Thought I would elaborate on the Charging system that was recommended by Larry Jacobs WA7ZBO.
We all use batteries of some type in our radio go-kits, I personally use a smattering of different AGM (Absorbent Glass Mat) Batteries. Mine come from old security, fire systems, and UPS systems that were changed out as regular maintenance. Now while used, they still have a lot of life in them if properly maintained. Here in lies my trouble, how do I charge these batteries so that I can squeeze the maximum amount of life from them. Larry gave me the answer and it is Genius.
So here it is:
You can use a Solar Charge Controller to charge your batteries. A Charge Controller does not care where it is getting current from as long as it falls within the window of voltage and current ( mine being 0-100VDC at 20A) you can use PV Panels, A power supply (Larry suggested a laptop power supply), Car power (usually around 14.2V), or even a hand crank or foot crank Generator.
Here is my Charge Controller. It handles the proper care and feeding of my AGM batteries.
This is one of the batteries that I have in the parallel array. Thanks to Roy W7ROY for the batteries.
This is the label on the power supply that I use to charge the array. I think I need a bigger one as this one gets really hot during a charge cycle. I think I need to upgrade to 90 Watt supply. I will have to watch the local salvage places. Note the voltage it 19V @ 3.42A, Still a little small for my system.
The charger works like this, it first bulk charges the battery, then a phase that is called Boost, but is better explained as equalize, as it equalizes the different batteries in the array. Then it float charges the battery, also known as absorption. Finally the controller trickle charges the battery as needed.
One of the features of this system is also that it will disconnect the batteries from the load if the battery voltage drops below 11.1V. This will prevent me from damaging the batteries from over-discharge.
I have tested this system on a small scale in my hamshack and have found that the system works well.
I am excited to add this to my go-kit power module as now I don't have to worry if the batteries will be charged correctly. I can charge my battery module on the way to the deployment from the car voltage so it is topped off when I get there and I don't have to worry, I don't have to worry, I don't have to worry, I don't have to worry. Do you sense a reoccurring theme?
Here is a link to the controller that I have, it is a Tracer-2210RN Charge Controller Regulator.
Now I did not pay what they want for this. I got mine at a salvage place for about $25 in the box. They really had no clue what they had nor did they really care so more gain to me.
de KG7RZX 73