There are several trickle chargers that will do the job. You might want 2 depending upon your house battery charger. STOP running your engine and genny as you are creating condensation. Either do nothing or drive it to get it completely warmed up.
I vote for PowerPulse and here's a link and information.
- Increase battery life upto 5x
- Provides greater charge acceptance
- Batteries charge faster and last longer
- No assembly required
- 10 in. L x 8 in. W x 2 in. H (1 lbs.) PowerPulse is not a charger. Charging does not eliminate the main cause of premature battery failures energy-robbing sulfate deposits on battery plates. During this process, the plates gradually become more and more clogged with microscopic lead sulfate deposits. These deposits eventually limit the surface area available for energy transfer and cut back the battery's ability to accept, store and release energy. PowerPulse generates an intermittent
PowerPulse Link is right here <a href="http://www.amazon.com/gp/product/B004I6QREK/ref=as_li_qf_sp_asin_tl?ie=UTF8&camp=1789&creative =9325&creativeASIN=B004I6QREK&linkCode=as2&tag=aff iliatechie-20">12 Volt Power Pulse Battery Charger</a><img src="http://www.assoc-amazon.com/e/ir?t=affiliatechie-20&l=as2&o=1&a=B004I6QREK" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />