Dual 6 volt GC2 batteries and charging characteristics

[busterbrown]

We just returned home to Michigan from a 24 day trip around the southwest. This was the first big test of our dual 6 volt battery bank (upgraded from a single group 24 12 volt).

As I have really no experience with charging behaviors of a serial 6 volt setup, I'm looking to see if I need to upgrade the OEM converter charger on my coach. This is what I noticed during our trip.

1. Started with a fully charged 13.3 volt bank on the morning of our departure after plugged into shore power for 48 hours. The Duracell (215 amp hour) flooded batteries are brand new.

2. After using typical appliances through a dry camping night, (inverter with television, furnace, led lights, LPG fridge, and water pump), the bank would drop to 12.4 to 12.6 volts. We would run our 3700 watt inverter generator for 5 to 6 hours during the next day to allow the converter to recharge the bank. I thought it was preforming as expected except that the converter would charge to about 12.8 to 12.9 volts. I never got back to 13.3 volts until we plugged into shore power at a full hookup campground.

3. On several legs of the journey, we would leave the dry camp location wothout running the generator in the morning and drive 4 or 5 hours to our next camp site. I checked the volts on arrival at the new site and my TV would barely provide a recharge (12.5 to maybe 12.6). The previous group 24 12 volt would be completely charged after just a couple of hours of running the truck. (Obviously, I have much more amp hours with the GC2s).

My concerns are:

1. Is my OEm converter the bottleneck in my coach's recharging capabilities?
2. For a dual 6-volt in-series battery bank (flooded), what should I expect as a full charge? I've read 13.3 volts as being 100% as a float charge but absorption voltage could be much higher.
3. Will a true 4 stage converter charger (bulk, absorption, float, equalize) help maximize battery usability and increase overall battery life?
4. If a new converter is needed, what size (amp) is preferred? Are converter/inverter types recommended as I see the price point goes much higher? Realistically, I would like to see a full charge after a couple hours of generator use.
5. Is a larger battery bank crippled by the inadequate charging abilities of the TV?

[Mogal]

Sorry for the bump on this one, but I would have posted the exact same.

I just picked up a generator. its 2000/1600 watt.
When the genny is plugged in, the voltage get up to 13.3-13.5.
And I never seem to get a full charge.
I have two GC2 batteries with 230AH ratings (Total 460)

I'm considering buying this BLACK+DECKER BC25BD charger. It's a 25amp charger and wondering if it would make the charging a little quicker over using the built in charge coverter. The converter that came with the trailer is a smart 3 stage unit.

Thanks

[chuckster57]

I would stay with the stock converter.

[Canonman]

Hi Mogal,
Just to be clear, 2, 6vdc batteries connected in series will provide 12vdc power output. The amp/hours of storage does not double.
How are you calculating when the batteries are at "full charge"?
13.2vdc is considered a "maintenance" charge from your converter. 13.6 is the normal charging voltage. 14.4 vdc is the bulk charge mode for recharging significantly discharged batteries. https://wfcoelectronics.com/wp-conte...eration-v2.pdf

[ChuckS]

For two GC2 batteries in series fully charged “Open” circuit will read 12.73 volts

Buying another converter or using an external battery charger will not yield any better results...

See battery charge table... from Trojan website...

The stock 3 stage WFCO will do as good as any regarding charge rate, charge times, etc... you won’t see over 12.7 volts when just in battery power

You will however see 13.4 to 13.8 when hooked to a 120 VAC source and converter is running.

The plates in the GC2 series battery are much more robust than typical flooded cell RV batteries

[ChuckS]

Also for me.. I use a specific gravity tester to determine my two GC2 batteries state of charge... quick, easy, and accurate

[ChuckS]

OP... you might enjoy this read ....

http://oldschooltech.info/2016/11/of...ry-principles/