Retevis RT-97 Battery Size Recommendation

[gortex2]

This has been discussed a few times. Here is the last post on one repeater.

 

 

[WRZT743]

On 1/26/2024 at 8:29 AM, gortex2 said:

This has been discussed a few times. Here is the last post on one repeater.

 

 

Maybe I missed something but that topic links back to this topic. How does that help?

[WRYS709]

14 minutes ago, WRZT743 said:

Maybe I missed something but that topic links back to this topic. How does that help?

"Like the signpost up ahead... 

"You're next stop...

"THE TWILIGHT ZONE!"

[WRFP399]

June 10th 2024 Update:

It is still up and running and does so well. All the RF noise issue I had before have not returned. 

[LeoG]

On 3/21/2023 at 12:37 PM, Lscott said:

Have you considered swapping out the simple PWM charge controller for a MPPT type? In theory it should allow you to capture more energy and store it in the battery. With large changes in solar radiance and panel temperatures this will make a noticeable improvement IMHO.

These controllers seem to work rather well. For about 100 watts of panel power a 10 amp controller would be right for your application.

https://sunforgellc.com/product/gv-10/

 

Which solar charge controller PWM-or-MPPT.pdf 2.32 MB · 3 downloads

I play solar all the time.  I have a system in my truck I use to power tools and if needed I can power my house.  Depending on what you can keep the temperature of the battery at when you put it into a hole you might consider a LiFePO4 battery.  They also have self heating batteries that will make sure the battery will stay warm enough to allow charging.

  Not sure if you are limited by size of funds but if I were to do this I would use a 50 or 100Ah battery with a Victron 10 or 15 Amp controller and a 100 watt solar panel.  Or possible a pair of 50s in parallel to try to avoid shadows from killing power output.  One of the main issues with a LiFePO4 battery is it's low temperature charging.  Usually 32ºF is the low limit, which is why I suggested a self heating.  It will deliver power until the temp gets to -4ºF but won't charge until 32ºF.  Or you could stick with the AGM battery, but make it much larger so it can hold more power so it doesn't get to a low enough discharge that it stops producing power for the repeater.

[WRZT743]

 Solar powered GMRS Repeater set up for off grid communications in UP Michigan. 

Items included -

powmr 45amp MPPT solar charge controller -$50 ebay

4 - 100watt eco worthy solar panels -$50 each =$200 total ebay

Retevis RT97S - $350 amazon

Raspberry pi /case -$50 amazon

Att 4g Hotspot - $50 ebay 4g service not included 

Retevis GMRS Base Antenna -$70 amazon

12v 100ah self heating Lifepo4 Battery -$220 amazon

say $1000 -$1200 when your all done with wires and brackets to set up everything 

comms will cover 5-10 miles easy

runs 24/7  365

8watts in stand by - 25watts tx low power - 35watts tx high power

(raspberry pi and hotspot are optional for controller) 

you only need the solar charge controller,  repeater, antenna,  battery, and solar panels to make it work 

with this set up it will use this many watts per hour 

3watts  in stand by 

20watts tx low power

30 watts tx high power