I too have used Jump Start batteries, but I have never used them to run my TMV71, or any other rig greater than 25 watts output. What you have to watch out for is that you do not run the voltage of the battery down too low during use. Doing so will damage the battery. You won't notice this lower voltage in receive mode until it is much too low. There are numerous little circuits to monitor the voltage, but none of them unfortunately are accessible as far as I know. I have been intending to suggest to at least one garage manufacturer of such gadgets that they consider including a microwave type beeper that could be switched into the circuit to sound whenever the low voltage LED flashes. I just haven't gotten around to doing that yet. I will make one more comment in a separate message in order to keep this one from being too long. K5XU ----- Original Message ----- From: "KK4AHX Darren Duff" <[log in to unmask]> To: <[log in to unmask]> Sent: Thursday, December 13, 2012 6:24 PM Subject: Backup battery for fixed station. Hi all. Now that I have my fixed station set up like I want I need a battery backup but I am not sure what to go with. I want something that could last me at least all day..... What are others using and what do you recommend for use with the TMV71a. I have a flow charger that I got from someone new still in the box, but I do not know how it works, or how to hook it up once I get a battery. 73. Darren Duff. amateur radio station KK4AHX. Vice President, Cherokee Amateur Radio Society. http://www.cherokeehams.com Cherokee County ARES. http://www.cherokee-ares.org