I saw a quote from kentobin, in a related post and thought it merited it's own thread...
Originally Posted by kentobin
If you're concerned about not having a backup 12v charger
on the 30 amp unit consider just buying
a portable 12volt charger
that you can use with it.
On Amazon you can buy a 1.5 amp microprocessor based unit or a 50 amp dumb charger for around $50.
If you're thinking of having a backup "car style" battery
charger, buy a "dumb one" without all of the bells and whistles... When you need it fast and reliable... The last thing you need is reduced output, check/ramp/float cycles... or your charger to say "screw you stupid sailor... Your battery is junk, and I'm not charging it"
When you know cranking 20A into the battery for an hour would get you out of trouble