Battery charger for Lion Battery

[Niki124]

Hello All,
I have 9.0 V 7.8Ah Lion rechargeable battery ,Please suggest me Battery charger IC or battery charging scheme .

 

[Nigel Goodwin]

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.

 

[Pommie]

It's probably two cells masquerading as a 9V battery as most things that use a 9V battery will work fine on a partially discharge battery.

Mike.

 

[alec_t]

It's probably two cells

Over at EP the TS says it's a 3S3P battery.

 

[Tony Stewart]

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.

 

[audioguru]

A 9V lithium battery can be made with three CR2032 (or smaller) coin cell Non-rechargeable batteries.

 

[Nigel Goodwin]

A 9V lithium battery can be made with three CR2032 (or smaller) coin cell Non-rechargeable batteries.

7.8Ah

 

[audioguru]

The battery charger must match the battery specs. But Niki never told us the detailed specs.