Ok here is my latest problem. I have been using an automotive charger to charge my accessory system for the EV. But I think the charger (this is a regular automotive charger “ Schumaker”) only charges to 14.8 volts before shut-off. I don’t think that is enough juice to maintain a deep cycle battery. This input AC, for the charger is wired in-line with the Zivan on-board charger on the EV. And I just found out that the hygrometry on the access battery was only 50 %, after the Schumaker read “ full charge. The Zivan charges the 120v pack to 165 v., So the accessory charging system should charge the accessory battery to 16.5 v for full charge. Now, I did take one of those cheep harbor freight chargers and hot wired it right off of the transformer, bypassing the circuit board and voltage regulator, through a switch ( labeled “ Manual”) and back to the selector switch and created basically a full current charger. I also added a 12 volt mini fan to blow over the transformer. This has worked fantastically well on the deep cycles for my RV and trolling battery. You do have to keep a rather tight eye on the charging cycle but I haven’t had any overheating or over gassing problems on group 24 and 27 lead batteries. And I’ve been able to maintain a good 100% charge on all of those systems. So the problem exists: how do I design an onboard system that charges the accessory system to the appropriate level that works in tandem with my onboard pack charging system? The onboard Zivan system is perfect! Now I need a charger that will charge the access. System to at least 15.5 volts or 16.5volts for equalization, and than turn off automatically. I guess that I can take out the Schumaker and attempt to hot wire it through a “ manual” switch, that added to a manual timer might be OK, unfortunately, I have opened the Schumaker and it is a rats nest of wires and circuits, the harborfreight unit was much easier to hotwire. What I really need is a 16.5 volt cutoff for the accessory charging system which I’m not enough of an engineer to figure out. So I guess my best option is to use the Harborfreight customized charger with a timer to fully charge the accessory system. I have located a number of inexpensive timers that I think I will try for the accessory system. It’s too bad that there doesn’t exist a good, economical deep cycle automatic charger for 12 volts. Oh well I will redesign and report back to ya all………… any ideas? Thanks again……….. Lou-Ace.