Ham gear is generally designed to operate on 13.8V and many transcievers will start FM-ing at anything below 12V. To protect your ham gear when battery voltage is high (equalizing) AND give it a good operating voltage when the batteries are low, you might want to look at the MFJ-4416 battery booster.

I installed one on my boat to make sure I have communications in an emergency even if my battery voltage is dropping (from running the bilge pumps or other reasons), but I find that it is also an excellent solution for keeping my Kenwood TS-570D at top performance at times when the batteries are not fully charged. After all, the only time they are near 13.8V or above is when the batteries are well charged and have an active charging source (solar, wind or diesel engine).

The only problem with the MFJ-4416 is that at max 25A, the capacity is a little too low when you want to add other gear in addition to your transceiver. The internal 30A fuse blew once when I was testing the transmission at 100W with a low battery. I assume the drain from the battery was more than 30A when the low battery voltage needed to be boosted to 13.8V. In future, I will reduce my power if I need to transmit when the batteries are low. Another point is that I make my living as a marine electrician. One of my specialities is marine SSB installations. Most marine SSB radios are 150W, so the capacity of the MFJ is too low for these installations.

The manual is here:
http://www.mfjenterprises.com/man/pdf/MFJ-4416.pdf

PS.I do not like the idea of the RF sensing circuit in the MFJ and don't use it. It would also be a bit difficult for me to implement since the Kenwood has two antenna connectors and I use both for two different antennas. (a longwire with SG-230 antenna coupler and a 14MHz vertical dipole) The unit is installed between the circuit breakers for the ham gear and the radio, so I simply switch it off at the breaker when I'm not using the radio.

PPS. Usual disclaimer. I do not sell MFJ equipment, I just use it and occasionally install for my customers.

PPPS. You'll often find me on the Maritime Mobile net on 14297.5 at 1900z on Saturdays and Sundays and also occationally on the MMSN at 14300 a bit later in the evening.