Battery Decision time

[StillinID]

Hi all,

First off, let me say I really appreciate the time and advice I have gotten from everyone here. The TT remodel is proceeding along, just a bit slower than anticipated.
Now, it is time to decide on a battery. I have read all of the library articles and quite a number of articles from various web resources.

I am looking for personal insights now.

We have a 79 Prowler TT. Only power items are the dome lights (1.5 amps per bulb) and the water pump (2.8 a min to 7a max). Add to that whatever the converter might consume. No slides, no furnace, no a/c.
We expect to boondock 90% of the time.
We anticipate having 2-4 lights on for 2-3 hours per day and about an hour total run time on the pump per day and we expect to only be out 2-3 nights at a time typically.
I am not great with battery maintenance so I know I want a "house" battery of the maintenance free AGM variety.
I have investigated the Lifeline, Universal, and other lines in both the dual 6v and single 12v options. (I think I will stick with a single 12v.)

I have received input that at our expected low usage levels to NOT pay for the more expensive type described above but rather to go with the basic Sears RV/Marine style (1/3 the cost) and just count on replacing it every 2 years instead of buying the maintenance items/time to make a more expensive model to last 5-6 years.

Opinions?

Note: We are also thinking about adding a solar panel right off the bat instead of a hauling a generator around. May as well sink the money into that instead to generate 10a /day (20w panel should work for that amount @ 8 hours per day if I understand things correctly) and appease our geek factor in addition. 

 

[silveradomike]

Solar is a good idea, have gone that way myself. It is nice not having to worry about your BATTERIES, if they are charged or not. I went with 12v only because I could not fit the 6v in my battery compartment. Another reason for 12v is if one goes bad you still have power as with the 6v if one goes bad you are dead in the water. Although I head the very seldom do the 6v go bad. One thing that I would do if you go with 12v is get two of them, especially if you are going to be doing a lot of boondocking. You will need them. One question I do have for you. How is it that you don't have a furnace? If you do any cool weather camping you are going to need one sooner or later. Good luck with your remodel, modifications never end.

 

[Marsha/CA]

We have a 79 Prowler TT. Only power items are the dome lights (1.5 amps per bulb) and the water pump (2.8 a min to 7a max). Add to that whatever the converter might consume. No slides, no furnace, no a/c.

So you do not have a refrigerator or a hot water heater in the trailer?  If you do those will have be added to your usage count.

Marsha~

 

[John From Detroit]

I am not that keen on AGM"s myself, I do not feel they give more benefit for the dollar.

If access for maintenance is not an issue the common Flooded Wet Cell golf car battery is hard to beat, a pair of them gives you 12 volts at 220 amp hours. that' is about two Group 29's in parallel

Deep cycle batteries of this type should be kept at least half charged (Which means you have 110 amp hours to play with) for best life,

Marine/Deep cycles are not nearly as good, they like to be kept somewhat "Fuller"

Starting batteries, fuller still.

Just so you know.

If, however, access for maintenance is an issue, then a maintenance free style is your best option.

 

[Gary RV_Wizard]

AGM vs a cheaper flooded cell is mostly a personal decision. Since you aren't much on battery maintenance, maybe AGM is right for you, despite the cost.

A 20W solar panel generates about 1.25 amps in full sun, pretty much directly overhead.  Less when the sun is at an angle and zero if there is any shade in the way.  You probably won't have full sun for 8 hours each day, but you might get enough charging in the off peak times to still get 8-10 amp hours per day.

 

[StillinID]

Marsha,

There are both items on board the TT however the heater is an old radiant style using propane. The refrigerator and the water heater are both propane units as well. (The propane system gets its very own overhaul once we empty the two 75% full 30lbs tanks...)

I did not count them as I do not intend to run them on battery power even if it is possible.

Are my calculations correct in assuming that given our low usage expectations that we should not have an issue with. say a 100 amp/hr battery. over the course of a weekend? (Assuming 50-60% drain)

 

[Marsha/CA]

The fridge will need 12 volt battery power to run the control board; and possibly the hot water heater.  I believe we have a list of amperage use in our library.  That would give you a total so that you will know just how much you need.  However, my gut instinct is you will be fine.  We ran a truck camper with fridge, lights, hot water heater on 1- 12 volt deep cell marine battery for a couple of days.

Also, fyi, an a/c will not work on battery, it needs 110 electric.

Marsha~

 

[Gary RV_Wizard]

Your also have an LP detector and maybe other safety devices that use 12v. Not much, but they all contribute a bit to the constant load.

As Marsha says, the fridge and water heater circuit boards use some 12v when operating in LP mode (and 120v electric mode too).

 

[ttyR2]

It's been posted before, but a great read on batteries, charging, and solar power: http://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/

 

[Mexray]

Here's my '2 volts' worth...   ...I'm the battery guy some claim to be about 2 volts shy of a full charge... :

1. Go with the more economical 12 volt DC - the Group 27 can be picked up at many sources, in about 015 Amp Hour rating, with about 250 Min's reserve @ a 25 amp load - Heavy is good!  Just make sure it's a DEEP CYCLE type - a 'Marine' DC is usually the same inside as an 'RV' DC battery, just different labeling - our common DC battery label actually says, "RV/MARINE DEEP CYCLE" Service - why have two labels when they're the same inside!

1.1.  The two 6 volt Golf Cart type DC's are also a good choice if you need the additional Amp Hour capacity - the 2 GC's will give you about 225 AH total, compared with 210 AH rating of tow Gr-27's...

2. You mentioned 'converter' usage - I believe you meant 'inverter'...the 'drain' on the battery, of course, by an inverter is totally dependent on the stuff you're trying to run, or load - it could be significant, for example if you're running a DVD player and TV for several hours - However, if you're just running a phone charger, that's not much to worry about, etc...

3. If you want to improve your usable capacity, look into replacing all those filament light bulbs with LED models, inside and out, including the tail/stop lights - search on the forum for some great deals recently!...We've gone completely LED on our Airstream, the tail/stop lights are much brighter, and leaving on an interior light longer than normal is no longer an issue, as is the 'heat' issue from those old filament bulbs!

4. If you have an older Refrigerator and water heater, there's no 12 volt circuit boards to 'drain' a few amps each day...

5. A solar panel is a good idea, but not really to replace the benefits of small, quiet generator - for example, do you plan to install a small microwave oven (a great, convenient, cheap appliance) - if so, the inverter won't handle it, so a short run time with the genny will get the popcorn popped or the hot dogs heated in a jiffy out there in the boonies during bad weather!   A genny will also recharge your battery quickly when plugged into your on board converter/charger, if you're on an extended stay away from the power grid... :

6. Of course it's my thing, but I'd recommend checking out what's available from your local 'Battery Specialist' - good old yellow pages under 'Batteries'...they will give you the straight scoop, and can show you what's available for your RV...IMHO  :

7. With proper care,  DC batteries should be usable in your RV for 4-6 years - that's assuming you don't store your rig and let the battery discharge and sit there for several months - Just like your car battery, your RV battery needs to maintained at a full charge to get the maximum life...maintenance is the key - clean terminals and cable ends, proper fluid levels (if your battery has vents on top that can be opened), etc., etc....

8. AGM's are great batteries, but their elevated cost might not be the best choice if you can care for a flooded cell battery - AGM's, if cared for properly might give you a couple of years more service, but not 2-3 TIMES the life of a flooded cell battery, when compared with the initial expense...again, just my 2 volts worth...

 

[StillinID]

Wow! Great read TTyR2! Thanks for that link. Quite the voice of experience that HandyBob seems to be. Will certainly be using that info when we finally decide on the solar.

Mexray, I VERY much appreciate your insights and the length you went to answer my question. We did go see a couple battery folks as you suggested and decided we would start out with a group 31 sealed unit. It seemed to fit the bill for us in terms of usage/maintenance/cost. We should be getting about 55 AH out of it (to 50% drain) with a buffer and that should work for us for 3 nights boondocking. (Remember no TV, microwave, furnace, etc. Just a few lights and water pump). Going for the two 6v has its appeal but we simply could not justify the weight and cost with what we are working with right now. We'll save that for the next RV.

We'll see how close our numbers are this weekend since I grabbed a Digital multimeter today. Then we can adjust and get a better feel for what our solar needs are going to be.
Incidentally, we saw that Costco has a Coleman solar package out there now for $200. It is 3 panels w/frame at 55w total with 7amp controller and an inverter (which we do not need.) Based on TTyR2's informative link, the controller should be upgraded to something more worthwhile but we are considering it since I am having trouble finding 55w of panels for roughly that price anyway.

Oh yes, I also took HandyBob's advice about wiring and purchased new number 6 cable (I think old is #10!!) to run from the battery to the inside just to ease things along. Lowe's carries the number 6 at $1.14/ft in a few colors FYI. New attachment ends run about $6.25/pair.

I will get that wire installed tomorrow when I have the bed frame pulled up (new supports and slides needed there) then test the propane system and with a bit of luck be camping Friday afternoon!

Thanks all!

 

[Gary RV_Wizard]

If all you are running is a few lights and the water pump, a single Group 31 battery will easily supply your needs for 3-4 days without charging.

 

[Conquest aka Robert]

Solar would be a help 8) Harbor Freight also has a kit it only does 3 amps at 45 watts. I have one the controller even has some 12volt outputs and some lower outputs. comes with a couple of 12 volt lights as well. I have seen it for as low as 169.00