SARA CLUB – Mt. Oso Solar Project

The SARA Club is undertaking a project to add solar power to our Repeater Site on the top of Mt. Oso. This projects unintimate goal would be to have the repeater site be independent of the PG&E power grid.

This will be be a multi-stage project. As with any project the thoughts and comments of the stake holders are an important requirement. As you all know the members of this club have a very wide background of knowledge and expertise which will help design and execute the best solution possible.

To that end, if you have any thoughts, comments, questions, funding sources or anything else, please email Mark N6ARP at or Lucian KF6NPG at or catch us at one of the monthly meetings.

General Information from August 27, 2022 Trip to Mt. Oso

Details below:

220 repeater 0.4 A idle, 6.8A TX
win system 0.32A idle, 3.78A TX
2/m MTR2000 1.34A Idle, 8.11A TX
controller  + fan 1A Total, 0.5A controller
440 repeater 0.94A idle, 3.43A TX
maxtrac – 0.33A idle

Battery status:

Observed 440 Battery swollen, and reading 109F on temp gun, was drawing 2.78A when measured – definitely excessive for a battery that has not been discharged recently and should be floating.
Battery was removed, and 440 side is AC power only fed by repeater internal PSU.
2M Battery was also showing signs of swelling as well, but current draw was 0.8A was still acceptable
Battery was removed based on swelling as a preventative measure.

220 System still had a pair of older dynasty branded batteries, they were on the Astron supply battery terminals, but voltage was only 12.69 V which is lower than recommended float voltage.
These batteries were transferred over to the 2M system to dedicate all battery power to our primary repeater.
Once swapped over, they started pulling 4.31 A as they charge up to the higher voltage. Draw expected to drop once fully charged.
On the assumption that the draw will drop back down to reasonable levels once charged, we should realize a notable drop in load

System summary

2M Repeater 145.390 – Gets majority of traffic – estimated duty cycle is 10.5% TX, 89.5% RX Resulting in 2.05A Average draw. = 50 AH/Day
This is based on data collected back on 1/28/21 covering 4 days of usage on the 2M system.

For the below, I am going to calculate based on 1Hr TX/23Hr RX as a light use model.
440 Repeater 440.225 – sees minimal traffic on typical days = 0.90 + 0.143 = 1.04 A Avg draw  = 25 AH/Day
220 Repeater 224.140 – sees minimal traffic on typical days = 0.38 + 0.28 = 0.67 A Avg draw = 16 AH/Day

Controller and fans 1A avg draw, 24AH/day

6M Repeater – unsure if it is even operational, overlooked trying to measure it – very likely that we will shut it down due to lack of use if it is not operational

Win System repeater – Currently light use due to mesh link to Turlock system being down – repeater is operational in local mode, but not linked to larger system.
As a result it is currently using minimal power. Can not evaluate duty cycle in current condition –
 it is a low power transmitter based on measured tx load, but potential duty cycle is high
Not connected to our Batteries or power supply – power from utility only
Sara Repeater system idle draw from 12V/Battery system: 4.78A or about 66W = 1.58 Kwh/Day
Batteries that were removed were drawing 3.58A or about 50W = 1.2 KwH/Day

Solar Project Team Visit on Sept 23, 2022 – California G.M.R.S. System Repeater site – Knight Ferry, CA

California G.M.R.S. Repeater Site
California GMRS Solar Site
California GMRS Solar Controller