Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
You need to figure out what voltage it is - it can't be 9V.
Personally I work on 4.2V per cell (fully charged), so three in series would be 12.6V and two only 8.4V - even if you work on the discharged voltage, you still can't get to 9V, as you don't discharge as low as 3V.
There is a tradeoff on Lithium battery capacity often boasted by those asian companies who utilize >=4.2V CV and <= 3.0 V cuttoff with 1C rates and thus greatly compromise the longevity in charge cycles and lifetime Ah expected. (mAh * charge cycles) (so obviously 3S voltage = 9V)
So decide what you prefer, lifeterm capacity or 1 cycle capacity and then choose a charger and product use to match. The longest life for example might be to use only 1/2 of the capacity and have two packs that can be easily swapped, so you only CV charge to 4.0V or 85% (?) capacity and then stop using at 35% SoC using only 50%.
According to battery university site, using only 50% of it's capacity in this approximate range yields >10x as many charge cycles.
But also realize a 1st order model of a battery cell is a capacitor with ESR resistance. So if using more than 1C discharge current, the threshold shifts due to I*ESR voltage drop from the resting voltage. A 2nd order model has 2 or more RC equivalent circuits with different RC=T time constants, short and long.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
