Using rechargeable battery with nRF51822

[sing]

I am working on a project to integrate nRF51822 with a rechargeable battery, and make it chargeable through micro USB cable.

Any recommendation on the battery model, charger and voltage regulator module ?

Thanks a lot.

[MartinBL]

Hi. It is difficult to answer such questions as there are no standard answers applicable to all applications. What kind of battery you need depends on your requirements to maximum output current, battery life, output voltage, physical size, etc. In addition, as you say, you will need a charging circuit/IC and most likely a regulator.

As we don't really provide any reference guides on batteries, chargers and regulators google's guess is as good as mine. One of the first hits on google is the LTC4053-4.2. A simple IC perfect for the widely used Li-Ion batteries. These batteries reach a peak voltage of 4.2V after charging. Hence, you can't use the nRF51's internal DC/DC regulator and will need an external voltage regulator.

This is a thread discussing something very similar to your questions (scroll down) and you can find some tips on voltage regulators and batteries there: nRF51822 and battery low level detection.

Here is another thread that might be relevant: LDO vs DCDC (nRF51822).

[sing]

Thanks a lot for the insight.

The key design factor for my project is physical size. The smaller the better. At the moment, I am looking into some Li-ion rechargeable coin batteries, and LiPo batteries.

[MartinBL]

A few google searches taught me that Li-ion batteries have higher energy density than LiPos, i.e. smaller in size, but with the same battery lifetime. LiPos are able to source more current, but I assume that you are making low power applications so a Li-Ion is usually sufficient even with its relatively low amperage. Link.

[sing]

True about the energy density, and theoretically true about the size. One of the main advantages of LiPo is its flexible form factor. so it is usually adopted in project with strict size limitation. link text