will a group 24 and a 50watt panel be enough for 2 week trip

Since that represents a tiny capacity bank I'd recommend at least 150 watts per 100 amp-hours. If 200 watts can be made to fit--great.

Mote wrote:
If I were move up to a group 31 battery what would be the ideal solar panel size I should move up to ?
Also, if I install a new solar panel should/can I wire it with the existing 50 watt that was installed on the camper when it was new?

Mote wrote:
If I were move up to a group 31 battery what would be the ideal solar panel size I should move up to ?
Also, if I install a new solar panel should/can I wire it with the existing 50 watt that was installed on the camper when it was new?

In most situations, the cable that is currently in your camper will be below standards to add additional Amps/watts-Solar Panel/s. You will need to determine what this cable is before adding to it. The rule of thumb is 60-100 watts to each 100 AmpH of your battery. The higher watt number would be for those that have High AmpH demands or 4 season use, like me. I am typically 190-220 daily AmpH. Most truck campers are 20-30 daily AmpH users. You being in colder country and with a family on an extended vacation will be on the higher end. The question would be to you, are you going to be better served by just investing in a pair of good AmpH batteries, that can be charged by 3 different sources already identified or spending more money to try to reach both Solar and Battery? I would go in phases and invest in two good Batteries (that fit in a place you can fit them) and upgrade your cables and purchase a good auxiliary charger for your generator to assist charging your batteries. You would be able to charge your battery through the converter and aux charger this way, shortening the charge time needed to get S.O.C. to 90% and remainder 10% topped by your existing solar panel. Or drive your camper to see the scenery and or museums or get on down the road.

In the long run you will be better off having Poly PVsolar panels and a charge controller that will allow you to expand if needed. My guess is the charge controller, if there is one, is adequate for the current panel and no more.

b

Check out Renogy.com for the best prices I've found for panels. Go for monocrystaline panels, they produce far better in shade and clouds than poly panels. You probably can use your old ones too. Go up to 200w and you will still do well on cloudy days.

If I were move up to a group 31 battery what would be the ideal solar panel size I should move up to ?
Also, if I install a new solar panel should/can I wire it with the existing 50 watt that was installed on the camper when it was new?

Making the battery bigger will only slightly increase the run time before it goes dead.

MikeJinCO wrote:
Just a comment. I have 4 group 24 batteries on my Ford F350 setup with a #4 truck to to battery charge wire thru a solenoid. I have been disappointed with the charge rate from my stock 110-120 amp alternator. According to my Trimetric at about 1500 RPM with 60-70 percent battery charge I only see about 15 amps. Where plugged in to 110 I'll see 45. The solar has worked much better for me, from my 3-100w panels I've seen 17 amps at times and 12 amps commonly.

Likely your problem is the resistance in the 4 AWG wire coupled with the fact that your alternator maybe doesn't have enough voltage overhead to push more current to the batteries.

4 AWG wire has a resistance of 0.0002485 ohms per foot. If your run from the alternator to the battery bank is 10 feet for the positive feed that would be 0.002485 ohms. At 100 amps you would have a voltage drop in the positive wire of 0.25 volts. I do not know what your return path (ground) is, but if it is also a 4 AWG wire with a 10 foot run leading back to near the alternator you would have another 0.25 volt drop there for a total of 0.5V drop.

For a typical battery to take 100 amps if not extremely discharged, you might need the voltage at the battery terminals to be 14.5 volts or higher. This means your alternator would have to provide 15 volts to overcome the 0.5 volt drop in the wiring, which it may not be able to do.

Or perhaps your run is longer. A 20 foot run with a total current path of 40 feet would mean 0.01 ohms of resistance and a 1 volt drop in the wiring at 100 amps. Your alternator would need to put out 15.5V to 16V to overcome this drop and pump that much current into the batteries.

This is all just a guess...maybe your four batteries are located right next to the alternator and there is some other issue.

Just a comment. I have 4 group 24 batteries on my Ford F350 setup with a #4 truck to to battery charge wire thru a solenoid. I have been disappointed with the charge rate from my stock 110-120 amp alternator. According to my Trimetric at about 1500 RPM with 60-70 percent battery charge I only see about 15 amps. Where plugged in to 110 I'll see 45. The solar has worked much better for me, from my 3-100w panels I've seen 17 amps at times and 12 amps commonly.

I have an RV solar planner spreadsheet I picked up off this forum years ago. It contains data on all or most RV appliances and it seems to be fairly accurate predicting the electrical usage in my Class B RV. When I plug in the devices you list that you'll be using along with some expected hours of use it indicates you'd be using close to half of your battery capacity each day. And I didn't include any time for the furnace which is the biggest electrical consumer on my RVs.

Other solar planning sites on the internet indicate you can expect an average of 4.2 to 4.5 hrs of solar sunlight daily in the Yellowstone area. The sun may not shine everyday, blocked by mountains, trees, clouds, etc. So conservatively you should expect that your solar panel will provide 1/4 to 1/3 of your recharge needs daily. The rest will need to be supplied by running the truck or using the genset.

You can probably make it work, but it will be a bit of a challenge.

Greetings,

I've never been to Yellowstone - we'd like to go one day.

You've already mentioned that you have three possible sources of energy to recharge your small #24 battery: Solar, Truck and built in Genset.

To us, the trick to long term "boondocking" is NOT getting awoke at 3-4AM by the sound of the propane leak detector (most RV's built in "low battery indicator") and the furnace trying to take the "chill" off.

If your going to stay in one spot for more than overnight running the onboard genset (or starting the truck) during the non-quiet times will help keep your battery up. Just check the voltage/charge level and top off as needed while still daylight. :)

The real worries I'd have is two fold - #1 is propane and #2 is holding tank space. (lastly maybe fuel for the truck)

While for 8yrs I had been able to boondock for 1 week at a favorite camp spot with 100-125W solar on the roof and just a single group #27 battery, my holding tanks had to be used very sparingly to last the week.

After the 1st few years of running out of propane we switched to heating cooking/cleaning water in a tea kettle on the stove. (propane water heaters are a close 2nd if not tied for 1st place in propane usage behind the furnace) 25gal of fresh water was usually enough for the week (we showered at campground facilities) however once or twice ran out of water the morning before departure. Heating water in the tea kettle also helped conserve fresh water.

Since I've never been to Yellowstone, I'm uneducated as to where one might empty holding tanks, refill the water tank and where (if any) propane and fueling station (for the truck) might be.

My EWAG (experienced wild ass guess) is that if your using your hot water heater and/or furnace with any frequency you'll have to venture out of the park to refill your propane tanks ~1week into your adventure/trip.

Mote wrote:
We are taking a two week to Yellowstone this summer taking the truck camper. Our camper has a group 24 wet cell battery and a 50 watt solar panel. I replaced the original solar controller with a sunsaver duo this winter as the old controller was bad.
Daily energy use would be the fridge on propane, interior lights (all are LED), water pump and water heater as we’ll shower each day in the camper. No TV thou.
Our plans are to leave the camper on the truck as we drive from place to place during the day so the truck will recharge the battery somewhat.
Will the current battery and solar panel be enough? I measured by battery compartment. I do not have room for two batteries but I could fit one group 31 or 29. How large of a battery would the 50 watt panel recharge on a typical sunny day in June?
Thanks for the help

A lot of folks have already mentioned a lot about watts, volts and amps etc.. It is my opinion that you would want more - probably at least a 100w panel.

However, not sure if anyone has mentioned this yet. You will most likely be using your heater as well. The average temp at Yellowstone in the Summer is around 70-75 - but at night it can get COLD - even below freezing in the SUMMER. Yes below freezing as in less than 32 at NIGHT. S0 -- plan on bringing some heavy blankets and plan on using a heater of some sort. If it's your RV furnace then count on having an empty battery each morning.

Also, plan for some days to be partly cloudy or completely cloudy. Weather changes on a dime in this part of the country. Any clouds in the sky and you're panel will be putting out half the rating. Also something to consider is that Yellowstone country is very mountainous meaning that you could be camped in a location that doesn't get any sunlight unless it's 12PM and the Sun is directly over head. By 1-2pm it's behind a Mountain again. Something to consider if you're planning your energy needs solely based on solar power.

http://www.nps.gov/yell/planyourvisit/weather.htm