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Electronics => Power & Renewable Energy => Topic started by: m3vuv on May 08, 2021, 09:02:36 am

Title: new lithium ion 18650 battery build
Post by: m3vuv on May 08, 2021, 09:02:36 am
I am planning on a new 18650 triangle battery build using samsung 15q 18650 cells ,its going to be a 13s 8p,i see repakir to match the cells capacity but no mention of the cells internal resistance,im testing all the cells using a litokala engineer lii-500,some of the cells read 30 milliohm ir and some 125,how should i arrange them regarding internal resistance to keep them ballanced,i have a bt smart bms but want to do the best i can to match them for ballance,cheers in advance.
Title: Re: new lithium ion 18650 battery build
Post by: m3vuv on May 10, 2021, 08:57:43 pm
can no one shed any light on this??
Title: Re: new lithium ion 18650 battery build
Post by: tunk on May 10, 2021, 10:05:14 pm
Not sure if a charger is a precision instrument, so the internal resistance
measurements may not be very accurate. Have you tried to measure it several
times for the same cell (taking it out for each time and then reinserting it)?
You may also want to check the self discharge.
Title: Re: new lithium ion 18650 battery build
Post by: uer166 on May 10, 2021, 11:27:13 pm
want to do the best i can to match them for ballance,cheers in advance.

Only use new cells for a new pack. That is a huge range of internal resistance, new cells shouldn't have that.
Title: Re: new lithium ion 18650 battery build
Post by: m3vuv on May 10, 2021, 11:33:13 pm
is the ir very important?