have a bench PSU and a load tester so I can check that they have the correct capacity when I get them.
Does anybody know what the ardiuno board with voltage measurements is? I saw it used in the MRBF explosive testing, but was thinking it might be a good way to watch/record/verify the capacity test independant of the meter I have which is the purple board with 4 resistors and is capable of 11 amps.
Beyond that I have some 3mm poron on order to put between the cells as insulators and am still deciding on either aluminum or steel or wood end plates. Presumably if I go to the local metal fab place with a drawing they can just use a laser and cut out the plates for me from either cold rolled steel or 5052 or 6061 - depending on what they stock. I only need 4 of the endcaps. I have 10ft of 1/2in threaded rod already and would just need to put springs over it to compress the cells.