RV battery / Solar panel questions

[Bhale]

We managed to kill the battery in the slide in and started looking into a new one along with solar panels. We've calculated our amp hour usage to be around 63 AH and are looking at 2 panels totaling 150-175 watts based on these numbers.



I've been told i shouldn't discharge a standard deep cycle battery past 50% of it's capacity as the recharge times can be longer than what i can expect to get from the afore mention panels.



Looking at batteries i've found dry cell batteries that don't mind deep discharges with a 65 AH rating. Gel cell batteries have a 55 AH rating and the big Sears Diehard has a 115 AH rating. Using only 1/2 of the deep cycle battery gives me about the same capacity as the dry and gel cells. Sound correct?



Questions:

How well do the dry cells recharge after a 70-80% discharge with the above panels?

Same question with the gel cells.

I like the idea of the dry and gel cell batteries since we could add a second one inside the camper and not have to worry about gas problems. This would give us 110-130 AH capacity.



Were setting up for future trips where we'll out of touch with civilization for several days at a time and want to make sure we'll still have lights and heat.



Thanks

Brian

 

[Lordsman]

Solar RV

I use (2) Seimans 75 watt panels mounted flat on the roof of my camper(raised up a few inches for drainage below). Then they are routed to a Golde Genisis Co. microprocessor charge controller, which then feeds (4) 6-volt Trojan 105 batteries(wired in series then parallel to acheive 12 volts). I put my batteries in the holding area meant for the generator which was already pre-wired and ready for 12-volt feed. This system has been in since either late '98 or early '99 and works great. I beleive the whole thing cost me $1500 for the parts which I installed. The hardest part for me was bending the EMT conduit correctly! Use my rig for hunting and fishing trips. Never bought replacement batteries since and the only maintenance is battery fluid. Always have power.

 

[klenger]

Check out my web page on RV solar at http://www.klenger.net/arctic-fox/solar/index.html. My system has two 120 watt panels and two golf-cart batteries.



Personally, I'd stay with lead-aicd batteries because of their lower cost and simpliicity, but I didn't research dry cell or gel cell batteries all that much.



You might want to consider supplementing the solar with a small generator to keep the system cost lower.

 

[Gary - K7GLD]

MUCH depends on your specific rig - what appliances/lights you want to use, and time off shore power...

We have a 24 foot fiver - use a pair of 6 volt seriesed golf car batteries - 210 AH each - and use a free-standing 2 amp solar panel to maintain the system - I manually position the solar panel thru the day for best exposure to the sun, since we normally like to park in the shade - which isn't very good for best panel operation when they are permanently attached to the roof. I have about a 20 foot heavy conductor cord from the panel to it's regulator... From that, we power all internal lights, stereo, TV/VCR, forced air heater (seldom used - we're "fair weather" RVers!). With a 300 watt DC to AC inverter, we power the TV/VCR,and stuff like out blender. With that setup, we can NORMALLY go for a couple of weeks with no problems - we DO carry a Honda 1kw generator in case of special needs. The golf car batteries are specifically designed for full, or nearly full dischage cycles with little problem or damage. An added benefit with the solar panels, is that it maintains the batteries even when the RV is parked at home for extended periods, with no needed connection to shore power.

 

[klenger]

Bhale



Regardless of the batteries you select, I don't think you will get 65 Amp-Hours out of the solar panels you are looking at. If the panels are mounted flat, and in direct sunlight, you an expect about 5 amps (or less) average over and 8 hour period. the panels produce almost no current when the sun is low. The wattage rating is with direct sun, cold temps, etc. You really need to look at the wattage curves and calculate the current output with less than direct sun to get a better idea of output.



Good luck

 

[Jay]

Concord AGM

I agree with klenger on both points. It's hard to beat the bang for the buck of lead acid batteries like Trojan T-105's. Another good, but pricey, alternative to gel-cells are Concord AGM's. I'ld use 40-45 amp hours per day for planning purposes with 2x75W flat mounted panels (which is what I have).