170 watts vs 340 watts

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Mark_K5LXP

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Nov 17, 2018
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Albuquerque, NM
Is is bad to be at 11.8 and be using power...???
For a battery in active use (being discharged by a load) 11.8V represents about 50% discharged. It's neither good or bad, it just is. If I was 3 days into a 10 day off-grid trip I would call it "bad". If it was like my last trip where I was around 50% after 3 days into a 3 day trip, check the box I made it with lots to spare. Knowing what your capacity is and expected loads is the gauge to use for assigning any particular state of charge as "good" or "bad".

Mark B.
Albuquerque, NM
 

Ex-Calif

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Thanks Gary, we typically are fully charged by nightfall we are not big consumers, but would like to watch more TV in winter...I am always panicking come evening that we have to keep our batteries at around 12.3 when we go to bed. As it seems that during night things still run in background, but most mornings we wake up to 12.2. But then the delimena do we turn TV on in am... until we get some charging happening?? Is is bad to be at 11.8 and be using power...??? Thanks. Donna

12.3 at night and 11.8 in the morning says your overnight loads are taking probably 1/4 of your 200 amps. I am presuming the fridge controller and water heater controller are the main overnight culprits. This could be like 3-4 amps for 12+ hours.

Are you ever getting above 12.3? A fully charged battery should be closer to 12.6 and during the day when charging and most loads off you should be seeing above 13V.

With one panel you get about 14 amps max charging. If the loads during the day are 6-7 amps you only have 7 amps to fill up the batteries. With 8 hours of sun that's about 56 amps.

So if you are taking 40+ out overnight and waking up with 11.8 the math on consumption makes sense. Basically you are marginally balanced for your current consumption patterns.

I would not worry abut a few more hours of TV. The TV only draws like 3 amps so 3 more hours of tv would only be 9 more amps used.

If you are getting to 12.3+ early in the day you might be OK just adding more battery for now.

If you are gonna add solar I would explore a non-dealer installer. The dealer seems way too expensive.
 

Gary RV_Wizard

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At our Silver Springs FL home
Why pay so much more for AGMs compared to flooded? I get it, they are "maintenance free". Any other compelling reason?
It's still a lead-acid chemistry battery, but "maintenance-free" has ramifications beyond just some effort. And there are a few other conveniences that maybe of value.
  • Checking & topping up electrolyte (water) levels in a flooded cell is not just extra effort. Failure to do results in loss of power and in extreme cases shortens battery life. Those prone to forgetting battery maintenance get more value than those who are more rigorous. What's the value of NOT having your fun spoiled by a dead battery?
  • Outgassing of a flooded cell makes a mess of the battery compartment and corrodes any nearby metal or electronics.
  • Vented compartment is not required.
  • AGMs can be mounted sideways or even upside down.
 

tanglemoose

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May 14, 2013
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518
12.3 at night and 11.8 in the morning says your overnight loads are taking probably 1/4 of your 200 amps. I am presuming the fridge controller and water heater controller are the main overnight culprits. This could be like 3-4 amps for 12+ hours.

Are you ever getting above 12.3? A fully charged battery should be closer to 12.6 and during the day when charging and most loads off you should be seeing above 13V.

With one panel you get about 14 amps max charging. If the loads during the day are 6-7 amps you only have 7 amps to fill up the batteries. With 8 hours of sun that's about 56 amps.

So if you are taking 40+ out overnight and waking up with 11.8 the math on consumption makes sense. Basically you are marginally balanced for your current consumption patterns.

I would not worry abut a few more hours of TV. The TV only draws like 3 amps so 3 more hours of tv would only be 9 more amps used.

If you are getting to 12.3+ early in the day you might be OK just adding more battery for now.

If you are gonna add solar I would explore a non-dealer installer. The dealer seems way too expensive.
We do get to 13 during day charging... so getting a good charge, I think. Many mornings we are at 12.2 or more, unless running furnace. Hot water tank is always off why dry camping, so don't think that us running batteries down..
 

tanglemoose

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I just checked, we paid $265 in 2020 for 200 watt panel, 30 ft of cabling, cable inlet box, mounting brackets and controller, all at the Q show. We had to buy sealer, caulking gun, screws etc. Total came in at $300. If someone is going to drill holes in my roof, I want it to be me. At least I then know how it is sealed. If you have connections on the roof already, the only holes might be for screwing the panel down. I bet someone at the rally if you're going, would help out if you have any concerns.
$599 for a 170 watt, someone's wanting your hard earned money🤔
Just found the zamp 170 watt on Amazon for $472. I just thought it would be so much easier to use same panels as the quick connect is on roof now. Just need a Zamp expansion panel. Yes, all we need is just holes drilled in roof, which personally scares me to death... in our new RV.. 71+hubby doesn't get on roof.. just me... the wife... so.. doing my homework on panels, installing, etc... sure appreciate everyone's input...
 

TonyL

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Dec 10, 2017
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UK
Just found the zamp 170 watt on Amazon for $472. I just thought it would be so much easier to use same panels as the quick connect is on roof now. Just need a Zamp expansion panel. Yes, all we need is just holes drilled in roof, which personally scares me to death... in our new RV.. 71+hubby doesn't get on roof.. just me... the wife... so.. doing my homework on panels, installing, etc... sure appreciate everyone's input...
$472 for a 170 watt panel still sounds waay too much. I am guessing your panel has mc4 connections to which splitters are easily available.
The only issues I see if someone else goes on your roof to fit the panel is liability if they either fall or damage the roof. It might be possible to fit them from the side using a ladder.
Are you going to Quartzite?
 

tanglemoose

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$472 for a 170 watt panel still sounds waay too much. I am guessing your panel has mc4 connections to which splitters are easily available.
The only issues I see if someone else goes on your roof to fit the panel is liability if they either fall or damage the roof. It might be possible to fit them from the side using a ladder.
Are you going to Quartzite?
Ha, I would love to go to Quartzite, but think other half would shell.out $500 to miss it! So... going to wait on our solar until we get south, maybe I will catch an rv show and get some!
 

TonyL

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UK
Ha, I would love to go to Quartzite, but think other half would shell.out $500 to miss it! So... going to wait on our solar until we get south, maybe I will catch an rv show and get some!
Living in Montana, I would have thought both of you would jump at the chance to camp somewhere warm😆
 

tanglemoose

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Living in Montana, I would have thought both of you would jump at the chance to camp somewhere warm😆
Oh.. no, we will be south... for warmth. Last year around Bullhead city for 60 days! Just getting him to go the next 100+ south is problem... live in town with no stoplights! And how many people are at Q??
 

Len and Jo

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Apr 25, 2005
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1,360
If you are using the 2000 watt inverter to its max. you need to double or triple your battery Ah. Solar panels larger than ~150w should be in the range of $1.50 per watt. Maybe you are also getting a larger MPPT controller to handle the panel wattage???
 
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TonyL

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UK
Oh.. no, we will be south... for warmth. Last year around Bullhead city for 60 days! Just getting him to go the next 100+ south is problem... live in town with no stoplights! And how many people are at Q??
A few more than your home town, but you needn't worry, you don't have to meet them all at once 😁😁
 

UTTransplant

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Cedar Falls, IA
Oh.. no, we will be south... for warmth. Last year around Bullhead city for 60 days! Just getting him to go the next 100+ south is problem... live in town with no stoplights! And how many people are at Q??
The camping areas have lots of space unless you want to be right next to town. The town gets really, really crowded during the big shows (RV and rock) due to everybody trying to get there at once without enough parking. We just don’t take our car into town then but ride our bikes from the RVForum area about 3 miles away. Quartzsite camping ranges from noisy, crowded RV parks in town to crowded BLM areas next to town to slightly crowded (someone 30’ away) to nicely empty, depending on where you go. There is something over 100,000 people, but they are spread out over many, many square miles.
 

Lou Schneider

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Oh.. no, we will be south... for warmth. Last year around Bullhead city for 60 days! Just getting him to go the next 100+ south is problem... live in town with no stoplights! And how many people are at Q??
There's plenty of room in the 25 square mile LTVAs south of town. Enough that a self proclaimed nudist colony has existed and thrived in a remote corner for the past 25 seasons without bothering anybody.
 

Frank B

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Calgary, Alberta
Trying to figure out if we had an additional 270 watts would batteries get charged faster, stay charged, etc.... can I run coffee maker, what is reason people add more watts? To get benefit do I need agm batteries??
OK, I've tried to address all your questions as simply as I can here below without burying you in figures and calculations.

Solar is best if you are off grid, or 'boondocking' a lot. If that is the case, then remember that no one ever complains of having too much solar. :LOL:

One of the major benefits is that it is silent. You and those around you don't have to listen to the drone of a generator.

A coffee maker can take us much as 1800 watts. This will drain a pair of golf cart style batteries VERY quickly. TV and other electronics take very little. If all you are concerned about is running a coffee maker or a microwave occasionally, a generator is a cheaper way to go. Start it up, use your power hungry appliances, shut it off. Nothing prevents you from having both solar for 'everyday' use, and a generator for 'heavy duty' use.

If you have to run a forced air furnace a lot, the furnace fan will also consume a lot of power. If you are camping off grid a lot in less than full sun, you will want more solar. However, the price you were quoted for that additional 270 watt panel was exorbitant, to say the least. Shop around.

AGM batteries will only benefit you if you have to mount them INSIDE the coach somewhere, as they don't release gases.

If you are in RV parks with power a lot of the time, then just getting more batteries may give you enough power for a few days when you cannot plug in.

A 2000 watt inverter is enough to run a coffee maker or a microwave (though not at the same time) if the inverter is close to the batteries and wired with very heavy gauge wire.

FWIW, my wife and I camp off-grid (boondock) almost exclusively. We prefer the absolute quiet that it offers, so are loathe to use a generator at all. For that reason, I put 6 x 205 watt panels on the roof of our 30' travel trailer, and installed 6 golf cart batteries. We have enough solar so that we never run the generator, and we make liberal use of an 1800 watt Tassimo coffee maker, a 900 watt microwave, a 600 watt pop-up toaster, and occasionally a 1500 watt hot air corn popper and a small waffle iron. We both have laptop computers, and I never ever even think about watching the TV whenever we want to. Even if we use them all in a day, in full sun in Arizona in the winter the batteries are typically fully charged by early afternoon. And if we have rainy or cloudy days, we cut back, but still get a useful charge.

Here is what I installed, as well as my thinking on why we did it.

Hope this helps.
 
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