increase Button batteries CR2450 life

RE: increase Button batteries CR2450 life

Jørgen Holmefjord — Fri, 21 Apr 2017 11:16:41 GMT

Note that the blog is talking about supercapasitors. It is not sufficient to use a regular capacitor to smoothen out the current draw over a long period of time (radio transmission time), for this it does not have large enough capacity. You should contact your electronics distributor for help on selecting the best part for your application.

RE: increase Button batteries CR2450 life

zcmm — Fri, 21 Apr 2017 10:59:28 GMT

ok,i want to pluse current from 17ma to 10 ma? how to calculate this capacitors parameters?

RE: increase Button batteries CR2450 life

Jørgen Holmefjord — Fri, 21 Apr 2017 10:55:29 GMT

No, the capacitors will be charged and then this charge will be used to power the device. You don't loose the energy.

RE: increase Button batteries CR2450 life

zcmm — Fri, 21 Apr 2017 10:53:19 GMT

the capcitors should repeated charging because of after advertising,so i think it should increase in powerconsumption,right?
if it is right,how to calculate the capacitors power consumption?

RE: increase Button batteries CR2450 life

Jørgen Holmefjord — Fri, 21 Apr 2017 10:45:35 GMT

Capacitors should not add any significant increase in power consumption, as it only consume extra power the first time it is charged. I think your options are to use a super capacitor, as described in the blog I linked above, select a different battery for your application that can handle the high peak currents without being damaged/get reduced capacity, or select different parameters for your application reduced advertising interval/ reduced TX-power, add DCDC etc.).

RE: increase Button batteries CR2450 life

zcmm — Fri, 21 Apr 2017 01:27:59 GMT

Shunt capacitance can bring extra power consumption?for exmaple,average current is 30ua,180mah can use 250 days.if i shunt capacitance(may be 47uf),the use day is 250 days or Less than 250 days?

RE: increase Button batteries CR2450 life

Jørgen Holmefjord — Thu, 20 Apr 2017 10:59:37 GMT

Yes, a super capacitor will smoothen out the peak draw from the battery, increasing the battery life. Frequent current drains with high peak will reduce the battery capacity.

RE: increase Button batteries CR2450 life

zcmm — Thu, 20 Apr 2017 10:47:27 GMT

thank you,Battery with a super capacitor,can increase the life,but the charge current will reduce the battery capacity??

RE: increase Button batteries CR2450 life

Jørgen Holmefjord — Thu, 20 Apr 2017 09:42:06 GMT

I see, you can get some tips to improve battery lifetime in this blog post. If you want to decrease the peak currents, you will have to reduce the output power and/or add DC/DC converter to your board. The radio of nRF52832 can also give lower current consumption, especially when using DC/DC.

RE: increase Button batteries CR2450 life

zcmm — Thu, 20 Apr 2017 09:06:09 GMT

average consumption is 60ua,i think the battery capacity utilization rate is according to the load current rather than the average current, if the big load current can reduce the use of capacitance

RE: increase Button batteries CR2450 life

Jørgen Holmefjord — Thu, 20 Apr 2017 09:02:19 GMT

Those settings should give an average current consumption of 2-300 µA, depending on your payload, or ~75-115 days with your battery capacity. If you don't have any current measurement equipment available, I would recommend that you get our power profiler kit, which can be used for power measurements in real-time and debugging current issues in your application. Then go through the link I posted above and see if you can figure out where the excessive current is drawn.

RE: increase Button batteries CR2450 life

zcmm — Thu, 20 Apr 2017 08:47:12 GMT

100ms 4dbm LDO 51822 TX POWER is 18ma standby current 3.7ua,just it advertising,it use 22 days for CR2450(550MAH)

RE: increase Button batteries CR2450 life

Jørgen Holmefjord — Thu, 20 Apr 2017 08:43:13 GMT

Hi,

Which chip are your device using? Have you done any current measurements? How long is the battery life?

For nRF52832, you can use the Online Power Profiler to calculate the expected current consumption. If your device is a beacon (only advertising), and you use the settings you mention (500 ms advertising interval, 4 dBm output power, and 3 V battery), your device should have a total average current consumption of 35 uA, even with full 31 bytes payload. Assuming your CR2450 battery have a capacity of 620 mAh, this should give a battery life of roughly 2 years.

If you get way shorter battery life than this, you might have something running in you application consuming excessive current. You should go through the current consumpiton guide (written for nRF51, but most of the consepts is valid for nRF52 as well), to fix potential issues.

Best regards,

Jørgen