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Topic: New 6v batteries in series (Read 179 times) previous topic - next topic
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New 6v batteries in series
Replaced both old 12v lead batteries for two 6v deep cell batteries wired in series. Each 6v battery supplies 225 Ah, so we gained some Ahs, can discharge them lower and they should last longer than our 12v batteries.  We only dry camp for 3 nights at a time at most so this takes care of our needs at a fraction of the cost of lithium. Besides, we would have to upgrade our 2-step inverter to a converter to go lithium and that's not going to happen anytime soon.
SoCal-Gal  (Tracy)
1991 26.5 RB
Previous 1988 22’ LD Multi plan
Previous 1992 Six-pack Camper
Spare the sealant, spoil the job.
Travelers: Tracy, spouse Anthony, Coton de Tulear, Gabby and parrotlet, Indigo

 
Re: New 6v batteries in series
Reply #1
Hi Tracy;   Sorry, but it doesn't work that way.  Each battery supplies 225 watt hours at 6 volts. Together they supply 225W hours at 12V,  The voltage adds, but not the watt hours.  To be sure, 225 watts at 12v is twice the amount of power of a 6v 225 watt battery.  Two 12v batteries in parallel will yield the same power as two 6v batteries in series.  The advantage is subtle;  in series the batteries behave better with each other, for a little added efficiency.  Two 12v batteries are hardly ever the same voltage, and the higher voltage one will try to charge the lower voltage one. That is why it is recommended that 12v batteries be very alike in age and type.
   Solar is still the best battery extender, especially now that 100 watt panels are about $100 each. One panel can provide about 3-4 amps charge rate, about 30-40 watt hours per hour (in good sunlight), and can keep the total charge depletion of your batteries to a level above the 12,5 volt threshold.   It is good to have new fresh batteries.
     My batteries at 4 years old, haven't been equalized properly and are exhibiting sulfation problems. With my 'new to me' R3000i controller, I need to turn that feature on.     RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB

Re: New 6v batteries in series
Reply #2
Each battery supplies 225 watt hours at 6 volts. Together they supply 225W hours at 12V,  The voltage adds, but not the watt hours.  To be sure, 225 watts at 12v is twice the amount of power of a 6v 225 watt battery.  Two 12v batteries in parallel will yield the same power as two 6v batteries in series. 

Thanks for the explanation RonB, we are still trying to figure this out. We were advised by an electronics specialist that two 6v batteries would be better than two 12v. Interesting.
For the time being, we’ll use the generator to recharge the batteries since it's already paid for, LOL.
SoCal-Gal  (Tracy)
1991 26.5 RB
Previous 1988 22’ LD Multi plan
Previous 1992 Six-pack Camper
Spare the sealant, spoil the job.
Travelers: Tracy, spouse Anthony, Coton de Tulear, Gabby and parrotlet, Indigo

Re: New 6v batteries in series
Reply #3
     My batteries at 4 years old, haven't been equalized properly and are exhibiting sulfation problems. With my 'new to me' R3000i controller, I need to turn that feature on.   

Ron, I seem to remember in the documentation my LD came with that the equalization feature on the SB3000i was turned off. Not sure why.
Greg & Victoria
2017 Mid-Bath  “Nocona” towing a manual 2015 Forester
Previously a 1985 TK
SKP #61264

Re: New 6v batteries in series
Reply #4
The electronics specialist was correct, two 6’s in series is better. With two 12’s In parallel you always have the potential of one fighting agent the other, a lower average so to speak. Also, the overall amp hour capacity is typically better.
Steve
2003TK

Re: New 6v batteries in series
Reply #5
Hi Greg;  Equalization is only used on vented wet lead acid cells.  Most recent LD's come with AGM batteries.  Trying to equalize non vented batteries would destroy them.  The built in routine does it just once a month for a few hours.  Driving with agitation, and the alternator charging, along with discharge at night during actual camping, achieves the same purpose.   RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB

Re: New 6v batteries in series
Reply #6
Ron, thanks for the explanation. These are the first AGM batteries I’ve ever owned so still learning about the.

Steve, I had always heard two 6-volt batteries wired in series is a better setup for RV use, as well.  I think that’s why LD went with it many years ago.
Greg & Victoria
2017 Mid-Bath  “Nocona” towing a manual 2015 Forester
Previously a 1985 TK
SKP #61264

Re: New 6v batteries in series
Reply #7
Bottom line this is no advantage just different pluses and minus. 

Most of the time it's what the person selling the product highlights that gets shared.   I've worked in both low voltage applications 1.2v to 400v and high voltage applications 15kv to 25Mev.  Folks spent their who life kicking the tires on this issue.   the most famous of course is the fight between Edison and Tesla.

The real issue is understanding the difference between series and parallel hook ups.   Then getting was best works for your personal application. 

glen
personal fine art photo stuff
TF Mack | Flickr
It's all good .......
2014 Twin King