I need to have my '69 Ambassador plugged in full time. Has anyone figured out how to safely charge the battery while leaving the Univolt constantly plugged in? It seems like lots of batteries are overcharging and thus prematurely failing. Also lots of corrosion from boiling battery.

Someone has to have figured out an external "smart charger" that you can hook between the Univolt and the battery. Does anyone have a link or a product that is available to make this work? Thanks!!
If there are other problems with leaving things plugged in full time that I am not aware off please chime in.