Battery power what to do

[oldtool2]

If you need hot water quickly when you get to the campgrounds you can use both gas and electric to heat it up quickly. Then just shut one or the other off and the remaining one should maintain your HW.


Jim

[TGR]

Originally Posted by redjet

I assume you mean FOUR (not for) 6v Interstate batteries. Why 6 V batteries? A 6V Interstate has 232 CCA, two in series (12V) is 464. A Group 27 Interstate 12V battery is 600 CCA and will carry a continuous 15 Amp load for 5.5 hours. Two in parallel will be close to 11 hours. No such data for the 6V. Again, assuming Four batteries - where in the world are you putting them? My Cardinal battery bay is pretty full with two Group 27 batteries.

A batteries CCA rating isn't useful in an RV battery, you can't compare the CCA rating to a battery's Ah capacity and 2 batteries in series don't increase the pair's Ah capacity.

A pair of 12V Interstate batteries provide about 10.5 hours of power at 15A and a pair of 6V Interstate batteries provide 14 hours of power at 15A. Double these times for 4 batteries. (scroll down the link above for the 6V batters)

Additionally, 6V batteries generally will last many more years than the 12V batteries because they are better designed for this task.

[Cag2515]

Thank you Scott Bernstein and the rest is I now figured it out I will be running my residential refrigerator on the inverter with the 6 volt batteries and no hot water heater till I get to my destination thank you once again I appreciate all the help

[ScottBrownstein]

Glad we got it straight. Actually the 2/12v vs 2/6v discussion has occupied a tremendous amount of space in these forums. The best answer that I have ever seen goes something like, you only have so many cubic feet to put batteries in and 2/6 volt batteries in series has far more plate area and active storage volume and much less plastic for separators. As such, 6 cells (2-6 volt batteries) gives you more active battery storage area than 2-12v batteries (12 cells, separators, caps, etc) in the same volume, and for the same weight. Personally I believe in deep cycle golf cart batteries than AGM units. They are cheaper and far more commonly available. I have generally used Trojans which are the top line in golf cart units.

[Evereddie]

Originally Posted by ScottBrownstein

Glad we got it straight. Actually the 2/12v vs 2/6v discussion has occupied a tremendous amount of space in these forums. The best answer that I have ever seen goes something like, you only have so many cubic feet to put batteries in and 2/6 volt batteries in series has far more plate area and active storage volume and much less plastic for separators. As such, 6 cells (2-6 volt batteries) gives you more active battery storage area than 2-12v batteries (12 cells, separators, caps, etc) in the same volume, and for the same weight. Personally I believe in deep cycle golf cart batteries than AGM units. They are cheaper and far more commonly available. I have generally used Trojans which are the top line in golf cart units.

That's a great explanation which I haven't seen before. Now it makes sense why 6 volt batteries in series. Thanx!

[PokerDealer]

That is the only modification I made before I took delivery last week. I had them take out the group 24, 12 volt battery and put in two 6 volt deep cycle batteries and wire them in series. I'm going to run my WH and fridge on propane and hopefully boondock 4 to 5 days if I'm careful. I looking to replace all of the 12v lights with LED's next month, before winter hits.... do you think 4 to 5 days is feasible. (I'll have my truck to charge things up a little if need be.
Question: is it better to charge a little everyday or try to go 3 or 4 days before using the TV to recharge the batteries?

[silverback 35ts]

I just must chime in here as this went so bad and in so many crazy directions! But after it all it seems that CAG2525 got WOW such a relief since i think some went by it through china.
I sure how that he got it, and i hope it help some others also in the end;
Happy Camping to all.

[ScottBrownstein]

You are saying before winter, do you have heat? If you do, the furnace will draw considerable current when it is running. LEDs will help but with reasonable use 4 days is a long time. Deep cycle batteries don't get damaged when they are drawn down like regular cells, but I would charge a little each day or every other day.

[Joe_GA]

Fortunately, the output from the inverter only goes to the refrigerator so people cannot overload the inverter. It does not have the capacity to power the water heater.

[Witch Doctor]

Originally Posted by TURBS

Water heater draws 9 to 13 amps on electric.
Good luck with that considering you want to run the fridge to! Lol
If you must run water heater during travel then I'd put it in gas mode.

Only way this would be reasonably possible is if wh was already to temp.

TURBS
08 duramax tuned n modded
2011 32bhok Sabre
2015 camping "24 nights"

X's 2 refer on inverter only w/h on propane. or just heat the water before you leave it will still be warm in 6hrs, just sitting in the tank.

[Blackhat6mike]

Originally Posted by oldtool2

What about something like this?

MK Battery | 6 Volt 200 AH Deep Cycle AGM RV & Marine Battery

915 cranking amps, 200 AH. Not bad and are AGM so no spilling or gas from charging because they are sealed.

Jim

I think you will find that is 200 AH @ 6 VDC, not 12 VDC. If you connect in series 2 x 6 VDC batteries at 200 AH each, you will have 200 AH @ 12 VDC. CCA mean nothing when you are talking AHs unless you figure in the reserve.
I checked out that MK Battery site. At $345 each for a 6VDC, 200 AH battery, you would end up paying $690 for 200 AH at 12 volts. I think I would look into Trogens or Interstate. I have 8 x 6VDC bats in my boat and I didn't pay even half that per battery.

[Tom48]

Originally Posted by Evereddie

OP has a residential fridge so propane is not an option. For water heater it is an option so I would definitely stay on propane there unless shore power is an option.

Yeah that was my point. No need for the propane with frig on elec. But definitely not Electric Water Heater.

[Tom48]

Originally Posted by Blackhat6mike

I think you will find that is 200 AH @ 6 VDC, not 12 VDC. If you connect in series 2 x 6 VDC batteries at 200 AH each, you will have 200 AH @ 12 VDC. CCA mean nothing when you are talking AHs unless you figure in the reserve.
I checked out that MK Battery site. At $345 each for a 6VDC, 200 AH battery, you would end up paying $690 for 200 AH at 12 volts. I think I would look into Trogens or Interstate. I have 8 x 6VDC bats in my boat and I didn't pay even half that per battery.

That site seems higher than a cat's back. IF you need batteries and do not have a good local price try Golf Cart Batteries - Trojan, US Battery - 6V 8V 12V Batteries - AtBatt. www.ATBATT.com

Not sure that meets everyone's needs but prices beat my local dealers.

Tom

[ScottBrownstein]

BTW,one thing that I forgot to mention that relates to 2/12v vs 2/6v batteries is that your converter may have more problems charging 2 batteries in parallel as it will see "back voltage" from both, well actually the back voltage from the most charged battery. The converter looks to see what the battery voltage is during charging in order to prevent overcharging. As time goes on, one 12 volt battery may develop a different internal resistance and it can eventually be confusing for the converter (not to mention it will drain the higher voltage battery first as well.) When you use 2 6 volt batteries in series, the problem is eliminated.

[Evereddie]

Originally Posted by ScottBrownstein

BTW,one thing that I forgot to mention that relates to 2/12v vs 2/6v batteries is that your converter may have more problems charging 2 batteries in parallel as it will see "back voltage" from both, well actually the back voltage from the most charged battery. The converter looks to see what the battery voltage is during charging in order to prevent overcharging. As time goes on, one 12 volt battery may develop a different internal resistance and it can eventually be confusing for the converter (not to mention it will drain the higher voltage battery first as well.) When you use 2 6 volt batteries in series, the problem is eliminated.

Another great point Scott and another reason why 2, 6 volt batteries in series work better. Thanks for that tip.

[pmsherman]

I fully agree that two 6V golf cart batteries in series easily beat two 12V batteries in parallel. Unfortunately, at Forest River's International rally in Goshen, the FR reps running the "Know Your Stuff" lectures are still claiming that using two 12V batteries in parallel is better.

12V marine deep cycle batteries, what's generally used in RVs are, internally, a hybrid design to provide cranking capability to start the boat's engine and deep cycle capability to run lights while anchored. The plates in these batteries are thicker than the ones in a car's starting battery but are still designed as a grid to increase surface area, necessary to provide high amperage for starting. Golf cart batteries use solid plates which have much less surface area but are a lot sturdier and vibration resistant. They're also more resistant to damage when deeply discharged.

Golf cart batteries should provide more power in an RV than the sticker rating. The reserve capacity number for a golf cart battery is determined under a 75A load, three times the load that's used for rating hybrid 12V deep cycle batteries. When a battery is providing power at a lower rate, there's less losses from internal resistance and more power is available to supply the load. A 300W residential fridge should draw less than 30A from your batteries WHEN THE COMPRESSOR IS RUNNING. Remember that the compressor doesn't run all the time, only when it's needed to provide additional cooling.

The one thing I'd do if I were running a residential fridge in a TT is to provide a #10 wire to charge the TT battery directly from the TV's alternator. Have the TV equipped with a higher capacity alternator and also add a #10 ground wire between the TT and TV. The charge line from the alternator also needs to have protective diodes in it to prevent drawing on the TT batteries when starting the TV. I'd use 60A, 50 or 100V diodes for this, a bit of overkill but something that shouldn't ever fail. The diodes will drop the alternator's 14.1V to 13.5V which will still charge the TT batteries.

Phil

[ScottBrownstein]

Phil,

All really good points. Since I am an RV guy, I already have that kind of setup and I do wish that my new 335DS didn't have FOUR 12V deep cycles for the reefer, so I have the parallel problem in spades. I would bet that the distance from the alternator to the batteries in a TT is a long run and to take full advantage of the alternator in the TV, #10 with diodes would be a really good upgrade.

[clr]

In my Ford f350 TV the battery charge lead runs through a relay so there is no current flow to the RV until the TV is running. So there is no need for the diodes to prevent the backflow of current from the RV to the TV when starting. Not for sure how other brands of TV operate.

[ScottBrownstein]

That's great because diodes will cost around 3/4 of a volt as well and will limit the TV's ability to charge the TT house batteries once the TV battery is up to 100%.