How much generator do I need?

[UT_Grandpa]

1. A Watt is Watt whether AC or DC. It is a measure of power. So if the converter has a max of 950 Watts a 900 Watt generator will not do if the converter wants the full 950 Watts.
2. Lead acid batteries can only give about half the rated capacity before dropping below 11.0 Volts at such point almost everything stops working.
3. Forget running any AC device (other than really low current stuff) off an inverter. Most inverters are really not that efficient and remember that heat=loss of power.
4. I use a CPAP at night and it pulls 95 Watts. Multiply by 8 hours sleep and I am using about 60 Amp Hours each night for the CPAP. This is nearly one Group 24 battery just for the CPAP per night. Add pumps and lights and fans and ???? and it is obvious you are not going to get two nights camping on a set of two Group 24 batteries.
5. I use a pair of 50 Watt solar panels and most days I can have things recharged in 8 hours of sunlight. I have recently upgraded to a pair of 100 Watt panels that are only 8 inches longer. I expect full batteries in about 4 hours of sunlight. I take a Honda 2000 Watt inverter style generator for days when the sun doesn't shine. My Honda recharged 12 batteries in our houseboat and would run for 13 hours on less than a gallon of gas.
6. Guaranteed that whatever you do you will be changes as you go along. I know I have over the years.
7. Solar makes no noise. Any generator makes noise. Some can be heard in the next campsite and others in the whole campground.

Good luck.

[jimmoore13]

Originally Posted by rk06382

You should check into a solar panel on your roof. One or two 100 watt panels would recharge your batteries without fuel or noise & produce 5-10 amps all day. You do not need a large solar system if have low power needs. You can also deduct 30% of solar cost off your taxes for 2018. My solar panels generate power even when it is raining.

Original question: Yes. The 700 watt Ryobi should be large enough. Your 24 batteries are 690 Cranking Amps with 140 Amp Hour Reserve Capacity. At 50% you would have 70 Amp hr per battery left.
Interstate Batteries: SRM-24
Attachment 182664

X-2. Best answer!

I have a single group 24 12-volt battery, and a realistic estimate of its total capacity is 75 to 80 amp-hours. Rule of thumb, use only half...40 amp hours +/-. My single 100 watt solar panel system delivers up to 7.5 amps in full sun, and it has the battery recharged by early afternoon. The fixed installation on the roof enables it to charge all the time.
I recommend either Windy Nation or Renology systems, because they make good charge controllers, and that's what counts. If you look closely at the panels, virtually every brand appears to be using the same exact panel from a factory in China.

I use my 2KW inverter generator to run appliances like the microwave, and as a backup if it rains nonstop for days. But the panel generates considerable amounts of energy even under less than ideal conditions. Frugal use of 12 volt power with solar will make you entirely energy independent in most cases.

[IsleDog]

My single 100 watt solar panel system delivers up to 7.5 amps in full sun, and it has the battery recharged by early afternoon.

i was unaware that they delivered that much power! thats pretty impressive. does it need a charge controller at that amperage?

Can someone please tell me if this is enough generator for my camper? might need a step down transformer though.


we were performing maintenance and thought of this thread and had to share.

[formerFR]

your case situation, as you lay it out as not needing much of anything while you are 'camping' looks like a prime case for Solar...and not necessarily a lot of it, but 200w with 10amp in during the peak sun hours of the day might suffice. Two 100w panels don't take up a lot of roof space(or you could consider just laying them out on the ground), and can provide some decent power recharging to your batteries during the day, with a simple 20a solar controller.

also, since the Solar power does not flow thru your converter or Charger, but directly to your batteries, the Solar controller itself provides the link between the panels and the charging of the batteries.

of course, having a small generator as a back up doesn't hurt, especially for overcast or rainy days, or in the event you DO need the air conditioner or microwave.

[jimmoore13]

This is a very handy, reliable calculator for figuring your power needs.

For example, plug in 100 watts (panel) and 12 volts, and you get 8.3 amps from my solar array. Allow for inefficiencies, and 7.5 watts/panel is reasonable.

Use it to calculate your loads in amps per hour...amp hours. Of course, some things give you the amps on the data plate, but if not, turn watts to amps easily.

Remember that a typical group 24 12 volt battery can safely deliver 35 to 40 amp hours before you start ruining it. A group 27 can deliver about 50 amp hours. Both are rated at double that amount, but use it all, and you destroy the battery.

I actually run a 400 watt inverter to run a 120 volt electric blanket (360 watts) for about 30 minutes to take the chill off the bed. That's a LOT of power. Use the calculator: 360 watts at 12 volts (remember that your battery is 12 volts regardless of the inverter delivering 120 volts), so that is 30 AMPS! 30 amps per hour is 30 amp hours. 1/2 hour is 15 amp hours. (These are rough estimates.)

My furnace uses 5 amps. On a cold night it might run on a 50% duty cycle. So, let's call that 4 hours of use at 5 amps...that's another 20 amp hours. Closing in fast on my available 40. That leaves the pump, spark ignition for the hot water heater and fridge, and parasitic losses from the propane/CO detector, and I'm maxed out for the night.

I use a propane mantle lantern and several LED lanterns for light...I don't use the camper lights even though they are LED. I also never use the built in stereo...I remove the face plate to get rid of the parasitic losses from the LED display. I don't camp to listen to music, but if I want to, a battery powered bluetooth speaker is up to the task. I can charge it from my truck's starting battery/cigarette lighter. If you don't want to be so austere, invest in another battery and more panels.

This has served me well for several years, and my battery is on its 5th season.

Note for the battery gurus out there. I'm using round numbers and simple rules of thumb. Meticulous analysis may reveal some differences, but, as I said, I'm in the middle of my 5th season with my dealer-supplied Deka group 24 battery. Nutnin, fancy, but it gets the job done.

By the way, you are hooked to solar 24/7, so stay on top of your battery's electrolyte. I have to top off with distilled water (using a turkey baster) about every 3 or 4 weeks. I don't let the water get below the rings at all, but it's well worth the effort. I won't risk exposing the plates.

My dream system for my HighWall PUP is 2 x 6-volt golf cart batteries (delivering about 110 to 120 USABLE amp hours) and adding another 2 panels. Then I could use the lights, the car stereo built in, and never have to think about conserving power.

[babock]

A 100w panel with a PWM controller will only output 5.5A. Absolutely no way it can output 7.5.

I am also not a Renogy fan. Better panels are available at less than $1/watt

[CastleRockcamper]

I purchased a 100 watt solar system from harbor freight and that should be sufficient to keep your batteries charged. I did purchase 2 Yamaha inverter generators but only use them when I need AC.

[Eidolon]

K.I.S.S.


I treat the RV like the land yacht it is. On a sailboat we run the diesel/generator 1 hr in the morning and again in the evening. As for what works, the Honda 2000 is versatile, quiet, and well up to the task. Remember that you do not have to carry enough gas for the entire trip either. I use a 2.5 gallon which does fine. It all depends on what your plans are of course.

[tomingram]

I got solar set up from harbor freight,sets on ground, when your camping.I run tv, dvd lights, never run out of power. and no noise.About $150.00

[Jlb27537]

Originally Posted by babock

A 100w panel with a PWM controller will only output 5.5A. Absolutely no way it can output 7.5.

I am also not a Renogy fan. Better panels are available at less than $1/watt

Yes, but 100w at what voltage. A 22vdc panel thru a good controler, converts excess voltage to amps, so depnds on panel voltage. I had 4x135w panels, 18vdc. I could see 35-40a on a good clear day on my Trimetric 2020 device. 4x6vdc gc batteries.

[tomingram]

Originally Posted by Jlb27537

Yes, but 100w at what voltage. A 22vdc panel thru a good controler, converts excess voltage to amps, so depnds on panel voltage. I had 4x135w panels, 18vdc. I could see 35-40a on a good clear day on my Trimetric 2020 device. 4x6vdc gc batteries.

I just know it works fine for me, but I don't run fredge on it.

[malcolmjwhitaker]

I have enjoyed reading everybody's responses to my original query. I ended up purchasing a 120 watt briefcase style solar panel from nature power for a little over $300 from a nearby camping world. Fits in the back of my durango when not in use and plugs directly into the zamp connection on the side of my rockwood mini lite trailer (with the polarity reversing cable). Will upgrade to some sort of genny in the future if I ever need ac while camping with no shore power available, but not likely.

[tomingram]

Originally Posted by malcolmjwhitaker

I have enjoyed reading everybody's responses to my original query. I ended up purchasing a 120 watt briefcase style solar panel from nature power for a little over $300 from a nearby camping world. Fits in the back of my durango when not in use and plugs directly into the zamp connection on the side of my rockwood mini lite trailer (with the polarity reversing cable). Will upgrade to some sort of genny in the future if I ever need ac while camping with no shore power available, but not likely.

I will say if you don't have a kill breaker on your system,when not in use.,many things will run your batterys down. I also added a small solar battery charger, that I leave hooked up all the time, to keep batteries maintained

[TitanMike]

Originally Posted by malcolmjwhitaker

I have enjoyed reading everybody's responses to my original query. I ended up purchasing a 120 watt briefcase style solar panel from nature power for a little over $300 from a nearby camping world. Fits in the back of my durango when not in use and plugs directly into the zamp connection on the side of my rockwood mini lite trailer (with the polarity reversing cable). Will upgrade to some sort of genny in the future if I ever need ac while camping with no shore power available, but not likely.

When you do buy your generator consider a dual fuel. You can run out of gasoline or you can run out of propane but rarely will one run out of both. Having a dual fuel means the last you run out of will be electricity.

As for size, look at the AC input wattage of your converter if you are only charging. Then size your generator so it can handle that load continuously. Almost all generators push the starting load which it will put out to start a motor, etc, but the continuous load is often 10-15% less, possibly more.

My generator is a Champion 3500W dual fuel with electric start. On propane it will run 15 hours charging and running AC. My 60 amp converter has max input of 1,000 watts and with the intermittent nature of the AC, and tapering charge rate of the battery bank I get the 15 hours. If battery charge only I'm guessing it could be even longer.

Weight? I just leave it in my truck and use a matching extension cord to my trailer power cord.

[wabakami]

Originally Posted by malcolmjwhitaker

rfk06382; I agree that solar panels on the roof would be the ideal solution. My trailer is pre-wired for Zamp solar panels but these can only be used while stationary. I am considering this avenue. Not ready to make holes in the roof for permanently mounted panels.

Panels attached to your roof, done correctly, will give you years of service, much cleaner and quiet compared to the geny, just clean them occasionally. The Ryobi I suspect will die shortly after your 3 year warranty expires.

You mention that you can only use the panels when stationary, quite correct if not attached permanently but then again you are probably not going to use the geny when driving down the road; you could but your tow vehicle is probably charging the battery set considerably more than the geny anyway.

Geoff

[wabakami]

Originally Posted by rsdata

YOU could put in larger gauge fused wires for less voltage drop, something on the order of 8 ga and have enough hi-output on your alternator to do the job, but most TV are not wired from the factory to give anything more than a trickle charge to the TT battery

There is quite a bit of info on etrailer dot com...

this is one resource...

https://www.etrailer.com/question-277094.html

My F150 charges anywhere up to 20 amps according to my in-line amp meter.
Even if his TV produces 5 amps it still matches the geny or the solar array.

Geoff

[wabakami]

Originally Posted by IsleDog

My single 100 watt solar panel system delivers up to 7.5 amps in full sun, and it has the battery recharged by early afternoon.

i was unaware that they delivered that much power! thats pretty impressive. does it need a charge controller at that amperage?

Can someone please tell me if this is enough generator for my camper? might need a step down transformer though.


we were performing maintenance and thought of this thread and had to share.

Ok, you win, yours is bigger than mine!
Now I have to go and hug my 60kw Kohler, it's feelings are hurt.

But hey, mine runs on propane

Geoff

[WolfWhistle]

Originally Posted by rk06382

You should check into a solar panel on your roof. One or two 100 watt panels would recharge your batteries without fuel or noise & produce 5-10 amps all day. You do not need a large solar system if have low power needs. You can also deduct 30% of solar cost off your taxes for 2018. My solar panels generate power even when it is raining.

Original question: Yes. The 700 watt Ryobi should be large enough. Your 24 batteries are 690 Cranking Amps with 140 Amp Hour Reserve Capacity. At 50% you would have 70 Amp hr per battery left.
Interstate Batteries: SRM-24
Attachment 182664

Jim, check your numbers. If the SRM24 in question, has 140 RC (140 minutes at 25 amps before volts drop to 10.5), the Amp-hour is 58.33 (140/2.4)(@20hours). Two batteries in parallel gives us 116.66 Ah. Or 58.33 "usable" for the pair, based on 50% used of full capacity.

WW

[babock]

Originally Posted by Jlb27537

Yes, but 100w at what voltage. A 22vdc panel thru a good controler, converts excess voltage to amps, so depnds on panel voltage. I had 4x135w panels, 18vdc. I could see 35-40a on a good clear day on my Trimetric 2020 device. 4x6vdc gc batteries.

Only if it's an MPPT which the guy who posted this number did not have. He had a PWM. Even an MPPT controller will only put out just over 7 in the best of circumstances.


My Victron with 700W input will put out 50A under ideal conditions.

[aeblank]

Originally Posted by babock

My Victron with 700W input will put out 50A under ideal conditions.

Holy crikey. I'm fixin' to put my 600w and Victron on tomorrow. That'd put me at up to 42A if my math was right. I can live with that!