When charging two 6V batteries is SERIES you should connect the 12VDC CHARGE cables to the +12VDC and FRAME GROUND LEADS like shown here.
DO NOT try to charge a single 6V BATTERY using the 12VDC Charger Battery Cables.
It will be a hit and miss using a PORTABLE BATTERY charger where have no control on the OUTPUT VOLTAGE when charging.
Consider this brochure report from PROGRESSIVE DYNAMICs on how long it takes to charge a battery.
"Progressive Dynamics ran this test on the amount of time it took a PD9155 (55-amp) converter/charger set to three different output voltages to recharge a 125 AH (Amp Hour) battery after it was fully discharged to 10.5-volts.
14.4-VOLTS (Boost Mode) – Returned the battery to 90% of full charge in approximately 3-hours. The battery reached full charge in approximately 11 hours.
13.6-VOLTS (Normal Mode) – Required 40-hours to return the battery to 90% of full charge and 78-hours to reach full charge.
13.2-VOLTS (Storage Mode) – Required 60-hours to return the battery to 90% of full charge and 100-hours to reach full charge."
Please notice how long 13.6VDC takes to re-charge your battery to 90% and to 100%. You will be home from camping over the weekend if you only have a 12VDC source of DC power to recharge with. Just connecting up your portable charge a couple of hours aday IMO is not going to get you anywhere close close to the 90% charge state. This is the point where your batteries will perform to their specs and not do any internal damage to the batteries if you re-charge to full 100% charge state after 10-12 cycles. This will be very hard on your batteries not being able to duplicate the above charging routine using manual charging procedures. Just my opinion - mind you...
The best way to do this is to use a SMART MODE TECHNOLOGY portable battery charger like the B&D VEC1093DBD 40AMP charger. Of course the price here is almost the same as changing out your trailer on-board converter/charger unit. I justify having a good smart mode technology 40AMP portable charger for PLAN B in case my on-board converter/charger fails on me.
I built this BATTERY MONITOR PANEL up using digital meters like you have shown to aid me in keeping tabs on my two battery banks. This arrangmment monitors both banks for 12VDC and also monitors the input/output DC AMPS when charging or using my batteries.
Your on-board older converter will most likely put out a constant 13.6VDC when you are on SHORE POWER which is right at the BOILING OUT BATTERY FLUIDS point. You must not let this happen to your new batteries. I would keep a weekly tab on checking the battery fluids in your two 6V batteries.
I have a PD9260C 60AMP smart mode converter/charger unit installed, beefed up battery cables to 4AWG size, installed additional batteries - my battery bank is setup for four each 85AH batteries (340AHs), and converterd my automotive bulbs over to LED bulbs.
My plan for camping in the woods off the power grid is to have my battery bank large enough to support all of the 120VAC items I want to run from a INVERTER (My Inverter is a 600W PURE SINE WAVE Inverter) and all of the 12VDC items directly connected to the battery bank system. This allows us to operate all of these tiems we want to have with us for the ONE DAY/ONE NIGHT run off the battery bank and then the next morning I will connect the trailer SHORE POWER CABLE directly to the 120VAC receptacle of the 2KW HOnda Generator and can re-charge my battery bank back up to its 90% charge state so we can do all of this all over again for the next day/night camping run off the power grid.
Using my BATTERY MONITOR METER PANEL I will keep a watch on the battery DC VOLTAGE and hopefully I have it planned out to read around 12.0VDC the next morning when I am allowed to run my generator to re-charge my batteries. I go by this chart showing VOLTAGE verses STATE OF CHARGE to get me pretty close to the 50% and 90% state of charge points using my meter panel inside my off-road POPUP.
Also the deep cycle batteries like your 6V GC2 GOLF CART Batteries will on allow for so many cycles from 50% charge to 90% charge states to prevent internal damage to the batteries. What works good for me is to re-charge to a full 100% charge time after 10-12 cycles which takes around 12 hours or so using smart mode charging technology. Normally we only camp out for usually a week so this allows me to do this 100% recharge procedure after we get back home. Most camp grounds will not allow the running of a generator for more than a few hours a day.
I think you should plan on getting to something like this if you truly want to start camping off the power alot and want to keep your batteries going for several years. IMO you will be flirting with battery failure using a manual method of keeping them charged up. The smart mode charging technology converter/charger unit will do all of this for you automatically... Keep in mind this is DEEP CYCLE BATTERY SCIENCE - NO SHORT CUTS here...
We have been very successful camping off the power grid for the past 5 years now using the smart-mode charging technology converter/charger unit and my 2KW Honda type generator.
My battery charging comments.
Roy Ken
