# Has anyone tried establishing battery backups for Purple Air?

by eustatic | 01 Apr 16:15

At Healthy Gulf, we have found, as has been published, that the Purple Air monitoring units function much more in line with federal reference (BAMM 1022) than the Clarity units.

However, the Clarity units provided solar panels and cel telecommunications options that are very useful in our area, which regularly lacks power and internet.

Purple Air now has a page for unofficial solar power planning, which states:

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Battery Power
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Battery packs can power the PurpleAir sensor. The power supply that can be included with the sensor is not necessary. We have experimented with a 20Ah battery pack, and found it was able to keep the sensor running for almost five days.

## Solar Power

We've heard of a number of individuals who are using solar to power their sensors. At this point we have not conducted in-house testing on PurpleAir sensors using solar power. However, it seems reasonable that a solar panel providing approximately 15W may be adequate to power a battery pack to run a PurpleAir sensor. How quickly that battery pack recharges is situationally dependent, and may require some experimenting on the owner's part to fit the seasonal sun conditions.

## Internet Access

A WiFi network may be supplied to the PurpleAir sensor in various ways. In addition to underground cables, Internet Service Providers (ISP) may provide internet access via cellular towers, and even satellite. We've heard of a number of individuals who are using these wireless methods to provide internet access to their sensors.
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20Ah powering the units for 5 days sounds like something we would like on the Gulf Coast, when the five days after a hurricane are critical for data collection, and Entergy Louisiana power can be out for weeks or months. I love the form factor of 20Ah power tool batteries, and was thinking of a hack, although for charge control, a bigger cheaper unit with an AC plug output, that would come in at less than $100. Other items work with 6500mAh High-capacity batteries, but would perform. 15W poly panels seem to be the size that power the Clarity units--although the Clarity Panels are super rugged. Others come in at less than$100.

Ting used to have a mobile plan that was $10 a month; now it seems like the cheapest plan is$25 a month. Run on a google pixel 2, and you'd have the cheapest hotspot I can think of.

Of course, the ideal unit would simply have 2 AC plugs off the inverter, one for the phone/hotspot, one for the Purple Air unit.

Security cameras, always popular, have units that do all this at less than \$200, why not purple air?

Has anyone put these pieces together to make Purple Air units operate in rural or poor infrastructure conditions?