RV Batteries 6v vs 12v

[509er]

I had a large 12v deep cycle on my trailer.  In the late season the furnace would run often due to the hybrid design of my trailer and the battery would be very low in the morning and I would have to charge daily.  I switched to 2 large deep cycle 6v batteries, I now can go 3+ days in similar weather/temps before recharging.

[THINK_N_ELK]

I had to replace my 12v batteries a couple years back, and was told that the on board inverter charger only charges at 2 amps. So therefore it order to charge with a generator with the on-board charger/inverter your generator would have to run for 2-3 days straight. However, the best way to get a good full charge in a short time is to plug the trailer into the tow vehicle (idling of course)and in 30-45 mins the batteries should have a good charge. It's called a hot charge. Gets the electrons all excited and they bounce around more creating a better charge.

And if you are storing or parking your trailer for a long period of time disconnect the main battery lead if plugged into shore power.

My hunting partner switched over to two 6v, he really hasn't given me any pro's or con's since the switch.

[Wanttohuntmore]

I run 2 6's after my dad started doing it in his Bighorn.  We both probably get twice the use out of the double 6's as we did with the double 12's.   I think it has something to do with how it draws down completely versus to the lowest of the one battery when running 12's in parallel.

That's one of the negative things about electric fans on campers/trailers, versus the old catalytic heaters or can heaters.  They use so much electricity.  We always had lots of problems hunting in neg. degree weather in montana when the heater would stop, water would freeze up, etc....  I think we've finally figured out the cold weather camping tricks...

[robodad]

I think we've finally figured out the cold weather camping tricks...

OK now I need a list !! We don't do a lot of cold weather camping but I have 2 kids that bring their friends and the inlaws come sometimes and so on and the lights are left on (I bought LED bulbs) and the water pump is on a lot to flush and wash hands and the fridge ignitor and the hot water heater etc... so keeping a charge is imparitive if I want to continue to take them all out, they must have the ammenities of home or they just stay home bottom line !!!

Thanks for all your suggestions so far !! Good discussion !!

[lee]

Concern'un re-chargeing the batteries, this is how I handle it. First off, as stated previously the inverters in most Rig's only provide a trickle charge to the batteries and it takes days to re-charge. A big ole noisey generator runn'un all dang day in camp is enough ta drive a man ta drink'un!

I picked up a small 1kw generator( nice and light, quiet, and runs forever on a tank of gas) and a fancy battery charger. I plug the charger into the generator and hook the charger directly to the batteries. I don't disconnect the batteries from the RV. At 15amps it only takes a few hours.

Yer mileage may vary....
Lee

[Rick]

6V batteries are the way to go. They're true industrial deep cycles with thicker plates and more lead. If you maintain them they'll have a longer lifespan than 12V batteries.

I went from 2 12V Interstate deep cycles to 2 6V Costco deep cycles and there is no comparison.

If you have a newer RV the converter will charge them just fine. My 2007 has a 3 stage converter with a bulk charge mode that will take the batteries from about 40% to 90% in just a couple hours on the generator.

[Rick]

However, the best way to get a good full charge in a short time is to plug the trailer into the tow vehicle (idling of course)and in 30-45 mins the batteries should have a good charge.

That would be incorrect. The charge wire from the truck to the trailer is usually like 12ga. Thats not very big to start with,by the time you factor in the loss from running that wire from the front of the truck to the trailer,you aren't putting much juice in the batteries.

Idling for 30 minutes will do a whole lot of nothing.

 

[Buckmark]

Also incorrect, the amp output from your vehicle is much higher than the rv inverter/charger, therefore if plugged into the vehicle the rv battery will be given a higher rate of charge and will be charged quicker than running through the rv @2amps, most vehicles will charge at approx 20amps at idle mininmal load and can go up with increase in engine rpms to the max charge rate of 80amps+, some as high as 105+ output from the vehicles alternator, regulated by the vehicle, but remember that the rv battery will only take what is known as a "surface charge" and not a deep charge as a slow charge will do.
Also note that your vehicles alternator is NOT a battery charger and damage can occur if the battery (s) are really discharged...
Figure approx 6-8 amps from the vehicle to the rv batteries, better than the 2amps from the inverter.
Can also add a solar panel of 75 watts and get around 3-4 amphrs on a good sunny day..

[robodad]

What if I were to run 2 6v batteries and 1 12v in a parallel configuration, would that be ok ??

[Rick]

Also incorrect, the amp output from your vehicle is much higher than the rv inverter/charger, therefore if plugged into the vehicle the rv battery will be given a higher rate of charge and will be charged quicker than running through the rv @2amps, most vehicles will charge at approx 20amps at idle mininmal load and can go up with increase in engine rpms to the max charge rate of 80amps+, some as high as 105+ output from the vehicles alternator, regulated by the vehicle, but remember that the rv battery will only take what is known as a "surface charge" and not a deep charge as a slow charge will do.
Also note that your vehicles alternator is NOT a battery charger and damage can occur if the battery (s) are really discharged...
Figure approx 6-8 amps from the vehicle to the rv batteries, better than the 2amps from the inverter.
Can also add a solar panel of 75 watts and get around 3-4 amphrs on a good sunny day..

Ok,lets charge my battery using your numbers.

My battery is 232amp hours. 50% discharge is 116 amp hours. If your vehicle is putting out 6-8 amps at the hitch it'll take 19 hours at 6 amps and 14 hours at 8 amps to charge the battery. Thats assuming you don't have anymore loss for a poor connection between the trailer plug and the hitch.

How exactly am I wrong when I said running your vehicle at idle for 30 minutes will do a whole lot of nothing?

By the way,the factory converter in my trailer puts out 55amps in bulk charge mode.

[Woodchuck]

What if I were to run 2 6v batteries and 1 12v in a parallel configuration, would that be ok ??

Would not work real well because the 12v would be pulled down quicker and then will start to pull on the 6's. Same principle as diesel trucks with 2 batteries.

[Buckmark]

Also incorrect, the amp output from your vehicle is much higher than the rv inverter/charger, therefore if plugged into the vehicle the rv battery will be given a higher rate of charge and will be charged quicker than running through the rv @2amps, most vehicles will charge at approx 20amps at idle mininmal load and can go up with increase in engine rpms to the max charge rate of 80amps+, some as high as 105+ output from the vehicles alternator, regulated by the vehicle, but remember that the rv battery will only take what is known as a "surface charge" and not a deep charge as a slow charge will do.
Also note that your vehicles alternator is NOT a battery charger and damage can occur if the battery (s) are really discharged...
Figure approx 6-8 amps from the vehicle to the rv batteries, better than the 2amps from the inverter.
Can also add a solar panel of 75 watts and get around 3-4 amphrs on a good sunny day..

Ok,lets charge my battery using your numbers.

My battery is 232amp hours. 50% discharge is 116 amp hours. If your vehicle is putting out 6-8 amps at the hitch it'll take 19 hours at 6 amps and 14 hours at 8 amps to charge the battery. Thats assuming you don't have anymore loss for a poor connection between the trailer plug and the hitch.

How exactly am I wrong when I said running your vehicle at idle for 30 minutes will do a whole lot of nothing?

By the way,the factory converter in my trailer puts out 55amps in bulk charge mode.

Sorry rick, i was refering to the post about only getting 2amps from the inverter, compared to more from the vehicle, not a bulk charger of 55amps, that is a no brainer.
Back to the OP, multi 6volts are the way to go if you can fit them onto your rv.....
As the 6v - 12v configuration hooked together, on any multiple battery configuration the battery with the higher charge will always discharge to the lower batteries unless you use a blocking diode setup which is a whole other discussion..

[6x6in6]

I would have much preferred going with a pair of 6v golf carts.  Wouldn't fit in the battery box in my camper without some modifications to the box.
I opted for 12v Group 31 AGM's.  AGM's are the way to go if sticking with 12v battery's is the way you go.  I leave my camper plugged in all the time, the solar charge wire hooked up and have no overcharging issues.  The battery people I have talked to before and after the purchase all said the same thing.  "Not as good as a pair of 6v's but but G31 AGM's are the next best thing.  And, with AGM's, never have to worry about overcooking them by leaving it plugged into 110." 
4th birthday last month on these batteries and still going strong.  All I do is dry camp so they get used a lot!!!
http://www.trojanbattery.com/Products/31-AGM12V.aspx
If you go 6v, Trojan has a 6v AGM RV battery that might be worth looking into.

[farmin4u_98948]

Good info.... Thanks

[Buckmark]

Just a FYI.
SEALED BATTERIES  Gel or AGM (absorbed glass mat) types damage easily from overcharge, and so should be used with a 3 stage charge control. Sealed batteries can be excellent deep cycle alternative energy batteries, cleaner and safer, but only if charging is precisely controlled. Since water cannot be replaced and hydrometer testing is not possible, they are considered special purpose batteries.