Enough power?

[campermama]

I currently have a 55W solar panel on the camper. Was out boondocking for a week and after a few showers and running the heater a few times in the morning, I see this panel can't quite keep up, as in not bringing the batteries up to full charge (2 12V).I usually do not use any other power. I am always outside until I come in and go to bed so using lights or anything at night is minimal.
I have decided to go to a 120W panel in place of the 55W, my controller can't handle both but can handle the 120W.
Question.....do you think the 120W will keep up the batteries after a few showers, and running the heater a few times? I am pretty much always in good sunshine so that is not a concern for me.

Thanks!!

[whizbang]

I took a look at Simplygib's calculations. They look about right.

It's probably the fridge drawing too much current.

I think the my last fridge control panel drew a steady 600 ma. (.6 x 24 = 14.4 amps per day).

[whizbang]

If I am reading the OP's posts correctly, two deep cycle batteries ONLY last a week with a few lights, the water pump, and some furnace operation in the morning.

I've had three campers, all of them would last a week under those conditions on one battery and no solar charging.

Our Alpenlite, with two deep cycle batteries, once lasted 3-1/2 days in sub freezing weather with the furnace running all day long. It easily would have lasted over a week of light duty operation.

I think you have current draws happening that you don't know about.

Another possibility you might investigate is your charging system on your truck. After a week of camping, when you do drive again, the alternator on your truck should bring the batteries up to full charge. If the batteries are still depleted after driving a bit, your charging system is inadequate and the solar panel probably won't catch up.

Quite frankly, in 12 years of RVing and extensive year round boondocking, our experience has been that we run out of fresh water or gray tank capacity long before the batteries are discharged.

Buy a meter. FIND OUT what is going on. Until then, we're all just guessing....

[campermama]

ewarnerusa wrote:

This pair of 12V batteries lasted for a week of boondocking and you suspect they are bad? Seems quite good to me.

Thank you! I can't understand why a few here keep saying my batteries are bad. :?

They are fine, just need more solar power.

[ewarnerusa]

whizbang wrote:
Test instruments are a beautiful thing.

You need to get an ammeter in line to measure your discharge current.

Personally, I have bought new batteries that were no good.

You either have excessive current draws or bad batteries.

Perhaps you can get the batteries tested.

This pair of 12V batteries lasted for a week of boondocking and you suspect they are bad? Seems quite good to me. yes, daily charging with a single 55W panel, but that's like 3A x 5hr = 15Ah of recharging a day. That's barely enough to cover the refrigerator control panel according to calcs in this thread.

[whizbang]

Test instruments are a beautiful thing.

You need to get an ammeter in line to measure your discharge current.

Personally, I have bought new batteries that were no good.

You either have excessive current draws or bad batteries.

Perhaps you can get the batteries tested.

[campermama]

FYI....my controller is a 10 amp Morningstar

I am going out for another week mid Feb. Hope to have the 120W with me so I will see how it goes....I can always upgrade controller and add the 55W if needed, which I may do anyway down the line.

[campermama]

smkettner wrote:
Mount the 120w to the side so there is room for a second 120w if needed.
Make sure your roof items cast no shadows on the panel. Even a small shadow on a single cell can cut production to near zero.

Unfortunately there is not a lot of room up there, but I always park for max sun on the panel.

[campermama]

Simplygib wrote:
Campermama - just trying to hazard a guess at your electrical usage based on your description and what my appliances draw, which may or may not match yours.

"A few showers" - my water pump draws about 7 amps. Assuming a shower takes 10 minutes that would be about 1.16 amps per shower. So lets say 3.5 for three of them. Note - I doubt you meant three showers in one day. If you're talking about one shower a day, this number would be 1.16. But for fun lets just say 3.5.

Lights - I'll assume you have incandescent bulbs and you burn two of them for 15 minutes a night. They usually use about 1.5 to 2 amps per bulb, so lets say 1 amp for lighting (since you're only using light for 15 minutes).

Heater - my heater fan draws 2.5 amps. Lets say three hours a day of heater use, so 7.5 amps there.

Fridge - I don't know what kind of fridge you have but I assume you're running it on propane. Still, there is a circuit board inside of it that probably draws about half an amp, 24 hours a day. This is going to be your biggest draw, unless there are other draws you forgot to mention. 12 amps.

These are all guesses, of course.

So we have 12 + 7.5 + 1 + 3.5 = 24 amps.

If that's correct, you have to put maybe 26 or so amps back into your battery bank on a daily basis (need to add more than you use due to inefficiencies in the system).

That amount of usage is about the same for me. I have 200 watts of solar on the roof and a 220 amp hour battery bank (two 6v batts). In your area (I'm usually out there for a month or so each winter) I can be recharged by noon or so each day. My panels tilt, which helps in winter.

With 120 watts I think you would be fine most days, probably getting totally recharged by mid afternoon or so.

Of course this is all based on guess work (as to your actual power usage) and the assumption that your solar system is set up correctly and your panel will tilt. If mounted flat it will take longer this time of year.

Hope this helps.....

Does help! You calculated way more then I actually use so I think I will be ok 🙂

[time2roll]

Mount the 120w to the side so there is room for a second 120w if needed.
Make sure your roof items cast no shadows on the panel. Even a small shadow on a single cell can cut production to near zero.

[Simplygib]

Campermama - just trying to hazard a guess at your electrical usage based on your description and what my appliances draw, which may or may not match yours.

"A few showers" - my water pump draws about 7 amps. Assuming a shower takes 10 minutes that would be about 1.16 amps per shower. So lets say 3.5 for three of them. Note - I doubt you meant three showers in one day. If you're talking about one shower a day, this number would be 1.16. But for fun lets just say 3.5.

Lights - I'll assume you have incandescent bulbs and you burn two of them for 15 minutes a night. They usually use about 1.5 to 2 amps per bulb, so lets say 1 amp for lighting (since you're only using light for 15 minutes).

Heater - my heater fan draws 2.5 amps. Lets say three hours a day of heater use, so 7.5 amps there.

Fridge - I don't know what kind of fridge you have but I assume you're running it on propane. Still, there is a circuit board inside of it that probably draws about half an amp, 24 hours a day. This is going to be your biggest draw, unless there are other draws you forgot to mention. 12 amps.

These are all guesses, of course.

So we have 12 + 7.5 + 1 + 3.5 = 24 amps.

If that's correct, you have to put maybe 26 or so amps back into your battery bank on a daily basis (need to add more than you use due to inefficiencies in the system).

That amount of usage is about the same for me. I have 200 watts of solar on the roof and a 220 amp hour battery bank (two 6v batts). In your area (I'm usually out there for a month or so each winter) I can be recharged by noon or so each day. My panels tilt, which helps in winter.

With 120 watts I think you would be fine most days, probably getting totally recharged by mid afternoon or so.

Of course this is all based on guess work (as to your actual power usage) and the assumption that your solar system is set up correctly and your panel will tilt. If mounted flat it will take longer this time of year.

Hope this helps.....

[Camper_Jeff___K]

Did not catch how many amps your controller was rated for. Remember solar panels are rated with a wattage of absolute best conditions. I have never seen my panel put out more than 70% of the rated wattage or actual measured (amps x volts). I like the Kyrocera 140 watt panel which under best real world conditions might put out 7.62 amps plus your existing 55 watt panel at 3.00 amps for a total output of 10.60 amps or 138 total real world (3.00 amps x 13.00 volts) = watts. If you get the 120 watt panel the amps/watts are about 9.52 amps and 124 watts. Is your controller rated to do that? Also, install a 6 or 4 awg wire from the truck alternator to the TC batteries to charge from your trucks alternator if you run low on power. Not as efficient as a genset but less stuff to carry and gas to run it.
Say you have 2 100 amp hour batteries and you ran them down to 60% charge each or about 12.1 or 12.2 volts. You need to replace 40 + 40 amp hours of battery charge. At 10 amps solar output, that will take 8 hours of good sun. Longer in reality.

[ewarnerusa]

campermama wrote:

whizbang wrote:
+1 what Redsky said.

I don't think your batteries are in good working condition.

??? batteries are brand new! Bought them a week ago. It is the small capacity solar panel that is the problem.

Like I said already, I use the lights a total of like 10 minutes a day! Don't need to switch to LED's for that.

I think the batteries sound like they are working fine and the problem is one 55 watt panel trying to charge 2 12 volt batteries. Just like you say. The fact that you made it 5 days boondocking, with furnace use and a small solar panel, suggests you have light power needs.

The furnace fan does represent a big amp load and is probably the biggest draw on your batteries.

I also think you really should be running both panels. It's free power falling from the sky, why not use all your buckets?

[chuckklr04]

Oldtymeflyr wrote:
We have an 85 watt panel and it has worked okay with a two 6 volt 235 amp deep cells. We are good for two days in the winter without starting up the truck. Our camper has LED's because we use the lights in the winter quite a lot.

Next on our list is a 140 watt panel, our controller is good to about 25 watts. My recommendation is to bite the bullet and go with a bigger panel and a bigger controller.

The thing I really like about solar is that its always trying to work, if there is enough light its working. A generator is noisy, dirty, takes a lot of valuable time and work. Solar is the best.

Good Luck!

And it starts working without you having to think about and throw a switch. also will keep the batts up to full charge when it's not in use, just sitting, waiting on you to use it.

[Oldtymeflyr]

We have an 85 watt panel and it has worked okay with a two 6 volt 235 amp deep cells. We are good for two days in the winter without starting up the truck. Our camper has LED's because we use the lights in the winter quite a lot.

Next on our list is a 140 watt panel, our controller is good to about 25 watts. My recommendation is to bite the bullet and go with a bigger panel and a bigger controller.

The thing I really like about solar is that its always trying to work, if there is enough light its working. A generator is noisy, dirty, takes a lot of valuable time and work. Solar is the best.

Good Luck!