I have experimented with several versions of a "portable" X-Band repeater in the past, but they all failed the test.
The mission drives the gear.
I would have been time ahead to have stuck to that old .MIL saying. Instead, I started out with a briefcase full of a Kenwood D700 radio, several 12hr SLABs, a solar panel, etc. with the intent of leaving it in place for several weeks.
I soon found that the batteries could not handle the extreme heat inside the Pelican case even if placed in the shade. The ambient was near 90F and inside was 120F+ which quickly fried the two SLABs.
The mission though was not to have a dedicated repeater, but a mid-point extension of comms while on patrol, patrol that would be less than 72hours 99% of the time.
What I ended up with was a "Non-Dedicated" setup that I could throw in the pack to drop off as I traversed over the surrounding hills of my AO when SIMPLEX was not making the trip back to base on VHF.
It consists of a TYT U8000E HT that is easy to program and because of it's battery eliminator that runs off of a $40.00 MIADY LifePO4 8Ah battery, I get several days use out of it as well as the ability to run off a vehicle for weeks.
The 8aH LifePO4 shown is 222% more battery life than that of the factory 3600Ah battery and will last up to 3 days in 24/7 “standby” mode with enough power to send more transmissions than you should be using in SHTF, it can be turned down though.
BREAKING DOWN A 8AH BATTERY IN A “REAL USE” SCENARIO
Because we are not using the transmitt on the X-band at full power except to send a SALUTE or EMCOMM, we are not draining the battery at radio’s speced ≤ 2.8A at 10W.
The value that is most important is the “standby” current draw which is not found in the Operator’s Manual, but I have measured it at ~ 0.09A (90mAh) average (0.06-0.13) using my BUDDIEPOLE POWERMini 2 charge controller, a highly recommended piece of kit BTW!
Depending on the battery composite you are using, you are only getting 4000mAh out of a Sealed Lead Acid battery (SLAB) or 6640 mAh out of a LifePO4 battery, both rated as 8000mAh or 8Ah batteries.
In my case, the 8Ah LifePO4 is going to give me (8000mAh * .83 / 90mAh = 73.8hours) of standby in theory. Depending on heat, the condition of the battery, etc. it will likely be less.
Let’s say 10 transmissions of say 1 minute at 10W are also made. That is a total wattage-hour usage of (10W * 10/60hours = 1.67wH / 12V = .139aH or 139mAh.
So total battery life is (((8000mAh * 83%) -139mAh) / 90mAh = 72.23hours) or 3 days of operation verse 1.8 days on a SLAB.
The LifePO4 is smaller, lighter, and longer lasting than a SLAB and the clear winner in comparison to a Sealed Lead Acid battery.
There are several advantages to using this setup, namely, extended range and resistance to being DF’d.