# Charge Li-ion Battery Over 1C?

I am making a small project that has a li-ion battery for power. I need to be able to charge the battery within the circuit and am trying to find the correct amperage to charge it with. The battery is a 3200mAh li-ion cell (3.8V), and I am wondering what the maximum (safe) amperage is to charge the cell. I know (think) the optimal amperage to charge with would be 3.2A (1C), but is it safe to use 4A (1.25C) or even 5A (1.56C) without blowing anything up?

EDIT: I am using an Anker 3200mAh battery, but couldn't find a datasheet on their website (after a quick search). LINK

-Ben

• What does the battery datasheet say? Oct 30, 2016 at 3:46
• Please edit your question to include the make and model of cell, and a link to a datasheet for it, if possible. If you don't have the make and model, then tell us where you got the cell and add a picture of it. Oct 30, 2016 at 3:46
• Post edited with battery information. Oct 30, 2016 at 4:03
• Given the lack of info, I think all one can surmise is that it is probably safe to charge in a Galaxy Note 3. Apart from that it is very hard to say. Oct 30, 2016 at 5:11

According to battery university the advised charge rate is between 0.5C and 1C, however certain batteries will happily charge at much higher rates. Either check the datasheet or (less reliable) check with the seller. From a little searching it seems the Galaxy Note 3 (the device that battery is designed for) charges at typically a current of approximately 1800mA.

However, bare in mind that charging cells at a higher rate generally reduces overall lifespan. If possible you're better off charging more slowly.

• If I were to charge at around 3A (1.9C), would I have to use a battery charger IC or can I just wire the 3A 5V directly to the battery? I would be using a USB Type-C charging block. Would this hurt the battery or would I still have to use a battery charger IC? Oct 30, 2016 at 15:25
• @AngryCupcake Do NOT connect it to a 3A 5V supply. There's a strong chance that will start a nasty fire. Don't mess around with this battery at your experience level. Get yourself some 18650 cells with built-in protection circuits (they don't all have those, so check). They'll still have good performance and will be much more forgiving. Oct 30, 2016 at 16:55
• @pericynthion I meant to say 0.9C, if that changes anything. Oct 30, 2016 at 16:57
• @AngryCupcake it doesn't, the 5V is the problem. Oct 30, 2016 at 17:33
• @pericynthion should I get a step down converter to take it down to 3.8V then? I have some 18650 batteries but I need the low profile of a cell phone battery. I assumed you could charge a 3.8V battery on 5V, but I may be wrong. Oct 30, 2016 at 17:36

It's entirely dependent on the battery and the thermal environment. 1C may be too much for some batteries (and for many, it's faster than is optimal for longevity). Others can take 5C or more.

Cellphone batteries are particularly specialized and although modern ones can charge quite quickly, they need active temperature monitoring to do so safely. Sadly, their datasheets are often not public.