> I recently suddenly realized that
> Li-ion battery can be simply charged
> by a 4.2 contant V source adding a max
> current limit resistant. That means a cheap LM317 for 2A charging
> or a 5A voltage regulator, plus a 1 Om 5W resistant,
> will do the job fine. cost is 5 dollar all together.
> It is sufficient, and has a basis: every Li-ion pack
> has build in protective pcb already.
>
> So, why still bother with the long list of Li-ion
> battery charging IC?
>
> Acid Lead battery is the same story.
>
> Am I wrong in this point?

There are multiple parameters to charging Li-ion, I will list an important
one:

If lithium-ion is below a certain voltage, you must trickle charge. Your
circuit would give it too much current.

Other things left out are also of some importance.

Cheers,

Bob


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