Battery help needed...

[thefatmike]

Ok, need some help guys, I feel as though I have never fully grasped the electrical system of my 07 20ft Safari SE (rear galley)...

I have solar drip chargers, and need to replace my batteries as they no longer hold a charge. I hear stories of people lasting weeks alone dry camping and having power... How?

First, I don't believe I'm storing it properly. When I'm occupying the trailer, the switch should be in the "Use" position correct? Conversely, when I'm not occupying the trailer (stored between trips) the switch should be in the "Store" position correct?

Second, when I get new batteries what do you recommend? We go out maybe 6 times a year, and store it the rest of the time... Should I invest in a Marine switch thing? Also, I would probably be using Les Schwab for my batteries unless there are major concerns with them...

Thirdly, what about when I'm plugged in at a Campground (shore power) Should my battery disconnect switch be in the use or store setting... I never seem to get my batteries to full power (at least thats what my monitor says, it always floats around 10%) If running off battery, I never can realy use my stereo or my interior lights for really long at all.

I love my Airstream with all I have, but still feel lost when It come to ths stuff... Thanks for the help!

[dsrtgrls]

i am also not understanding the battery disconnect protocol so will be looking forward to responses to you questions. was your solar factory installed by the way?

[blickcd]

Assuming your batteries were new from the factory in '07 it seems like they died more or less on schedule. If you have the battery boxes that are physically inside the trailer though accessed thru and outside locking door, a group 27 battery is the largest that fits in there.

I suspect you have two group 27's already, which is a very good starting point. Not sure what type of converter/charger comes standard. I installed a Progressive Dynamics charger on mine which has variable charging rates. For example if I was boondocking and plugged into a generator I could set the converter for a fast charge and limit generator run time.

For a wet cell group 27 battery you don't want to discharge it more than 70%, otherwise you shorten the lifespan. Off hand I don't remember the numbers but a full battery puts out lets say 13 volts but is at 70% at around 12 volts. I've never boondocked long enough to have to check but I have a 12 volt plug connected to leads for a multimeter so I can easily check battery voltage.

Since you have a solar panel I assume that when boondocking that will be slowing down battery drain. You will need to find out how much power that panel puts out. Some are only designed to keep the batteries from going dead when the trailer is stored and won't be much help when boondocking.

I can't answer much more on solar panels as I have none. All my boondocking to date has been in wooded areas and I like to be in the shade, so panels are of little use to me.

A while back I modified my trailer to house four group 27 batteries. Two in the original outside accessible boxes, and two inside a vented wooden box behind the sofa, centered below the front window. See the attached photo of the work in progress, sans sofa.

Based on my limited boondocking experience I'll state a rule of thumb as one day per battery, assuming you are a real power mizer. A search here will probably turn up many ideas for conserving power. Since you have a modern refrigerator, when running on LP the brain is still drawing battery power. Not sure how big a drain that is.

Christopher

[n2916s]

With the battery switch in the "store" position you are still powering the carbon monoxide detector and/or the propane detector. Your solar chargers may be able to keep up with this load but that is under ideal conditions. If they cannot, then these ghost loads will bring your battery down to where the solars just can't bring them back up.

If I was using the rig 6 times a year, I would simply remove a battery lead when placing the unit in storage. You could, of course, put in an isolation switch (most use marine grade) which would accomplish the same goal.

Personally, I believe that any time you are using the rig, shore power or not, you should have the battery(ies) in the circuit. Without getting technical, it serves as a huge filter, removing spikes and odd noise. It is also good for the batteries that they be discharged to a reasonable degree on a regular basis (no deeper than 50% of capacity).

Clean connections, checking electrolyte levels regularly, reasonable use will see decent deep cycle batteries go about 5 years or so. You can go higher end (AGM's), but at your usage level I don't see a reasonable return on the investment.

mike

[Dwight]

I had some of those ghost loads that were draining my batteries when in covered storage.

It turns out that the solar monitor meters that I have will definitely drain the batteries down. I have since added a Blue Sea battery disconnect to the solar MPPT charger that prevents any power from being drained.

[Mexray]

Christopher,
Nice Looking installation to add some additional Amp Hours for those boondocking experiences...

I added an alum battery box behind the propane tanks that is mounted between the frame rails - it holds one more 27 DC battery for a total of three...

I've found that the three batteries are enough for us when boondocking. I run the quiet Honda 2000W genny for a couple of hours EACH day we're in the outback, to keep our charge 'up' if we've been using the Sat TV, DVD player or furnace fan motor, the night before...

[bryanl]

re: "I hear stories of people lasting weeks alone dry camping and having power... How?" - they either don't use battery power or they have some means to recharge them.

Figure that 2 group 27's have a weight of about 120#. Usable battery energy is 10 to 15 watt hours per pound so that's a bit over 1 kilowatt hour of usable energy. The alarms and control boards (fridge, water heater, furnace) can pull up to about 10 watts. That means the control boards alone will drain the batteries after 100 hours or less than a week (the Peukert factor will extend this a bit, but still, it's not weeks).

The service you get from batteries depends mostly on how you use and maintain them. The first thing to do is to upgrade your converter charger to one that has better charging intelligence and also has a maintenance mode that will keep the charge up and do something to inhibit sulfation. The charge wizard based ones or the WFCO ones seem to do well at this.

Keep in mind that a batteries needs a full 8 to 12 hours to become properly charged. It needs proper exercise, too, so discharging 15% to 50% of its capacity followed by a vigorous charge can help keep it healthy. Don't take it below 12.0v as measured in nominal temperatures after the battery has been resting with no significant charge or discharge for at least a half hour.

Watch out for the bull on the forums. Get batteries from a retailer who sells a lot to folks like you and will stand behind what he sells. Look at warranty, specs, and price. Watch out for marketing hype like "deep cycle" or "6 volt" or "golf cart" and such things that have no objective measure anyone will put money behind.

But don't expect too much from batteries. They just don't hold a lot of energy for the weight of batteries you can carry.

[2airishuman]

the 20 footers are ideally designed for weekends or a few daze the grid...

water, juice, food storage/refer, holding tanks and so on all limit prolonged remote escapes...

so the electrical systems are designed with that time frame.

Originally Posted by thefatmike

...I hear stories of people lasting weeks alone dry camping and having power... How?...

the stories are just that.

OR these folks have BIG solar collectors and MANY holding tanks (batteries) and all the associated gizmos...

or they are using candles and wood and propane, not electricity.

Originally Posted by bryanl

...But don't expect too much from batteries. They just don't hold a lot of energy for the weight of batteries you can carry.

heed b's take home message.
_________

IF the original batteries were poorly maintained (full discharges, no water, partial RE charges...)

get new ones.

i think your unit came with group 24s? these are just a tad less juice than grp 27s...

but fitting/space is the issue, so unless u wanna EXPAND the space/location for batteries REPLACE with same sized cells.

IF u want batteries that don't require ADDING WATER, get agms...

many threads on these here.

they will cost 2-3x but will survive abuse better and recharge quicker and MAYBE last more years...

the agms on my unit are 6 years old and still going strong, but that's not a guarantee in your application.

in order to have MORE electrical reserves one needs to...

1. install MORE batteries or LARGER/heavier batteries...

2. then properly tweak the charging system to FILL those larger, heavier, multiple juice tanks.

3. just like having more water means hauling LARGER/heavier containers for liquids.

expect 2-3 days of camping from 2 batteries and typical consumption.

use LESS or recharge with a generator and days OFF the grid will be extended.

so a tiny 1000 watt genset (honda or yamaha) is a light/simple way to reliably REcharge while boondocking.
_________

ANY hope that solar will prolong dry camping is entirely dependent of a PROPERLY set up and SIZED system...

here's a reasonable thread for starting your solar exploration...

http://www.airforums.com/forums/f448...ice-39392.html

cheers
2air'

[Dwight]

This is a pretty interesting blog on solar.....Robert and I have compared notes on several items and have helped each other on ideas...

HandyBob's Blog

[blickcd]

Thanks for the compliment, Ray. Directly behind my propane tanks is a rectangular metal box on top of the frame rails for storing the stabilizer jack handle and other similar toys. Too convenient to part with, though I suppose there is room to add a battery box like yours so long as the top was flush with the top of the frame. Hey, maybe the equipment storage box could be built into the lid of a hitch mounted battery box...

Thanks for giving me some ideas for the future, though for now four batteries is enough for me. I've thought of posting some pics taken during that installation on my blog since adding batteries is always a popular topic.

Christopher