Help with solar for Petcool

[Lgboro]

I would like to have my tear available during power outages with air conditioning and for campgrounds without power. I believe my petcool should use 3.6 amps or less to operate. So an eight hour run should use a little less than 30 amps. How big a solar panel will it take to replenish 40 or so amps the next day if the sun cooperates. I have a 85 watt ul solar panel on the way and was wondering if another 85 would be close for this application.

What size inverter would it take to run the PetCool as all my lights are 12 volt led and a 13 inch led 12 volt tv? Morningstar makes a 350 watt pure sine (Sure Sine 350) unit that claims to have a peak 92% efficiency. Is that enough to run a petcool?

[8ball_99]

The petcool alone is 3.6 amps so thats almost 400 watts.. My guess is it probably pulls a little more on start up. 350 watt inverter isn't going to do it.. You have to remember that petcool is AC current not DC. 400+watts is a lot of power to replace with a solar panel. Just think of it this way. If you run 400 watts of juice for 7-8 hours then the amount of solar you would need to recharge would be atleast the same.. You figure 6-9 hours of good sunlight. I don't know I could be way off. But in my mind this is a lot of juice to that much wattage on a inverter for an extended period of time.

[eamarquardt]

You're talking apples and oranges here. Your pet cool uses 3.6 amps of 120 volts ac. To make that much with a converter would take (in round numbers) about 40+ amps of 12 volt dc or nearly 500 watts of solar power routed through an inverter. You'd be better off using a generator in those rare instances when you have no ac power.

Cheers,

Gus

[madjack]

...basically what Gus said...the first thing to realize is the 10 fold difference in amp draw from 12vdc to make up the wattage difference when using 120vdc...in other words, that 3.6amp draw from 120vac, will require 36amps of 12 vdc to make up the wattage difference...that is 430watts, whether it is supplied by AC or DC...or the sun...so, it will require 5 of those 85watt panels, running at maximum output(you will be lucky to get 50-75% efficiency) just to run the PetCool...if you wanted to run the unit 24hrs, you would need 10 or 15 panels and a few large batteries to store all that power....even if the PetCool only ran 50% of the time, that is a daunting undertaking not to mention expensive...oh yeah, the compressor on the PetCool will require an 8amp or so surge when it kicks on, meaning you would need a 1000watt inverter to operate, with 8-6 ga wire between it and your battery bank...with all that under consideration, a generator is a much simpler...and cheaper solution
madjack

[8ball_99]

On the plus side 3.6amps @110v is pretty low and even that 8 amp startup isn't bad. Some really good honda knock off small generators at good prices.. Solar is nice. I plan on adding a panel or two on mine for boon docking. But the cost vs watt is pretty high. Couple lights, fantastic fan, maybe a radio isn't to hard to maintain with solar but trying to run a AC or electric heaters just isn't practical.
Heck I've had a hard time trying justify A couple of panels and a decent charger. I've already got a generator for the few hundred bucks I'd have to spend on the panels and the charger. I could buy a whole lot of gas for my little honda. It will run about 10 hours putting out a couple hundred watts.. Thats One gallon of gas for 10 hours.. So on a 3 day boondocking camping trip I might use a couple bucks worth of gas. Since all we do is fire it up for an hour here and there.
Some do it because they feel its better for the planet. But the batteries aren't great for the planet. The more you rely on solar the more likely you are to need multiple batteries. Most of those batteries will only last a couple years. Weather you use the trailer or not. When you figure most of us only camp a weekend here and there I don't really think its all that much greener to go solar. sorry for the rant lol.. Like I said its something I've been thinking about.

[48Rob]

Most of those batteries will only last a couple years. Weather you use the trailer or not.

I'm new to solar, but if 6 volt golf cart batteries will last 10 years + with a regular smart charger, why would solar cause them to fail much, much sooner?

Isn't the secret to long (deep cycle) battery life to do shallow discharging and get them recharged as soon as possible?

Rob

[mikeschn]

I don't believe you can do it with solar... try this instead...



or



Mike...

[bdosborn]

Most of those batteries will only last a couple years. Weather you use the trailer or not.

I'm new to solar, but if 6 volt golf cart batteries will last 10 years + with a regular smart charger, why would solar cause them to fail much, much sooner?

Isn't the secret to long (deep cycle) battery life to do shallow discharging and get them recharged as soon as possible?

Rob

Rob,
A battery that only lasts a couple of years has either been abused or has been discharged to deeply or fast. 10 year life is pretty optimistic, 3-5 years is average and 5-7 is pretty darn good for a well maintained battery. Battery life is directly proportional to depth of discharge and capacity is proportional to the discharge rate:





Most battery manufacturers recommend a charge rate of between 5-13% of the 20 hour rate and no longer than 72 hours till recharge. I've been averaging 20-30 amp-hrs discharges on my 230 amp-hr golf cart batteries at a 4.5 amp rate, with an occasional 40 amp-hrs here and there. My batteries have always been 100% recharged the next day via PV panels or the charger. I'm on my third season so we'll see how long mine last.

Bruce

P.S. I know what my battery discharge rate is because of the trimetric meter I use.
trimetric link

[Lgboro]

As many times as I have read most of the above info I should have known the answer. I can see a honda genny in the not to distant future, hopefully before the next extended power outage caused by hurricane or ice storms. Not really a matter of justifying the cost as I waste money on other things all the time (my son has been warned that I plan to break even when I croak). Besides I will be 62 in March and don't need to mess with a bank of batteries to go floundering instead of a 40 # genny therefore about 3 uses for the generator.

[madjack]

any good brands that are cheap around a affordable 200 to 300 bucks that is not a run you out of the country side noize maker?

SLow.

...nope...down here in hurricane country, everybody and their brother in law have a gennie or two(or three) and if you want QUIET, ya gotta pay for it...a Kipor(Honda clone) is about as inexpensive as you can find...2Kwatts for around 700bux.................
madjack

[8ball_99]

Sorry when I said the batteries last a couple years I was talking about the typical lead acid Deepcycle batteries most people use in their campers, And your right if maintained right its more like 3-5. Although I've Never got more then 4 years out of one. I replaced one not to long ago and even the guy at the counter said wow you got little over three years out of it thats pretty good. Higher quality AGM batteries would probably do a little better but they also cost even more.
At anyrate your talking atleast 70-80+ for one battery. Even more if you do the golf cart batteries cause you need 2 at 80+ each.. Then another few hundred for a panel and controller. All that for what 85 watts give or take. That 85 watts is also at peak. Panels on average put out maybe 50-80% of their listed wattage for 8 hours if your lucky.. Its just a lot of cash for a little bit of juice IMO.. If you use your camper constantly and your constantly using that little bit of juice then it makes more since.. Most of us use a lot of juice for a couple days then none for weeks maybe months, so the panels never really even pay for their self..

Honda Inverter gens are great.. My little 2000I is probably around 4 years old and runs great.. Cranked it up today matter of fact. Very expensive, But they are quiet and start easily.. I have used mine for everything from keeping the freezer cold in outages to powering a paint sprayer to paint my barn.. Even jumped off my tractor with it once when it was pulled into a corner and jumper cables wouldn't reach..

Kipors look pretty good to. Pretty much a honda clone for less money. I've seen one running but I don't know anyone that owns one. Might be worth trying one to save a few bucks. Northern tools sells them I think

[bdosborn]

At anyrate your talking atleast 70-80+ for one battery. Even more if you do the golf cart batteries cause you need 2 at 80+ each.. Then another few hundred for a panel and controller. All that for what 85 watts give or take. That 85 watts is also at peak. Panels on average put out maybe 50-80% of their listed wattage for 8 hours if your lucky.. Its just a lot of cash for a little bit of juice IMO.. If you use your camper constantly and your constantly using that little bit of juice then it makes more since.. Most of us use a lot of juice for a couple days then none for weeks maybe months, so the panels never really even pay for their self..

You're going to have batteries with or without a generator so that really doesn't figure into the costs. The best system really depends on your energy usage. No A/C or inverter favors a PV system as panels have come down a lot in price over the last couple years.

Honda generator = $850 +fuel costs for the life of the generator

85 watt solar panel = $200
Solar controller = $50
No fuel costs ever

Our 80 watt panel on the teardrop had the battery charged by noon everyday.

Bruce

[madjack]

I agree Bruce, however, that PV panel will not run an AC unit, a coffee maker or a hair dryer and certainly won't do so at night...I realize it is not a fair comparison but it all depends on what type and where you are going to be camping...or using a paint sprayer.........
madjack

[48Rob]

Bruce and 8 ball,

Thanks!

I've been known to be overly optimistic...

I have two Trojan T-105 batteries that are 6 years old, and still going strong.
They do get light use though (heavy use while camping) but only a few weeks a year, and are connected to a smart charger the rest of the time.

I picked up a 125 Watt panel and 10 Amp charger that I plan to connect into the system.
No A/C or inverter use planned.
Time will tell...

Rob

[8ball_99]

I guess in my mind I just figure if your going to boon dock with no generator then you need a pretty decent solar setup. As in multiple batteries and panels. Again I forget most here have very small trailers with very minimal power needs. I've heard several times they just want to run a vent fan for a night or two..We have a converted cargo trailer and a couple kids.. So It has everything from a microwave to a 12v fridge and radio. We don't have to have a ton of power but just running the fantastic fan, radio, water pump and a light here or there will drain a battery pretty quick. Much less trying to run the microwave or my boot dryer single battery.
I guess if you just use a amp or two a day solar might be worth it. LoL at any rate I guess we can all agree that the OT of running a AC on solar isn't very practical!