Charger for different Li-Ion Voltage Profiles, 4.3 MAX, 2.75 and 3.00 MIN

[YoshiMoshi]

I have some Samsung 28A 18650 cells whose maximum charge voltage is 4.30 V +/- 0.03 V and a discharge cut-off voltage of 2.75 V.

I also have some Panasonic CGR18650AF 18650 cells which have a maximum charge voltage of 4.2 V and a discharge cut off voltage of 3 V.

Is there a charger anyone can recommend that supports these not so common voltage Profiles?

I have a XTAR VC8S which only seems to support lithium ion 4.2 maximum voltages and 2.5 discharge cut off

 

[harrisonpatm]

If you use a 4.2v charger on a 4.3v cell, nothing bad will happen to the cell, and you'll lose a minuscule amount of capacity. If anything, it will be better for cell longevity to to use a lower charge voltage.

If you still insist on using 4.3v, you could probably get away with a CC/CV buck converter module, if it has current limiting function. I use several of these in different applications, you just need to set the output voltage to 4.25/4.3v.

 

[YoshiMoshi]

Ah but how do I capacity test these cells?

 

[rafalg]

Depends on what you want to achieve with capacity test.
If you just want to compare the cells and find if they're more or less same capacity, you can charge to 4.2V like every other cell. The resulting capacity will be lower, but still fine for finding faulty cells.
BTW if you want to charge to 4.3v you also need a BMS that handles this correctly (balancing, for example)

 

[YoshiMoshi]

Yea but like my VC8S discharges down to 2.5 V for capacity test, which is lower than the 2.75 V cut off and the 3 V cut off so I don't know if there's much I can do but watch the voltage during the test

 

[dominik h]

Most newer rc Chargers like the isdt Q8 can charge and discharge higher voltages lipos.

 

[E-HP]

You could get one with an adjustable LVC

https://www.aliexpress.us/item/3256805226549030.html?aff_fcid=1ffec4d15da74cd3bcab207899858c93-1742161911297-05025-_DdF0oct&tt=CPS_NORMAL&aff_fsk=_DdF0oct&aff_platform=shareComponent-detail&sk=_DdF0oct&aff_trace_key=1ffec4d15da74cd3bcab207899858c93-1742161911297-05025-_DdF0oct&terminal_id=f845a38dfec34e9c8df192d3a9fd06b4&afSmartRedirect=y&gatewayAdapt=glo2usa4itemAdapt

https://www.amazon.ca/Fattoz-Capacity-Automatic-Internal-Resistance/dp/B0DBVLFQRT/ref=sr_1_4?crid=1327P81342DLZ&dib=eyJ2IjoiMSJ9.l1YqINU8HXuGnNbxouotBGANl-DzBr4ZT5ecs_x3JJYncDsXqFCvasrXd9n3SaiFQBZKVomup6Fu57gn8d_CtHNPQRMhe75P9_5tSCgrK3mLCSacSZ-BKrbqh76iBftXp0PGR0dwhODt-MnR_YfSxNabSZREmDkMV457CzqCryORZESBIZG82tMRyCeJOJgymCQ5udhANDdesQKecDLvCFX78ixR-xgw5niGcJy5-cc4MMrIM5v1JqM4jaG0FNiKsYKxLmQ-t-zJNABCX6YzFQtR1xROnjno85RcZW0ACsMIzfpZgLsuZAEvQlgOFdAptuhBE2VTx1YC1-UUmtm-M34bphyiJaCC3pTlm5op-NbLoUaqnECW0GdeZR3ITkGP15h53X5bDOsJXpek7R3grDpIvkqhg1SFa1_29-zzhUEhmjYX5IkqZVHOad_pr8PY.GlLJ7Iu2eNVsikGrmM4JK5xlkIIDmibeiV_-jBUyfyc&dib_tag=se&keywords=18650+Lithium+Battery+Capacity+Tester+MAh+MWh&linkCode=sl2&linkId=116c0dc9dd6e0d69037c21cd0eb35f32&qid=1742161976&sprefix=18650+lithium+battery+capacity+tester+mah+mwh+%2Caps%2C86&sr=8-4

 

[rafalg]

much I can do but watch the voltage

If it were me, i'd just ignore the specs and discharge down to 2.5V. Then it would be clear if it can be done or not. I believe one such test will not harm the cells (and also I'm lazy and dont care that much about cells, especially old ones). During normal use you rarery discharge to 2.5V, usually there's BMS or controller cutoff around 3V.