Rechargeable coin batteries for nRF52 DK?

[Ladasky]

Hello,

I have a need to construct multiple portable devices on a short time frame. We expect that building Arduino-format shields for our peripherals and using nRF52 DK boards will be the quickest way to accomplish our task.

These devices will see heavy use, so we don't want to use disposable batteries. Previously, I asked about using lithium polymer batteries to power the nRF52. I was informed that the upper safe limit for the chip is 3.6V, so a LiPo battery (which, when fully charged, can reach 4.2V) would certainly damage it.

Here are my current questions:

1. what RECHARGEABLE COIN batteries are safe to use on the nRF52 DK boards?

2. Is anyone actually using rechargeables, for example, lithium-manganese ML2032 batteries? I am looking at the ML2032 because its nominal voltage is slightly lower than the more common LR2032, and some spec sheets show the LR chemistry going over 4.0V at high states of charge and light loads.

3. If you are using rechargeables: how do you recharge your batteries? I have encountered many vague web pages which hint that all coin battery rechargers are not the same. They must be matched to battery chemistry. I am not entirely certain of that, however, since when I try to shop for coin battery rechargers, their specifications are not clear.

I am looking at the PCA10040 schematic, and the only thing I see in the battery circuit is a safety diode. But that may help. The diode contributes about a 0.5-volt drop, according to my measurements with a disposable CR2032 battery. So if I read 3.1 volts across the battery, when I use it to power the eval board I get around 2.6 V across VDD and ground (running Blinky, it is surprising to me how much that voltage fluctuates as the LED's switch on and off, but that's probably an issue for another day.) This suggests that coin batteries up to 4.1 V can be used on the eval board. That could possibly allow any lithium battery chemistry, except for LiPo. Can anyone confirm that?

Thanks for any advice and suggestions.

[Roger Clark]

I use a specialist company in china to make bespoke boards.

You could also just buy a nRF52 module and solder it onto a PCB, as thats a lot easier.

I have developed PCB's for other clients where I used a TI chip based module and also a ESP8266 module on a PCB, which were soldered by the client inhouse, as the modules are fairly easy to solder etc

Not sure about the Arduino Primo, I know the guys at Arduino.org but their recent track record of delivering boards is not that good. The Arduino OTTO (STM32) board is about a year late.

I'm not sure what you mean the Arduino Primo Core. If you mean a Arduino third party core, I'd recommend you look at what Sandeep Mistry is doing (see github)