How to calculate how big battery of Retevis RT97 repeater needs?

As mentioned in our previous article, Retevis RT97 Repeater can be connected to solar cells, which is why many customers choose Retevis RT97 Repeater, not only for its high cost performance, but also for its flexible power supply options. For example, distance solutions for farms, outdoor long-distance communication for off-road teams, ATVs group long talking range extend on woods, etc. Connecting solar cells to RT97 is a common power supply solution in many outdoor fixed site application scenarios. Not only the cost is acceptable, but also the solution is simple and easy to succeed.

Solar panels installed in the wood

Even though they know that Retevis RT97 can be used to connect solar battery, many initial customers still have a lot of doubts about how much capacity to choose. This article will tell you how to calculate the capacity of solar battery that RT97 needs.

How to calculate how big battery of Retevis RT97 repeater needs?

First, we need to know the formula for calculating the capacity of the battery:

Battery capacity (vah) = rated output voltage (V) × rated output current (a) × discharge time (h)

Secondly, we need to understand that the working voltage of the Retevis RT97 repeater is 12-24V, and solar cells are usually 12V, so we take 12V as the standard.
The standby current is 80-100mA, we usually go to the middle-value 90mA, which is 0.09A
The maximum working current is 2.3A.

Finally, taking 24 hours as a time period, we can conclude that if the Retevis RT97 GMRS repeater is always in the transmitting and receiving state, then the battery capacity calculation method it needs is:
Battery capacity=12V*2.3A*24h=662.4Wh.
If there is no transmission and reception, and it is always on standby, then the battery capacity required by the Retevis RT97 repeater is:
Battery capacity=12V*0.09A*24h=25.92Wh.

Solar battery power the retevis RT97 repeater

These are two extreme values. In normal use, we usually settle separately according to the standby time and working time and then aggregate them. Because the Retevis RT97 relay cannot continuously receive the transmitter for 24 hours, and the possibility of being on standby is relatively small. Our general production is calculated according to the ratio of 1:1, that is, there are 12 hours of work in 24 hours, and 12 hours standby.
Thus, the required battery capacity is:
Battery capacity=12V*0.09A*12h+12V*2.3A*12h=12.96+331.2=344.16Wh

In other words, if you choose a 12V 350Ah battery, you can easily meet the needs of the whole day.

Finally, it should be noted that we do not provide solar equipment and batteries. If you need them, you can buy them yourself. It should be noted that it must be ensured that the voltage cannot exceed the tolerance range of RT97.

If you have any questions about the calculation or need help, please contact us: info@retevis.com.

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